Trigeminofacial reflex: A means of detecting proximity to ophthalmic and maxillary divisions of the trigeminal nerve during surgery

Abstract

Object. The aim in this paper was to localize and detect incipient damage to the ophthalmic and maxillary branches of the trigeminal nerve during tumor surgery. Methods. This was an observational study of patients with skull base, retroorbital, or cavernous sinus tumors warranting dissection toward the cavernous sinus at a university hospital. Stimuli were applied as normal during approach to the cavernous sinus to localize cranial nerves (CNs) III, IV, and VI. Recordings were also obtained from the facial muscles to localize CN VII. The trigeminofacial reflex was sought simply by observing a longer time base routinely. Results. Clear facial electromyography responses were reproduced when stimuli were applied to the region of V1, V2, and V3. Response latency was increased compared with direct CN VII stimuli seen in some cases. Responses gave early warning of approach to these sensory trigeminal branches. Conclusions. The authors submit this as a new technique, which may improve the chances of preserving trigeminal sensory branches during surgery in this region.