Case 24 Neurology

Progressive Numbness and Paresthesias

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

Clue 1

A 35 y/o woman presents with numbness in feet and legs, paresthesias, imbalance, and frequent falls, progressing over a period of months.

Your astute med student notices high arched feet and bent toes. What do these findings suggest?

Clue 2

The history along with the presence of pes cavus (high arch) and hammertoes (toes bent at middle joint) suggest peripheral neuropathy (eg, polyneuropathy). Let’s perform a hypothesis-driven exam. What would we expect the reflexes to be like in a patient with polyneuropathy?

Clue 3

Our pt has brisk upper extremity reflexes and absent lower extremity reflexes. Polyneuropathy is usually length-dependent, beginning in the legs before affecting the arms.

Next, we’ll test sensation, starting with pain and temperature (small fiber, anterolateral cord).

Clue 4

Pain/temp deficits are present, but not severe. How about vibration and proprioception (large fiber, dorsal column)?

Clue 5

Quite abnormal.

How about Romberg? It evaluates proprioception (not cerebellum!). To maintain balance at least 2 of these must be intact: vision, vestibular function, proprioception. When proprioception is impaired, closing the eyes results in a loss of balance, seen here:

Clue 6

The vibration/proprioception deficits are more severe than the pain/temp deficits. And what about those brisk upper extremity reflexes?

Does this pattern of involvement suggest any particular etiology in our differential?

Clue 7

We can begin to narrow our differential almost immediately. Our pt has acquired this condition later in life, making hereditary causes unlikely. The absence of fever and other constitutional symptoms makes inflammatory polyneuropathy less likely (though still possible).

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