Segmental myoclonus. Clinical and pharmacologic study
J. Jankovic and R. Pardo
We observed 37 patients (mean age at onset, 48.5 years; range, 13 to 84
years) with segmental myoclonus (18 branchial, 19 spinal). Etiologies for
branchial myoclonus included brain-stem demyelination, cerebrovascular
disease, Meige's syndrome, cerebral arteritis secondary to bacterial
meningitis, central nervous system Whipple's disease, acute
cervicomedullary trauma, and cerebellar degeneration. Spinal myoclonus was
associated with laminectomy, remote effect of cancer, spinal cord injury,
post-operative pseudomeningocele, laparotomy, thoracic sympathectomy,
poliomyelitis, herpes myelitis, lumbosacral radiculopathy, spinal
extradural block, and myelopathy due to demyelination, electrical injury,
acquired immunodeficiency syndrome, and cervical spondylosis. The latency
between the predisposing condition and the onset of myoclonus ranged from
immediate to 33 years (mean, 2.9 years). In six patients, the myoclonus was
the presenting symptom of a serious underlying disease. Treatment with
clonazepam, tetrabenazine hydrochloride, or other medications provides a
satisfactory control in most patients.
