Patients’ experiences of living with superior canal dehiscence syndrome

The Supine Superior Semicircular Canal Dehiscence Test

Purpose The purpose of this clinical focus article is to describe a new method for assessment of superior semicircular canal dehiscence by laying the patient supine during Valsalva-induced nystagmus testing. Method The traditional Valsalva-induced nystagmus test is described, followed by a new method for assessment of superior semicircular dehiscence conducted by laying the patient supine during testing. A case study is presented to illustrate this new testing technique known as the Supine Superior Semicircular Canal Dehiscence Test. Results It is hypothesized that during Valsalva-induced nystagmus testing performed in the upright, seated position, the dura mater could potentially seal the superior semicircular canal fistula, thereby concealing a defect in the bony labyrinth and yielding a false-negative test. To circumvent this, the patient should be placed in the supine position during Valsalva-induced nystagmus testing in order to prevent the dura mater from inadvertently sealing itself against the petrous portion of the temporal bone. The Supine Superior Semicircular Canal Dehiscence Test may reveal the defect in the bony labyrinth and improve the sensitivity of the Valsalva-induced nystagmus test. Conclusions The Supine Superior Semicircular Canal Dehiscence Test may be more sensitive for identifying superior semicircular canal dehiscence in patients with traditional symptoms and a negative Valsalva-induced nystagmus test in the seated position. While a case study is presented to illustrate the potential benefits of including the Supine Superior Semicircular Canal Dehiscence Test in the battery of diagnostic tests, further research is needed in larger samples.

Current Trends, Controversies, and Future Directions in the Evaluation and Management of Superior Canal Dehiscence Syndrome

Patients with superior canal dehiscence syndrome (SCDS) can present with a range of auditory and/or vestibular signs and symptoms that are associated with a bony defect of the superior semicircular canal (SSC). Over the past two decades, advances in diagnostic techniques have raised the awareness of SCDS and treatment approaches have been refined to improve patient outcomes. However, a number of challenges remain. First, there is currently no standardized clinical testing algorithm for quantifying the effects of superior canal dehiscence (SCD). SCDS mimics a number of common otologic disorders and established metrics such as supranormal bone conduction thresholds and vestibular evoked myogenic potential (VEMP) measurements; although useful in certain cases, have diagnostic limitations. Second, while high-resolution computed tomography (CT) is the gold standard for the detection of SCD, a bony defect does not always result in signs and symptoms. Third, even when SCD repair is indicated, there is a lack of consensus about nomenclature to describe the SCD, ideal surgical approach, specific repair techniques, and type of materials used. Finally, there is no established algorithm in evaluation of SCDS patients who fail primary repair and may be candidates for revision surgery. Herein, we will discuss both contemporary and emerging diagnostic approaches for patients with SCDS and highlight challenges and controversies in the management of this unique patient cohort.

Prospective Analysis of an Evidence-Based Symptom Set in Superior Canal Dehiscence Syndrome

INTRODUCTION

Superior canal dehiscence syndrome (SCDS) is characterized by a defect in the bone overlying the superior semicircular canal. This third mobile window generates an abnormal low-impedance pathway for sound/pressure transmission into the inner ear resulting in the characteristic symptoms.

OBJECTIVE

To perform a prospective analysis of symptoms in patients with SCDS.

METHODS

An aggregated symptom set was studied prospectively and compared with a healthy control group. The 31 items inquired about the presence and severity of symptoms. Initial comparison between both groups was performed using the Kolmogorov-Smirnov test and nonparametric Mann-Whitney U test. For analysis of the internal consistency, the Cronbach's alpha coefficient was determined. Finally, the prevalence of symptoms obtained in the present study was compared to the prevalence of symptoms obtained as part of a recent retrospective systematic review.

RESULTS

Responses from the 29 patients with SCDS in the case group and the 58 healthy controls were not normally distributed. Those with SCDS had a higher prevalence and more severe symptoms for almost all items. The Cronbach's alpha coefficient of 0.969 indicates an excellent internal consistency. The prospective prevalence of most symptoms was higher than the retrospective prevalence reported earlier.

CONCLUSIONS

SCDS causes a variety of vestibular and auditory symptoms. This prospective study demonstrates that their prevalence and severity are higher than reported previously. This symptom set demonstrates excellent internal consistency and will serve as a foundation toward developing a disease-specific patient-reported outcome measure for SCDS.

LEVEL OF EVIDENCE

NA.