Stiff-man syndrome and dementia.

Stiff-man syndrome is characterized clinically by fluctuating muscular stiffness and spasm, and electromyographically by continuous motor unit activity at rest, which is abolished by sleep, general anesthesia, nerve block, curare, and several centrally-acting medications. A spinal or supraspinal origin has been proposed for this disorder. Some clinical and electrophysiologic features, along with an occasional association with encephalopathy, may support a proposed supraspinal cause. An elderly man with progressive dementia and concomitant development of stiff-man syndrome is described. He had not had stiff-man syndrome one year earlier, when he had only mild dementia. An association between stiff-man syndrome and dementia has not been previously described. Increased muscle tone and muscular rigidity is frequently encountered in patients with dementia, however, and pathologic reflexes involving neck and proximal musculature have been described in dementia. It is possible that this patient represents an exaggerated form of such motor disturbances in dementia, and that clinical and electromyographic features of stiff-man syndrome may be present with increased incidence in patients with dementia.