Spinal Segmental Myoclonus

Spinal segmental myoclonus (SSM) is characterized by involuntary, semirhythmic contractions of skeletal muscle groups innervated by a limited spinal cord region.1-10It is usually not affected by sensory stimuli but rather is increased by fatigue and emotional stress and usually ceases with sleep.3,8,11Patients with SSM do not have a generalized neurological disorder, and there are no associated EEG changes.1,2,8,11The primary abnormality is in the spinal cord,3-8,11-13and multiple etiologic factors have been implicated: infection,3,6,9,11,12intramedullary and extramedullary tumors,1,4,7-9,14 trauma,4osteoarthritic lesions,11arteriovenous malformation,10meningomyelocele,15and degenerative motor system disease.11,13Previously reported treatment has largely consisted of pharmacotherapy.8,11We describe a patient with SSM due to cervical spondylosis cured by surgical decompression of the spinal cord. To our knowledge, this communication is the first to report successful surgical therapy for SSM.