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

SECTION 1 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. Neurologic examination demonstrated decreased sensation in all 3 trigeminal divisions on the left and a reduced corneal reflex on the left. Masseter bulk, tone, and strength were normal bilaterally. Contractions were noted in the jaw-closing muscles. Mouth opening was limited during speech. There was no facial weakness. There was no palatal tremor. Head rotation, shoulder shrugging, and tongue movements were normal. With the exception of mild-to-moderate distal sensory deficit, the remainder of the neurologic examination was unremarkable.