Spinal rigidity following acute myelitis.

A patient with a 2(1/2)-year history of painful spasms and rigidity of both lower limbs is described. Symptoms began after an episode of acute myelitis. The spasms--which were spontaneous and stimulus sensitive and occurred on voluntary action--involved the repetitive grouped discharge of motor units. Continuous motor unit activity was present at rest in the muscles of both legs, and cutaneomuscular reflexes were abnormal. This patient is similar to those recently reported as having stiffness and spasms of the legs due to a possible chronic spinal interneuronitis and provides further evidence that this kind of movement disorder may be caused by spinal cord pathology.