Here, we’ll take a look at
continuation of peripheral neuropathy.
We looked at plexopathies and we
looked at the roots in greater detail
including Erb’s and Klumpke.
Here, we’ll take a look at individual
nerves that has been damaged,
And which particular nerve has
been damaged is important.
So here, commonly, a site of
injury will be the radial nerve.
Most commonly at the spiral
groove of the humerus.
That’s extremely important anatomically.
How did it occur?
It could be at the side of the axilla.
Now, think about where you are.
And I know that many of you have
heard of Saturday night palsy,
but what does that
Well, during the evening, shall we say
you’re at a club or a bar or whatever
and as you continue to indulge,
and then at some point in time,
maybe you’re sitting on a stool.
And on a stool, you put your
arm back on your arm chair,
and you are not in your proper senses,
and you have forgotten that you left
your arm there over the arm chair
and therefore causing
compression of the axilla.
That’s really what
this is about.
look at crutches.
Where do you place crutches?
On the axilla.
And so therefore may cause
injury to the radial nerve.
If you take a look at the schematic here,
I want you to focus upon the
radial nerve that you see.
And so therefore, in the forearm,
the posterior interosseous syndrome
is something that you want to keep in mind
as well for the radial nerve, please.
include wrist drop,
patient unable to extend wrist
or fingers up.
Occasional forearm, maybe
hand and thumb numbness
could also be seen as well
with radial nerve damage.
leaning on arms or axilla,
sleeping in the wrong
of course, may cause
issues with demyelination or
mononeuropathy in many of the nerves,
but here, specifically,
a possible risk factor.
Wrist drop with inability to extend
your fingers as we talked about.
And then check the three
Triceps: ask the subject
to extend the elbow.
Brachioradialis: ask the subject with thumb
pointing to ceiling to flex the forearm.
Extensor indicis proprius:
with the hand flat on a bed, ask
subject to raise index finger up.
Occasional numbness/decreased sensation
over dorsum of the hand
or thumb may be seen.
Difficulty spreading the fingers,
Correctible when wrist is held with
level with forearm by examiner.
These are important physical
exams for radial nerve.
They're fairly localized.
So three possible locations
determined by exam,
triceps, brachioradialis, and
extensor indicis proprius.
Axilla: Triceps, brachioradialis,
extensor indicis proprius, all weak.
If it’s the humeral spiral groove,
triceps strength is normal.
Weak brachioradialis and weak
extensor indicis proprius.
Forearm, posterior interosseous syndrome:
triceps and brachioradialis are normal.
But then the extensor
indicis proprius is weak.
Spend a little bit of time with
proper physical examination
with that of the radial nerve because
it is a common site of injury
and the three possible locations that we’ve
walked you through in greater detail.
If the other nerves are involved,
it could be a brachial
Don’t make a mistake of diagnosing
a superimposed ulnar neuropathy
because the interossei
“appear” being weak.
Remember the pseudo that
we talked about earlier.
Bilateral radial palsies.
Always look for lead poisoning.
Remember, lead poisoning is not
just restricted to one nerve.
So you want to think of it
as being a differential.
And so therefore, if there’s bilateral,
then maybe your lead is the culprit.
Very rarely, very rarely,
We’ll talk about myotonic
dystrophy in greater detail.
It could cause weakness,
but you also have wasted forearm
and bilateral wrist drop.
Once again, with myotonic dystrophy
as being a differential diagnosis.
Usually, it’s not
going to just be one.
Wrist/fingers splint to
keep the fingers extended
in moderate to severe
Passive wrist/fingers range of
motion to maintain mobility.
That actually becomes
of utmost importance.
The longer that a particular
position is held,
there’s every possibility that
further damage could be caused
and that’s extremely important.
You want to make sure that mobility
is always somehow maintained.