Acute temporomandibular joint pain-dysfunction syndrome: neuro-otologic and electromyographic study.

To test the hypothesis that the acute temporomandibular joint pain-dysfunction syndrome might represent a variant of acute benign cranial polyneuritis, a prospective study was designed using neuro-otologic examination and electromyography. Seven consecutive patients with cardinal symptoms of the temporomandibular joint pain-dysfunction syndrome (pain, tenderness, clicking, and limitation of jaw movement) were examined within one week after the onset of their acute symptoms. Another three with chronic symptoms were tested for comparison to the acute cases. All seven patients with the acute condition had asymptomatic hypesthesia of all three divisions of the trigeminal nerve and decreased volitional muscle action potentials in the masseter and temporalis muscles. At the end of three weeks the hypesthesia resolved in all seven patients, and the muscle action potentials returned to normal in six of the seven. Electromyographic testing of the single patient with persistent decreased muscle action potentials and three patients with chronic symptoms showed fibrillations, decreased polyphasic regeneration potentials, and spontaneous fasciculations with clinical atrophy and spasm of the affected masseter and temporalis muscles. Other acute cranial nerve findings included unilateral hypesthesia of the glossopharyngeal and second cervical nerves, motor paralysis of the superior laryngeal branch of the vagus nerve, and increased facial nerve latency. These findings suggest an organic neuromuscular, rather than a psychophysiologic, cause for the temporomandibular joint pain-dysfunction syndrome.