Adult-Onset Subacute Sclerosing Panencephalitis First Seen as Craniocervical Myoclonus
We describe a 30-year-old man who had myoclonus of the craniocervical musculature as the initial and only symptom of subacute sclerosing panencephalitis (SSPE) for >3 years, with a normal electroencephalogram (EEG). SSPE is included in the differential diagnosis of symptomatic myoclonus (1) but may be overlooked in the absence of mental changes and EEG abnormalities.
CASE REPORT
In 1992, at the age of 27 years, a previously healthy man began to have "tics in his neck." The family history was negative for neurologic disorders. He had had uncomplicated measles at the age of 8 months. His medical history was irrelevant.
During the first 2 years, the movements were infrequent and often passed unnoticed by the patient himself. In June 1994, the patient was referred to our hospital because the muscle jerks became very frequent and disturbed his speech. He was unable to suppress them and did not feel any urge to move his neck. The movements persisted during sleep. Neurologic examination was unremarkable except for the presence of brief, pseudoperiodic involuntary contractions of the neck and both shoulders, more intense and frequent on the left side. On closer clinical examination, the muscles mainly involved were the platysma and trapezius bilaterally. The movements were basically jerky but were sometimes more prolonged, giving rise to maintained postures such as shrugged shoulders (see videotape). The movements did not appear to change with postural adjustments or during action and were not stimulus sensitive.
O n T2-weighted images, magnetic resonance imaging (MRI) showed an increased signal in the white matter surrounding the occipital horns. In the cerebrospinal fluid (CSF), the cell count and protein and glucose levels were all normal; the immunoglobulin G (IgG) was 8.32 rngldl (normal, 2-4 mg/dl), the IgG index was 1.6 (normal, <0.7), and three oligoclonal bands were detected. Blood cell A vidcotape accompanies this article.