MM305 - Vestibular Dysfunction in Children with Non-Syndromic Genetic Hearing Loss

Abstract:
Association of between vestibular impairment and syndromic forms of genetic hearing loss such as Usher or Waardenburg syndrome is well-known. In contrast, studies of peripheral vestibular function in children with non-syndromic genetic hearing loss are sparse. A few investigations of vestibular function in patients with hearing loss due to GJB2 gene mutations have been published as they are the most common cause of non-syndromic hearing loss. Considering vestibular dysfunction has not been well-recognized in young children with other non-syndromic genetic hearing loss, our presentation is to describe a variety of clinical presentations of peripheral vestibular dysfunction.

Summary:
Objectives
To investigate vestibular function in children with non-syndromic genetic hearing loss and raise the awareness of possible vestibular impairment in these children

Rationale
Hearing loss in young children nowadays can be identified very early on and medical workups including genetic testing on hearing loss has been routinely conducted. Consequently, specific gene mutations can be readily revealed in cases of non-syndromic genetic hearing loss. In contrast, balance and vestibular concerns in these children is rarely raised or addressed. Previous studies on this topic reported conflicting findings which are somewhat controversy. Therefore, we decide to conduct a clinical study in order to have a better understanding about this important issue.

Design
A Cohort study with controls. Study group included pediatric patients with known genetic mutations and hearing loss. A control group with healthy children was used to compare vestibular testing outcomes.

Results
A total of 48 pediatric patients (25 girls and 23 boys, aged 7 months to 16 years old) underwent vestibular work-up. About a half of the patients in the study group had at least one abnormal vestibular testing, which includes Videonystagmography (VNG), Rotary chair test , video Head Impulse Test (vHIT) and vestibular evoked myogenic potential (VEMP) testing, conducted. Of note, not all subjects had every single vestibular test vestibular testing. For VEMP outcome, 34% of the ears from the study patients had abnormal finding while all were normal in Control Group. Twenty nine patients from the study group had rotational test and 13 had abnormal findings. Neither the degree of hearing loss nor the type of gene mutation can be used to predict the vestibular loss.

Conclusions
Peripheral vestibular loss may be more prevalent in children with non-syndromic genetic hearing loss. Nonetheless, no reliable factor can be used to estimate the vestibular loss. Preferably, all patients with hearing loss due to genetic mutations should have comprehensive balance and vestibular evaluation so that impairment can be identified as early as possible. At minimal, a balance/vestibular function screening is needed for this group of children.

Brief Summary of Clinical Takeaways:
Be aware of the possibility of vestibular loss in children with non-syndromic genetic hearing loss.