Spontaneous SSCD Auto-Plugging: Clinical, Electrophysiological and Radiological Evidence

Background: Superior semicircular canal dehiscence (SSCD) is characterized by a bony defect of the superior semicircular canal (SSC), leading to vestibular and auditory symptoms. A process of spontaneous "auto-plugging," in which the overlying dura mater progressively occludes the SSC, may replicate the effects of surgical canal plugging but remains under-recognized. The present study reports diverse clinical, instrumental, and 3d High Resolution MRI findings in patients with SSCD and subsequently confirmed to present with spontaneous complete or partial auto-plugging. Methods: We retrospectively reviewed 11 patients with SSCD diagnosed on high-resolution CT and suspected auto-plugging based on clinical atypia and large dehiscence (>4 mm). Patients underwent comprehensive neurotological assessment, including pure-tone audiometry, vestibular testing, and HR MRI with 3D labyrinthine reconstructions to identify partial or complete auto-plugging. Auto-plugging was classified as partial (Canalis semicircularis superior depressus) or complete (absence of endolymph fluid signal; Canalis semicircularis superior obturatus). Results: Among 13 ears with auto-plugging, 6 were partial and 7 complete. The mean SSCD size in auto-plugged ears was 5.5 mm. Most ears had normal or near-normal vestibular function on VHIT, with minimal air-bone gaps and preserved VEMP responses. Imaging demonstrated varying degrees of dural contact with the SSC, confirming partial or complete canal occlusion. Conclusions: Spontaneous auto-plugging of the SSC is a plausible, under-recognized phenomenon that may reproduce functional effects of surgical plugging. Dedicated 3D labyrinthine MRI enhances detection and characterization. Prospective multimodal studies are needed to clarify the pathophysiology, progression, and clinical implications, optimizing patient selection for surgical versus conservative management.