Bilateral Superior Semicircular Canal Dehiscence Syndrome

Abstract

Nearly one-third of all SCDS cases present with bilateral pathology [1], however, emerging reports with larger cohorts estimate this number may be closer to 50% [2–4]. The clinical manifestation of bilateral SCDS, similar to its unilateral counterpart, is towards the sixth decade of life and has a modest predilection for females (Table 17.1) [2–4]. Similarly, the diagnostic triad consists of a combination of comprehensive clinical evaluation, including audiogram and vestibular evoked myogenic potential (VEMP) testing, and confirmed with high resolution computed tomography (HRCT) imaging [5–7] (Fig. 17.1). While the characteristic profile of SCDS is similar between unilateral and bilateral disease, specific symptoms such as vertical oscillopsia, impaired visual acuity upon movement, unsteady gait, and vertical and torsional jerk nystagmus have been reported in cases of distinct bilateral presentation [2, 8, 9]. One study found a potential correlation between bilateral disease and history of head trauma [2], and it has also been suggested that dizziness, internal sound amplification, and hearing loss, and disequilibrium may be more common in patients presenting with bilateral pathology as well (Table 17.2) [2–4].