Comparison of patients with and without intraopic neural response threshold in those who had cochlear implant surgery in terms of the most comfortable sound levels measured at the 6th month and 1st year postop

Objective: In the cochlear implant device, each electrode directly stimulates the auditory nerve when electric current comes in. It definitely triggers a sense of hearing. The electrical current required to trigger an auditory sensation is different for each individual and each stimulation channel. Therefore, the speech processor must be set individually, with each stimulation channel for each user, and this process is called programming or mapping. Post-operative device adjustment of cochlear implant users remains a difficult challenge today, especially for congenitally deaf children. Intraoperative Neural response levels can be used as a guide in the initial phase. These Intraoperative Neural response levels can be correlated with stimulation levels to be used in early psychophysical testing. The use of objective measurements in the cochlear implant postoperative period has greatly contributed to the most comfortable sound level, especially for infants and young children, as they provide certain values that form the basis for the beginning of the mapping process. Material and Method: Between January 2014 and January 2022, patients aged 0-6 years who had cochlear implant surgery in the Otorhinolaryngology clinic of Dicle University will be retrospectively examined. 50 patients (Study group) for whom we did not get the Neural response threshold at all during the cochlear implant surgery, and 50 patients whose Neural response thresholds were completely received during the surgery will be determined as the control group. The most comfortable sound levels of patients with and without a neural response threshold were compared at the 6th month and 1st year postoperatively. Results: When the effect of gender on the mcl values measured in the 6th and 12th months in the NRT(+) and NRT(-) groups was evaluated, it was found that the mcl value at the 12th month was statistically significantly higher in males than in females only in the NRT(+) group. (p=0.010) When the change in mcl values at 6th and 12th months in NRT(+) and NRT(-) groups was evaluated according to the surgical method, it was observed that mcl values were statistically significantly higher in the NRT(+) group only in the cochleostomy group (mean=247.50±31.82) compared to the group that underwent round window intervention (mean=181.94±35.94) in the NRT(+) group at 12 and 12.months (p=0.042). mcl value (mean= 213.70±74.63) was found to be statistically significantly higher than the mcl value measured at 6 months (mean=201.96±67.60). (p<0.001) When the mcl values measured at the 6th and 12th months in the NRT (+) group were compared, it was found that the mcl value at the 12th month (mean= 199.12±41.71) was statistically significantly higher than the mcl value at the 6th month (mean=184.56±37.79). (p<0.001) Conclusion: Especially pediatric age group after cochlear implantation surgery It is very important to follow up with electrophysiological parameters in patients. In these parameters detected anomalies enable the patient to be followed up more closely. In accordance with the literature, we realized in our own study that the impedance and stapes reflex thresholds measured during cochlear implant surgery are more valuable than whether NRT is taken or not. KEY WORDS Cochlear implant, neural response threshold, most comfortable sound level, electrophysiological parameter