Hearing impairment after subarachnoid hemorrhage

Abstract

Background: Subarachnoid hemorrhage (SAH) survivors experience significant neurological disability, some of which is under-recognized by neurovascular clinical teams. We set out to objectively determine the occurrence of hearing impairment after SAH, characterize its peripheral and/or central origin, and investigate likely pathological correlates.

Methods: In a case-control study (n = 41), participants were asked about new onset hearing difficulty 3 months post-SAH, compared with pre-SAH. Formal audiological assessment included otoscopy, pure tone audiometry, a questionnaire identifying symptoms of peripheral hearing loss and/or auditory processing disorder, and a test of speech understanding in noise. A separate cohort (n = 21) underwent quantitative susceptibility mapping (QSM) of the auditory cortex 6 months after SAH, for correlation with hearing difficulty.

Results: Twenty three percent of SAH patients reported hearing difficulty that was new in onset post-SAH. SAH patients had poorer pure tone thresholds compared to controls. The proportion of patients with peripheral hearing loss as defined by the World Health Organization and British Audiological Society was however not increased, compared to controls. All SAH patients experienced symptoms of auditory processing disorder post-SAH, with speech-in-noise test scores significantly worse versus controls. Iron deposition in the auditory cortex was higher in patients reporting hearing difficulty versus those who did not.

Conclusion: This study firmly establishes hearing impairment as a frequent clinical feature after SAH. It primarily consists of an auditory processing disorder, mechanistically linked to iron deposition in the auditory cortex. Neurovascular teams should inquire about hearing, and refer SAH patients for audiological assessment and management.

Figure 1

Susceptibility weighted imaging and mapping. (A and E) magnitude images; (B and F) filtered phase images; (C and G) susceptibility‐weighted images (SWI); (D and H) quantitative susceptibility maps (QSM). (A–D) SAH patient without new onset hearing difficulty. (E–H) SAH patient with new onset hearing difficulty. Iron deposition can be observed in multiple locations as high signal intensity on the QSM image (such as within the red border, which encircles the Sylvian fissure and auditory cortex).

Figure 2

Hearing and auditory processing questionnaire. Lines connect APD questionnaire scores of individual patients before and after SAH. Wilcoxon test.

Figure 3

Speech‐in‐noise (Bamford‐Kowal‐Bench, BKB) test scores. The BKB score was the percentage of correct answers, Student t test.

Figure 4

Pure tone audiogram. ANCOVA estimated marginal means for right and left pure tone audiogram mean thresholds.

Figure 5

Regression‐based mediation analysis: path diagram. A positive coefficient is indicative of poorer hearing when mean PTA threshold (peripheral hearing deficit) is the outcome, while a negative coefficient is indicative of poorer hearing when BKB score (APD) is the outcome. NS = P > 0.05, * = P < 0.05, **** = P < 0.0001

Figure 6

Auditory cortex region of interest (yellow in A–C). (D–F) SAH patient without hearing difficulty. (G–I) SAH patient with hearing difficulty. Red denotes voxels in the auditory cortex region of interest with detectable iron signal.

Figure 7

Quantitative susceptibility mapping. Medians (and interquartile range), Mann–Whitney test.