Clinical trial NCT06556160: Fundamental and Clinical Study of Cochlear Synaptopathy
Official title: Basic and Clinical Studies of Cochlear Synaptopathy
Study type: INTERVENTIONAL
Overall status: RECRUITING
Phase: NA
Conditions: Hearing Loss
Keywords: Hearing Loss
Deafness
Micro vascular decompression
otoneurosurgery
retrosigmoid approach
Lead sponsor: CHU de Reims
Sponsor class: OTHER
First posted: 2024-08-15
Enrollment: 20
Sex: ALL
Minimum age (years): 18
Maximum age (years): 70
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NON_RANDOMIZED
Intervention model: PARALLEL
Primary purpose: BASIC_SCIENCE

Brief summary: In humans, surface electrophysiological recording of the cochlear nerve in response to a sound stimulus provides information about the integrity and function of synapses (synaptic transmission) and nerve fibre function. However, this information remains global. The investigators have preliminary data showing that it is possible to extract and characterise the functional properties of nerve fibres during otoneurosurgery in humans, and therefore to isolate the neuronal sub-populations mentioned above more precisely than is currently possible. The use of these electrophysiological data from near-field recordings, i.e. in contact with the nerve, will enable the design and improvement of a mathematical model of the human cochlea. This model will provide access to the individual responses of each nerve fibre and fill the current gap in knowledge between the functioning of these fibres and global surface recordings.

Detailed description: During functional surgery on the cerebellopontine angle, a ball electrode is placed on the human cochlear nerve to monitor hearing. Once the electrode is in place, clicks and random noise bands will be delivered in order to analyze the cochlear electrophysiological signal produced. Depending on the characteristics recorded, this signal can be used at a given frequency and intensity to identify the populations of auditory neurons mainly involved. Prior to surgery, each patient will have been examined by the audiologist in order to determine the auditory thresholds in silence and noise, in tone and in speech, to carry out the digit test and to perform an electrocochleography and distortion products. Each result analyzed will be the subject of a further analysis using the mathematic model of the human cochlea.

Eligibility criteria: inclusion criteria :

Patients with normal hearing will be included:

* male or female
* over 18 and up to 70 years of age
* normal otoscopic examination
* due to undergo surgery on the cerebellopontine angle (microvascular decompression).
* free of neuro-sensory deafness, defined by mean hearing thresholds of less than or equal to 20 dB HL in pure tone audiometry in air conduction bilaterally on the side of the ear operated on and on the non-operated side from 0.25 to 8 kHz
* affiliated to a social security scheme
* have read the information note describing the study and have agreed in writing to take part by signing the informed consent form.

Patients with a hearing impairment will be included:

* male or female
* over 18 and up to 70 years of age
* normal otoscopic examination
* due to undergo surgery on the cerebellopontine angle (microvascular decompression).
* have a sensorineural hearing loss defined by hearing thresholds of 20 dB HL or better from 0.25 to 2 kHz and from 20 dB HL excluded to 55 dB HL at frequencies above 2 kHz.
* have read the information note describing the study and have agreed in writing to take part by signing the informed consent form.

exclusion criteria :

- Patients will be excluded from the study for whom the auditory nerve is not accessible during surgery, in particular because of complete tumour invasion of the cochlear nerve (stage III and IV neuroma, advanced meningioma) or because of a particular anatomical feature not identified during the preoperative examination, making it impossible to expose the nerve for recordings (protrusion of the posterior surface of the rock).

Primary outcomes:
measure: In response to a stimulus, the neurophonic potential recorded in the form of a wave called PSTR will be characterised patients defined as normo and hearing loss based on preoperative audiometric tests
timeFrame: At 48 months
measure: Compare the amplitude and spectrum of global evoked auditory nerve activity with basic stimuli between patients defined as normo and hearing loss based on preoperative audiometric tests
timeFrame: At 48 months
Secondary outcomes:
measure: compare the primary objective with the results obtained with a mathematical model of the human cochlea in order to improve the responses of our model.
timeFrame: At 48 months
Other outcomes:
Locations:
city: Reims
country: France
facility: Damien JOLLY
Study officials:
References: