A Retrospective Comparative Chart Review of Hearing Recovery in Neural and Sensory Type Sudden Sensorineural Hearing Loss Patients

Background: The pathogenesis of Sudden Sensorineural Hearing Loss is complex, and the prognosis for recovery is variable. While the pathological lesion is thought to be localized to the cochlea, recent microRNA findings suggest a primarily neuro-topic pathogenesis at least in some patients. This study seeks to use established hearing-loss categorization systems to distinguish neural from non-neural hearing loss patients and determine if the two groups differ in functional recovery. Methods: The Charts of 132 Sudden Sensorineural Hearing Loss patients presenting at Vancouver General Hospital (November 2013-June 2019) were retrospectively reviewed. Patients’ characteristics, treatment modality, Pure Tone Audiometric thresholds (averaged across four frequencies: 0.5, 1, 2, and 3 kHz), and Word Recognition Scores were collected. Neural type Sudden Sensorineural Hearing Loss was defined as a presenting Word Recognition Score (<60%), with a Word Recognition Score reduction 20% greater than expected based on the averaged pure tone audiometric loss. Hearing recovery was defined as an improvement of ≥ 10 decibels in pure tone audiometric thresholds. Results: 48 patients meeting the American Academy of Otolaryngology Head and Neck Surgery 2019 diagnostic criteria and with comprehensive data were included. 12 (mean age ± standard deviation: 57.7±14.9 years) and 36 (55.3±15.2 years) patients were classified as neural and sensory Sudden Sensorineural Hearing Loss, respectively. 66.7% (8/12) and (24/36) of neural and non-neural Sudden Sensorineural hearing loss patients, respectively demonstrated hearing recovery. The affected ear’s initial Word Recognition Score (mean ± standard deviation %): 17.1±17.6 and 71.5±35.5 (p < 0.0001), and Word Recognition Score change with treatment: 46.9±29.8 and 3.2±25.8 (p < 0.0001), in neural and non-neural patients, respectively were significantly different. Conclusion: The hearing recovery rate in neural and sensory type Sudden Sensorineural Hearing Loss patients was similar. Patients with a neural type of hearing loss demonstrated greater word recognition score recovery after treatment than those in the sensory group.