Pontine stereotactic surgery and facial nociception

Pontine stereotactic tractotomy was performed on 13 patients for the relief of intractable pain. The results of electrical stimulation performed to localise target sites and confirm electrode trajectory are described. Stimulation sites included the cerebellum, cerebellar peduncle, trigeminal nucleus, facial nucleus, cochlear and vestibular nuclei and the trigeminal descending quintothalamic and spinothalamic tracts. Particular attention was given to facial sensory responses. Stimulation of the trigeminal nucleus produced discrete sensations, but quintothalamic stimulation gave more general ipsilateral facial sensation. Medullary trigeminal nucleotomy is recommended for facial deafferentation pain because it interrupts intranuclear trigeminal connections in the caudal trigeminal nucleus where the point of neuronal hyperactivity and stimulus convergence lies.