gms | German Medical Science

Objective: In a previous study [1], four different intraoperative BAEP pattern could be identified and correlated with postoperative hearing preservation following acoustic neuroma surgery. A following prospective study [2] showed, that patients with an intraoperative reversible loss of BAEP benefit from postoperative vasoactive treatment consisting of hydroxyethyl starch and nimodipine. The present study investigates this effect on postoperative hearing preservation in all four BAEP pattern.

Methods: A study was designed based on a consecutive series of 92 patients operated upon between 1999 and 2005. Based on intraoperative BAEP pattern, patients scheduled for therapy received postoperative vasoactive treatment for 10 days. Serial audiological examination was performed in all cases.

Results: All 13 patients with stable waves showed hearing preservation and no difference in hearing quality, regardless of vasoactive treatment. In all 24 patients with abrupt loss and in all 25 patients with irreversible progressive loss of BAEP postoperative hearing loss was documented. All 30 patients with reversible loss of BAEP received vasoactive treatment, based on the previous study [2]: 70% showed postoperative hearing preservation.

Conclusions: The present study confirms the previously published results [2]. In patients with reversible loss of BAEP a disturbed microcirculation is most likely the underlying pathophysiological mechanism. In patients with abrupt loss and irreversible progressive loss of BAEP additional mechanical injury of nerve fibres seems to be the determinating factor for hearing outcome. In patients with stable waves, vasoactive treatment does not seem to improve hearing quality. This study gives evidence, that only patients with reversible loss of BAEP should be scheduled for vasoactive treatment on a routine basis.