A Guide to Carpal Tunnel and Other Nerve Conditions

Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Dr Gavin Nimon (00:00):
Have you ever wondered what causes that
tingling sensation in your handsor feet, or why some patients
struggle with unexplainednumbness and pain?
Peripheral neuropathy is acomplex and often misunderstood
condition that affects millionsof people worldwide.
In today's episode, we'rediving deep into this intricate
topic with Dr Jessica Hafner, aneurologist from the Queen
Elizabeth Hospital.
Whether you're a medicalstudent, a seasoned practitioner

(00:21):
or someone just curious aboutthe human nervous system, this
episode promises to unravel themysteries of peripheral
neuropathy and offer practicalinsights into diagnosis and
management.
G'day and welcome to Aussie MedEd, the Australian medical
education podcast designed witha pragmatic approach to medical
conditions by interviewingspecialists in the medical field
.
I'm Gavin Nimon, an orthopaedicsurgeon based in Adelaide, and

(00:42):
I'm broadcasting from Kaurnaland.
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I'd also like to remind youthat, if you enjoy this podcast,
please subscribe or leave areview or give us a thumbs up,
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owners of the land on whichthis podcast is produced.

(01:03):
Acknowledging the traditionalowners of the land on which this
podcast is produced, the Kaurnapeople and pay my respects to
the elders, both past, presentand emerging.
Well, it's my pleasure now tointroduce Jessica Hafner, a
consultant neurologist from theQueen Elizabeth Hospital,
working in the public sector.
She describes herself assomeone who's got a strong
passion in medical education andteaching.
She's also Director of BasicPhysician Training and she's

(01:24):
going to talk to us aboutneurology and peripheral nerve
disorders in general.
Welcome, jessica.
Thank you very much for comingon.
Aussie Med, ed.
It's great to have you here.

Dr Jessica Hafner (01:32):
Thank you.
Thanks for the invitation.

Well, peripheral nerve disorders are something I
see regularly as an upper limborthopedic surgeon, but
obviously it's more than just acarpal tunnel that can cause
peripheral nerve reductionsensation in the hands.
It's quite a huge area.
I thought I'd like to ask youabout how you consider
peripheral nerve disorders whenyou're actually working someone
up.
What is the thoughts that gothrough your head when you're
assessing them?

Yeah.
So I think probably the firstquestion is really around
looking at what the pattern ofit is, and that's going to be
the thing that tells us howworried we need to be about this
sensory change and obviously togo even one step back.
Obviously sensory and motorchanges can come not just from
the peripheral nervous systembut also the central nervous

(02:16):
system, and so really when wesee a patient who's had sensory
and or motor symptoms, that'sour first thought as a
neurologist is where is thelesion?
And the trick there is reallyat looking at the pattern and
understanding enough about ourneuroanatomy to be able to tell
what part of that neural axis isgoing to be involved.

(02:39):
So for peripheral nervedisorders, the few main patterns
that we see, the most commonwould be things such as carpal
tunnel, where we're just gettingsymptoms very local in the
hands, usually coming on atnight time, tingling, waking
people up we all know the sortof plastic syndrome but then
also tingling in both of thefeet would be probably the other

(03:03):
really common way thatperipheral nerve disorders
presents and that sort ofsymmetrical pattern starting in
the feet, because they're thelongest nerves and the longest
nerves are the ones that are themost vulnerable to the really
common things that causeperipheral neuropathy, such as
diabetes.
And so that's my first questionreally is where are the symptoms
?
Is it just in one side, bothsides, starting in the feet,

(03:27):
starting in the hands, or is itall of them, hands and feet?
And then also making sure thatwhen I do an examination I'm
really confirming that the signsfit, with the problem being in
the peripheral nervous systemand not something more centrally
.
So making sure that we don'thave any outgoing plantar
responses or increased tone orhyperreflexia or anything that

(03:50):
makes us think we might bedealing with like a spinal cord
issue and bowel and bladderdysfunction.
That sort of thing would beanother thing to really screen
for.
If you've got particularlybilateral leg symptom and then
in terms of also the other thingthat would be a clue to a
central nervous system disorderwould be symptoms like down just
one side of the body, so an armand a leg on one side, or the

(04:11):
face involved as well.
Really, then you're thinkingabout, you know, could be a
stroke, or something else in thebrain and then I guess, once
you've worked out where theproblem is and you've confirmed
that it's a peripheral nerveproblem by looking for, you know
, loss of reflexes and loss ofsensation, what's the pattern?
Is this something that'ssymmetrical on both sides and

(04:31):
sort of just coming up the legs,or is it something that's just
affecting a particular nerveroot or a particular peripheral
nerve, and that'll help usreally narrow down where the
lesion is?
And then also the tempo of theproblem.
And that's the other thing wereally need to pay attention to,
because things that come onvery slowly and insidiously.

(04:51):
We've got time to work it out,we can think through it, we can
do some tests and sort of reallyget a picture before we need to
worry.
If something's come on veryquickly and there's red flag
symptoms, then we might need tomove much faster and think much
more quickly.
In terms of red flag symptomsfor peripheral nerve disorders,
the things that really make ussort of sit up and listen is if

(05:13):
it's rapidly progressive.
So sensation, that sort of oh,I had a tingle in my toes
yesterday, but now it's up to myshins and I'm starting to feel
like I'm having trouble standingup out of a chair.
We really need to move quickly.
We're thinking is thisGuillain-Barre, is this spinal
cord compression?
That's the kind of situationthat you might need to send
someone straight to theemergency.

(05:34):
Other things that are red flagsis asymmetrical symptoms.
So I've got sort of reallysevere symptoms in sort of one
arm, but not in the other arm.
You're sort of thinking there'ssomething going on.
It's not just your averageneuropathy.
Lots of motor involvement early.
So somebody who's getting lotsof it looks like a peripheral
neuropathy, but it seems to bejust affecting the motor nerves

(05:56):
and not really the sensorynerves.
You start to think is thismotor neuron disease or
amyotrophic lateral sclerosis?
And then then also, if it'svery painful so someone who
develops a foot drop and it'svery painful, or a wrist drop
and it's very painful then weworry is this vasculitis?
And that can obviously can be amedical emergency as well.

(06:17):
And then early autonomicinvolvement.
So peripheral neuropathy.
And suddenly they've also gotreally bad postural hypotension
or something as well as tinglingin their toes, a bit of a red
flag, could be amyloidosis,could be perineum plastic.
And then the other thing issomeone who's very systemically
unwell.
So as well as havingneuropathic symptoms, they've

(06:38):
also got night sweats and weightloss and all of those other
things that would make us sit upand listen in any circumstance.
So they're the sorts of thingsthat I'm assessing when I first
see somebody with sensory andmotor symptoms Where's the
lesion and how fast is it moving, and are there any red flag
features?

And it sounds like a lot of them are more
central type conditions ratherthan peripheral type conditions.

They're really about red flag peripheral
nerve disorders.
So vasculitis affecting theperipheral nerve and motor
neuron disease is border zone.
It's obviously affecting theanterior horn cells which are in
the spinal cord and that's thepoint between the peripheral and
the central nervous system andthat is why you get a mixture of
signs in that condition andthen things that give rapidly
progressive things.

(07:21):
I did mention spinal cord,obviously as an emergency, but
Guillain-Barre disorder is aninflammation of the peripheral
nerve can be a medical emergencyas well.

Are there any central conditions themselves
that we need to be watching outfor that also have red flags too
, then.

Yes, so similar.
In things that are rapidlyprogressive and people have
rapidly acquired disability.
We always have to thinkcarefully, and central things
could do that as well.
So things that come on oversort of seconds to minutes we're
thinking about strokesparticularly Things that come on
over sort of hours to days,particularly if the distribution

(07:58):
is suggestive of a centrallocation, so affecting one side
of the body or beingcharacterized by ataxia or
involving the cranial nerves,double visions, word speech.
Think about things likedemyelination of the central
nervous system, so that'smultiple sclerosis as opposed to
demyelination of the peripheralnerves, which is more

(08:19):
Guillain-Barre.
And then also thinking aboutother things coming on over sort
of weeks to months, Obviouslyworry about things like brain
tumours or space-occupyinglesions, people that are getting
evolving neurological symptomsover slightly longer periods of
time.

Right, Okay.
So a question that comes tomind when you're talking about
those conditions withGuillain-Barre
parsing-neutrality syndrome,where you get peripheral
neuropathy secondary to aviral-type causation how does
that vary compared toGuillain-Barre, which I thought
there was some sort of viraletiology for it or some sort of
autoimmune disorder?

That's a really good question, gavin.
So both of those conditions areinflammatory.
So the thing that's causing theproblem in the nerves is
inflammation and it's beingdriven actually by the immune
system rather than infection.
So it's an autoimmune typeinflammation.
Parsnage-turner, which we alsosometimes call brachial neuritis

(09:14):
, is inflammation affecting thebrachial plexus and it can be
triggered by things such asvaccination or a viral illness.
But it's not an infectionactually causing it.
It's more the immune responseto that insult that then sort of
seems to aberrantly attack thenerves in the plexus and cause

(09:34):
problems.
Classically that will presentwith very severe pain.
People often end up presentingto emergency services and
requiring opiates.
It's very severe neuropathicpain and then followed up sort
of days afterwards by adevelopment of motor weakness.
Similarly, guillain-barre isalso an autoimmune inflammatory

(09:57):
condition which is oftenoccurring in the setting of some
sort of immune stimulation.
So it can occur, you know, ofsome sort of immune stimulation,
so it can occur several weeksafter a viral infection.
We do see cases ofGuillain-Barre which seems to be
linked to having hadvaccinations or by other

(10:19):
stressors such as surgery.
Classically in medical schoolwe all learned about
Guillain-Barre being triggeredby a campylobacter jejuni, and
that certainly can be the caseor it can actually just occur
without any obvious drivingfactor.
But both of those conditionsare similar in that they are
sort of a dysregulation of theimmune system causing peripheral
nerve damage, one in thebrachial plexus and the other
sort of more generally,particularly approximately the

(10:42):
lumbosacral roots and the plexusand the nerves all being
affected in Guillain-Barre.

Right.
Obviously, there's such a hugelist of causes that can cause
tingling and numbness in thehands or in the limbs as well,
and weakness in general.
How do you go about reallynutting it down to what actual
condition is?

Yeah, so that's a really good question.
So I think when you're facedwith this person who's presented
with sensory symptom and you'vedone your history and exam and
you've worked out that you thinkit's a peripheral nerve problem
and either it's affecting justone nerve or it's affecting sort
of all the nerves andparticularly the feet, then that
helps to focus yourinvestigations.
So for the most commongeneralized peripheral

(11:24):
neuropathy picture, which wouldbe that sort of, you know,
tingling in the feet but sort ofslowly spreading up the legs,
there are some common andpotentially treatable causes of
that that are often screened forin the community by general
practitioners before patientsare referred for non-GP
specialist care, and that wouldinclude diabetes, followed by
diabetes diabetes and then nextafter that is diabetes Very,

(11:46):
very common cause of thisproblem in the community.
Other things that are reallyvaluable to check for is B12
deficiency and that can causevarious neurological
presentations but can cause aperipheral neuropathy.
Also, thyroid dysfunction bothunder and overactive thyroid can
be attributed to this.

(12:08):
And the other thing that oftenactually gets missed in the
community is alcohol excess, andexcess alcohol consumption is
probably one of the more commoncauses I see for people who have
an insidious, slowlyprogressive neuropathy for which
all the other blood testshaven't really shown a cause.
And then you spot the elevatedGGT and ask the right question

(12:29):
and it turns out to be relatedto alcohol.
So that's the first thing, andthen I think the other thing in
terms of initial investigationsis really some nerve conduction
studies, because one of thethings that's quite tricky is
that there's not really anyreliable clinical clues on
examination that help youdifferentiate between a

(12:51):
peripheral neuropathy that's dueto a sort of a metabolic
situation such as diabetes,versus an inflammatory
neuropathy where the immunesystem is actually driving the
damage and something that canpresent Guillain-Barre usually
presents more acutely and sothat makes it clearer.
But there is another variant ofthat which is quite similar,

(13:12):
which is called chronicinflammatory demyelinating
polyneuropathy, or CIDP, andthat presents quite insidiously
and slowly and can reallyclinically look very much like a
more sort of common neuropathy.
And the main way todifferentiate those things is
with a nerve conduction study.
So I think anyone who hasperipheral nerve symptoms that

(13:33):
are disabling enough for them tobe presenting to the GP
probably does deserve at least aone-off nerve conduction study,
just to make sure we're notmissing one of those conditions
that needs a very differenttreatment approach.

Well, now's probably a good time to explain
what actually is involved in thenerve conduction studies and
when you actually do nerveconduction studies versus an EMG
study as well, which I think isslightly different, isn't it?

Yeah, so they're often done together and
it would be very unusual to doan EMG without doing a nerve
conduction study.
But certainly people do donerve conduction studies without
needing to do an EMG and nerveconduction study.
But certainly people do donerve conduction studies without
needing to do an EMG and theseare also a great first-line
investigation for something likecarpal tunnel, and usually with
carpal tunnel you wouldn'tnecessarily need to go checking

(14:15):
for B12 deficiencies et cetera,but you might just go straight
to nerve conduction to try andconfirm the diagnosis.
So when we do a nerveconduction study, usually
there's a brief history andclinical examination before we
start the test, make sure we'retesting the right thing, and
then what we do is apply smallrecording electrodes over either
the nerve or the muscle andthen use a probe to stimulate

(14:38):
the nerve by delivering a smallelectrical pulse and then
recording, using the littleelectrodes we've stuck on the
skin, how quickly that impulsetravels through the nerve and
how large the response is thatwe're able to record and using
that information we're able toget a clue about how well the
nerves are conducting electricalimpulses and whether the

(14:59):
problem is due to the axonsthemselves not working well or
whether there might be the axonsintact, but there's a problem
with the myelin surrounding theaxons, causing slowing or block
of the messages going throughthose nerves.
So that's the main thing, andthe important thing with doing a
nerve conduction study is doingthe right study.

(15:20):
So if someone comes withclassical carpal tunnel symptoms
and I do a study that's reallyfocusing on their ulnar nerve,
I'm not going to get theinformation I need to make the
diagnosis.
So that's why it's important wedo a histrion exam before we
start and we've got goodinformation on our referral so
we know exactly what we'relooking for, because we can't do
all the nerves for everybody.
We would be there all week,yeah.

Can you explain what some of the numbers mean,
though on it.

Yeah.
So there's a lot of numberscome out, and when you get your
nerve conduction study reportI'm sure you've received these
Gavin where you get this blackbit chart with all these numbers
in it and very littleexplanation as to what to make
of it all.
Hopefully there's a goodsummary at the end.
But usually we'll do eithersensory nerves or motor nerves.
There are some situations wherewe record over what we call
mixed nerve, where the fibres inthat nerve are transmitting

(16:08):
both sensory and motor messages.
But in simple terms, thesensory nerves we're recording
over the nerve and stimulatingover the nerve, and so what
we're recording is very, verysmall in microvolts, and so it
can be quite technical in termsof getting a good response.
The amplitude is a sort of asurrogate marker for the number

(16:30):
of axons that are able totransmit messages.
So in somebody who has anaxonal neuropathy so a
neuropathy that is due to lossof axons the amplitude will be
smaller because there are lessaxons translating that message,
and so you're getting less ofthe signal arriving at your
endpoint.
With a motor nerve, we'rerecording actually over the

(16:53):
muscles, so the size of thething we're recording is
actually dependent on the numberof muscle fibers that are
firing off.
So that can be small if we'vegot axon loss, because less
axons means less message gettingto the muscle and less muscle
firing.
But it can also be small inother conditions, such as if
somebody had a severe myopathyand had lost muscle fibers due

(17:14):
to that.
You would also get smallamplitudes on your motor studies
.
The velocity I think you'vementioned sort of makes sense.
It's talking about the speedwith which the message is
transmitted through the nerves.
And then there are some otherwords which kind of sound a
little bit more complicated butare simply markers of the same
thing.
So you might see mention ofthings like distal motor latency

(17:37):
or distal sensory latency.
And the reason we call it thatrather than a velocity is that a
latency is a time measurement,so it's the time between when
the stimulus was sent and whenthe message was received.
And the reason that we need todo that with motor studies is
that because we're stimulatingover the nerve but recording

(17:59):
over the muscle, it's not justthe message traveling through
the nerve that we're measuring.
We're measuring the signalgoing through the nerve, through
the neuromuscular junction andthen through the muscle fibers
to our recording electrode.
And so if we calculated avelocity on that.
That would be sort of odd,because the speed with which the

(18:19):
impulse travels through thenerve, the junction and the
muscle is all variable.
So you'd get this kind ofaverage and it wouldn't really
be truly meaningful.
So we use latency instead,because that's what we are able
to measure.
We're not really able tomeasure the velocity.

So that's only when you're measuring motors, is
it?

Yeah, it's only when you're measuring
motors.
People do report digitalsensory latencies and all that
means is that they haven'tconverted it to a velocity.
But if they had taken adistance measurement, they would
be able to use the latency tocalculate a velocity.
Right, yeah.

And what about fibrillation and things like
that on the muscle fibers aswell?
Because that's also a sign ofsomething going on as well,
isn't it?

Yeah, so that's in the EMG, so I'll talk
a little bit about that as well.
So you mentioned about havingEMG as well as nerve conduction.
So what I've described so far isreally what we call nerve
conduction, and then in certainsituations it's helpful to also
perform a needle EMG.
And what we're doing in thattest is using a small needle
that's got a recording electrodein the tip of it and we insert

(19:21):
that needle into the muscle andthen record the electrical
activity that is within themuscle itself.
So due to the muscle fiberscontracting, and so we don't
give any stimulation with that,we just sit and listen and we
record both while the person isrelaxing their muscle as best
they can sometimes a bit harderthan other times and then also

(19:41):
getting them to activate themuscle, and looking at the
muscle fibers firing off, and byanalyzing that and it's
something that's sort ofanalyzed live by an expert who's
been trained in it we're ableto get all sorts of information.
So fibrillations and positivesharp waves are two words for
essentially the same thing, andthey are generated when small

(20:06):
individual muscle fibers havelost their axonal connection and
they just sort of fire off ontheir own, sort of like a kind
of like a pacemaker kind ofeffect if you like.
The little muscle fiber justfires off on its own when it's
lost that input from an axon.
So if we see that in muscles,that gives us a clue that
there's some denervation that'soccurred.
And there's all sorts oftimeframes in which if a

(20:30):
denervation occurred fiveminutes ago you might not see
fibrillation.
So that's why we often say sendthe patient back in six weeks,
because then we'll be able tosee the fibrillation potentials
and it's often a marker of itbeing a reasonably active or
acute process.
However, that nothing inmedicine and certainly nothing
in neurology is cut and dry andthere are people who have
fibrillations present in theirmuscles for very long periods of

(20:53):
time after the insult.
But it's thought to beprimarily a marker of active or
acute denervation.
And then we also can assess themuscle fibers when the patient
is trying to activate theirmuscle.
We can get information aboutwhether or not the muscle has
good axonal inputs or whetherthere's good messages coming in

(21:14):
from the nerve and then alsowhether the muscle fibers
themselves are healthy.
So in myopathies we also can getabnormalities in the EMG with
seeing very small muscle fibersto the motor units, which is the
group of muscle fibers that areall talking to the one axon get
much smaller and many more ofthem need to fire off to

(21:35):
generate the same amount ofmuscle strength, whereas in a
nerve problem, particularly achronic nerve problem, where the
axon has sprouted and tried tore-innovate the muscle, you can
get these very big motor unitsthat fire off very, very quickly
and have to work very hard totry and generate force.
So there's all sorts of thingswe look at and you get words

(21:56):
like recruitment and polyphasiaand all that sort of stuff, but
it's all just the description ofwhat the motor units look like
and that should be.
Hopefully, when you get thosereports synthesized for you and
we can come up with things aboutwhether there's active or acute
or chronic denervation,re-innovation indicating a nerve

(22:18):
process, a neurogenic process,or whether there's features
suggesting a primary muscleproblem, a myopathic process.

That EMG actually is really interesting
because if you're listening tothe muscle tone and you've
worked out what different wavesrepresent different conditions,
then obviously with this new AIera, being able to analyze all
those different measurementswith AI, must be able to sort of
fine-tune these results evenmore so I would have thought.

Yeah, it's definitely an area that there's
lots of interest in.
For some time there's been asort of computer-assisted
interpretation of EMG, which isnot used that commonly, but
so-called quantitative EMG,where they measure a lot of the
parameters of these musclefibers and try to get sort of
more nuanced data than can comefrom the live human

(23:07):
interpretation.
But yeah, I certainly thinkthat and EEG are the two kind of
leading places where AIapplications I think are going
to be very interesting to watchin the next decade or so in
neurology.
Yeah, Right.

So in working these patients up, we've taken a
good history and we've sortedout the sort of patterns they're
representing.
A couple of blood tests thatcame to my mind as well were
things like VDRL for syphilis,and also I know there's a
condition of hypersensitivity topressure on nerves.
Is that a blood test that'salso done as well as a screen,
or is that an expensive testthat's too hard to do routinely?

Oh look.
So to answer your firstquestion about syphilis,
syphilis wouldn't be something Iwould usually test for.
If I just had someone with afairly typical peripheral
neuropathy, that would be a veryunusual way for that to present
.
But certainly if there werefeatures to suggest some spinal
cord involvement as well orother things, then that may be
something that we could consider.

(24:02):
As neurologists we always thinkof syphilis when we have people
with unexplained cognitiveproblems and then also with
myelopathy spinal cord issues Interms of the HNPP, which is
hereditary neuropathy withpredisposition to pressure
palsies.
That's quite an easy andstraightforward blood test to do
.
It is MBS reimbursed, butusually I would only send that

(24:24):
off if, after doing nerveconduction studies, I found
multiple compressionneuropathies.
And then I would only send thatoff if, after doing nerve
conduction studies, I foundmultiple compression
neuropathies, and then I wouldconsider doing it.
Obviously, with any genetictesting, it's always important
to make sure that your patientis fully counseled and informed
before proceeding with anygenetic testing, because it can
have implications beyond thediagnosis for family members and

(24:46):
also for them personally.

Of course, excellent.
So we've done our bloods andwe've done our nerve conduction
study.
Where do we progress from there?
What's the next things we'redoing?
And working someone up.

Well, it really depends on the patient.
So if the patient has a sort ofvery slowly progressive,
bothersome but non-disablingsensory predominant neuropathy
and the initial investigationshaven't really revealed a cause
and this is not an infrequentsituation that we find ourselves
in, unfortunately I think inthe next decade or so we're

(25:18):
going to discover that quite alot of these sort of slow,
insidious, late-onsetneuropathies are probably
actually genetic in origin, theones that we sort of can't find
the cause for.
In those situations where it'snon-disabling, then usually we
do shift to a symptomatic focusand preventing complications
making sure people are seeingpodiatrists, good footwear,

(25:40):
physio if they've got sort ofbalance issues, falls prevention
and making sure that we'reavoiding any medications or
situations that could worsenneuropathy, so counselling them
about alcohol minimisation,making sure they've got good
nutrition, not giving themantibiotics that could cause a
neuropathy, that sort of thingIn someone who's got more

(26:00):
disabling symptoms or theirsymptoms are more progressive
and we're much more concerned.
Then there is a next level ofinvestigation that you can go to
with looking for more rare andunusual causes of neuropathies,
Looking at things likeamyloidosis, HIV, hepatitis C
and cryoclobulinemia can giveyou a neuropathic presentation

(26:24):
and that sort of thing.
That next level would usuallybe at the level of being in
neurology specialist care.
If you've got somebody who'sprogressing and the initial
screening hasn't worked up andthere's a sort of a list of
various things that they wouldgo looking for and then also
considering you know, could thisbe a genetic condition?
And looking for other clues tothat, and considering genetic

(26:46):
testing.
We do now have access to reallyquite affordable, comprehensive
genetic panels.
We can test for 20, 50 genes ata time, and so we'll be guided
by the clinical situation as towhether that might be indicated,
and then for more focalneuropathies.
So, coming back to things suchas your ulnar neuropathy or your

(27:06):
median neuropathy, such as acarpal tunnel, In addition to
the nerve conduction studies,the other thing that is
increasingly used and, I think,exceptionally useful is imaging
and with either ultrasound orMRI depending on the patient and
the situation, and that wouldbe something that I might also
consider in some of those moreprogressive neuropathies as well

(27:28):
, looking at lumbosacral nerveroots and that sort of thing as
well.
Yeah, Right.

Obviously I understand the MRIs for cervical
or lumbar spine, looking fornerve entrapment there.
One of the interesting thingsI've found is the idea that
carpal tunnel, where the nerveis supposed to be compressed,
the ultrasound shows the nerveactually larger.
Can you explain why that occurs?

Yes, so we think that the nerve is actually
engorged, so it's compressedand that's disrupting sort of
microvascular flow through thatnerve, and so the nerve actually
becomes edematous and engorged.
And that's possibly why thingslike steroid injections work for
so long, because even thoughyou think, well, surely the

(28:10):
steroid wears off pretty quickly, probably the nerve gets
trapped in a bit of a viciouscycle that it swells up and then
the more swollen it is, themore compressed it is, the more
swollen it becomes.
And so by just temporarilyinterrupting that inflammatory
swelling situation you can kindof short circuit it and give
relief, even for extendedperiods of time, with a single

(28:32):
steroid injection.

In your area as a neurologist, what are the more
common things you wouldinvestigate?
I presume a standard carpaltunnel with a nerve conduction
stays, confirming the diagnosis.
You wouldn't routinely do anultrasound for that, would you?
Oh?

I mean I probably wouldn't, except for
various situations, I think,certainly in anybody who you're
sort of surprised by how severethe carpal tunnel is or you're
not entirely sure that theproblem is in the wrist and
whether it's somewhere else andyou're considering sending
someone for surgery, I thinkit's pretty reasonable to do
some imaging just to confirmthat there is actually

(29:05):
entrapment before you go sendingsomebody for an invasive
procedure such as surgery,particularly if there's atypical
features or something about thestory that doesn't quite make
sense.

What I would say is what I find really useful
when I'm assessing carpal tunnelor alder nerves is something
like the simple Tennell's test,which I think is probably my
favourite examination techniqueof the lot.
And it actually is very, veryreliable.
Am I just biased, or is thatactually well-spoken?

I don't know what the evidence is around a
sign in terms of how sensitiveor specific it is.
I certainly do do it and I findit quite useful.
And, yeah, when I find it I cansort of guarantee that my nerve
conductions are going to beabnormal.
The other one I like to also dois the Phelan's test with
putting the hands in a sort of a90 degrees flexed position and

(29:53):
holding them there for a minute,and because sometimes,
particularly if your percussiontechnique's off with your
tonnels, you might not get it,but a phalanx will bring out
carpal tunnel symptoms in mostpeople as well.

All right.
So you've done all these sortof things your area, you say you
treat a lot of the steroids andobservation.
What sort of success rates haveyou found with those sort of
scenarios?

Yeah.
So I mean, I think really mostof this is actually done in the
community rather than by me.
I don't often follow thesepatients up.
Mostly my contact with them isin the nerve conduction clinic.
So for the mild cases and bymild I'm really talking about on
the nerve conduction studies,we can just see that the sensory
responses are a little bitslowed as they go through the
wrist, but there's not reallyany evidence of axon loss or

(30:38):
difficulty with the motor nerves.
In those situations usually wewould suggest splinting
conservatively, and for somepatients that's really helpful.
Just wearing a splint thatholds the wrist in a slight
degree of extension,particularly at nighttime, can
be helpful.
This is a really importantstrategy, particularly when the
cause of the carpal tunnel issomething that's reversible,

(30:59):
such as women experiencing acarpal tunnel during pregnancy.
Nocturnal splinting until thepregnancy is over is usually all
that they need to do.
In people who have moderate tosevere involvement and by that
on the nerve conduction studies,that means we're starting to
see the motor nerves beinginvolved or there's evidence of
axon loss, and particularly ifthere's functional impairment

(31:20):
with weakness, eitherfunctionally or on examination,
those are the patients wherewe're really considering we
might give them a trial of asteroid injection.
Some people have a very goodresponse to that, but those with
axon loss or functionimpairment then really, I
usually am referring them on tosee a surgeon to discuss their
options about a release of thecarpal tunnel.

(31:42):
One of the challenges, though,if there is evidence of axon
loss, is that even with surgicalintervention that doesn't
necessarily result in a recoveryof function.
If there's been axon loss,those axons can be quite slow to
grow back, and that may beincomplete.
So some people, evenpost-surgery, do have residual
symptoms.
And then another thing I guess,to monitor for post-surgery we

(32:04):
do see a small proportion ofpatients who, after having had
surgery, down the track get arecurrence of their symptoms,
and so we frequently see thosein nerve conduction lab being
referred back to have studiesdone again, and in those
situations I'd definitely berecommending imaging.
So ultrasound, particularly ifrepeat surgical intervention is

(32:24):
being considered Scarringpost-operatively can be a cause
of worsening symptomspost-surgery.

Yeah, it's interesting and we obviously do
a lot of carpal tunnels and Iaudited my results for last year
too, but we don't seem to getas a lot of carpal tunnels.
I audited my results for lastyear too, but we don't seem to
get as many recurrences that weexpect.
I don't think there's been thatmany.
Carpal tunnels can be releasedin numerous ways, and when we're
talking about surgery,obviously we're releasing the
flexor adenaculum in the palmaraspect and that can be done
through endoscopic or openapproaches, and I do them under
open, them under open and thenthe vast majority under local

(32:53):
anesthetic alone.
So the patient's wide awake andthe vast majority of nerves are
actually really quite big.
You can see them being squashedby the flexor inaculum.
It's surprising how big thenerve is in general.

I think you're right.
I think a lot of people whomake it to surgical intervention
have probably already triedsplinting and some of them will
have had a steroid injection ortwo, but by the time those
things aren't responding, thendefinitely surgical intervention
can be really powerful andhelpful for a lot of people.

Brilliant.
The other thing too.
I noticed we're talking aboutulnar nerves.
There's actually a large numberof people who have some
subluxing ulnar nerves too.
I believe the figure's aboutone in six.

Yeah, so 16% of people with their ulnar nerve
flicks over their medialcondyle when they flex their
elbow, and some people get akind of little electrical sort
of zing when that happens,unpleasant kind of feeling.
And I think people who havesubluxation they are a bit more
vulnerable to externalcompression injuries because
instead of the nerve beingsafely in the groove when

(33:48):
they're leaning on their elbow,they're leaning directly on the
nerve.
I must say, though, one of thechallenges is, unless you've got
a very sort of thin person withnot a lot of overlying tissue,
it can be quite tricky to beclinically confident that
they're subluxing.
And so you can actually dodynamic ultrasound to watch the
subluxation in real time.
What the intervention is forthat I don't know.

(34:11):
Maybe you'll have someinformation for me on that.
I just tell people not to leanon their elbows, but I'm not
sure if there's anything more tobe done, because obviously the
other issue with the ulnar nerve, and why it's so vulnerable to
problems, is that even when itdoes sit in that groove, it's
quite vulnerable to traction.
Every time you bend your elbowyou're sort of stretching that
nerve, and some people seem tohave shorter nerves than others

(34:32):
and they're much more prone tothat.

Yes, I believe part of the problem with ulnar
nerves or any of the nervesactually is the fact that it's
thought to be not only justlocal compression but traction
as well as an issue, and that'swhy the physiotherapists like
doing traction and doing nervemobilization techniques to try
and improve the symptomatology.
When we do see an ulnar nervethat's actually subluxing from
behind the medial epicondyle andit is causing issues, either
from pain or from ulnarneuropathy, we then tend to
actually release the nerve andtranspose in front of the medial

(34:59):
epicondyle and secure it there,either subcutaneously or
through the muscle or underneaththe muscle, and there's
different various techniques ofdoing that through smaller or
bigger incisions as well.
But that sort of surgery is alot bigger than just doing a
simple carpal tunnel release butcan have very good results as
well.

And it's important for those patients
who've had their nervetransposed to let us know,
because next time we go to dotheir nerve conduction studies
we need to know where the nerveis.
It's often quite a long wayfrom where we're looking for it.

Right, but apart from carpal tunnel and ulnar
nerves, what other nerves canyou see, for focal compressions
as well, that you might bepresented with?

Yeah, so there's probably two that
present reasonably commonly inthe lower limbs.
I mean, there are others ofcourse, but the two most common
ones that we would see in thelower limbs would be a common
perineal neuropathy, which isnow technically called a common
fibula neuropathy, and the mostcommon cause we see for that is
habitual leg crossing.
So the nerve sits very close tothe fibula head with not much

(35:56):
in the way of padding over it inmost people, and so if they
habitually cross their legs itoften sits right on the patella
of their other leg and can causecompression there from external
compression rather than anintrinsic sort of anatomical
compression, such as the carpaltunnel.
And also people who spendprolonged periods sitting

(36:16):
cross-legged on the floor orprolonged periods squatting can
also develop this type ofneuropathy due to external
compression of fibula nerve,which usually manifests with
sort of numbness down thelateral aspect of the leg and
into the side of the foot, andalso if they get motor
involvement they can also have afoot drop due to that.
And then the other one that wesee not infrequently is a

(36:38):
moralgia parastheticusentrapment of the lateral
femoral cutaneous nerve as itsort of comes out from
underneath the inguinal ligament.
It sort of can get kinked there,particularly in patients who've
over a short period of time puton a bit of weight around their
middle, can sometimes cause thenerve to kind of kink more than
it would have previously.
Or, interestingly, rapid weightloss can also precipitate it

(37:01):
and that's usually.
Patients will report this kindof achy, burny, numbness, you
know, sort of a hand-sized patchover the anterior natural
aspect of the thigh, and we cando a conduction study to look
for that.
It is a little bit of atechnically tricky study but
it's possible, and ultrasoundcan also be quite helpful as

(37:21):
well for just confirming thatthat nerve is getting kinked or
compressed.
It's often that condition sortof remits on its own over a
period of weeks to months withjust some reassurance.
However, some people do getpersistent symptoms and in that
situation if it's sort of goingon for more than three to six
months and it's quite bothersomeand painful, then we can send

(37:42):
people for a ultrasound guidedlidnicaine injection and if that
really relieves the symptoms,then they can be considered for
surgical decompression.

Excellent, all right, we head back towards the
general neuropathy that cancause us some sensations.
How do you go about treatingthose?
We've actually done our workup.
We've done a nerve conductionstudies.
We're thinking that it's notpurely a compression neuropathy.
It's got some generalizedissues.
Diabetes is the main cause,obviously.
So obviously controlling thatwould be important.
What other conditions can causea generalized neuropathy that

(38:14):
can be treated as well?

Yeah, so probably B12 deficiency would be
the next one.
That is pretty easily treatableand there's sort of two phases
to treating that.
One is just replacing thevitamin.
Often there's a problem withabsorption, and so intramuscular
replacement is the mosteffective, and particularly if
you've got significantneurological manifestations,
intramuscular replacements wouldbe recommended.

(38:37):
But then it's also important totry and work out why the B12
was low in the first place.
So whether there's a dietarydeficiency usually not seen
unless somebody's adhering to astrict vegan diet or if there's
a problem with absorption, sochronic pro-champump inhibitor
use can predispose to B12deficiency.
Because my understanding as aneurologist is that the

(38:58):
intrinsic factor that helps youabsorb B12 relies on an acidic
environment.
So PPIs can impair that.
That's my understanding.
But also things like perniciousanemia, where there's an
autoimmune process that'sinterfering with your ability to
absorb B12.
So they're the kind of keythings.
Obviously, if it's attributedto thyroid disease, then

(39:18):
treating your thyroid diseaseprocess that interfering with
your ability to absorb B12.
So they're the kind of keythings.
Obviously, if it's attributedto thyroid disease, then
treating your thyroid disease.
Those sorts of things are key.
Alcohol obviously abstinence andor reduction are important, and
then some of the other lesscommon neuropathies, such as the
chronic inflammatorydemyelinating polyneuropathy
that I mentioned before.
Those require specificimmunotherapies and can be

(39:40):
treated either with sort oftraditional kind of
immunosuppression such asprednisolone, usually given with
a steroid-sparing agent such asazathioprine or something like
that, or with intravenousimmunoglobulin, which is very
expensive and there's all sortsof hoops to jump through to use
that.
So you really need to make sureyou're definitely treating the
right thing before you startgoing down the immunosuppression

(40:02):
or IVIG path.
So that's the kind of thingthat would normally be done in
conjunction with a neurologist,and not only nerve conduction
studies but additionalsupportive investigations such
as spinal fluid analysisconfirming that there's an
inflammatory process in thespinal fluid and that sort of
stuff.

Right, you mentioned earlier about the use
of some antibiotics also causeperipheral neuropathy.
Perhaps outline the ones thatwe need to be aware of.
That are obviously useful intreating other conditions, but
obviously you can have some sideeffects.

Yeah.
So it's pretty unusual for theantibiotics to cause a
peripheral neuropathy, but thereare some medications that we do
need to be aware of, both interms of if someone develops a
neuropathy, being aware thatsome of the medications we might
be giving them could becontributing to the neuropathy,
and also, if somebody alreadyhas an established neuropathy,
making sure that we avoid thingsthat could make it worse.

(40:55):
So the classical drugs that wecome to mind most easily when we
think about drugs causingneuropathy are chemotherapy
agents, and particularly thevinca-alcohoids and such as
vincristine and the taxols suchas paclitaxel, are particularly
high risk for this.
But other things that we mightnot necessarily think of,

(41:15):
including some reasonably commonantibiotics such as
ciprofloxacin and metronidazoleand nitrofurantoin, can also
contribute to neuropathy andconsidered sort of moderate risk
, particularly if somebodyalready has an underlying nerve
condition.
Other medications that we maynot sort of necessarily think of
but amiodarone is a reasonablycommon medication culture seen

(41:39):
particularly if it's been usedover extended periods of time.
And another thing that is alsoworth just checking for is
making sure that people aren'taccidentally taking too much B6.
Increasingly, b6 is included inlots of different sort of
health supplements, not onlysort of B complex, but also it's
in energy drinks, it's inpretty much lots of the

(42:02):
supplements that you grab, evenif they don't say B on them.
So some magnesium supplementscontain B6 and people taking
multiple supplements canaccidentally be taking way too
many B6 containing supplementsand end up giving themselves a
B6-toxic neuropathy.
So classically it can presentas a sensory neuropathy.
It can be quite severe or as apainful sort of small fiber-type

(42:25):
neuropathy with pain andtingling in the fingers and toes
.
So always worth checking onthat one as well if someone
comes to you with a newneuropathic symptoms.

And with this general peripheral neuropathy I
may presume the optic nerve andthe auditory nerve is really a
part of central nervous system.
They're not affected in thesesituations.

Yeah, so that's a really interesting
question.
So cranial nerves tend to not beinvolved in all of these
conditions that we've beentalking about, such as the toxic
and metabolic peripheralneuropathies In diabetes.
Some people can get cranialnerve involvement, and it tends
to be more of a very suddenonset.
So, probably due tomicrovascular disease and people

(43:09):
presenting with a sudden onsetcranial nerve 3 palsy, for
example, in the setting ofdiabetes, and then some of the
much less common causes ofperipheral neuropathy, such as
Sjogren's syndrome orsarcoidosis, these rare
autoimmune conditions do have apredisposition for involving the
cranial nerves as well.

(43:30):
So certainly, if you haveperipheral neuropathy with
cranial nerve involvement, thenyou do need to keep your eyes
and ears open and think aboutless common things.
Obviously, though, a Bell'spalsy is a very common cranial

(43:57):
nerve problem that doesn'tnecessarily need to ring huge
alarm bells unless it doesn'tget better.
As expected and similar to whatwe were talking about before
with the brachial neuritis andthe Guillain-Barre, it's thought
to be probably an autoimmune,inflammatory sort of
dysregulation, often triggeredby a virus or some other
physiological stressor.

Yeah, brilliant.
We've covered a lot of groundand I'm sure there's so much
more to talk about, but there'sa lot to take in.
Anything else you'd like tocover or that we've missed out,
or perhaps a take-home point tothe medical students and GPs?

Yeah, look, I think that one of the key
things is that peripheralneuropathy, particularly the
sort of mild, insidious type youoften will miss it unless you
look for it and asking patientsabout it and checking their feet
, checking their sensation, canbe really important because by
making sure that we're lookingafter people's feet and
recognizing that they might beat increased risk of falls which

(44:47):
they certainly can be, isthey've got impaired sensation
in their feet.
If we can pick those things upearly and look after their feet,
get them doing the exercisesthey need, the physio they need,
managing their nutrition,minimizing their alcohol, we can
really do a lot for people withindependence and mobility as
they age, and I think it'ssomething that's often

(45:07):
under-recognized and contributesa lot to particularly falls in
the elderly.
So, yeah, keep your eyes andears open and recognise those
red flags.
I think that's the other thingrecognising when you need to
escalate things.
If it's rapidly progressive.
People have got motor weakness.
It's asymmetrical.
There's other things going on.
Making sure you think aboutthose other things as well.

Well, it's been absolutely brilliant hearing
from you, learning about allthese other conditions as well,
not just purely my carpaltunnels and all the nerve
entrapments, and it's reallyeye-opening to hear about all
this little stuff.
So thank you very much, jessica, for giving up your time.
Really appreciate having you onboard and thank you for coming
on.
Aussie Med Ed.

Yeah, that's my absolute pleasure, Gavin,
thanks for inviting me again.

I'd like to remind you that all the
information presented today isjust one opinion and that there
are various ways of treating allmedical conditions.
Therefore, you should alwaysseek the opinion from your
health professional in the areain which you live.
Also, if you have any concernabout the information raised
today, please speak to yourgeneral practitioner or seek
advice from health organisationssuch as Lifeline in Australia.

(46:12):
If you've enjoyed the podcast,please subscribe to the podcast
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