Is there a relationship between melanocytes and sensorineural hearing loss? Clinical evaluation of 51 patients with alopecia areata

Assessing Auditory and Cochlear Function in Alopecia Areata Patients: Exploring the Link to Cochlear Melanocyte Damage

Introduction Alopecia areata (AA) is an autoimmune disorder causing hair loss, including eyebrows, eyelashes, and body hair, primarily due to melanocyte impact. Though the precise AA melanocyte hearing loss mechanisms are not fully clear, it's speculated that cochlear melanocyte inflammation could disrupt endolymph production, which is necessary for sound signal transmission. Cochlear melanocytes maintain crucial potassium ion levels, which are pivotal for hearing. The potential AA-melanocyte-hearing loss link underscores the need to monitor auditory and cochlear function and consider interventions for AA-related hearing challenges. The study aimed to assess auditory and cochlear function using OAE and audiometry measurements to correlate disease severity and duration with OAE outcomes. Materials and methods In this study, we included 32 patients diagnosed with AA; the control group consisted of 29 healthy volunteers. We collected data on the patient's age, gender, onset age, family history, and disease duration. Audiological and otological evaluations were conducted, including pure tone audiometry (PTA), speech discrimination test (SD), and otoacoustic emission (DPOAE) measurements at frequencies of 500, 1000, 2000, 4000, 6000, 8000, and 10000 Hz. The patients were divided into two groups based on age: 18-25 and over 25 years old, and all parameters were compared. To examine differences between the right and left ears, gender, and age groups, we initially tested the variables for normal distribution using the Kolmogorov-Smirnov and Shapiro-Wilk tests. An independent sample t-test was conducted to compare the means for normally distributed variables. Results There were statistical differences at the 5% significance level in the mean DPOAE values of the 1 KHz SNR and 6 KHz SNR variables. According to the Mann-Whitney U test results, a significant difference was found in the gender-based DPOAE value at 2 kHz SNR (p=0.041), which was lower in men than women. Although there were no significant differences in the audiological parameters based on age, significant differences were found in the otoacoustic emission values. Variables, including 4 kHz DP1 (p=0.049), 500 Hz SNR (p=0.045), and 1 kHz SNR (p=0.023), differed significantly between age groups, with these values being lower in patients over 25 years old. Conclusion Overall, our study contributes to the growing body of evidence supporting an association between AA and auditory dysfunction, emphasizing the need for comprehensive assessment and management of hearing-related issues in individuals with AA.

Hearing impairment in patients with alopecia areata

Background Alopecia areata is an autoimmune disease that damages hair follicles and follicular melanocytes can be involved in the autoimmune process. Therefore, similar to vitiligo, there may be a relationship between sensorineural hearing loss and alopecia areata. Aims/objectives This study aimed to investigate potential hearing impairments in patients with alopecia areata. Methods A total of 42 subjects with alopecia areata and 42 healthy individuals enrolled in this cross-sectional study. The hearing was evaluated by vestibular evoked myogenic potential, otoacoustic emission and pure tone audiometry tests in the patients and control subjects. Results A normal otoacoustic emission was reported in 59.5% and 100% of subjects with alopecia areata and the controls, respectively (P = 0.02). Higher speech recognition thresholds (P = 0.02) and speech discrimination scores were reported more in subjects with alopecia areata than in controls (P < 0.001); however, the most comfortable level of speech was not significantly different between the groups (P = 0.06). The greatest increase in the hearing threshold was recorded at a frequency of 8000 Hz, while at frequencies of 500 and 1000 Hz, the patients and controls did not significantly differ (P > 0.05). About 6 (14.3%) and 2 (4.8%) of patients with unilateral and bilateral involvement, respectively, demonstrated no vestibular evoked myogenic potential response in the alopecia areata group. The patients and controls did not significantly differ in terms of amplitudes of the vestibular evoked myogenic potential test (P = 0.097). Limitation Small sample size and qualitative measurement of otoacoustic emission were limitations of our study. Conclusion Hearing loss was more common in alopecia areata patients than in healthy individuals. Follicular melanocytes may be involved in the alopecia areata inflammatory process, and destroying melanocytes may impact hearing function in the inner ear. However, there was no significant relationship between the duration and severity of alopecia areata and hearing loss.

Hair Follicle Melanocytes Initiate Autoimmunity in Alopecia Areata: a Trigger Point

Alopecia areata (AA) is characterized by common non-scarring alopecia due to autoimmune disorders. To date, the specific pathogenesis underlying AA remains unknown. Thus, AA treatment in the dermatological clinic is still a challenge. Numerous clinical observations and experimental studies have established that melanocytes may be the trigger point that causes hair follicles to be attacked by the immune system. A possible mechanism is that the impaired melanocytes, under oxidative stress, cannot be repaired in time and causes apoptosis. Melanocyte-associated autoantigens are released and presented, inducing CD8⁺ T cell attacks. Thereafter, amplification of the immune responses further spreads to the entire hair follicle (HF). The immune privilege of HF subsequently collapses, leading to AA. Herein, we present a narrative review on the roles of melanocytes in AA pathogenesis, aiming to provide a better understanding of this disease from the melanocyte's perspective.

There is no evidence of cochlear and vestibular melanocyte damage in patients with alopecia areata

PURPOSE

Follicular melanocytes are known to be damaged in alopecia areata (AA). However, it is not clear whether melanocytes are the primary target of autoimmunity and whether melanocytes in the inner ear are affected. This study aimed to detect possible cochlear and/or vestibular melanocyte damage in AA patients.

METHODS

Thirty-two AA patients and 35 sex- and age-matched healthy volunteers were evaluated between November 2018 and March 2020 at the Karabük University Training and Research Hospital. The conventional pure tone audiometry test and distortion product otoacoustic emission test were performed to evaluate hearing. To evaluate the vestibular function, the following tests were performed: the vestibulospinal reflex tests (Romberg test, tandem stance test and tandem walking test); positional balance tests (Dix-Hallpike test, supine roll test and head hanging test); vestibulo-ocular reflex tests (caloric test, head shake test) and oculomotor tests (saccade, smooth pursuit and optokinetic).

RESULTS

The mean age of AA patients was 31.94 ± 11.86 years (range, 15-67 years). There were no significant differences in the results of the hearing and balance tests between the groups. Furthermore, disease parameters (duration of the last attack, recurrence, positive family history, positive pull test, the severity of the disease, etc) were not associated with hearing loss and vestibular damage.

CONCLUSION

AA patients did not exhibit hearing loss or balance abnormalities that would indicate cochlear and vestibular melanocyte damage. The lack of damage to the inner ear melanocytes in AA patients may indicate that follicular melanocytes are affected secondary to autoimmune damage in the hair bulb, and melanocytes are not the primary target in the pathogenesis of AA.