Acoustic Reflex Decay and Acoustic Reflex Latency Threshold Test Findings in Patients with Cerebellopontine Angle Tumors Correlation with Tumor Type, Size, and Extent

Abstract

Context: This was a comparative prospective study. Aims: (1) To characterize acoustic reflex decay (ARD) and acoustic reflex latency threshold (ARLT) profiles in cerebellopontine angle (CPA) tumors. (2) To correlate ARD and ARLT test results with the type, size, and extent of tumors. Study Design: Comparative prospective study. Setting: Primary versus Tertiary referral center. Subjects: The clinical group comprised 98 patients with CPA tumor and the control group comprised 100 normal hearing subjects. Subjects and Methods: ARD and ARLT were estimated at 500 Hz and 1000 Hz both ipsilaterally and contralaterally for both the groups. Statistical Analysis Used: Statistical analysis for clinical group versus control group was carried out using analysis of covariance for age and gender covariates. For discrete clinical groups, analysis of variance followed by post hoc (Turkey) test was used. An independent sample t-test was used for the statistical analysis of tumor ear versus nontumor ear. Results: Test results indicated that the proportion of ears with abnormal reflex decay (0%–25%) was less compared to those with normal findings (75%–100%) in the patient group reflecting the poor efficacy of ARD to identify the presence of CPA tumors. Statistical analysis for ARLT was possible mainly for nontumor ear stimulation and it did not give any clear indications regarding the presence of brain stem compression. Conclusions: In the present study, an estimation of ARD and ARLT did not appear to be useful indices for CPA tumor identification.

Keywords

• acoustic reflex decay; acoustic reflex latency threshold; cerebellopontine angle