Case: 32-year-old Woman with Weakness

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.