Abstract

Myoclonus is a hyperkinetic movement disorder characterised by sudden jerky movement shorter than 100 ms. On the other hand, segmental myoclonus is a hyperkinetic movement disorder of muscles innervated by one segment and neighbouring segments in the brain stem and spinal cord which is rhythmical and generally has 50-500 ms duration. Previously healthy three patients aged 18, 19 and 72-years-old were admitted with the complaint of jerky involuntary movements which had segmental distribution and which were triggerred by various stimuli. Electrophysiological investigations revealed spinal segmental myoclonus. While syringomyelia was detected in one case, no etiological factors could be demonstrated in the other two patients despite extensive investigations. Although, structural, neoplastic and systemic disorders as well as toxic factors should be searched carefully in spinal segmental myoclonus which is diagnosed by neurological examination and electrophysiological findings, it should be kept in mind that this kind of myoclonus may be idiopathic. In this article, the literature about spinal segmental myoclonus is briefly reviewed in the context of three spinal segmental myoclonus cases.