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Jaw Clonus: A Rhythmic Oscillatory Movement, but Not Tremor
Laura Williams1, Marie Ryan2, Ronan Kilbride1
1Department of Neurology, Mater Private Hospital, IE.
Background:
Jaw clonus is rhythmic, oscillatory contraction of jaw muscles induced by stretch and is caused by lesions of the descending motor neurons in the corticopontine tracts.
Phenomenology Shown:
We illustrate jaw clonus elicited with jaw activation and upon testing of the jaw jerk in a patient with amyotrophic lateral sclerosis.
Educational Value:
This video clearly demonstrates the uncommon sign of jaw clonus, a finding which needs to be distinguished from tremor and should direct the examiner to consider lesions of the corticopontine fibres, including amyotrophic lateral sclerosis.
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