A clinical case of a patient with subtotal ossification of the cochlea: results of cochlear implantation using neuroimaging methods to control dynamics

Background. Nowadays cochlear implantation (CI) is a globally recognized method of rehabilitation of people with deafness, which allows not only to improve the quality of life of the patient, but also to integrate them into the hearing environment. Ossification of the labyrinth is one of the most challenging problems faced by a surgeon during a CI. Patients with cochlear ossification have a set of problems that an audiologist encounters. Among them: duration of deafness; previous difficulties with hearing aids due to lack of effectiveness and severity of discomfort when wearing a hearing aid; severity of damage to the microstructures of the ear, leading to the need to use high levels; potential incomplete insertion of an electrode or insertion of an electrode through a cochleostomy; the occurrence of non-auditory sensations in the form of stimulation of the facial nerve; Functional neuroimaging can provide insight into the neurobiological factors that contribute to differences in individual hearing outcomes after cochlear implantation. To date, measuring neural activity in the auditory cortex of cochlear implant users has been a difficult task, primarily because the use of traditional neuroimaging techniques is limited. Functional near-infrared spectroscopy (fNIRS) is a new technology that offers advantages to this group of patients because it is non-invasive, compatible with CI devices and is not subject to electrical interference. The knowledge gained using this technique makes it possible to objectify the quality of auditory-speech rehabilitation of patients by fixing the activity of the cerebral cortex.

Aim. To describe a clinical case of a patient with subtotal ossification of the cochlea with an assessment of auditory-speech rehabilitation using neuroimaging techniques.

Materials and methods. In November 2022, patient M. was admitted to Saint-Petersburg Research Institute of Ear, Throat, Nose and Speech with complaints of hearing loss up to deafness, tinnitus, discomfort when wearing hearing aids. It was known from the anamnesis that the patient had suffered from purulent meningitis of unknown etiology at the age of 5. The patient was monitored by sign-language specialists for a long time, and from the age of 15 she had hearing aids on both ears without significant effect. In 2021, she noted a complete loss of the effectiveness of hearing aids, and therefore decided to undergo an examination for the CI. The patient's speech was represented by complex sentences with agrammatism, speech perception was mainly performed visually by lip reading. CT scans of the temporal bones from 27.03.2022 revealed signs of subtotal ossification of the labyrinth structures on both sides with unreliable signs of partial patency of the spiral canal of the cochlea on the right. Due to the high risks of incomplete insertion of the electrode, up to the impossibility of its introduction, the decision on surgical treatment was made by a concilium consisting of 2 otosurgeons, an anesthesiologist, an audiologist and a neurologist. Intraoperatively, it was decided to use a short straight electrode with a length of 11 mm. Good auditory-speech results were obtained, the objectivity of the data obtained was confirmed by the method of near-infrared functional spectroscopy.

Conclusion. The fNIRS technique made it possible to obtain an objective picture of the reaction of the temporal lobe cortex specifically to sound stimulation in a patient with RP without the use of invasive or radiological research methods, which in some cases may have an application error. We believe that the use of this technique is promising in patients with profound hearing loss before and after cochlear implantation.