Incidence of hearing loss in young and elderly patients following spinal anaesthesia for cystoscopy

Abstract

Introduction: Multiple studies have described a variable incidence of transient hearing loss (hypoacousis) from 0.4% to 40% after subarachnoid block, especially in the low-frequencies range (125 – 500 Hz) (1, 2). The mechanism of transient hypoacousis is attributed to leakage of cerebrospinal fluid, which leads to a decrease in perilymph pressure within the cochlear.

Hypothesis: The study hypothesis was based on an assumption that hearing loss is more frequent in young patients who undergo spinal anaesthesia in comparison with elderly patients.

Objective: 1) To determine the incidence of hearing loss after spinal anaesthesia in the young versus elderly patients.

Materials and Methods: Ninety-eight male patients (ASA 1 - 11) scheduled for cystoscopy under spinal anaesthesia were recruited for the study. Recruitment of patients for the study was age-dependent and was divided into two groups: One group (49 patients) had patients aged between 17 and 44 years (Group Y) and the other group had 49 patients aged between 45 and 77 years made up group two (GROUP E). Subarachnoid injection at L3-4 was performed using a standard 22-gauge Quincke spinal needle with patients in the sitting position and 2,5 ml to 3 ml of 0.5% isobaric bupivacaine was administered. Patients were evaluated on the day before spinal anaesthesia by pure tone audiometry at three different frequency sounds viz. 125 – 500 Hz (Low frequency), 500 – 2000 Hz (Speech frequency) and at 2000 – 4000 Hz (High frequency). This assessment was repeated 48 hours after the spinal block was given.

Statistical Analysis: Analysis was descriptive providing information on the mean (or median) and standard deviation of the variables for each of the two groups. The results of the audiometry were analyzed using repeated measures analysis of variance and transformation to p-value. Differences in outcomes of the study between the two groups were recorded as being statistically significant if p-value is ≤ 0.05.

Results: No patient from the two groups developed hearing loss either at low or high frequencies. However, there was a statistically significant improvement in audiometric results (p-value ranging from 0.0001 and 0.063) 48 hours post-surgery in the elderly group as compared with patients in the younger group.

Conclusion: The study revealed no hearing loss post-spinal anaesthesia in both groups. It did, however, show that the elderly group have better hearing acuity at all three frequency levels of sound compared to the younger group after spinal anaesthesia.