Superior semicircular canal dehiscence syndrome as assessed by oVEMP and temporal bone computed tomography imaging

Abstract

To evaluate the role of oVEMP and multidetector CT scan in patients with superior canal dehiscence syndrome. Prospective study was conducted on nine patients with superior canal dehiscence syndrome (5 females, 4 males) age ranged 19-49 with mean age of 32.7 ± 9.3 years, complaining of intolerance to loud sounds and/or oscillopsia. The mean duration of illness was 18.7 ± 6.9 months, nine normal individuals as control (age and gender matched) were also included in the study. All of them underwent oVEMP and MDCT scan. Patients were of bilateral normal hearing sensitivity with no conductive impairment. All of the studied subjects (patients and controls) had identifiable contralateral oVEMP responses. MDCT scan showed dehiscence in all the patients. The dehiscence was unilateral (n = 7) and bilateral [n = 2 the other ear had a defect of 2 mm and thus was excluded from the study for fear or false diagnosis of Superior semicircular canal dehiscence syndrome (SCDS)]. Unlike the normal subject (nI = 0.94 µV ± 0.03 and pI = -0.42 µV ± 0.09), with stimulation of the affected side in SCDS, there were augmented amplitude responses (nI = 2.64 µV ± 0.35 and pI = -3.10 µV ± 0.44) in the eye contralateral to the stimulus "contralateral to the lesion". Mean oVEMP threshold for SCDS ears were 82.5 ± 7.55 dBnHL compared to 100 ± 5.77 dBnHL of the control ears. We concluded that combination of physiological and anatomical information from oVEMP and MDCT increased accuracy for diagnosis of dehiscence of superior semicircular canal.

Correlation of Superior Canal Dehiscence Surface Area With Vestibular Evoked Myogenic Potentials, Audiometric Thresholds, and Dizziness Handicap

“…Further, we recognize that previous studies have highlighted that volume averaging may lead to a misleading dehiscent appearance, especially for defects under 2 mm. 25 We feel that diagnosis of a clear dehiscence with subsequent confirmation by a neurotologist limits, but does not eliminate, the potential bias introduced by volume averaging. Future studies are ongoing in which intraoperative dehiscence measurements are taken to validate our segmentation analyses.…”

Epley manoeuvre for posterior semicircular canal benign paroxysmal positional vertigo in people with multiple sclerosis: protocol of a randomised controlled trial

“…One of the possible affections of the inner ear is the posterior semicircular canal dehiscence, caused by a defect in the bony roof of the temporal bone. Thus, Thabet et al 55 state that contralateral oVemps (extraocular vestibular-evoked myogenic potential) response and multidetector CT scanner (MDCTS) are essential to rule out inner ear defects and to reach a correct diagnosis. Reaching a correct vestibular diagnosis in MS is difficult, which is why diagnostic tools such as VNG, electronystagmography, cervical or ocular Vemps, magnetic resonance, MDCTS and specific vestibular manoeuvres, along with clinical manifestations, could play a fundamental role in the neuro-otological examination.…”

Practice guideline: Cervical and ocular vestibular evoked myogenic potential testing

“…One retrospective study looked at 9 patients with SCDS matched to controls. 35 Mean raw amplitudes were greater in SCDS ears, 2.68 mV (95% CI 2.46-2.90 mV), than in controls, 0.93 mV (95% CI 0.91-0.95 mV). Using an n10 amplitude of $1.5 mV, oVEMP had 100% sensitivity and 100% specificity in differentiating patients with SCDS from controls.…”

“…25,28,29,31,[35][36][37] oVEMP amplitude. One retrospective study looked at 9 patients with SCDS matched to controls.…”