Into the cerebral venous system: monitoring an open approach to the cavernous sinus

Background: Epidermoid cysts of the cavernous sinus are rare benign tumours. Their closeness to neurovascular structures carries a certain morbidity when it comes to plan their radical removal, which has been reduced by the development of minimally invasive approaches, such as modern endoscopic techniques. Still, for cases where wider exposure of the workspace is required, the use of intraoperative neurophysiologic monitoring (IONM) gains value. Methods: We present the case of a 19 years old woman with acute photopsia and headache. Magnetic resonance imaging showed a cavernous sinus lesion, suggestive of an epidermoid cyst. Due to expected lesion growth and symptoms, surgery was recommended. Neurosurgeons planned a Dolenc approach for intradural resection. We performed IONM, in order to preserve the main structures at risk (cranial nerves II, III, IV, V and VI, and internal carotid artery). Results: An optimal resection was achieved, without any critical alarm along the surgery. Neurological manifestations improved, and no new focal deficits were found. Conclusions: We state the use of IONM as a valuable tool, in order to preserve the neurological structures at the same time a radical removal is safely achieved, on unusual approaches for rare tumours such as the Dolenc technique for cavernous sinus lesions.