This disorder, first described by Weisenburg in 1910, resembles trigeminal neuralgia in many respects except that the unilateral stabbing pain is localized to one side of the root of the tongue and throat. It is far less common than trigeminal neuralgia. Sometimes the pain overlaps the vagal territory beneath the angle of the jaw and external auditory meatus. It may be triggered by coughing, sneezing, swallowing, and pressure on the tragus of the ear. Temporary blocking of the pain by anesthetizing the tonsillar fauces and posterior pharynx with 10 percent lidocaine spray is diagnostic. Rarely, herpes zoster may involve the glossopharyngeal nerve. Fainting as a manifestation of vagoglossopharyngeal neuralgia is described in Chap. 9.
The same antiepileptic and other drugs that are helpful in the treatment of tic douloureux may be used to treat glossopharyngeal neuralgia, but their efficacy is difficult to judge. Regarding vascular compression of the nerve as a cause of glossopharyngeal neuralgia, Resnick and colleagues have reported the results of microvascular decompression of the ninth nerve in 40 patients; in 32 of these, relief of symptoms was complete and was sustained during an average followup of 4 years; 3 patients remained with permanent weakness of structures ostensibly innervated by the ninth nerve. A similar high rate of success has been achieved by others. If syncope is associated with the pain, it can be expected to cease with abolition of the attacks of pain. Syncope can also occur when the ninth nerve is involved by tumors of the parapharyngeal space; most of these are squamous cell carcinomas and both the ninth and tenth nerves are implicated. Section of rootlets of the ninth nerve has reportedly reduced or abolished the episodes of fainting in these cases.
The Tenth, or Vagus, Nerve
This nerve has an extensive sensory and motor distribution and important autonomic functions. It has two ganglia: the jugular, which contains the cell bodies of the somatic sensory nerves (innervating the skin in the concha of the ear), and the nodose, which contains the cell bodies of the afferent fibers from the pharynx, larynx, trachea, esophagus, and thoracic and abdominal viscera. The central processes of these two ganglia terminate in the nucleus of the spinal trigeminal tract and the tractus solitarius, respectively. The motor fibers of the vagus are derived from 2 nuclei in the medulla—the nucleus ambiguus and the dorsal motor nucleus. The former supplies somatic motor fibers to the striated muscles of the larynx, pharynx, and palate; the latter supplies visceral motor fibers to the heart and other thoracic and abdominal organs. The distribution of vagal fibers is illustrated in Fig. 44-4, and their participation in swallowing is described in Chap. 25.