The Impact of Hypotension due to the Trigeminocardiac Reflex on Auditory Function in Vestibular Schwannoma Surgery

Abstract

Objective. To study the impact of the trigeminocardiac reflex (TCR) on postoperative auditory function in vestibular schwannoma surgery. Surgery for vestibular schwannomas (acoustic neuromas) and other procedures close to the fifth cranial nerve at its intra- or extracranial course may lead to patient’s bradycardia or even asystolia along with arterial hypotension. This phenomenon is described as the TCR. Clinical Material and Methods. One hundred subsequent patients scheduled for vestibular schwannoma surgery were studied prospectively for parameters that might influence the postoperative auditory function. The evaluation included gender, age, pre- and postoperative auditory function, preoperative mean arterial blood pressure, preoperative medical diseases or medication (e.g. antiarrhythmic drugs), tumor size and localization, and the intraoperative occurrence of the TCR. Results. The overall hearing preservation was 47% among all tumor sizes. TCR occurred in 11% of the patients. In the TCR group the rate of hearing preservation was 11%, while in the non-TCR group the hearing preservation rate was 51.4%, considering all tumor sizes (p=0.005). In larger tumors (T3 and T4), patients with intraoperative TCR had a significantly worse postoperative hearing function than those without a TCR (p<0.005). Conclusion. The hypotension following TCR is a negative prognostic factor for hearing preservation in vestibular schwannoma surgery. Referring to this knowledge patients’ information can be increased pre- and postoperatively. Further study of this phenomenon will advance the understanding of the underlying mechanisms and may help to improve hearing preservation by controlling the occurrence of the TCR.

In der vorliegenden prospektiven Studie wurde der Einfluss des intraoperativen trigemino-kardialen Reflexes auf die postoperative Hörfunktion bei Vestibularis-Schwannom-Operationen untersucht. Dieser Reflex kann bei Operationen auftreten, bei denen der fünfte Hirnnerv (Nervus trigeminus) tangiert wird, und ist gekennzeichnet durch eine vorübergehende Hypotension und Bradykardie. An einem Kollektiv von 100 Patienten mit Vestibularisschwannomen konnte gezeigt werden, dass das Auftreten des trigemino-kardialen Reflexes ein negativer prognostischer Faktor für das postoperative Hörvermögen ist.