Functional and Radiological Profile of Spontaneous Autoplugging in Superior Canal Dehiscence.

OBJECTIVE

To characterize the clinical, radiologic, and electrophysiological features of spontaneous autoplugging in superior semicircular canal dehiscence (SSCD) and compare them to untreated and surgically treated cases.

METHODS

This retrospective observational study was conducted in a tertiary referral center in Paris, France. Fifty-nine SSCD ears were categorized into 3 groups: untreated (n=36), autoplugging (n=5), and surgically plugged (n=18). Autoplugging was defined as the absence of a fluid signal in the dehiscent canal on high-resolution 3D T2-weighted MRI in patients with no history of ear surgery. All patients underwent clinical assessment, audiometry, video head impulse test (vHIT), cervical vestibular-evoked myogenic potentials (cVEMP), and high-resolution imaging. Group comparisons used nonparametric tests with FDR correction and power analysis.

RESULTS

vHIT gain was significantly reduced in both the autoplugging (0.56 ± 0.09) and surgical groups (0.57 ± 0.13) compared with untreated SSCD (0.77 ± 0.19, P =0.0003). The reduction was confined to the superior canal, whereas lateral and posterior canal gains remained normal. Autophony persisted in the autoplugging group (80%) but was significantly reduced in the surgical group (22.2%, P <0.0001). cVEMP thresholds were abnormally low in untreated (62.0 ± 11.1 dB) and autoplugging ears (62.5 ± 9.6 dB), and significantly higher post-surgery (83.5 ± 12.3 dB, P <0.001).

CONCLUSION

Autoplugging mimics surgical plugging in terms of canal dysfunction but fails to alleviate third-window symptoms. It may represent an incomplete, spontaneous adaptation in SSCD pathophysiology.

LEVEL OF EVIDENCE: Level 3.