Facial F wave recording: a novel and effective technique for extra- and intraoperative diagnosis of facial nerve function in acoustic tumor disease.

Abstract

To investigate the diagnostic yield of facial F wave recording in patients with acoustic neurinomas intraoperatively and extraoperatively. Study design and setting Prospective study, comparative evaluation of facial F waves, transcranial magnetic stimulation of the facial motor cortex, blink reflex, and intraoperative online electromyographic activity. The study was performed in the neurosurgical department of a university hospital. Extraoperatively, only F wave latencies were closely correlated to tumor diameter as an independent variable. Intraoperatively, loss of F waves was specific for the development of a severe to total facial paresis postoperatively. A transient loss of F waves heralds an imminent danger of severe facial dysfunction. Facial F wave recording provides valuable information on the functional status of the nerve intra- and extraoperatively. Facial F wave recording should be used as a standard electrodiagnostic technique in addition to transcranial magnetic stimulation and blink reflex recording. It seems particularly useful for intraoperative facial nerve monitoring.