Intra-operative monitoring of the facial nerve with an air inflated balloon. Technical note.

A simple, reliable and cheap device for intra-operative monitoring of the facial nerve during surgery for cerebellopontine angle tumours is presented. It consists of a single use tracheostomy tube with a low pressure air inflatable cuff placed in the mouth of the patient on the side of the tumour, connected by a pressure transducer to a monitoring unit. It records any pressure changes in the patient's mouth induced by muscular contractions as a result of excitation of the inferior parts of the facial nerve.