Pyridoxine dependent epilepsy with iatrogenic sensory neuronopathy.

An 18-year-old man was treated from birth with chronic high dose pyridoxine (vitamin B6) up to 2000 mg per day for pyridoxine-dependent seizures. Within two years of onset of treatment, he developed a sensory neuropathy which did not progress over the following 16 years. Electrophysiological studies were consistent with a pure sensory neuronopathy expressed as centripetal degeneration of processes of the dorsal root ganglion cells.