Phenotypic spectrum of patients with mutations in CHD7: clinical implications of endocrinological findings

Objective: Heterozygous CHD7 mutations cause a broad spectrum of clinical phenotypes ranging from typical CHARGE syndrome to self-limited delayed puberty. This study aimed to investigate the clinical characteristics of endocrine dysfunction in patients with CHD7 mutations. Methods: The clinical features and endocrine findings from 30 patients with CHD7 variants were retrospectively reviewed. A diagnosis of CHARGE syndrome was based on the Verloes diagnostic criteria. Results: Seventeen patients fulfilled the criteria for typical CHARGE syndrome, one patient for partial/incomplete CHARGE, and the remaining 11 patients had atypical CHARGE syndrome. One patient was diagnosed with Kallmann syndrome and unilateral deafness. The most frequently observed features were inner ear anomalies (80.0%), intellectual disability (76.7%), and external ear anomalies (73.3%). The mean height and weight SDSs at diagnosis were -2.6 ± 1.3 and -2.2 ± 1.8, respectively. Short stature was apparent in 18 patients (60%), and one patient was diagnosed with growth hormone deficiency. Seventeen males showed genital hypoplasia, including micropenis, cryptorchidism, or both. Seven patients after pubertal age had hypogonadotropic hypogonadism with hyposmia/anosmia and olfactory bulb hypoplasia. Truncating CHD7 mutations were the most common (n = 22), followed by missense variants (n = 3), splice-site variants (n = 2), and large deletion (n = 2). Conclusions: A diverse phenotypic spectrum was observed in patients with CHD7 variants, and endocrine defects such as short stature and delayed puberty occurred in most patients. Endocrine evaluation, especially for growth and pubertal impairment, should be performed during diagnosis and follow-up to improve the patient’s quality of life.

Current criteria for selecting cochlear implant in deaf patients: a review

Cochlear implantation is indicated in patients with severe to profound hearing loss that cannot be adequately treated by other auditory rehabilitation measures. The definitive indication of cochlear implantation is made on the basis of an extensive interdisciplinary clinical, audiological, radiological, and psychological diagnostic work-up. There are numerous changes are happening in cochlear implant candidacy. These have been associated with concomitant changes in surgical techniques, which enhanced the utility and safety of cochlear implantation. Currently, cochlear implants are approved for individuals with severe to profound unilateral hearing loss rather than previously needed for bilateral profound hearing loss. Studies have begun using the short electrode arrays for shallow insertion in patients with low-frequency residual hearing loss. The advancement in designs of the cochlear implant along with improvements in surgical techniques reduce the complications and result in the safety and efficacy of the cochlear implant which further encourages the use of these devices. This review article aims to discuss the new concepts in the candidacy of the cochlear implant, cochlear implant in younger children and hearing preservation, a cochlear implant for unilateral deafness, bilateral cochlear implant, and cochlear implant with neural plasticity and selection of patients for the cochlear implant.

COVID-19-related sudden sensorineural hearing loss

Background: Sudden sensorineural hearing loss (SSNHL) can be a feature of COVID-19. It may present alone or with other symptoms of the disease. However, there is little written in the literature about its occurrence. We aimed to evaluate the socio-clinical characteristics and outcome of confirmed mild- to moderate COVID-19 cases with SSNHL in Tikrit city, Iraq. Materials and Methods: This descriptive study was conducted at the Otolaryngology Department, Tikrit General Hospital, Tikrit city, Iraq. The period of the study was from December 1, 2020 to June 30, 2021.Mild and moderate COVID-19 subjects confirmed by real-time polymerase reaction were included in the study. Detailed demographic (age, gender, and smoking habit) and clinical characteristics (onset and duration of deafness, side, severity, associated ear, nose, and throat symptoms, and comorbidity) were recorded for every patient. Outcomes following the steroid treatment protocol were also registered. Results: SSNHL was identified in 26 patients, of whom 20 (76.9%) were women, 20 (76.9%) were in the age group ≥ 30 years, and 21 (80.8%) were non-smokers. Around three-quarters of the subjects were identified within the first week of deafness occurrence. Bilateral (18/26) was more common than unilateral deafness (8/26); therefore, the total number of deaf ears was 44. Besides, bilateral symmetrical deafness (13/18) outnumbered the asymmetrical type (5/18). Around three-quarters were of moderate severity. The most common otological symptom was tinnitus (25/26). The most common nose and throat symptom was anosmia (6/26). The mean hearing threshold before and after treatment with oral steroids ± intratympanic steroids was 50.91 ± 11.777 dB and 40.24 ± 15.693, respectively. One patient with bilateral SSNHL was lost to follow-up; the remaining number of deaf ears was 42, and half of them were partially improved. The outcome of the treatment showed no statistically significant relation with the duration, side, and severity of SSNHL (p>0.05). Conclusion: The majority of COVID-19-related SSNHL cases presented within one week of onset, with bilateral outnumbering unilateral cases. Tinnitus was the most common associated symptom. Treatment with steroids achieved partial improvement in half of the cases, and this outcome was not affected by the duration, side, and severity of deafness.

Ear-Specific Hemispheric Asymmetry in Unilateral Deafness Revealed by Auditory Cortical Activity

Profound unilateral deafness reduces the ability to localize sounds achieved via binaural hearing. Furthermore, unilateral deafness promotes a substantial change in cortical processing to binaural stimulation, thereby leading to reorganization over the whole brain. Although distinct patterns in the hemispheric laterality depending on the side and duration of deafness have been suggested, the neurological mechanisms underlying the difference in relation to behavioral performance when detecting spatially varied cues remain unknown. To elucidate the mechanism, we compared N1/P2 auditory cortical activities and the pattern of hemispheric asymmetry of normal hearing, unilaterally deaf (UD), and simulated acute unilateral hearing loss groups while passively listening to speech sounds delivered from different locations under open free field condition. The behavioral performances of the participants concerning sound localization were measured by detecting sound sources in the azimuth plane. The results reveal a delayed reaction time in the right-sided UD (RUD) group for the sound localization task and prolonged P2 latency compared to the left-sided UD (LUD) group. Moreover, the RUD group showed adaptive cortical reorganization evidenced by increased responses in the hemisphere ipsilateral to the intact ear for individuals with better sound localization whereas left-sided unilateral deafness caused contralateral dominance in activity from the hearing ear. The brain dynamics of right-sided unilateral deafness indicate greater capability of adaptive change to compensate for impairment in spatial hearing. In addition, cortical N1 responses to spatially varied speech sounds in unilateral deaf people were inversely related to the duration of deafness in the area encompassing the right auditory cortex, indicating that early intervention would be needed to protect from maladaptation of the central auditory system following unilateral deafness.

UNILATERAL PROFOUND DEAFNESS – A POSSIBLE MECHANISM

Purpose: To explain the clinical findings of patients with profound unilateral deafness who have recovered the hearing function after a combined treatment of hyperbaric oxygenation and dehydrant therapy. Material and method: 11 patients with profound sudden unilateral hearing loss above 90 dB SPL, intolerance to sounds similar to recruitment, at levels 10-20 dB above the hearing threshold (105-120 dB SPL), positive glycerol test and unexpected good recovery of hearing within 1-2 months are described. Results: All patients have perfect outcome results without the use of glucocorticoids. Conclusions: Based on articles about experiments with genetically modified animals and acquired deafness, we propose a possible mechanism of damage explaining the clinical findings and the favorable outcome of the disease – a disconnection between the tectorial membrane and stereocilia. Thus mechano-electrical transducer (MET) of hair cells cannot be activated. The combined use of hyperbaric oxygenation and dehydrant medications can lead to recovery of the hearing function.

Cortical Reorganization in Unilateral Deafness Revealed by Auditory Evoked Response

Profound unilateral deafness reduces the ability to detect the location of sounds, which is achieved with binaural hearing. Furthermore, the findings from previous studies have shown that unilateral deafness can cause a substantial change in the pattern of cortical activation, thereby leading to central reorganization in the whole brain. In the present study, we compared N1/P2 auditory cortical activities and the pattern of hemispheric asymmetry of normal hearing, unilaterally deaf, and simulated acute unilateral hearing loss groups during passively listening to speech sounds at different locations. The results show that P2 latencies were prolonged for left-side stimulation with greater angles in the horizontal plane. In the source analysis, a differential lateralization pattern was revealed such that the N1 source activation in the normal hearing subjects was greater in the left hemisphere, while contralateral activity was found in response to the stimulated side for the right-sided deaf and simulated acute hearing loss groups. However, no hemispheric lateralization was found for the left-sided deaf or simulated acute hearing loss groups. In addition, the cortical N1/P2 activities were inversely related to the duration of deafness in the right auditory region. These findings indicate that the cortical reorganization induced by monaural hearing deprivation differs depending on the side and duration of deafness.