Prognostic value of the blink reflex in acoustic neuroma surgery

OBJECTIVE: The study goal was to demonstrate that blink reflex analysis can predict postoperative facial nerve outcome in cerebellopontine angle tumor surgery. STUDY DESIGN, SETTING, AND PATIENTS: In an open and prospective study conducted at a single tertiary care center over 3 years, 91 subjects with a vestibular schwannoma filling the internal auditory meatus were enrolled and operated on via a translabyrinthine approach. The difference in latency of the early response (DeltaR1) of the blink reflex between the pathologic side and the healthy side was calculated in every patient during a complete electrophysiologic examination of the facial nerve performed on the day before surgery. MAIN OUTCOME MEASURES. DeltaR1 was compared with the other preoperative data (tumor volume, facial function), with the perioperative observations (difficulties with the dissection of the facial nerve), and especially with the postoperative status after I year. The statistical, study was conducted using polynomial, regression. RESULTS: Patients with a negative or zero DeltaR1 have normal facial function at I year. For those with a positive DeltaR1 the outcome is not favorable unless the tumor is small. For patients presenting with an immediate complete facial paralysis, the value of DeltaR1 is also indicative of facial function outcome. CONCLUSION. Statistical analysis shows that the blink reflex, through DeltaR1, has an excellent prognostic value in anticipating the difficulties with facial nerve dissection and postoperative facial function after 1 year.