[Progressive encephalomyelitis with rigidity. Clinical and electrophysiological aspects]

A 72-year-old man presented with a chronic illness constituted by muscle rigidity affecting his lower limbs, trunk and neck, either spontaneous or triggered by stimuli, together with a spastic paraparesis, manual amyotrophy and pseudobulbar syndrome. The electrophysiologic study showed continuous motor unit activity integrated by normal motor unit potentials. Biochemical and imaging results were normal. These data suggest the diagnosis of idiopathic progressive encephalomyelitis with rigidity. Following administration of gabapentin (2000 mg daily), muscle rigidity and electromyographic continuous motor unit activity were suppressed. Transient drowsiness was the only side effect. The authors have tried to relate these findings to those found in the literature.