Acute motor axonal neuropathy with selective involvement of the lower limbs.

We report an unusual variant of acute motor axonal neuropathy completely restricted to the lower limbs and responding rapidly to intravenous immunoglobulin (IVIG). A 31-year-old man presented with 4 weeks of progressive weakness in the lower limbs. Magnetic resonance images of the spine had been normal. On neurologic examination he had symmetric weakness in the lower limbs, but muscle strength in the arms was normal. Tendon reflexes were absent. Cranial nerves and sensation were normal. Electromyography (EMG) revealed an axonal involvement with changes restricted to the lower limbs. A lumbar puncture 4 weeks after onset showed elevated protein content; cell count was normal. The patient improved rapidly after treatment with 0.4 g/kg IVIG per day for 5 days. Eight weeks after treatment EMG revealed fast reinnervation, and the only clinical sequelae was slight weakness of ankle flexion.