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.