Clinical Reasoning: a 57-year-old man with jaw spasms.

A 57-year-old man presented with spasms of his left jaw. Two years prior, he had developed left-sided facial numbness followed by development of left-sided shock-like pain and then involuntary and repetitive movements of the jaw-closing muscles. Jaw muscle contractions were episodic, interfered with chewing and talking, and led to frequent tongue biting. Individual spasms varied from seconds to minutes and he reported that function in between episodes was normal, although his wife felt he spoke with reduced mouth opening. He sometimes awoke with a bloody tongue, suggesting that contractions occurred during waking and sleep. He had no history of premonitory sensation or relief associated with the spasms. He reported no difficulty swallowing.