Spasmodic torticollis following unilateral VIII nerve lesions: neck EMG modulation in response to vestibular stimuli.
Three patients with spasmodic torticollis following VIII nerve lesions (VIII-ST) underwent quantitative assessment of their sternomastoid EMG during vestibular (otolith and semicircular canal) stimulation. The results were compared with a normal control group and with six patients with idiopathic spasmodic torticollis (ST). Backwards tilt of the VIII-ST patients resulted in a marked increase in the EMG, especially in the more affected sternomastoid, whereas this manoeuvre did not have a significant effect in normal subjects, or had a variable effect in the ST group. These results suggest that those with torticollis following VIII nerve lesions are a distinct group. Since there was no relationship between the side of the VIII nerve lesion and the direction of the torticollis a direct aetiological link between the two is, however, unlikely. The unusual EMG/tilt responses are explained on the basis of peripheral imbalance of utricular signals (maximal in the supine position) in the presence of central deranged processing of information concerning head posture.
D004576:Electromyography; D003639:Hearing Loss, Sudden / Q000503:physiopathology; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000503:physiopathology; D008875:Middle Aged; D009132:Muscles / Q000294:innervation*; D009334:Neck Muscles / Q000294:innervation*; D014724:Vestibular Function Tests; D014725:Vestibular Nerve / Q000503:physiopathology; D000159:Vestibulocochlear Nerve / Q000503:physiopathology*