Case 28 Neurology

Weakness

Work it one clue at a time. The diagnosis stays hidden until you reveal it.

Clue 1

A man presents with weakness. Let’s walk through an approach to this problem.

Clue 2

The etiologies of weakness can be subdivided into 4 main categories:

Clue 3

What are the signs of an UMN lesion?

No (or minimal) muscle atrophy, no fasciculations, increased tone, + Babinski’s, and increased reflexes, the latter of which is demonstrated below in a different patient with a L-sided stroke.

Clue 4

What are the signs of a LMN lesion?

Severe atrophy, decreased tone, decreased reflexes, absent Babinski’s, and the presence of fasciculations, the latter of which is demonstrated below in a different patient with Guillain-Barré syndrome.

Clue 5

What is the hallmark clinical sign of the most common neuromuscular junction disorder?

Fatiguability, as demonstrated below in a different patient with myasthenia gravis. Notice that the ptosis significantly worsens after the patient stares at the ceiling for a minute.

Clue 6

Our patient has none of these clinical features, making a lesion of the UMN, LMN, and neuromuscular junction unlikely.

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