Ipsilateral trigeminal sensory responses to cortical stimulation by subdural electrodes.

Twelve patients with medically intractable epilepsy had plates of chronic subdural electrodes placed over the lateral and basal cortical hemispheres during evaluations for surgical therapy. During cortical stimulation, ipsilateral sensations involving any of the branches of the trigeminal nerve were noted in the eye, face, and mouth. Some responses could have been due to dural or direct trigeminal nerve trunk stimulation, but others were probably due to electrical stimulation of trigeminal fibers accompanying the pial-arachnoidal vessels. These fibers had been demonstrated in animals, but not in humans.