Significance of Postoperative ABRs after Cerebellopontine Angle Surgery

Objectives: The main objective was to compare postoperative hearing function assessed by audiometry and ABRs. Materials and Methods: All charts of patients operated on for tumor of the cerebellopontine angle surgery (CPA) were retrospectively analyzed. Charts of patients with preserved hearing were selected. The mean PTA was calculated. The speech discrimination was assessed by the speech discrimination score (SDS), and by the maximum score of dissyllabic-word intelligibility (MIS). Patients were sorted out through their AAO-HNS auditory classification. ABRs were categorized in three groups: NORMAL (waves I-III-V clearly identified), ALTERED (identification of wave V only), and ABSENT (no waves). Correlations were searched between the MIS and the pattern of ABRs, using an ANOVA. Auditory status assessed through the AAO-HNS classification was compared with ABRs (chi-square test) (p < 0.05 considered as significant). Results: In this study, 17 charts were analyzed. Mean age was 53.41 ± 5.14 years old. Postoperative tonal results were better on lower frequencies, with an average of 29.71 ± 8.1 dB in 250 Hz, 31.76 ± 9.71 dB on 500 Hz, 39.41 ± 10.87 dB on 1,000 Hz, 54.41 ± 17.76 dB on 2,000 Hz, and 72.06 ± 22.4 dB on 4,000 Hz. MIS on average was 85.88 ± 13 dB. No correlations were found between the MIS and the results of ABR (p = 0.19). No correlations were found between the AAO-HNS score and the aspect of ABRs (p = 0.08). Conclusion: Postoperative hearing can be good or at least useful even though ABRs are lost after CPA surgery.