Unilateral leukonychia and hair depigmentation in multifocal motor neuropathy.

Neurophysiology studies in a 50-year-old man with slowly progressive weakness of the left upper limb revealed conduction block in the ulnar nerve above the elbow. His weakness remained stable with regular subcutaneous immunoglobulin, but he noted gradual hemibody hair depigmentation. Examination also revealed unilateral left hand leukonychia (figure). MRI of the brain and cervical spine was normal