Effect of trigeminal tractotomy on dental sensation in humans

Two patients with intractable pain of the head and neck due to cancer underwent trigeminal tractotomy and rhizotomy of the ninth and 10th cranial nerves, as well as an upper cervical dorsal rhizotomy. Postoperatively, cutaneous analgesia ws present ipsilaterally in peripheral portions of the face and the neck, but paramedian facial regions and the oral mucosa were hypalgesic. The procedures had no significant effect on dental pain perception in these patients, as tested electrically and thermally. These results are similar to those in recent reports of dental sensation after trigeminal tractotomy in animals. The results raise questions about the validity of the commonly espoused hypothesis that trigeminal nucleus caudalis is the exclusive locus for processing of orofacial nociceptive information. The findings are consistent with the idea that the entire spinal trigeminal nucleus serves as a site for integration of pain-related information from orofacial structures that are supplied by afferent fibers in the fifth, seventh, ninth, and 10th cranial nerves and the upper cervical nerve roots.