October 7, 2024 • 39 mins
We continue our series targeted at people preparing for the internal medicine (IM) board and in-service exams.
Today's topic: neuromuscular disorders!
A challenging topic, but getting some basic frameworks down can make a huge difference!
Topics covered include:
- Exam signs to help you localize in the peripheral nervous system
- ALS
- Peripheral neuropathy
- Neuromuscular junction disorders
- Myopathy
- and more!
- Check out our website at www.theneurotransmitters.com to sign up for emails, classes, and quizzes!
- Would you like to be a guest or suggest a topic? Email us at contact@theneurotransmitters.com
- Follow our podcast channel on 𝕏 @neuro_podcast for future news!
- Find me on 𝕏 @DrKentris
The views expressed do not necessarily represent those of any associated organizations. The information in this podcast is for educational and informational purposes only and does not represent specific medical/health advice. Please consult with an appropriate health care professional for any medical/health advice.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
Hello and welcome back to a new episode of the
Neurotransmitters as we continueour board review series for
internal medicine boards on thesubject of neurology.
So today we are covering what Iconsider to be one of the
biggest monsters in subtopics,which is neuromuscular disease.
I always find neuromusculardisease is one of the hardest
(00:23):
subtopics of neurology to teachbecause a lot of times you get
one chapter and it's the entireperipheral nervous system that
you have to cram into onechapter, and I know in a lot of
my neurology textbooks it'soften the biggest chapter.
So we're going to cover alittle anatomy and then a fair
amount of pathology on thingsthat are most likely to show up
on the IM in in-service examsand boards.
(00:45):
This will of necessity be arather broad overview and I'm
sure that down the line we willbe coming to some of these
topics more in depth.
So what does the peripheralnervous system contain?
So, broadly speaking, we tendto start proximally and go
distally.
So proximally we have theanterior horn cells, the dorsal
root ganglia, the nerve roots,the plexus, both in the brachial
(01:08):
plexus and the lumbosacralplexus, peripheral nerves, the
neuromuscular junctions and thenthe muscles themselves.
So one of the best things to dofor yourself is to kind of
build a framework to help us sayis this more likely a
peripheral pathology or acentral pathology?
That I'm seeing.
So for most peripheral keyemphasis on most these diseases
(01:31):
tend to be less acute,definitely not hyper acute like
we see with stroke or a seizure,but more in the acute to
subacute to more chronic inonset.
As always, we want to localizeif we can.
So what are some patterns thatwill make us think of more
peripheral things?
So we want to look atspecifically the patterns of
weakness and numbness.
(01:51):
With diseases involving theperipheral nervous system
primarily, we tend to see thingsthat are a lot more localized,
things that are involving aspecific dermatome, myotome,
root level, involving just onelimb, as opposed to things in
the central nervous system like,say, a stroke that's causing
weakness in the face and thehand right.
There's a little bit distancebetween those two things.
Sometimes you'll get the entirehalf of a body involved for
(02:14):
some kinds of strokes or otherkinds of central pathology.
So those sorts of patternsshould clue you in a little bit
and unfortunately there's no wayaround it.
You do have to know someperipheral nerve anatomy to say
like, oh, this pattern ofnumbness, this pattern of
weakness suggests thislocalization, and we'll touch on
that a little bit as we gothrough some of these different
disorders.
But it's one of the things thatmakes neuromuscular medicine a
(02:36):
little more challenging.
Everyone tends to learn more ofthe central nervous system
anatomy and the peripheralnervous system anatomy does take
a bit of work to get into thememory.
That being said, if you learnjust a few nerves and a few root
levels, you can cover a lot ofyour bases for the most common
things.
So if we think of our arms ashaving root level innervations,
(02:57):
primarily from C5 through T1,and then we kind of know our
three main peripheral nerves inthe arm going to be our median
radial and ulnar, and similarlyin the legs, we've got our
peroneal and our tibial distallyin the leg.
That will cover a lot of thequestions that you'll probably
see on your exams.
So we got to talk about examfindings as well.
(03:17):
Right, there's always theclassic ones.
So for upper motor neuronversus lower motor neuron
findings right, everyoneremembers these.
For upper motor neuron versuslower motor neuron findings
right, everyone remembers these.
So for upper motor neuron kindsof findings, we expect
increased tone, increasedreflexes.
For lower motor neuroninvolvement, we expect decreased
tone, a little more placidityand decreased reflexes.
(03:38):
Obviously, a big giveaway forsomething being more likely to
be central nervous systempathology is if you have
cortical symptoms, and some ofthe classic ones of these would
be things like aphasia orneglect.
Similarly, having somethinglike a homonymous hemianopia
should obviously clue you into acentral pathology.
So let's move into ourpathology and again we're going
to start proximal and go distal.
So first up we have theanterior horn cells and the
(04:01):
family of disorders thatobviously is going to be
affecting these the most ismotor neuron disease,
classically ALS, amyotrophiclateral sclerosis.
So the classic findings we havehere are a mixture of upper and
lower motor findings on ourexam right, some hyperreflexia,
atrophy, fasciculations, andthese can involve different
areas of the body.
So typically our diagnosis ofthis is going to require both
(04:25):
clinical and electrodiagnostic,such as on EMG evidence of these
findings in at least two ormore areas.
You know there's differentlevels of probability.
You know possible, probable,definite.
So the more areas that areshowing the typical findings,
the more likely the diagnosis iscorrect.
And the different areas we haveare there's four.
So we have the bulbar, thefacial muscles, the arms, the
(04:49):
legs and the thoracic typicallythe thoracic paraspinals on EMG.
So in addition to EMGs and nerveconduction studies, we're often
doing MRIs, as sometimes a highcervical compressive myelopathy
or a multifocal myelopathicprocess could mimic a similar
disease presentation.
So you do have to rule outstructural or other causes of
(05:10):
spinal disorders.
You may also need to get someblood work.
Some common things that mayshow up are things like B12
levels, copper, maybe Lymeparathyroid hormone, tsh and, in
addition, basic labs like CBC,cmp, so some of the other things
that can mimic it.
So you can at least we alreadymentioned one mimic with spinal
cord pathology.
(05:31):
But you can get other kinds ofneuropathies like multifocal
motor neuropathy.
And it's also important toremember that not all
fasciculations are ALS.
There is benign fasciculationsyndrome.
Particularly if you have ayounger person without weakness
who's maybe stressed oroverusing caffeine and they're
just getting some twitchingaround the face or the hands,
that more often is going to besomething like benign
(05:52):
fasciculation syndrome.
So a lot of times you're doingsome of this workup, making sure
there's no red flags and kindof providing reassurance.
In those situations.
Treatment is mostly supportive.
We don't have any definitivedisease modifying treatments,
unfortunately, so a lot of thebest practices involve
multidisciplinary care.
So we're bringing inpulmonologists, we're bringing
(06:12):
in different therapists physicaloccupational speech, sometimes
gi and that's because we may betalking about peg tube placement
for someone who may be havingprogressive dysarthria and
dysphagia, getting non-invasivepositive pressure ventilation,
or even talking abouttracheostomy cough assist
devices, various other assistivedevices that can be helpful as
the disease progresses.
(06:33):
There is also an associationwith ALS and frontotemporal
dementia and subsequently apseudobulbar affect.
So you do have to watch out forcognitive issues, right?
It's perhaps not as pure of amotor neuron disease as we think
, so there can be other thingsgoing on under the hood.
So you have to ask about thosesorts of things as well, both
when you're talking with thepatient as well as family
(06:54):
Medication-wise.
Rilazole is kind of the old kidon the block.
It's a glutamate blocker andit's modest for most people.
The other medication that's outthere is Adaravone, and this is
a pre-radical scavenger.
It's a little more burdensometo get administered because it's
not oral.
It has to be given as aninfusion and, again, rather
(07:14):
modest effect overall.
So just to re-emphasize,supportive care is really the
name of the game when managingsomeone with ALS.
Next up we have our ganglia, soa sensory ganglionopathy.
These are a little unusual butcan be quite dramatic when they
do show up on your doorstep.
So these will show up, usuallywith a severe loss of vibration
(07:35):
and proprioception sense, and soyou can sometimes get what's
called a sensory ataxia.
So they can be very off balance, very uncoordinated, and this
has a few unique causes that youlook for.
So one of the things that I'veseen rarely is a B6 toxicity.
So someone's drinking a ton ofenergy drinks that have
excessive amounts of vitamin B6may show up with this
(07:55):
incoordination and some pain.
Also you can also see aganglionopathy, with different
kinds of perineoplasticsyndromes and some autoimmune
diseases, in particularSjogren's syndrome.
Next up are the roots.
So the most common pathologywe're seeing here are
radiculopathies, right, so somecompression, typically from
bulging discs, degenerative discdisease, degenerative joint
(08:17):
disease, and classically we'regoing to see sensory involvement
more than motor involvement.
It's very unusual to have apure motor radiculopathy.
So if you're not havingtypically that radiating pain
from the neck down into the armor the back into the leg, then
you should be questioning isthis really correct?
And you do want to make surethis is where the anatomy
(08:38):
becomes important that thesymptoms correspond to an
appropriate root level.
So if it's radiating down aclassic root level territory,
then you'd be like, ah yes, thisall makes sense.
I know what kind of imaging, orif I need to get imaging, that
I need to do so.
As we said earlier, the commoncauses are gonna be compression
due to disc disease.
Sometimes you can also seethese things show up in people
(09:01):
who maybe have a history ofcancer, in particular with bony
metastases.
These things show up in peoplewho maybe have a history of
cancer, in particular with bonymetastases.
So those are just some of thethings that might make you even
more suspicious, and obviously ahistory of recent falls or
trauma are going to make you alittle more suspicious as well
for a mechanical cause here.
There are, of course, othercauses of radiculopathy or
radiculitis, but we're not goingto be covering those today as
(09:21):
we keep on moving into thedistal peripheral nervous system
.
We have next the plexus.
Generally speaking, we're goingto be thinking about a lesion
in the plexus when we seeprimarily one limb is involved,
with both sensory and motorsymptoms, and it's not really
localizing to just one nerve orroot level territory.
So we're going to be keepingthis very broad right.
(09:43):
No one's going to be drawingthe brachial plexus out by the
end of this podcast.
So let's hit on some commoncauses.
So some of the things that maycommonly cause a plexopathy
either in the arm or the legdiabetes and this is something
we're going to come to over andover again is that diabetes can
cause nerve injuries anywhere inthe peripheral nervous system.
It is a real pain in thebuttignancy.
(10:04):
So if you have some sort ofmetastatic infiltration of the
brachial plexus or thelumbosacral plexus, if you had
radiation therapy to like, say,the upper lung field, that can
sometimes involve the brachialplexus.
Similarly, in the pelvis withthe lumbosacral plexus trauma is
a very common thing.
Now we may think back tomedical school and be like oh
(10:25):
you know, they want me to sayit's like an Erb's palsy or
Klumke's palsy or something likethat in the arm.
Very often when we have traumaas a cause of, like, say,
abrachial plexopathy, it oftenwon't localize as well as the
textbooks do.
That's because you get somesort of stretch, injury of
multiple nerves, multiple partsof the plexus, so it's kind of
all affected to an extentgreater or lesser and so it
(10:47):
doesn't localize as well beyondjust the plexus.
And that does happen in reallife sometimes.
One unique thing that can causea brachial plexus injury is
something called ParsonageTurner Syndrome, aka idiopathic
brachial plexitis, aka neuralgicamyotrophy.
So this is kind of a strangething.
It often will present in asingle limb, obviously usually
(11:10):
the arm, and it tends to be mostprominent around the shoulder
girdle, so kind of proximal nearthe shoulder, and it will come
with this kind of severe pain,oftentimes some weakness.
The pain will usually subsideover a span of days to weeks,
but the weakness may remain tosome extent and in severe cases
you can get some prominentatrophy in the shoulder girdle
(11:32):
muscles or any of the musclesthat were involved.
Sometimes it can go more distalinto the limb.
So that is something that canhappen.
Workup-wise we often getimaging of the neck and the
brachial plexus itself, lookingfor any compressive lesions or
inflammation.
Very often these will be normaland then you also end up
getting some blood work, usuallylooking for different kinds of
autoimmune or inflammatorydisorders.
A similar process can alsoaffect the lumbosacral plexus
(11:55):
and it's thought to be alsoimmune mediated.
Some of these things can bepost-viral, post-infectious.
It can look in the leg verysimilar to a diabetic amyotrophy
, which we'll talk about later,and an EMG can help you
differentiate between the two.
We are finally here.
We are in the thick of it now.
We are at the peripheral nerves.
So peripheral neuropathy.
(12:15):
There are hundreds, if notthousands, of causes of
neuropathy.
So what are we going to lookfor in terms of neuropathy?
So we're looking at patterns.
A lot of neuropathy evaluationis pattern recognition.
So what are some of the keyfeatures we need to look at?
Symmetry Is it distal versusproximal, focal versus more
(12:37):
generalized?
What are the types of fibersinvolved Motor, sensory, small
or large, fiber, autonomic andwhat are the things that are
going to make us more worriedabout different causes?
And then the other thing,obviously, is the timeline.
So most neuropathies, or Ishould say of the common
quote-unquote sort, are going tobe on the chronic, insidious
(12:58):
end of the time spectrum,something in the more acute to
subacute phase.
You're going to be obviouslyperking up those red flags.
So those red flags are if wehave market asymmetry in our
symptoms, if it is proximal morethan distal involvement, if it
is a named nerve or a focalinvolvement as opposed to a
polyneuropathy, and if the motorsymptoms are greater or out of
(13:20):
proportion to the sensorysymptoms, any of these should
prompt an EMG nerve conductionstudy evaluation.
I'm just going to call it EMG,so any of you pedantic people
out there just get used to it.
So you should be doingneurodiagnostic evaluations on
those at that point in time andthat should also guide your lab
workup.
So our most common neuropathies,say from something like
(13:42):
diabetes, is going to be alength-dependent, that is,
stocking-in-glove typedistribution right, worse,
distally, less bad, proximally.
By the time those tend to getto the knees they start to
affect the fingertips and hands.
So it's going to belength-dependent,
sensory-predominantpolyneuropathy, typically axonal
on your nerve conductionstudies.
So what kind of labs are wegetting for a length dependent,
(14:07):
sensory predominantpolyneuropathy?
And I just want to pause for amoment and say very often you
will find more utility with asafety pin and a tuning fork
doing an assessment at thebedside than you will for a
nerve conduction study, unlessyou have any of these
aforementioned red flags in yourhistory or exam.
Because if you have this mostcommon flavor of neuropathy, a
chronic onset, length-dependent,sensory-predominant
(14:30):
polyneuropathy, then you'regoing to get more utility from
doing blood work looking for thecause of neuropathy than you
are from a nerve conductionstudy or EMG.
So basic labs you always want tobe checking in these people.
Usually you want a CBC, atleast a BMP, maybe a CMP,
depending on what their othermedical history may look like if
(14:50):
they have other liver issues.
An ESR plus or minus the ESR isplus or minus.
That's usually going to be morebeneficial for someone younger.
Serum protein electrophoresiswith immunofixation.
Looking for anyparaproteinemias, tsh is a
little debatable.
Very often it is going to beunremarkable.
Rarely you may find somethingHemoglobin A1c or a glucose
(15:14):
tolerance test.
Those are going to be, in theUnited States at least very high
yield and then a vitamin B12level.
Now let's say we have someonewith one of those red flags.
Well, what are the extra teststhat we're going to want to do?
Well, that really depends onwhat the clinical presentation
is.
So there are, as I said earlier, hundreds of causes of
neuropathy, and so the clinicalhistory is going to have to
(15:36):
guide you a little bit on that,and that may prompt other things
.
It's obviously going to promptanother EMG and that's going to
make you look for things likedemyelinating disease EMG and
that's going to make you lookfor things like demyelinating
disease.
So we have acquired, versusinherited, demyelinating
disorders.
So our classic acquireddisorders are something like
Guillain-Barre syndrome or, onthe more chronic side, cidp,
(15:57):
chronic inflammatorydemyelinating polyradicular
neuropathy.
The classic inheriteddemyelinating neuropathy is
Charcot-Marie-Tooth type 1,which in reality is diagnosed
probably more on genetic teststhan it is in the EMG lab
anymore these days, although I'mnot a child neurologist so your
mileage may vary on that.
Other testing that you may seedone CSF testing.
Again, in things likeGuillain-Barre syndrome you may
(16:19):
get a lumbar puncture, lookingfor that albuminocytologic
dissociation.
You may also be checking forother kinds of inflammatory
markers.
Cytologic dissociation you mayalso be checking for other kinds
of inflammatory markers.
You may also get a nerve biopsy.
In particular when you'rethinking of things like
vasculitis, that's going to besomeone who presents with
something called mononeuritismultiplex which is where you get
these random different nerves.
Your named nerves get pickedoff kind of in a
(16:40):
non-length-dependent,non-confluent fashion, although
over time it may becomerelatively confluent.
You're also looking for signsof infection or infiltration
with things such as cancer.
So nerve biopsy you definitelywant to make sure that the nerve
is already damaged becauseyou're going to be cutting the
nerve to do the biopsy.
Autonomic testing can also bedone, although it can be a
(17:00):
little challenging logistically,depending on your practice
setting.
There's a test called the QSARTQuantitative Pseudomotor Axon
Reflex Test.
This is essentially a sweattest and it can be helpful in
people who have primarily smallfiber neuropathies, where your
nerve conduction studies may beotherwise unremarkable and you
still think like something looksa little fishy.
So it can be helpful in certaindisorders.
(17:22):
A tilt table test could also beconsidered in someone who's
having a lot of autonomicsymptoms that you're wanting to
evaluate further.
So two broad camps as we moveforward we have mononeuropathies
and polyneuropathies.
So mono one, poly many.
So some of the mononeuropathies.
Obviously a mononeuropathy canaffect any nerve in the body,
but we're just going to touch ona couple that are likely to
(17:44):
show up.
So obviously carpal tunnelsyndrome, the most common
entrapment neuropathy in thebody, right Median neuropathy
due to compression at the wrist.
So very often on exam you'll geta history of someone who's got
paresthesias or tingling intheir hand.
Classically they'll want toshake their hand out when they
first get up in the morning, ormaybe exacerbated by certain
activities such as running abicycle or driving a car, other
(18:07):
kinds of manual relatedactivities, and when it
progresses you may get somenumbness over the thenar aspect
of the hand.
You may also get some atrophyof the thenar aspect of the hand
weakness, with thumb abduction,and so you're going to try
conservative therapy first withthings like wrist splints, and
if that's unsuccessful, orthey're already showing signs of
(18:28):
weakness in the hand, you'regoing to be getting an EMG
looking for signs of activedenervation, make sure to
confirm that the localization iscorrect, and then you're going
to be sending them to a handsurgeon for surgical
decompression.
The other mononeuropathy thatwe're going to be talking about
is Bell's palsy.
So Bell's palsy, by definition,is idiopathic, so it is a
(18:48):
facial nerve palsy or seventhnerve palsy causing upper and
lower facial weakness, althoughthis can be variable and may
progress over time.
So you may get people who aremore lower than upper, but there
is usually some degree ofasymmetry.
Also, if they have weaknesswith forced eye closure on the
affected side, that is veryhelpful, because that is going
(19:09):
to be more of that seventh nerveweakness.
You may also see and these aresome things that I think are
very helpful if there ishyperacusis, that is to say the
nerve distipedius isn't able totamp down on that loud reflex,
or if they have altered taste.
A lot of times I'll takesomething either salty or sweet
like a sugar.
If I'm in the ED, I'll take along tip applicator and just put
(19:30):
some saline water on one sideand see if there's impaired
taste on one side of the tongueor the other.
If there is, then that tells meyes, it's definitely Bell's
palsy.
Right, it's the seventh nerve.
It's doing taste of the tongue.
So, as I mentioned, bell's palsyquote unquote is idiopathic,
that is to say we don't know whyit happened.
So that doesn't mean we don'tcheck for things.
You still have to check forthings.
Otherwise it is a facial nervepalsy due to X.
(19:52):
So, for instance, we're in Ohio, where I am, so we have to
check for Lyme disease, right?
I check for it on every personwho comes in with a seventh
nerve palsy and we get a handfulof people who test positive for
Lyme disease every year.
So this is something to keep inmind if you are in an endemic
area.
Other causes that you do have tokeep in mind things like HIV,
(20:12):
sarcoidosis, diabetes, as wementioned can affect any part
and then sometimes malignancy,right, if there's infiltration
of that seventh nerve, thatcould also cause a similar
presentation.
The classic treatment is, ofcourse, of steroids.
There is some debate as towhether antivirals may be
helpful, and you do need toprovide some supportive care as
well.
So that typically involves eyedrops, ointment and making sure
(20:35):
the eye is patched appropriatelyduring sleep so people don't
develop a corneal ulceration.
Moving on to polyneuropathiesthere are so many causes of
polyneuropathy so we're justgoing to focus on a handful.
So first off, diabetes-relatedit can affect any part of the
nerve.
As I have said several times,we can even start seeing some
neuropathy start to develop withthe quote-unquote pre-diabetes
(20:58):
or just impaired glucosetolerance.
This tends to be sensory morethan motor.
You will also tend to getautonomic involvement.
That's why you can see thatredness distally in people who
have had diabetes for a longtime in their legs.
You can also get this diabeticamyotrophy.
What is diabetic amyotrophy?
So it is an acute painfuldisorder typically affecting the
(21:19):
thigh compartment in someonewith diabetes.
And you can actually get MRIsof the muscles.
You can see some swelling andedema in there.
So it may seem like more of amuscle disorder on presentation,
but it does have nerveinvolvement.
We mentioned hereditaryneuropathies in passing earlier.
Right CMT, type 1, autosomaldominance, demyelinating
neuropathy.
On exam you'll typically seehigh arches in the feet, hammer
(21:43):
toes, they may have distal legatrophy.
On nerve conduction studiesyou'll see slowed nerve
conduction velocities withoutconduction block.
So conduction block issomething you typically see with
acquired neuropathies, theseimmune-mediated neuropathies.
Speaking of Guillain-Barresyndrome, so it is a
polyradiculoneuropathy and ittends to have an acute to
(22:04):
subacute progressive pattern ofnumbness and weakness and
reduced or absent reflexes.
In reality those are the onlycriteria.
Is this progression of numbnessand weakness and reduced
reflexes?
Often in the vignettes on testsyou'll see a preceding illness,
whether that's GI or an upperrespiratory illness of some sort
.
More severe cases may have someautonomic instability
(22:25):
associated with them.
So you can see these big swingsin blood pressure and heart
rate and such, and that canprompt them to need to be in the
ICU even before they starthaving any bulbar weakness or
respiratory issues which canalso develop.
The differential diagnosis forthis includes some very strange
things like botulism toxicity,west Nile virus, polio which we
(22:46):
don't see, thankfully, too oftentick paralysis if you're in an
endemic area and some otherdisorders also.
So there are multiple subtypesof Guillain-Barre syndrome.
The one that we tend to see inthe United States most often is
AIDP acute inflammatory,demyelinating, polyradicular
neuropathy.
But there are axonal variantsAMAN and AMSAN and, of
(23:08):
particular note, there issomething called the
Miller-Fisher variant which isassociated with a ganglioside
antibody, gq1b, and that has thetriad of ataxia,
ophthalmoparesis and areflexia.
When we're working up someonefor GBS, typically, as we
mentioned, we have nerveconduction studies cooking.
We also are going to usually bedoing a lumbar puncture and
(23:28):
looking for changes in the CSF,typically an elevated protein
with a relatively normal whiteblood cell count, which is
referred to as analbuminocytologic dissociation.
First-line treatments includeIVIG and plasmapheresis.
These have been found to berelatively equivalent.
Ivig may not be as quick in itsaction as plasma exchange but
(23:49):
it does tend to be a little moreaccessible, depending on your
resources available.
So you kind of have to look atthe treatment setting.
But A second course that'ssomething you'll see sometimes
if someone's not improving asexpected.
It's been studied.
It hasn't been found tonecessarily be particularly
helpful.
So you do need to watch, as wementioned earlier, the negative
(24:11):
inspiratory force, the vitalcapacity, and make sure that
people's respiratory vitals staystable, especially if they are
having progressive weakness tothe point where they are unable
to ambulate and they may behaving some dysarthria or
dysphagia to the point wherethey are unable to ambulate and
they may be having somedysarthria, dysphagia, cidp or
chronic inflammatorydemyelinating polyradicular
neuropathy typically has arelatively subacute presentation
.
It tends to be length dependent.
(24:31):
A lot of times they'll havesome sensory changes in the feet
, maybe developing some footdrop, ankle weakness and you
kind of have this progressive orrelapsing weakness and numbness
presentation.
So nerve conduction studies aregoing to be the key for coming
to this diagnosis, with somedemyelinating changes and
conduction block, and you veryoften will get a lumbar puncture
on these people as well,looking for again this same
(24:54):
albuminocytologic dissociation.
So first line for treatment istypically steroids, usually
prednisone, although you can useother therapies as well, like
IVIG and plasma exchange.
If the steroids are too high ofa dose for too long, you will
be looking at adding onsteroid-sparing therapy.
The most common oneshistorically have been things
(25:15):
like azathioprine andmycophenolate and then you would
sometimes see, in more extremecases, cyclosporine,
cyclophosphamide, and there areother immunotherapies that are
now also becoming available.
Something that you will see ifyou work in the ICU is a
critical illness neuropathy, andwhat this is is essentially
someone who spends a prolongedperiod of time in the ICU and
(25:36):
they develop weakness.
They've come off the ventilator, but they're awake and they
just can't move.
They're weak, they havenumbness, and so you can also
have a concurrent criticalillness myopathy.
Your EMG will help youdifferentiate between these two,
but very often a criticalillness, neuropathy and myopathy
travel together and there isn'tany definitive treatment for
this entity.
(25:56):
It's just more to help you withprognosis and to give you some
guidance in terms of like.
Why is this person still soweak, even though you know maybe
their illness is better?
They should be getting out ofbed, they should be
participating in rehab, andthey're just not able to Next up
paraprotonemic neuropathies.
So this is a bit of an unusualfamily of disorders.
So these are often sensorypredominant, but they can be
(26:17):
sensory motor, multifocal oreven involve cranial nerves.
So there's a few classicentities here.
One of these is MGUS, ormonoclonal gammopathy, of
undetermined significance.
Mgus is associated withneuropathy, but very often we
need to do some further workupand you may, depending on your
comfort level, need to rope in ahematologist oncologist.
There may be things likebiopsies that need to be done,
(26:39):
bone biopsies or kappaappalambda, light chains, etc.
Etc.
So you do have to maybe rope inthe hematology oncology
department for a little furthertesting, depending on the
clinical milieu.
So other things that can beassociated with neuropathy in
this family multiple myeloma,waldenstrom's, macroglobulinemia
, amyloidosis or otherhematologic malignancies.
(27:02):
Another entity that they love toask about I think it's probably
more prevalent on boardquestions than it is in real
life is POEMS syndrome, whichstands for polyneuropathy,
organomegaly endocrinopathy andmonoclonal plasma cell disorder
and skin changes.
So it is a lambdaparaprodinemia, and it may look
very similar to CIDP in terms ofits presentation, but you'll
(27:24):
have these other things right,typically the organomegaly, the
endocrine disorders and the skinchanges.
Those are things that you don'tsee with CIDP, so that can
sometimes prompt furtherevaluation.
Something that also shows up inthe questions from time to time
is something called DADS, whichis distal acquired
demyelinating symmetricpolyneuropathy, which is an
(27:44):
anti-MAG, m-a-gmyelin-associated glycoprotein
antibody associated disorder.
Autonomic neuropathies can alsomanifest.
They may occur with other formsof neuropathy or they may occur
by themselves, so they can, asalways, occur with diabetes.
The classic one to think of,though, is amyloidosis, and this
can either be monoclonal or itcan be genetic trans-thyretin
(28:06):
mutation related.
Autonomic neuropathies can alsobe seen with HIV, and there is
a perineoplastic syndromeassociated with anti-ganglionic,
nicotinic acetylcholinereceptor antibodies.
We made it.
We made it through theneuropathies, we're past the
(28:27):
nerves, we are now to theneuromuscular junction.
So we've got two primedisorders that it's always good
to know about for neuromuscularjunction disorders.
So first up we have myastheniagravis.
This affects the post-synapticneuromuscular junction.
So there's a bimodaldistribution here.
We've got young women,typically third decade, and
older men over the age of 50.
Those are the most commonpopulations that we'll see
myasthenia show up in.
Very often the first symptomswill be things like ptosis,
(28:50):
diplopia, but about half ofthose may develop generalized
symptoms within a couple ofyears and about 10% will present
with bulbar weakness and somecervical involvement, that is,
the neck.
So it's not uncommon for thesepeople to be seen by optometry
or ophthalmology first due tothe ocular symptoms that can be
so common.
At presentation.
Diagnosis wise these days theantibody testing is really good.
(29:13):
About 90% of patients will beantibody positive.
85% are going to be the moretypical binding blocking or
modulating antibodies.
5% of those might be musk,which is going to be a little
bit more bulbar onset.
They tend to have morerespiratory involvement, more
facial weakness, so a littlemore aggressive course, and they
don't respond as well totreatment as the people who are
(29:35):
positive for the otherantibodies.
Sometimes you may still need todo neuroconduction studies and
that'll show a decrementalchange on repetitive stim.
So that may show up in aquestion stem.
There is some debate aboutinitial treatment.
So symptomatic treatment isusually with periodostigmine,
aka mestinone, which is acholinesterase inhibitor.
You do have to watch out itwill increase secretions right,
(29:56):
saliva, diarrhea, tearing thingslike that.
So any place that makes fluidmaking more fluid.
And there is some debate aboutwhether to start disease
modifying treatment when peoplehave purely ocular symptoms.
If periodostigmine is able tokeep things under wraps, I tend
to be of the party that I thinkmaybe disease modifying
treatment is more appropriate tostart at beginning, just
(30:17):
because of so many peopledeveloping generalized symptoms
over time.
So our typical disease modifyingparadigm, first line is very
often prednisone and you titrateup slowly.
If you start at too high of adose it can paradoxically worsen
things and cause a myasthenicexacerbation.
If you're not able to getsomeone down to a low dose of
(30:38):
maintenance prednisone, you'regoing to be using steroid
sparing therapy and those areagain classically mycophenolate
and azathioprine.
You can also use things likeIVIG or plasma exchange and
there are a number of newmonoclonal antibodies and other
types of disease-modifyingtreatments out there.
I don't know if those arestarting to hit the test just
yet, so we're not going to gointo them too much.
(30:59):
A word about a myasthenic crisis.
So this can present with verysudden worsening weakness of the
bulbar muscles, respiratorymuscles, and this can be
triggered by stress, differentkinds of antibiotics such as
aminoglycosides, infections,recent surgery, certain
medications, as we mentionedaminoglycosides, quinolones,
(31:20):
magnesium, beta blockers,hydroxychloroquine.
So people definitely need toknow before they start a new
medication whether or not it isgoing to be safe for them with
myasthenia.
And you may need sometimes, toquote medically optimize someone
with myasthenia prior to havingan elective surgery, and that
may mean giving them a shortcourse of IVIG or some other
(31:40):
kind of treatment.
So that just really depends onthe context and your particular
patient that you're taking careof.
Another treatment that is outthere is thymectomy.
So if they have a thymoma,obviously we're going to remove
that.
For people who don't have athymoma, there may still be some
benefit, not immediately per se, but over time.
They generally require lessimmune suppressive medication.
(32:03):
Next up in our NMJ isLambert-Eaton-Myasthenic
syndrome.
So this is a presynapticneuromuscular junction disorder
and it's associated withantibodies against voltage-gated
calcium channels.
So very often this will beassociated with small cell lung
cancer, although there can beperineoplastic versions as well.
So if they have the cancer,treat the cancer.
(32:23):
If they have no cancer, thenyou treat with immunosuppression
, ivig, plasma exchange, kind ofthe usual things at this point.
So typically if this is a man,you'll get some autonomic
symptoms, including erectiledysfunction very commonly, and
they'll get some kinds ofweakness.
You can see hyporeflexia aswell and you can see this
phenomenon called augmentation,where if you have them flex a
(32:47):
muscle and then you check thereflex before and after
activating that muscle, thereflexes will often be brisker
after you have them use thatmuscle for a short period of
time.
And you'll see a similar thingon nerve conduction studies as
well, with repetitivestimulation.
We are in the home stretch, weare at the muscles.
So let's talk about myopathies.
So the classic pattern for amyopathic process is going to be
(33:11):
weakness, typically proximalmore than distal, and obviously,
because it's the muscle, youusually shouldn't have sensory
involvement unless there'ssomething else going on.
Lab-wise you're going to bechecking a CK level, maybe an
aldolase.
Very often you'll be doing EMGsand nerve conductions on these
and this will show typicalpatterns.
The typical pattern for amyopathy on needle EMG is going
(33:33):
to be low amplitude, polyphasicand early recruitment, which is
kind of the opposite of what wenormally see for a neuropathic
process.
So in some severe cases you mayalso need a muscle biopsy.
Now a word about EMGs andmuscle biopsies and CK levels.
You want to check your CKbefore you poke the muscle,
right, you poke the muscle witha needle, it may raise the CK
(33:55):
and similarly the muscle biopsyitself may cause an elevation in
CK as well.
You also don't want to biopsythe muscle that you also poked a
needle into, because thatmicrotrauma may influence the
pathology a little bit, so itmay be a little less reliable.
So, moving on, our first familyis inflammatory myopathies.
Now some of these are going tosound really familiar
(34:15):
Polymyositis, dermatomyositisand inclusion body myositis.
Then you also have immunemediated necrotizing myopathy.
So polymyositis and inclusionbody myositis.
Then you also haveimmune-mediated necrotizing
myopathy.
So polymyositis, right, youtend to have that classic
pattern of weakness, elevatedCKs, dermatomyositis, elevated
CKs, strong association withdifferent kinds of cancers.
So you need to check out forthat and you're looking for that
(34:37):
skin involvement, that rash,that shawl sign.
Immune-mediated necrotizingmyopathy very often will be
triggered by statins, may havean association with HMG-CoA
reductase antibodies and againyou'll treat this with
immunotherapy.
Inclusion body myositis oftenhas a very slow course.
Typically you'll have earlyweakness of the distal upper
(34:57):
extremity flexors, the quads,bulbar muscles potentially, and
on muscle biopsy you'll get,obviously, inclusion bodies.
That's kind of the big takeawaythere, so that can be very
helpful in that case.
Moving on to endocrine-relatedmyopathies so different
endocrine disorders can causemyopathic changes.
(35:18):
So hypothyroidism can causemyalgias, proximal weakness,
myxedema changes.
So hypothyroidism can causemyalgias, proximal weakness,
myxedema, hyperthyroidism youcan get fasciculations,
ophthalmoplegia, hyperreflexiaand then, as we mentioned
earlier, you know, kind of thelooks like an endocrine related
myopathy.
Is the diabetic amyotrophyno-transcript getting weaker
(35:50):
again, more in their shouldersand legs, and it's like this
isn't the same kind of weaknessthey had before.
Well, you might need to backoff on the steroids.
So you will oftentimes check aCK.
It's going to be normal.
Emg very often will be normal.
Some steroids are more likelyto do this than others
Dexamethasone more so thanprednisone or hydrocortisone.
(36:10):
So you do have to watch outwhen you're using steroids to
treat one other condition asthat may cause this kind of
paradoxical new problem.
Moving on to toxic myopathies.
So the poster child for thisfamily are statins, which can
cause pain, very often in theshoulders and the thighs, and in
more severe cases, weakness aswell.
In those severe cases, thereally severe cases, it'll go to
(36:31):
that necrotizing myopathy thatwe mentioned earlier.
Other medications can alsocause a toxic myopathy.
Ck levels may be mildly orsignificantly elevated.
Typically remove the offendingagent and most people should get
better.
Finally, inherited myopathies soa lot of these will present
early in life.
There are some that willpresent in adulthood, so a
(36:52):
couple that I want to touch on.
So myotonic dystrophy veryoften is associated with some
other systemic disorders.
You can see myotonia, which isthis impaired relaxation of
muscles.
So for instance, you go toshake somebody's hand, they
can't open their hand right awayand you can use sometimes like
sodium channel blockers, likephenytoin or other types of
things to help with that.
So type 1 myotonic dystrophyyou typically have distal
(37:15):
weakness, they have cataracts,frontal balding, they'll also
have some cardiac and endocrineassociated disease and they
might have some mild cognitiveissues as well.
Mitochondrial myopathy this iskind of a wide category,
significant variabilitydepending on the syndrome.
But whenever you have amitochondrial disease you expect
multi-organ involvement.
(37:35):
So myalgias, ophthalmoplegia,other organs, and obviously it
tends to be maternallytransmitted due to the
mitochondria.
Some of the classic metabolicadult-onset myopathies may
present with exercise-inducedweakness, cramps, myoglobinuria
right, you get that dark urinemyocardial disease, carnitine,
palatoyl transferase IIdeficiency are probably the two
(37:57):
most common.
You can also see Pompe diseaseor acid maltase deficiency.
So it has an adult onset formwith proximal weakness and
respiratory muscle weakness.
And you can check the alphaglucosidase activity as well as
genetic testing.
There is a treatmentalglucosidase alpha, and just
like that we have made it to theend of the muscle category and
(38:18):
we have finished our rapidsurvey through the peripheral
nervous system.
If you made it to the end, goodon you.
Thank you so much for spendingyour time listening to me rattle
on about neuromuscular diseases.
I know this is a lot ofinformation and it's still a
little bit longer than I wouldhave liked it to be, but it's
just such a broad category.
Obviously, we will have torevisit some of these topics in
(38:38):
more depth in the future.
I hope this was at leastedifying in some fashion and
will help you on some of yourexams and hopefully even more so
in real life when you're takingcare of patients.
If you found this podcasthelpful, educational, leave us a
five-star review, leave us somefeedback.
You can check out our past workat theneurotransmitterscom.
You can also find me on Twitter.
(38:58):
Slash x at drkentrisd-r-K-E-N-T-R-I-S, or the
podcast itself at neurounderscore podcast.
Again, thank you for listeningand if you have any show
suggestions, ideas, you canalways get a hold of us through
our website.
Hello and welcome back to a new episode of the
Neurotransmitters as we continueour board review series for
internal medicine boards on thesubject of neurology.
So today we are covering what Iconsider to be one of the
biggest monsters in subtopics,which is neuromuscular disease.
I always find neuromusculardisease is one of the hardest
(00:23):
subtopics of neurology to teachbecause a lot of times you get
one chapter and it's the entireperipheral nervous system that
you have to cram into onechapter, and I know in a lot of
my neurology textbooks it'soften the biggest chapter.
So we're going to cover alittle anatomy and then a fair
amount of pathology on thingsthat are most likely to show up
on the IM in in-service examsand boards.
(00:45):
This will of necessity be arather broad overview and I'm
sure that down the line we willbe coming to some of these
topics more in depth.
So what does the peripheralnervous system contain?
So, broadly speaking, we tendto start proximally and go
distally.
So proximally we have theanterior horn cells, the dorsal
root ganglia, the nerve roots,the plexus, both in the brachial
(01:08):
plexus and the lumbosacralplexus, peripheral nerves, the
neuromuscular junctions and thenthe muscles themselves.
So one of the best things to dofor yourself is to kind of
build a framework to help us sayis this more likely a
peripheral pathology or acentral pathology?
That I'm seeing.
So for most peripheral keyemphasis on most these diseases
(01:31):
tend to be less acute,definitely not hyper acute like
we see with stroke or a seizure,but more in the acute to
subacute to more chronic inonset.
As always, we want to localizeif we can.
So what are some patterns thatwill make us think of more
peripheral things?
So we want to look atspecifically the patterns of
weakness and numbness.
(01:51):
With diseases involving theperipheral nervous system
primarily, we tend to see thingsthat are a lot more localized,
things that are involving aspecific dermatome, myotome,
root level, involving just onelimb, as opposed to things in
the central nervous system like,say, a stroke that's causing
weakness in the face and thehand right.
There's a little bit distancebetween those two things.
Sometimes you'll get the entirehalf of a body involved for
(02:14):
some kinds of strokes or otherkinds of central pathology.
So those sorts of patternsshould clue you in a little bit
and unfortunately there's no wayaround it.
You do have to know someperipheral nerve anatomy to say
like, oh, this pattern ofnumbness, this pattern of
weakness suggests thislocalization, and we'll touch on
that a little bit as we gothrough some of these different
disorders.
But it's one of the things thatmakes neuromuscular medicine a
(02:36):
little more challenging.
Everyone tends to learn more ofthe central nervous system
anatomy and the peripheralnervous system anatomy does take
a bit of work to get into thememory.
That being said, if you learnjust a few nerves and a few root
levels, you can cover a lot ofyour bases for the most common
things.
So if we think of our arms ashaving root level innervations,
(02:57):
primarily from C5 through T1,and then we kind of know our
three main peripheral nerves inthe arm going to be our median
radial and ulnar, and similarlyin the legs, we've got our
peroneal and our tibial distallyin the leg.
That will cover a lot of thequestions that you'll probably
see on your exams.
So we got to talk about examfindings as well.
(03:17):
Right, there's always theclassic ones.
So for upper motor neuronversus lower motor neuron
findings right, everyoneremembers these.
For upper motor neuron versuslower motor neuron findings
right, everyone remembers these.
So for upper motor neuron kindsof findings, we expect
increased tone, increasedreflexes.
For lower motor neuroninvolvement, we expect decreased
tone, a little more placidityand decreased reflexes.
(03:38):
Obviously, a big giveaway forsomething being more likely to
be central nervous systempathology is if you have
cortical symptoms, and some ofthe classic ones of these would
be things like aphasia orneglect.
Similarly, having somethinglike a homonymous hemianopia
should obviously clue you into acentral pathology.
So let's move into ourpathology and again we're going
to start proximal and go distal.
So first up we have theanterior horn cells and the
(04:01):
family of disorders thatobviously is going to be
affecting these the most ismotor neuron disease,
classically ALS, amyotrophiclateral sclerosis.
So the classic findings we havehere are a mixture of upper and
lower motor findings on ourexam right, some hyperreflexia,
atrophy, fasciculations, andthese can involve different
areas of the body.
So typically our diagnosis ofthis is going to require both
(04:25):
clinical and electrodiagnostic,such as on EMG evidence of these
findings in at least two ormore areas.
You know there's differentlevels of probability.
You know possible, probable,definite.
So the more areas that areshowing the typical findings,
the more likely the diagnosis iscorrect.
And the different areas we haveare there's four.
So we have the bulbar, thefacial muscles, the arms, the
(04:49):
legs and the thoracic typicallythe thoracic paraspinals on EMG.
So in addition to EMGs and nerveconduction studies, we're often
doing MRIs, as sometimes a highcervical compressive myelopathy
or a multifocal myelopathicprocess could mimic a similar
disease presentation.
So you do have to rule outstructural or other causes of
(05:10):
spinal disorders.
You may also need to get someblood work.
Some common things that mayshow up are things like B12
levels, copper, maybe Lymeparathyroid hormone, tsh and, in
addition, basic labs like CBC,cmp, so some of the other things
that can mimic it.
So you can at least we alreadymentioned one mimic with spinal
cord pathology.
(05:31):
But you can get other kinds ofneuropathies like multifocal
motor neuropathy.
And it's also important toremember that not all
fasciculations are ALS.
There is benign fasciculationsyndrome.
Particularly if you have ayounger person without weakness
who's maybe stressed oroverusing caffeine and they're
just getting some twitchingaround the face or the hands,
that more often is going to besomething like benign
(05:52):
fasciculation syndrome.
So a lot of times you're doingsome of this workup, making sure
there's no red flags and kindof providing reassurance.
In those situations.
Treatment is mostly supportive.
We don't have any definitivedisease modifying treatments,
unfortunately, so a lot of thebest practices involve
multidisciplinary care.
So we're bringing inpulmonologists, we're bringing
(06:12):
in different therapists physicaloccupational speech, sometimes
gi and that's because we may betalking about peg tube placement
for someone who may be havingprogressive dysarthria and
dysphagia, getting non-invasivepositive pressure ventilation,
or even talking abouttracheostomy cough assist
devices, various other assistivedevices that can be helpful as
the disease progresses.
(06:33):
There is also an associationwith ALS and frontotemporal
dementia and subsequently apseudobulbar affect.
So you do have to watch out forcognitive issues, right?
It's perhaps not as pure of amotor neuron disease as we think
, so there can be other thingsgoing on under the hood.
So you have to ask about thosesorts of things as well, both
when you're talking with thepatient as well as family
(06:54):
Medication-wise.
Rilazole is kind of the old kidon the block.
It's a glutamate blocker andit's modest for most people.
The other medication that's outthere is Adaravone, and this is
a pre-radical scavenger.
It's a little more burdensometo get administered because it's
not oral.
It has to be given as aninfusion and, again, rather
(07:14):
modest effect overall.
So just to re-emphasize,supportive care is really the
name of the game when managingsomeone with ALS.
Next up we have our ganglia, soa sensory ganglionopathy.
These are a little unusual butcan be quite dramatic when they
do show up on your doorstep.
So these will show up, usuallywith a severe loss of vibration
(07:35):
and proprioception sense, and soyou can sometimes get what's
called a sensory ataxia.
So they can be very off balance, very uncoordinated, and this
has a few unique causes that youlook for.
So one of the things that I'veseen rarely is a B6 toxicity.
So someone's drinking a ton ofenergy drinks that have
excessive amounts of vitamin B6may show up with this
(07:55):
incoordination and some pain.
Also you can also see aganglionopathy, with different
kinds of perineoplasticsyndromes and some autoimmune
diseases, in particularSjogren's syndrome.
Next up are the roots.
So the most common pathologywe're seeing here are
radiculopathies, right, so somecompression, typically from
bulging discs, degenerative discdisease, degenerative joint
(08:17):
disease, and classically we'regoing to see sensory involvement
more than motor involvement.
It's very unusual to have apure motor radiculopathy.
So if you're not havingtypically that radiating pain
from the neck down into the armor the back into the leg, then
you should be questioning isthis really correct?
And you do want to make surethis is where the anatomy
(08:38):
becomes important that thesymptoms correspond to an
appropriate root level.
So if it's radiating down aclassic root level territory,
then you'd be like, ah yes, thisall makes sense.
I know what kind of imaging, orif I need to get imaging, that
I need to do so.
As we said earlier, the commoncauses are gonna be compression
due to disc disease.
Sometimes you can also seethese things show up in people
(09:01):
who maybe have a history ofcancer, in particular with bony
metastases.
These things show up in peoplewho maybe have a history of
cancer, in particular with bonymetastases.
So those are just some of thethings that might make you even
more suspicious, and obviously ahistory of recent falls or
trauma are going to make you alittle more suspicious as well
for a mechanical cause here.
There are, of course, othercauses of radiculopathy or
radiculitis, but we're not goingto be covering those today as
(09:21):
we keep on moving into thedistal peripheral nervous system
.
We have next the plexus.
Generally speaking, we're goingto be thinking about a lesion
in the plexus when we seeprimarily one limb is involved,
with both sensory and motorsymptoms, and it's not really
localizing to just one nerve orroot level territory.
So we're going to be keepingthis very broad right.
(09:43):
No one's going to be drawingthe brachial plexus out by the
end of this podcast.
So let's hit on some commoncauses.
So some of the things that maycommonly cause a plexopathy
either in the arm or the legdiabetes and this is something
we're going to come to over andover again is that diabetes can
cause nerve injuries anywhere inthe peripheral nervous system.
It is a real pain in thebuttignancy.
(10:04):
So if you have some sort ofmetastatic infiltration of the
brachial plexus or thelumbosacral plexus, if you had
radiation therapy to like, say,the upper lung field, that can
sometimes involve the brachialplexus.
Similarly, in the pelvis withthe lumbosacral plexus trauma is
a very common thing.
Now we may think back tomedical school and be like oh
(10:25):
you know, they want me to sayit's like an Erb's palsy or
Klumke's palsy or something likethat in the arm.
Very often when we have traumaas a cause of, like, say,
abrachial plexopathy, it oftenwon't localize as well as the
textbooks do.
That's because you get somesort of stretch, injury of
multiple nerves, multiple partsof the plexus, so it's kind of
all affected to an extentgreater or lesser and so it
(10:47):
doesn't localize as well beyondjust the plexus.
And that does happen in reallife sometimes.
One unique thing that can causea brachial plexus injury is
something called ParsonageTurner Syndrome, aka idiopathic
brachial plexitis, aka neuralgicamyotrophy.
So this is kind of a strangething.
It often will present in asingle limb, obviously usually
(11:10):
the arm, and it tends to be mostprominent around the shoulder
girdle, so kind of proximal nearthe shoulder, and it will come
with this kind of severe pain,oftentimes some weakness.
The pain will usually subsideover a span of days to weeks,
but the weakness may remain tosome extent and in severe cases
you can get some prominentatrophy in the shoulder girdle
(11:32):
muscles or any of the musclesthat were involved.
Sometimes it can go more distalinto the limb.
So that is something that canhappen.
Workup-wise we often getimaging of the neck and the
brachial plexus itself, lookingfor any compressive lesions or
inflammation.
Very often these will be normaland then you also end up
getting some blood work, usuallylooking for different kinds of
autoimmune or inflammatorydisorders.
A similar process can alsoaffect the lumbosacral plexus
(11:55):
and it's thought to be alsoimmune mediated.
Some of these things can bepost-viral, post-infectious.
It can look in the leg verysimilar to a diabetic amyotrophy
, which we'll talk about later,and an EMG can help you
differentiate between the two.
We are finally here.
We are in the thick of it now.
We are at the peripheral nerves.
So peripheral neuropathy.
(12:15):
There are hundreds, if notthousands, of causes of
neuropathy.
So what are we going to lookfor in terms of neuropathy?
So we're looking at patterns.
A lot of neuropathy evaluationis pattern recognition.
So what are some of the keyfeatures we need to look at?
Symmetry Is it distal versusproximal, focal versus more
(12:37):
generalized?
What are the types of fibersinvolved Motor, sensory, small
or large, fiber, autonomic andwhat are the things that are
going to make us more worriedabout different causes?
And then the other thing,obviously, is the timeline.
So most neuropathies, or Ishould say of the common
quote-unquote sort, are going tobe on the chronic, insidious
(12:58):
end of the time spectrum,something in the more acute to
subacute phase.
You're going to be obviouslyperking up those red flags.
So those red flags are if wehave market asymmetry in our
symptoms, if it is proximal morethan distal involvement, if it
is a named nerve or a focalinvolvement as opposed to a
polyneuropathy, and if the motorsymptoms are greater or out of
(13:20):
proportion to the sensorysymptoms, any of these should
prompt an EMG nerve conductionstudy evaluation.
I'm just going to call it EMG,so any of you pedantic people
out there just get used to it.
So you should be doingneurodiagnostic evaluations on
those at that point in time andthat should also guide your lab
workup.
So our most common neuropathies,say from something like
(13:42):
diabetes, is going to be alength-dependent, that is,
stocking-in-glove typedistribution right, worse,
distally, less bad, proximally.
By the time those tend to getto the knees they start to
affect the fingertips and hands.
So it's going to belength-dependent,
sensory-predominantpolyneuropathy, typically axonal
on your nerve conductionstudies.
So what kind of labs are wegetting for a length dependent,
(14:07):
sensory predominantpolyneuropathy?
And I just want to pause for amoment and say very often you
will find more utility with asafety pin and a tuning fork
doing an assessment at thebedside than you will for a
nerve conduction study, unlessyou have any of these
aforementioned red flags in yourhistory or exam.
Because if you have this mostcommon flavor of neuropathy, a
chronic onset, length-dependent,sensory-predominant
(14:30):
polyneuropathy, then you'regoing to get more utility from
doing blood work looking for thecause of neuropathy than you
are from a nerve conductionstudy or EMG.
So basic labs you always want tobe checking in these people.
Usually you want a CBC, atleast a BMP, maybe a CMP,
depending on what their othermedical history may look like if
(14:50):
they have other liver issues.
An ESR plus or minus the ESR isplus or minus.
That's usually going to be morebeneficial for someone younger.
Serum protein electrophoresiswith immunofixation.
Looking for anyparaproteinemias, tsh is a
little debatable.
Very often it is going to beunremarkable.
Rarely you may find somethingHemoglobin A1c or a glucose
(15:14):
tolerance test.
Those are going to be, in theUnited States at least very high
yield and then a vitamin B12level.
Now let's say we have someonewith one of those red flags.
Well, what are the extra teststhat we're going to want to do?
Well, that really depends onwhat the clinical presentation
is.
So there are, as I said earlier, hundreds of causes of
neuropathy, and so the clinicalhistory is going to have to
(15:36):
guide you a little bit on that,and that may prompt other things
.
It's obviously going to promptanother EMG and that's going to
make you look for things likedemyelinating disease EMG and
that's going to make you lookfor things like demyelinating
disease.
So we have acquired, versusinherited, demyelinating
disorders.
So our classic acquireddisorders are something like
Guillain-Barre syndrome or, onthe more chronic side, cidp,
(15:57):
chronic inflammatorydemyelinating polyradicular
neuropathy.
The classic inheriteddemyelinating neuropathy is
Charcot-Marie-Tooth type 1,which in reality is diagnosed
probably more on genetic teststhan it is in the EMG lab
anymore these days, although I'mnot a child neurologist so your
mileage may vary on that.
Other testing that you may seedone CSF testing.
Again, in things likeGuillain-Barre syndrome you may
(16:19):
get a lumbar puncture, lookingfor that albuminocytologic
dissociation.
You may also be checking forother kinds of inflammatory
markers.
Cytologic dissociation you mayalso be checking for other kinds
of inflammatory markers.
You may also get a nerve biopsy.
In particular when you'rethinking of things like
vasculitis, that's going to besomeone who presents with
something called mononeuritismultiplex which is where you get
these random different nerves.
Your named nerves get pickedoff kind of in a
(16:40):
non-length-dependent,non-confluent fashion, although
over time it may becomerelatively confluent.
You're also looking for signsof infection or infiltration
with things such as cancer.
So nerve biopsy you definitelywant to make sure that the nerve
is already damaged becauseyou're going to be cutting the
nerve to do the biopsy.
Autonomic testing can also bedone, although it can be a
(17:00):
little challenging logistically,depending on your practice
setting.
There's a test called the QSARTQuantitative Pseudomotor Axon
Reflex Test.
This is essentially a sweattest and it can be helpful in
people who have primarily smallfiber neuropathies, where your
nerve conduction studies may beotherwise unremarkable and you
still think like something looksa little fishy.
So it can be helpful in certaindisorders.
(17:22):
A tilt table test could also beconsidered in someone who's
having a lot of autonomicsymptoms that you're wanting to
evaluate further.
So two broad camps as we moveforward we have mononeuropathies
and polyneuropathies.
So mono one, poly many.
So some of the mononeuropathies.
Obviously a mononeuropathy canaffect any nerve in the body,
but we're just going to touch ona couple that are likely to
(17:44):
show up.
So obviously carpal tunnelsyndrome, the most common
entrapment neuropathy in thebody, right Median neuropathy
due to compression at the wrist.
So very often on exam you'll geta history of someone who's got
paresthesias or tingling intheir hand.
Classically they'll want toshake their hand out when they
first get up in the morning, ormaybe exacerbated by certain
activities such as running abicycle or driving a car, other
(18:07):
kinds of manual relatedactivities, and when it
progresses you may get somenumbness over the thenar aspect
of the hand.
You may also get some atrophyof the thenar aspect of the hand
weakness, with thumb abduction,and so you're going to try
conservative therapy first withthings like wrist splints, and
if that's unsuccessful, orthey're already showing signs of
(18:28):
weakness in the hand, you'regoing to be getting an EMG
looking for signs of activedenervation, make sure to
confirm that the localization iscorrect, and then you're going
to be sending them to a handsurgeon for surgical
decompression.
The other mononeuropathy thatwe're going to be talking about
is Bell's palsy.
So Bell's palsy, by definition,is idiopathic, so it is a
(18:48):
facial nerve palsy or seventhnerve palsy causing upper and
lower facial weakness, althoughthis can be variable and may
progress over time.
So you may get people who aremore lower than upper, but there
is usually some degree ofasymmetry.
Also, if they have weaknesswith forced eye closure on the
affected side, that is veryhelpful, because that is going
(19:09):
to be more of that seventh nerveweakness.
You may also see and these aresome things that I think are
very helpful if there ishyperacusis, that is to say the
nerve distipedius isn't able totamp down on that loud reflex,
or if they have altered taste.
A lot of times I'll takesomething either salty or sweet
like a sugar.
If I'm in the ED, I'll take along tip applicator and just put
(19:30):
some saline water on one sideand see if there's impaired
taste on one side of the tongueor the other.
If there is, then that tells meyes, it's definitely Bell's
palsy.
Right, it's the seventh nerve.
It's doing taste of the tongue.
So, as I mentioned, bell's palsyquote unquote is idiopathic,
that is to say we don't know whyit happened.
So that doesn't mean we don'tcheck for things.
You still have to check forthings.
Otherwise it is a facial nervepalsy due to X.
(19:52):
So, for instance, we're in Ohio, where I am, so we have to
check for Lyme disease, right?
I check for it on every personwho comes in with a seventh
nerve palsy and we get a handfulof people who test positive for
Lyme disease every year.
So this is something to keep inmind if you are in an endemic
area.
Other causes that you do have tokeep in mind things like HIV,
(20:12):
sarcoidosis, diabetes, as wementioned can affect any part
and then sometimes malignancy,right, if there's infiltration
of that seventh nerve, thatcould also cause a similar
presentation.
The classic treatment is, ofcourse, of steroids.
There is some debate as towhether antivirals may be
helpful, and you do need toprovide some supportive care as
well.
So that typically involves eyedrops, ointment and making sure
(20:35):
the eye is patched appropriatelyduring sleep so people don't
develop a corneal ulceration.
Moving on to polyneuropathiesthere are so many causes of
polyneuropathy so we're justgoing to focus on a handful.
So first off, diabetes-relatedit can affect any part of the
nerve.
As I have said several times,we can even start seeing some
neuropathy start to develop withthe quote-unquote pre-diabetes
(20:58):
or just impaired glucosetolerance.
This tends to be sensory morethan motor.
You will also tend to getautonomic involvement.
That's why you can see thatredness distally in people who
have had diabetes for a longtime in their legs.
You can also get this diabeticamyotrophy.
What is diabetic amyotrophy?
So it is an acute painfuldisorder typically affecting the
(21:19):
thigh compartment in someonewith diabetes.
And you can actually get MRIsof the muscles.
You can see some swelling andedema in there.
So it may seem like more of amuscle disorder on presentation,
but it does have nerveinvolvement.
We mentioned hereditaryneuropathies in passing earlier.
Right CMT, type 1, autosomaldominance, demyelinating
neuropathy.
On exam you'll typically seehigh arches in the feet, hammer
(21:43):
toes, they may have distal legatrophy.
On nerve conduction studiesyou'll see slowed nerve
conduction velocities withoutconduction block.
So conduction block issomething you typically see with
acquired neuropathies, theseimmune-mediated neuropathies.
Speaking of Guillain-Barresyndrome, so it is a
polyradiculoneuropathy and ittends to have an acute to
(22:04):
subacute progressive pattern ofnumbness and weakness and
reduced or absent reflexes.
In reality those are the onlycriteria.
Is this progression of numbnessand weakness and reduced
reflexes?
Often in the vignettes on testsyou'll see a preceding illness,
whether that's GI or an upperrespiratory illness of some sort
.
More severe cases may have someautonomic instability
(22:25):
associated with them.
So you can see these big swingsin blood pressure and heart
rate and such, and that canprompt them to need to be in the
ICU even before they starthaving any bulbar weakness or
respiratory issues which canalso develop.
The differential diagnosis forthis includes some very strange
things like botulism toxicity,west Nile virus, polio which we
(22:46):
don't see, thankfully, too oftentick paralysis if you're in an
endemic area and some otherdisorders also.
So there are multiple subtypesof Guillain-Barre syndrome.
The one that we tend to see inthe United States most often is
AIDP acute inflammatory,demyelinating, polyradicular
neuropathy.
But there are axonal variantsAMAN and AMSAN and, of
(23:08):
particular note, there issomething called the
Miller-Fisher variant which isassociated with a ganglioside
antibody, gq1b, and that has thetriad of ataxia,
ophthalmoparesis and areflexia.
When we're working up someonefor GBS, typically, as we
mentioned, we have nerveconduction studies cooking.
We also are going to usually bedoing a lumbar puncture and
(23:28):
looking for changes in the CSF,typically an elevated protein
with a relatively normal whiteblood cell count, which is
referred to as analbuminocytologic dissociation.
First-line treatments includeIVIG and plasmapheresis.
These have been found to berelatively equivalent.
Ivig may not be as quick in itsaction as plasma exchange but
(23:49):
it does tend to be a little moreaccessible, depending on your
resources available.
So you kind of have to look atthe treatment setting.
But A second course that'ssomething you'll see sometimes
if someone's not improving asexpected.
It's been studied.
It hasn't been found tonecessarily be particularly
helpful.
So you do need to watch, as wementioned earlier, the negative
(24:11):
inspiratory force, the vitalcapacity, and make sure that
people's respiratory vitals staystable, especially if they are
having progressive weakness tothe point where they are unable
to ambulate and they may behaving some dysarthria or
dysphagia to the point wherethey are unable to ambulate and
they may be having somedysarthria, dysphagia, cidp or
chronic inflammatorydemyelinating polyradicular
neuropathy typically has arelatively subacute presentation
.
It tends to be length dependent.
(24:31):
A lot of times they'll havesome sensory changes in the feet
, maybe developing some footdrop, ankle weakness and you
kind of have this progressive orrelapsing weakness and numbness
presentation.
So nerve conduction studies aregoing to be the key for coming
to this diagnosis, with somedemyelinating changes and
conduction block, and you veryoften will get a lumbar puncture
on these people as well,looking for again this same
(24:54):
albuminocytologic dissociation.
So first line for treatment istypically steroids, usually
prednisone, although you can useother therapies as well, like
IVIG and plasma exchange.
If the steroids are too high ofa dose for too long, you will
be looking at adding onsteroid-sparing therapy.
The most common oneshistorically have been things
(25:15):
like azathioprine andmycophenolate and then you would
sometimes see, in more extremecases, cyclosporine,
cyclophosphamide, and there areother immunotherapies that are
now also becoming available.
Something that you will see ifyou work in the ICU is a
critical illness neuropathy, andwhat this is is essentially
someone who spends a prolongedperiod of time in the ICU and
(25:36):
they develop weakness.
They've come off the ventilator, but they're awake and they
just can't move.
They're weak, they havenumbness, and so you can also
have a concurrent criticalillness myopathy.
Your EMG will help youdifferentiate between these two,
but very often a criticalillness, neuropathy and myopathy
travel together and there isn'tany definitive treatment for
this entity.
(25:56):
It's just more to help you withprognosis and to give you some
guidance in terms of like.
Why is this person still soweak, even though you know maybe
their illness is better?
They should be getting out ofbed, they should be
participating in rehab, andthey're just not able to Next up
paraprotonemic neuropathies.
So this is a bit of an unusualfamily of disorders.
So these are often sensorypredominant, but they can be
(26:17):
sensory motor, multifocal oreven involve cranial nerves.
So there's a few classicentities here.
One of these is MGUS, ormonoclonal gammopathy, of
undetermined significance.
Mgus is associated withneuropathy, but very often we
need to do some further workupand you may, depending on your
comfort level, need to rope in ahematologist oncologist.
There may be things likebiopsies that need to be done,
(26:39):
bone biopsies or kappaappalambda, light chains, etc.
Etc.
So you do have to maybe rope inthe hematology oncology
department for a little furthertesting, depending on the
clinical milieu.
So other things that can beassociated with neuropathy in
this family multiple myeloma,waldenstrom's, macroglobulinemia
, amyloidosis or otherhematologic malignancies.
(27:02):
Another entity that they love toask about I think it's probably
more prevalent on boardquestions than it is in real
life is POEMS syndrome, whichstands for polyneuropathy,
organomegaly endocrinopathy andmonoclonal plasma cell disorder
and skin changes.
So it is a lambdaparaprodinemia, and it may look
very similar to CIDP in terms ofits presentation, but you'll
(27:24):
have these other things right,typically the organomegaly, the
endocrine disorders and the skinchanges.
Those are things that you don'tsee with CIDP, so that can
sometimes prompt furtherevaluation.
Something that also shows up inthe questions from time to time
is something called DADS, whichis distal acquired
demyelinating symmetricpolyneuropathy, which is an
(27:44):
anti-MAG, m-a-gmyelin-associated glycoprotein
antibody associated disorder.
Autonomic neuropathies can alsomanifest.
They may occur with other formsof neuropathy or they may occur
by themselves, so they can, asalways, occur with diabetes.
The classic one to think of,though, is amyloidosis, and this
can either be monoclonal or itcan be genetic trans-thyretin
(28:06):
mutation related.
Autonomic neuropathies can alsobe seen with HIV, and there is
a perineoplastic syndromeassociated with anti-ganglionic,
nicotinic acetylcholinereceptor antibodies.
We made it.
We made it through theneuropathies, we're past the
(28:27):
nerves, we are now to theneuromuscular junction.
So we've got two primedisorders that it's always good
to know about for neuromuscularjunction disorders.
So first up we have myastheniagravis.
This affects the post-synapticneuromuscular junction.
So there's a bimodaldistribution here.
We've got young women,typically third decade, and
older men over the age of 50.
Those are the most commonpopulations that we'll see
myasthenia show up in.
Very often the first symptomswill be things like ptosis,
(28:50):
diplopia, but about half ofthose may develop generalized
symptoms within a couple ofyears and about 10% will present
with bulbar weakness and somecervical involvement, that is,
the neck.
So it's not uncommon for thesepeople to be seen by optometry
or ophthalmology first due tothe ocular symptoms that can be
so common.
At presentation.
Diagnosis wise these days theantibody testing is really good.
(29:13):
About 90% of patients will beantibody positive.
85% are going to be the moretypical binding blocking or
modulating antibodies.
5% of those might be musk,which is going to be a little
bit more bulbar onset.
They tend to have morerespiratory involvement, more
facial weakness, so a littlemore aggressive course, and they
don't respond as well totreatment as the people who are
(29:35):
positive for the otherantibodies.
Sometimes you may still need todo neuroconduction studies and
that'll show a decrementalchange on repetitive stim.
So that may show up in aquestion stem.
There is some debate aboutinitial treatment.
So symptomatic treatment isusually with periodostigmine,
aka mestinone, which is acholinesterase inhibitor.
You do have to watch out itwill increase secretions right,
(29:56):
saliva, diarrhea, tearing thingslike that.
So any place that makes fluidmaking more fluid.
And there is some debate aboutwhether to start disease
modifying treatment when peoplehave purely ocular symptoms.
If periodostigmine is able tokeep things under wraps, I tend
to be of the party that I thinkmaybe disease modifying
treatment is more appropriate tostart at beginning, just
(30:17):
because of so many peopledeveloping generalized symptoms
over time.
So our typical disease modifyingparadigm, first line is very
often prednisone and you titrateup slowly.
If you start at too high of adose it can paradoxically worsen
things and cause a myasthenicexacerbation.
If you're not able to getsomeone down to a low dose of
(30:38):
maintenance prednisone, you'regoing to be using steroid
sparing therapy and those areagain classically mycophenolate
and azathioprine.
You can also use things likeIVIG or plasma exchange and
there are a number of newmonoclonal antibodies and other
types of disease-modifyingtreatments out there.
I don't know if those arestarting to hit the test just
yet, so we're not going to gointo them too much.
(30:59):
A word about a myasthenic crisis.
So this can present with verysudden worsening weakness of the
bulbar muscles, respiratorymuscles, and this can be
triggered by stress, differentkinds of antibiotics such as
aminoglycosides, infections,recent surgery, certain
medications, as we mentionedaminoglycosides, quinolones,
(31:20):
magnesium, beta blockers,hydroxychloroquine.
So people definitely need toknow before they start a new
medication whether or not it isgoing to be safe for them with
myasthenia.
And you may need sometimes, toquote medically optimize someone
with myasthenia prior to havingan elective surgery, and that
may mean giving them a shortcourse of IVIG or some other
(31:40):
kind of treatment.
So that just really depends onthe context and your particular
patient that you're taking careof.
Another treatment that is outthere is thymectomy.
So if they have a thymoma,obviously we're going to remove
that.
For people who don't have athymoma, there may still be some
benefit, not immediately per se, but over time.
They generally require lessimmune suppressive medication.
(32:03):
Next up in our NMJ isLambert-Eaton-Myasthenic
syndrome.
So this is a presynapticneuromuscular junction disorder
and it's associated withantibodies against voltage-gated
calcium channels.
So very often this will beassociated with small cell lung
cancer, although there can beperineoplastic versions as well.
So if they have the cancer,treat the cancer.
(32:23):
If they have no cancer, thenyou treat with immunosuppression
, ivig, plasma exchange, kind ofthe usual things at this point.
So typically if this is a man,you'll get some autonomic
symptoms, including erectiledysfunction very commonly, and
they'll get some kinds ofweakness.
You can see hyporeflexia aswell and you can see this
phenomenon called augmentation,where if you have them flex a
(32:47):
muscle and then you check thereflex before and after
activating that muscle, thereflexes will often be brisker
after you have them use thatmuscle for a short period of
time.
And you'll see a similar thingon nerve conduction studies as
well, with repetitivestimulation.
We are in the home stretch, weare at the muscles.
So let's talk about myopathies.
So the classic pattern for amyopathic process is going to be
(33:11):
weakness, typically proximalmore than distal, and obviously,
because it's the muscle, youusually shouldn't have sensory
involvement unless there'ssomething else going on.
Lab-wise you're going to bechecking a CK level, maybe an
aldolase.
Very often you'll be doing EMGsand nerve conductions on these
and this will show typicalpatterns.
The typical pattern for amyopathy on needle EMG is going
(33:33):
to be low amplitude, polyphasicand early recruitment, which is
kind of the opposite of what wenormally see for a neuropathic
process.
So in some severe cases you mayalso need a muscle biopsy.
Now a word about EMGs andmuscle biopsies and CK levels.
You want to check your CKbefore you poke the muscle,
right, you poke the muscle witha needle, it may raise the CK
(33:55):
and similarly the muscle biopsyitself may cause an elevation in
CK as well.
You also don't want to biopsythe muscle that you also poked a
needle into, because thatmicrotrauma may influence the
pathology a little bit, so itmay be a little less reliable.
So, moving on, our first familyis inflammatory myopathies.
Now some of these are going tosound really familiar
(34:15):
Polymyositis, dermatomyositisand inclusion body myositis.
Then you also have immunemediated necrotizing myopathy.
So polymyositis and inclusionbody myositis.
Then you also haveimmune-mediated necrotizing
myopathy.
So polymyositis, right, youtend to have that classic
pattern of weakness, elevatedCKs, dermatomyositis, elevated
CKs, strong association withdifferent kinds of cancers.
So you need to check out forthat and you're looking for that
(34:37):
skin involvement, that rash,that shawl sign.
Immune-mediated necrotizingmyopathy very often will be
triggered by statins, may havean association with HMG-CoA
reductase antibodies and againyou'll treat this with
immunotherapy.
Inclusion body myositis oftenhas a very slow course.
Typically you'll have earlyweakness of the distal upper
(34:57):
extremity flexors, the quads,bulbar muscles potentially, and
on muscle biopsy you'll get,obviously, inclusion bodies.
That's kind of the big takeawaythere, so that can be very
helpful in that case.
Moving on to endocrine-relatedmyopathies so different
endocrine disorders can causemyopathic changes.
(35:18):
So hypothyroidism can causemyalgias, proximal weakness,
myxedema changes.
So hypothyroidism can causemyalgias, proximal weakness,
myxedema, hyperthyroidism youcan get fasciculations,
ophthalmoplegia, hyperreflexiaand then, as we mentioned
earlier, you know, kind of thelooks like an endocrine related
myopathy.
Is the diabetic amyotrophyno-transcript getting weaker
(35:50):
again, more in their shouldersand legs, and it's like this
isn't the same kind of weaknessthey had before.
Well, you might need to backoff on the steroids.
So you will oftentimes check aCK.
It's going to be normal.
Emg very often will be normal.
Some steroids are more likelyto do this than others
Dexamethasone more so thanprednisone or hydrocortisone.
(36:10):
So you do have to watch outwhen you're using steroids to
treat one other condition asthat may cause this kind of
paradoxical new problem.
Moving on to toxic myopathies.
So the poster child for thisfamily are statins, which can
cause pain, very often in theshoulders and the thighs, and in
more severe cases, weakness aswell.
In those severe cases, thereally severe cases, it'll go to
(36:31):
that necrotizing myopathy thatwe mentioned earlier.
Other medications can alsocause a toxic myopathy.
Ck levels may be mildly orsignificantly elevated.
Typically remove the offendingagent and most people should get
better.
Finally, inherited myopathies soa lot of these will present
early in life.
There are some that willpresent in adulthood, so a
(36:52):
couple that I want to touch on.
So myotonic dystrophy veryoften is associated with some
other systemic disorders.
You can see myotonia, which isthis impaired relaxation of
muscles.
So for instance, you go toshake somebody's hand, they
can't open their hand right awayand you can use sometimes like
sodium channel blockers, likephenytoin or other types of
things to help with that.
So type 1 myotonic dystrophyyou typically have distal
(37:15):
weakness, they have cataracts,frontal balding, they'll also
have some cardiac and endocrineassociated disease and they
might have some mild cognitiveissues as well.
Mitochondrial myopathy this iskind of a wide category,
significant variabilitydepending on the syndrome.
But whenever you have amitochondrial disease you expect
multi-organ involvement.
(37:35):
So myalgias, ophthalmoplegia,other organs, and obviously it
tends to be maternallytransmitted due to the
mitochondria.
Some of the classic metabolicadult-onset myopathies may
present with exercise-inducedweakness, cramps, myoglobinuria
right, you get that dark urinemyocardial disease, carnitine,
palatoyl transferase IIdeficiency are probably the two
(37:57):
most common.
You can also see Pompe diseaseor acid maltase deficiency.
So it has an adult onset formwith proximal weakness and
respiratory muscle weakness.
And you can check the alphaglucosidase activity as well as
genetic testing.
There is a treatmentalglucosidase alpha, and just
like that we have made it to theend of the muscle category and
(38:18):
we have finished our rapidsurvey through the peripheral
nervous system.
If you made it to the end, goodon you.
Thank you so much for spendingyour time listening to me rattle
on about neuromuscular diseases.
I know this is a lot ofinformation and it's still a
little bit longer than I wouldhave liked it to be, but it's
just such a broad category.
Obviously, we will have torevisit some of these topics in
(38:38):
more depth in the future.
I hope this was at leastedifying in some fashion and
will help you on some of yourexams and hopefully even more so
in real life when you're takingcare of patients.
If you found this podcasthelpful, educational, leave us a
five-star review, leave us somefeedback.
You can check out our past workat theneurotransmitterscom.
You can also find me on Twitter.
(38:58):
Slash x at drkentrisd-r-K-E-N-T-R-I-S, or the
podcast itself at neurounderscore podcast.
Again, thank you for listeningand if you have any show
suggestions, ideas, you canalways get a hold of us through
our website.
Popular Podcasts
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com
On Purpose with Jay Shetty
I’m Jay Shetty host of On Purpose the worlds #1 Mental Health podcast and I’m so grateful you found us. I started this podcast 5 years ago to invite you into conversations and workshops that are designed to help make you happier, healthier and more healed. I believe that when you (yes you) feel seen, heard and understood you’re able to deal with relationship struggles, work challenges and life’s ups and downs with more ease and grace. I interview experts, celebrities, thought leaders and athletes so that we can grow our mindset, build better habits and uncover a side of them we’ve never seen before. New episodes every Monday and Friday. Your support means the world to me and I don’t take it for granted — click the follow button and leave a review to help us spread the love with On Purpose. I can’t wait for you to listen to your first or 500th episode!