Idiopathic palatal myoclonus: report of two cases

We report two patients with idiopathic palatal myoclonus presenting as a synchronous up-and-down beating of the soft palate, to-and-fro thrusting of the tongue, and contraction of pharyngeal and laryngeal muscles. The obvious pulsatile movements were visible on the submental surface and a loud clicking noise was audible from a distance. The involuntary jerkings predominantly appeared when the mouth was kept shut, but could be interrupted by some oro-lingual maneuvers such as phonation, swallowing, and sticking the tongue out. Although the palatal myoclonus did not affect the function of the mouth, the patients were socially embarrassed by the loud clicking sound and pulsatile movements. On clinical examination and laboratory investigations, no evidence of lesion in the brainstem or cerebellum was obtained. A therapeutic trial with trihexyphenidyl did not bring any benefit. To conclude, because the idiopathic palatal myoclonus is a rare movement disorder which has never been documented in Taiwan, we describe its clinical characters in two Chinese patients and discuss the differential diagnosis with other involuntary lingual movements.