Intraoperative direct electrical stimulation of the lamina quadrigemina ina case of a deep tectal cavernoma

Despite the recent neuro-imaging and microsurgical advances, a high rate of postoperative morbidity still remains in brain stent surgery. We report an original case of cavernous angioma of the right inferior colliculus withou t extension to the surface, operated on using brain stem electrical stimula tions. Peroperative ocular motor responses were obtained. allowing identifi cation of essential neural structures before dissection of the brain stem s urface, and accurate definition of the limits between the lesion and functi onal tissue in depth. Total removal of cavernoma and surrounding gliosis wa s then performed, with normal postoperative neurological status. As already reported at the cortical level, peroperative direct brain stem s timulations constitute a safe and easy method of functional mapping. A more intensive use of this neurophysiological technique might permit one to ext end the indications for brain stem surgery, with minimisation of postoperat ive morbidity and maximisation oi tumour resection.