Speech-activated myoclonus masquerading as stuttering

Despite having had normal speech until age 21 when he contracted varicella encephalitis, this 53-year-old man had always considered himself a stutterer. Neurologic examination revealed lightning-like facial and neck contractions during speech, which were absent at rest (video). Brain and cervical spine MRI had normal results. Surface EMG confirmed intermittent high-amplitude, short-duration bursts suggestive of cortical myoclonus (figure and video).

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Figure Surface EMG during speech and during grimacing

Surface EMG of the sternocleidomastoid and pharyngeal muscles during speech revealed short-duration, high-amplitude bursts (<100 msec) suggestive of cortical myoclonus (A). This is in contrast to the relatively prolonged bursts (>250 msec) of voluntary muscle contraction, as demonstrated when the patient voluntarily grimaced as quickly as possible (B).

Speech-activated myoclonus is an unusual variant of segmental action myoclonus.^1,2 The etiology in this patient was likely postinfectious, and treatment with valproic acid led to a moderate symptomatic improvement. The myoclonus occurred with speech in both English and his native Ukrainian.

1 Slee M, Parasivam S, Blessing B, Truck K, Day B, Thyagarajan D. Speech-activated myoclonus: an uncommon form of action myoclonus. Mov Disord 2005;20:1120–1126.

2 Bartolomei F, Farnarier G, Elias Z, et al. Facial reflex myoclonus induced by language: a neuropsychological and neurophysiological study. Neurophysiol Clin 1999;29:263–270.OpenUrlCrossRefPubMed