[Primary progressive multiple sclerosis as a differential diagnosis of ALS: a case report]

A 44-year-old man was admitted to our hospital because of a five year history of chronic progressive gait disturbance. Neurological examination revealed mild weakness and atrophy of the upper extremities, but severe of the lower ones, and without sphincter disturbance or apparent sensory impairment. Hyperreflexia and positive pathological reflexes of the lower extremities were apparent. EMG showed a reinnervation pattern and decreased number of motor units in the extremities, suggesting ALS. However, multiple plaques on the head and spinal MRI, a prolonged central conduction time of MEP and SEP, a delayed P100 latency of VEP, and a increased IgG index in the CSF indicated primary progressive type multiple sclerosis. After receiving steroid pulse therapy, the weakness of the lower extremities showed slight improvement. Diffuse inflammation in the spinal cord involving not only the pyramidal tract but also the anterior horn cells/intramedullary ventral roots explained the ALS-like clinical picture.