[Study on the clinical characteristics of auditory neuropathy patients with normal pure tone average or mild hearing loss].

Objective: The purpose of this study was to analyze the clinical characteristics of auditory neuropathy (AN) patients with normal hearing or mild hearing loss. Methods: Data from Multicenter Study on Clinical Diagnosis and Intervention of Acoustic Neuropathy (registration number: ChiCTR2100050125). According to the Chinese clinical practice guideline of auditory neuropathy (version 2022), these patients divided into two groups: the normal hearing group (PTA Normal, PTA^N group, the average hearing threshold<20 dB HL) and the mild hearing loss group (PTA Mild hearing loss, PTA^M group, the average hearing threshold between 20-35 dBHL). The audiology characteristics, clinical features, and follow-up were analyzed. Data analysis was conducted using GraphPad Prism 8 and SPSS 20.0 software. Results: A total of 75 AN with normal hearing or mild hearing loss were included in this study. The PTA^N group consisted of 19 patients (38 ears), including 12 males and 7 females. The average onset age was (16.9±4.5) years old, while the test age was (22.1±5.8) years old for PTA^N group. The PTA^M group consisted of 56 patients (112 ears), including 29 males and 27 females. The average onset age was (16.2±7.9) years old, while the test age was (23.9±9.0) yeas old for PTA^M group. The average hearing threshold of low frequency (0.125-0.5 kHz) was significantly decreased. ABR disappeared in 86.00% (126/150) of the patients. The speech recognition rate was 71.80±22.44% in the PTA^N group and 58.08±29.28% in the PTA^M group.-SP/AP was 0.98±0.47 in the PTA^N and 1.07±0.63 in PTA^M group; 40 (53.33%) patients had tinnitus. 29 patients (58 ears) were followed up, including 10 patients (20 ears) in the PTA^N group and 19 patients (38 ears) in the PTA^M group. There was no significant change in hearing threshold in short-term follow-up (<3 years). With the extension of the disease duration (>3 years), the PTA^N group tended to decrease at low frequency, and the PTA^M group decreased at high frequency first. The hearing threshold at 0.25 kHz in the PTA^N group and 4 kHz in the PTA^M group decreased significantly. Conclusions: AN patients with normal hearing or mild hearing loss exhibit abnormal results in audiological examination results, including ABR, electrocochleography and speech discrimination score. A combination of audiological tests should be used to make the diagnosis of AN. With the progression of the disease, AN with normal hearing or mild hearing loss tends to decrease.