Propriospinal Myoclonus: Clinical and Neurophysiologic Characteristics

J Korean Neurol Assoc > Volume 21(1); 2003 > Article

Journal of the Korean Neurological Association 2003;21(1): 82-88.

척수고유성 간대성근경련:임상 및 신경생리학적 특성

문소영 , 김병준 김경문 서대원 홍승봉 이원용

성균관대학교 의과대학 삼성서울병원 신경과학교실

Propriospinal Myoclonus: Clinical and Neurophysiologic Characteristics

So-Young Moon

"Department of Neurology Samsung Medical center, Sungkyunkwan University School of Medicine"

Abstract

"Background : Propriospinal myoclonus (PSM) is characterized by rhythmic or arrhythmic, flexion or extension movements of the axial body muscles involving many spinal segments linked by long propriospinal pathways. We described the clinical and electrophysiological features of 7 PSM patients. Methods : Neurophysiologic studies include-ed routine electroencephalography, polymyography, and posterior tibial somatosensory evoked potentials (PTSEP). R e s u l t s : Myoclonic jerks originated from the rectus abdominis in 3 patients, and pectoralis major, thoracic paraspinalis, sternocleidomastoid, and vastus lateralis in every other case. Polymyography showed rostral and caudal propagations from the originated muscles. The durations of myoclonic jerks were about 100 to 400 ms and their veloci-ties ranged from 3.2 to 6.7 (5.4 ±1.4) m/s. PSM developed after cervical trauma in 2 patients (cases 1, 2), after general anesthesia in case 4, and after infectious or inflammatory myelopathy in case 3. PSM in 3 patients were idiopathic, of which one patient had diabetes mellitus for 10 years with autonomic and somatosensory polyneuropathy. Two patients, who showed PSM after general anesthesia and myelopathy respectively, were cured completely within one month. Though others had not completely recovered, they had a relatively benign course. Conclusions : In our cases, the gener-ators of myoclonus seemed to be most commonly located in the midthoracic lesion of the spinal cord with up and down propagation of slowly conducting pathways, such as propriospinal fibers. Cervical trauma can lead to the partial release of a spinal pattern generator, which is capable of recruiting muscles through long propriospinal pathways into complex rhythmic activity.Key Words : Propriospinal myoclonus, Polymyography, Somatosensory evoked potential, Propriospinal fibers, Cervical trauma"