By Mia Miller, MD and Helena Wichova, MD
In the last two decades, superior semicircular canal dehiscence syndrome has become a more familiar diagnosis. Patients usually complain of sound and pressure-induced dizziness, trouble hearing, ear fullness, and hearing one’s heartbeat or breathing. When we suspect this diagnosis, a high-resolution computed tomography (CT) helps identify an area of missing bone overlying the superior semicircular canal, which is responsible for these symptoms. Because some patients may have dehiscence on CT without any symptoms, a clinical test measuring cervical vestibular evoked myogenic potentials (cVEMP) is used. Specifically, signals over the sternocleidomastoid muscle are measured as sound is presented to the ear to gauge the reactivity of the balance system. Abnormal cVEMP readings are only detected on the side of dehiscence with normal findings on the normal ear.
Treatment for symptomatic patients involves surgical resurfacing and/or plugging of the dehiscent superior semicircular canal. Given the variable locations of dehiscence, it can sometimes be challenging to ensure that the entire dehiscence has been covered. Studies looking at revision surgery in patients who remained symptomatic after repair show that, in 74% of the cases, resurfacing material did not entirely cover the area of dehiscence. After successfully resurfacing the superior semicircular canal dehiscence, cVEMP readings return to normal.
This project obtains real-time feedback with intraoperative cVEMP measurements, confirming superior semicircular canal dehiscence repair and normalization of cVEMP readings prior to finishing surgery. Intra-operative cVEMP monitoring allows surgeons to perform superior canal dehiscence repair with much higher precision, ensuring the best chance of successfully repairing and resolving symptoms without adding extra steps or clinic visits.