Abstract

Relevance: Coronavirus disease (COVID-19) may present with a wide range of manifestations and health consequences, including impairments of the sensory systems. Neurological and auditory manifestations can be observed both during the illness and after recovery.

The purpose of this study is to assess auditory function using subjective audiometry in patients who have recovered from COVID-19 of varying severity.

Materials and methods: A total of 54 patients with a history of COVID-19 and sensory system impairments were examined. The patients were divided into two groups according to the clinical course of the disease: the first group included 32 patients with a mild form of COVID-19, while the second group consisted of 22 patients who had experienced a moderate course of the disease.

The audiometric examination was performed in a soundproof booth, with a background noise level not exceeding 30 dB, using clinical audiometer AC 40 manufactured by Interacoustics (Denmark).

Results and discussion: According to subjective audiometry, patients who had recovered from COVID-19 and reported post-illness hearing impairment predominantly exhibited sensorineural hearing loss. In most cases of COVID-19 patients with sensorineural impairment, a gently sloping audiometric curve was observed, with the greatest elevation of hearing thresholds at high frequencies.

The mean hearing thresholds for pure tones in the conventional frequency range in patients from both groups were significantly elevated at 4; 6 and 8 kHz compared to the control group. Specifically, the 4 kHz threshold was 15,72±1,86 dB in Group 1 and 20,95±1,96 dB in Group 2. In Group 2, thresholds were also significantly higher than controls at 1; 2 and 3 kHz. At 6 and 8 kHz, a significant difference (P < 0,05) in hearing thresholds was observed between the two patient groups. Speech audiometry measures (50% numeral recognition test and 100% speech recognition test) in the examined patients were within normal limits.

The most pronounced elevation of pure-tone hearing thresholds was observed at 12; 14 and 16 kHz in the extended frequency range. In Group 1, thresholds were 67,9±2,14; 69,5±2,54 and 55,3±2,1 dB, respectively, while in Group 2 they were 70,9±2,18; 79,5±2,84 and 57,9±1,91 dB, respectively.

Conclusions:

In COVID-19, hearing impairments of the sensorineural type are observed, being more pronounced in cases with a more severe course of the disease.

The most pronounced and statistically significant elevation of hearing thresholds (P<0,01) relative to normal values was observed in the extended frequency range, as well as within the conventional range at 4, 6, and 8 kHz.

The elevation of hearing thresholds was more pronounced in the group of patients with a moderate course of COVID-19, with a statistically significant intergroup difference observed at 6 and 8 kHz.

Early detection of sensorineural hearing loss using subjective audiometry in the extended frequency range may facilitate timely initiation of treatment and implementation of preventive measures.

Keywords: subjective audiometry, sensorineural hearing loss, COVID-19.