Lt. Robertson et Jp. Hammerstad, JAW MOVEMENT DYSFUNCTION RELATED TO PARKINSONS-DISEASE AND PARTIALLY MODIFIED BY LEVODOPA, Journal of Neurology, Neurosurgery and Psychiatry, 60(1), 1996, pp. 41-50
Objectives-To test the hypotheses that Parkinson's disease can differe
ntially produce deficits in voluntary and rhythmic jaw movements, whic
h involve different neuronal circuits, and that levodopa treatment imp
roves specific components of the motor deficit. Methods-Patients with
idiopathic Parkinson's disease and control subjects were tested on a s
eries of jaw motor tasks that included simple voluntary movement, isom
etric clenching, and natural and paced rhythmic movements. Jaw movemen
ts were measured by changes in electromagnetic fields and EMG activity
. Patients with Parkinson's disease with fluctuations in motor respons
es to levodopa were tested while off and on. Results-During the off st
ate, patients with Parkinson's disease were significantly worse than t
he control subjects on most tasks. The deficits included a decrease in
amplitude and velocity during jaw opening and closing, aberrant patte
rns and low amplitude of EMG activity during clenching, and low vertic
al amplitude and prolonged durations of occlusion during rhythmic move
ments. No decrements were found in the amplitude of voluntary lateral
jaw movements or the frequency of rhythmic movements. During the on st
ate, improvements occurred in the patterns and level of EMG activity d
uring clenching and in the vertical amplitude and duration of occlusio
n during rhythmic movements, although a significant decrement occurred
in the lateral excursion of the jaw. Conclusions Parkinson's disease
affects the central programming of functionally related muscles involv
ed in voluntary and rhythmic jaw movements and levodopa replacement in
fluences only certain aspects of jaw movement, most likely those requi
ring sensory feedback.