Progressive encephalomyelitis with rigidity.

Two cases of encephalomyelitis are described in which the major clinical manifestation was muscular rigidity and stimulus-sensitive muscular spasms. It is suggested, from pathological evidence, that this rigidity was of spinal origin, and that this disorder is a rare but recognizable entity. Comparison is made with previously reported cases of rigidity of spinal origin, including encephalitis lethargica, and with 'subacute myoclonic spinal neuronitis' and the 'stiff man syndrome.'