00:01
Let's review a case,
and think about this
in a little more detail.
00:04
This is a 32-year-old woman
who presents with weakness.
00:08
This woman presents for
new evaluation of weakness.
00:12
She's noticed that
over the past two weeks,
she is having trouble reading due to
intermittent double vision,
and is felt weaker
when walking into the store.
00:21
She reports double vision
that worsens
after she's been reading
for 30 to 45 minutes.
00:26
And she's weaker
when leaving the store
than when she first starts shopping.
00:30
She is on no other medications,
and has no other
past medical history problems,
or prior surgeries.
00:37
Examination reveals ptosis
so we're seeing bulbar findings,
which worsens
with sustained upgaze.
00:44
The patient has to diplopia
at extreme left gaze,
and dysarthria that is more apparent
at the end of your examination
than at the beginning.
00:53
There are no major findings
on other cranial nerve testing.
00:56
The patient is weak
with 4 out of 5 strength
in the proximal muscles.
01:01
And deep tendon reflex exam
shows 2+ normal reflexes
that are symmetric.
01:06
Cerebellar testing is normal
and there are no sensory findings.
01:10
So where does this problem localize?
Well, let's walk through some
of the key features of the case.
01:15
Let's think about the distribution,
sensory findings, reflex exam,
and then look for some
of those wildcard findings.
01:23
First of all,
in terms of the distribution,
the patient has
proximal weakness
and also the presence
of bulbar findings.
01:30
We see ptosis and diplopia
and the presence of dysarthria,
which point to involvement
of bulbar fibres.
01:36
And suggest that this weakness
is not coming from the muscle,
but it's more likely coming
from the neuromuscular junction.
01:43
There are no sensory findings.
01:45
Sensory findings are common
in most polyneuropathies.
01:48
And we don't see that here.
01:49
So the absence of
sensory findings is important
in pointing away
from a nerve problem
and towards a
neuromuscular junction disorder.
01:58
The reflex examination
shows the patient has normal
and symmetric reflexes,
and that's supportive of a
neuromuscular junction localization.
02:06
And then importantly, we're starting
to see evidence of fatigability.
02:10
When the patients
walking around the store
symptoms are worse
at the end of the day
with sustained upgaze,
we see ptosis that worsens
with that sustained upgaze
with more prolongation of activation
of muscles in the eye.
02:24
So where do we localize
this problem?
Is it muscle?
Is it neuromuscular junction?
Is it peripheral nerve?
And like we've said,
we don't like peripheral nerve
for this case.
02:34
There's an absence
of sensory findings,
the reflexes are normal.
02:37
This doesn't seem like a
peripheral nerve localization.
02:41
Proximal weakness is very common
in muscle disorders.
02:44
But here we see the presence
of bulbar findings,
which points us away
from a muscle problem
and towards
neuromuscular junction,
so muscle is also not
the appropriate localization
in this case.
02:55
This is a good case for a
neuromuscular junction localization.
02:59
We have proximal weakness with the
presence of bulbar findings,
normal sensation,
and fairly normal reflexes
with that wildcard
of the presence of fatigability.
03:09
Symptoms that worsen the
longer the muscle is activated.