Evaluation of the hearing in pedi̇atri̇c patients with biotinidase deficiency

Biotinidase deficiency (BD) is the result of lack of biotinidase enzymes which transform biotin. BD is one of the autosomal recessives (AR) disorders (www.genetiks.com.tr). It is characterized by neurological and cutaneous symptoms, including sensorineural hearing loss. (Heller, AJ, Stanley, C., Shaia, WT, Sismanis, A., Spencer, RF ve Wolf, B. -2002). Frequency of AR BD in Turkey is 1:11.000 which is over the world average due to preference of consanguine marriages. (Icke, S., & Genc, R. E. -2017). 75% of newborn babies with BD may have hearing loss if not treated. Hearing loss, which is one of the BD symptoms, can be prevented with early treatment. (Nance, W. E.-2003). Therefore, our study focused on hearing evaluation in pediatric patients treated for BD diagnosis. Hearing levels were determined using objective test batteries after treatment started in diagnosed BD cases at an early stage thanks to metabolic screening tests. As developed hearing loss in patients with BD is irreversible, it is aimed to control with early diagnosis and treatment if hearing related symptoms are developed or not in BD cases, and to point out developed hearing loss although having treatment. A total of 21 children treated for BD diagnosis, 9 girls and 12 boys, ranging from 5 months to 65 months old, were included in our study's experiment group. 90,5% of participants in the experiment group were diagnosed and their treatment had started in the first 30 days, 9,5% of them had their diagnosis and treatment within 31-60 days. Participants were compared to 20 children with normal hearing, whose demographics were similar. Participants were evaluated audiologically. By obtaining brainstem auditory evoked potential (BAEP) records, the hearing of the participants was found to be at a normal level. Using information from Bilateral BİUP records, I., III. and V. wave latencies and I-III, III-V, I-V interpeak latencies were compared. When BAEP recordings with 6 kHz Tone Burst stimulus were compared between the experimental and control groups, I, III. and V. wave latencies and I-III, III-V, I-V interpeak latency ranges increase was statistically significant (p<0,005). No significant differences were found in the statistical analysis based on the age and gender variables (p>0,005). When BAEP records tested with the click stimulus were compared, no significant differences were observed between the groups (p>0,005). At the same time, the Signal-to-Noise Ratio (SNR) values were compared during Transient Otoacoustic Emission (TEOAE) test for those with BD and control group. It was determined that right ear 4 kHz scores of experimental group participants had statistically significant decrease (p<0,005). In the immitancemetry measurements, similarities were observed in the results of all participants in terms of complement, gradient and pressure values, and a Type A tympanogram was obtained in all participants. Obtained information shows that hearing related symptoms are not developed as a result of early diagnosis and treatment in BD cases. It is believed that the elongation of latency determined in the BAEP records indicate the effects of BD on the central hearing system, and the differences in TEOAE 4 kHz are caused by the effect of low cochlear reserves.