Ulnar nerve - pseudoulnar palsy

Causes

Contralateral cerebral infarction may produce a syndrome resembling ulnar palsy. The most frequently described locations of the infarction are:

• White matter of angular gyrus of inferior parietal lobule
• Precentral knob (hand representation area)
• Anterior aspect of postcentral gyrus

Presentation with pseudoradial or isolated index finger palsies have also been described.

Symptoms & signs

• May be clinically indistinguishable from ulnar nerve palsy.
• Can present as pure motor or sensorimotor deficit.
• Sensory deficits that don’t respect the ulnar nerve distribution borders might be the only clue to the central origin.

Examination

• Consider brain imaging for evaluation for stroke in patients with isolated finger palsies especially if no sensory symptoms exist.