Abstract

Topicality: The World Health Organization (WHO) claims that the frequency of sensorineural hearing loss is increasing every year. The last time a viral infection can be attributed to the causes of sudden sensorineural deafness Covid-19, because more cases of hearing loss after exposure SARS-CoV-2 described in the literature. One of the forms of sudden sensorineural hearing loss is acute ischemia of the labyrinth owing to a sharp decrease in blood supply cochlea through the labyrinthine artery. This artery has a very small diameter and is extremely sensitive to the processes of blood clotting, slowing of blood flow, spasm, and thrombus formation.

Aim: To study the frequency and clinical picture of sudden sensorineural hearing loss in patients with COVID-19.

Materials and methods: The data of 182 examined patients with COVID-19 were analysed. All patients were comprehensively examined using instrumental methods: subjective audiometry, ENT endoscopy, rheoencephalography (REG), electroencephalography (EEG). If necessary, patients with hearing impairment underwent objective audiologycal examinations – otoacoustic emission (OAE), impedance audiometry, auditory evoked potentials (AEP).

Results and discussion: The study examined 182 patients who had contracted COVID-19 and complained of changes in the state of their sensory systems – hearing, smell, and taste disorders of varying severity and duration in various combinations.  

Of the 182 patients with COVID-19, 109 (59.8%) had hearing loss.  According to the audiological examination, we found sensorineural hearing loss of varying degrees in most of these patients. Some of these patients had a unilateral hearing loss or a sharp unilateral deterioration in the state of hearing function in those who had a history of chronic sensorineural hearing loss. There were also cases of sudden and acute sensorineural hearing loss.

Hearing impairment, decreased speech intelligibility, and tinnitus were reported by 59.8% (109 people) of the examined patients with COVID-19. In some patients (35.2% of cases, 64 men), symptoms of damage to the auditory system manifested themselves directly during the disease, and in addition to a decrease in hearing function and subjective tinnitus, they often also had inflammatory manifestations in the form of congestion, ear pain, etc. In many of these patients, the symptoms resolved after recovery either immediately or 1-3 months after recovery. However, 23.1% (42 people) of them had hearing impairment for more than 4-6 months.

In other patients (29.2%, 53 men), hearing impairment occurred (or was noticed by patients) after recovery – there were delayed signs that occurred after recovery and developed slowly (mostly sensorineural disorders). Signs of hearing analyser damage occurred mainly 1-2 months after recovery and even 3-4 months later. It should be noted that 26.9% of patients (49 people) had perceptual hearing impairment before COVID-19, and the disease led to the progression of sensorineural hearing loss. In addition to a decrease in hearing acuity, patients also noted a deterioration in speech intelligibility (19.2% (35 people) and subjective tinnitus (53.8%, 98 people).

In general, including all cases of hearing impairment, both those that occurred directly during the disease and those that developed later, sensorineural hearing impairment in the form of SNP was detected in 48.9% of cases (89 people).  Among these 89 patients with sensorineural hearing impairment, there were 13 cases of sudden sensorineural hearing loss due to labyrinthine infarction. This amounts to 14.6% of cases, which, given the rather rare occurrence of this pathology, significantly exceeds the overall percentage of such conditions (1-5%) among cases of sensorineural hearing loss.

To a large extent, the effect of SARS-CoV-2 on the auditory system of patients is realized through vascular mechanisms, primarily disorders of blood clotting, which leads to the formation of blood clots or haemorrhages, hemodynamic disorders, primarily cerebral, and changes in blood pressure. So, there is a basis for the development of labyrinth infarction in this patient population and the risk of such pathology is high.

It should be noted that in all such patients with sudden hearing loss after COVID-19, we found cerebral circulation and central nervous system (CNS) functional disorders. This condition requires complex treatment with the use of nootropics, vascular drugs, peripheral vasodilators, sedatives, and antioxidants. In most of the patients we treated, we achieved a positive effect after individually selected complex drug treatment.

Conclusions:

1. Sudden sensorineural hearing loss can often occur as a result of a transferred viral disease SARS-CoV-2.
2. Certain manifestations of COVID-19, primarily specific effects on the cardiovascular system, such as impaired blood clotting, which leads to the risk of thrombosis, hemodynamic disorders, primarily cerebral, and changes in blood pressure, create the basis for the development of labyrinthine infarction in this patient population.
3. The percentage of labyrinth infarction detection in sensorineural hearing loss in the setting of COVID-19 is higher than in the total number of cases of sensorineural hearing impairment of various aetiologies.
4. Timely diagnosis and comprehensive treatment of hearing impairments that occur in the context of COVID-19 helps to restore or improve hearing function, or stop the progression of sensorineural hearing loss in complex cases.

Key words: sensorineural hearing loss (SNHL), hearing impairment, COVID-19, auditory function, labyrinth ischemia.