Superior Canal Dehiscence Syndrome Affecting 3 Families | Vestibular Disorders | JAMA Otolaryngology–Head & Neck Surgery | JAMA Network
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Original Investigation
July 2017

Superior Canal Dehiscence Syndrome Affecting 3 Families

Author Affiliations
  • 1Division of Otology-Neurotology, Department of Otolaryngology–Head and Neck Surgery, University of Michigan Health System, Ann Arbor
  • 2Division of Pediatric Otolaryngology, Department of Otolaryngology–Head and Neck Surgery, University of Michigan Health System, Ann Arbor
JAMA Otolaryngol Head Neck Surg. 2017;143(7):656-662. doi:10.1001/jamaoto.2016.4743
Key Points

Question  Do familial cases of superior canal dehiscence syndrome support a molecular genetic basis for the condition?

Findings  Seven individuals in 3 families in this case series were diagnosed with superior canal dehiscence syndrome or near dehiscence. Because 5 of the 7 patients were not obese, obesity alone does not explain the occurrence of superior canal dehiscence syndrome.

Meaning  This report provides evidence in support of a potential genetic contribution to the etiology of superior canal dehiscence syndrome.

Abstract

Importance  Superior canal dehiscence syndrome (SCDS) is an increasingly recognized cause of hearing loss and vestibular symptoms, but the etiology of this condition remains unknown.

Objective  To describe 7 cases of SCDS across 3 families.

Design, Setting, and Participants  This retrospective case series included 7 patients from 3 different families treated at a neurotology clinic at a tertiary academic medical center from 2010 to 2014. Patients were referred by other otolaryngologists or were self-referred. Each patient demonstrated unilateral or bilateral SCDS or near dehiscence.

Interventions  Clinical evaluation involved body mass index calculation, audiometry, cervical vestibular evoked myogenic potential testing, electrocochleography, and multiplanar computed tomographic (CT) scan of the temporal bones. Zygosity testing was performed on twin siblings.

Main Outcomes and Measures  The diagnosis of SCDS was made if bone was absent over the superior semicircular canal on 2 consecutive CT images, in addition to 1 physiologic sign consistent with labyrinthine dehiscence. Near dehiscence was defined as absent bone on only 1 CT image but with symptoms and at least 1 physiologic sign of labyrinthine dehiscence.

Results  A total of 7 patients (5 female and 2 male; age range, 8-49 years) from 3 families underwent evaluation. Family A consisted of 3 adult first-degree relatives, of whom 2 were diagnosed with SCDS and 1 with near dehiscence. Family B included a mother and her child, both of whom were diagnosed with unilateral SCDS. Family C consisted of adult monozygotic twins, each of whom was diagnosed with unilateral SCDS. For all cases, dehiscence was located at the arcuate eminence. Obesity alone did not explain the occurrence of SCDS because 5 of the 7 cases had a body mass index (calculated as weight in kilograms divided by height in meters squared) less than 30.0.

Conclusions and Relevance  Superior canal dehiscence syndrome is a rare, often unrecognized condition. This report of 3 multiplex families with SCDS provides evidence in support of a potential genetic contribution to the etiology. Symptomatic first-degree relatives of patients diagnosed with SCDS should be offered evaluation to improve detection of this disorder.

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