What is the recommended treatment for semi-circular canal dehiscence?

Treatment of Superior Semicircular Canal Dehiscence (SSCD)

For patients with severe, debilitating symptoms of superior semicircular canal dehiscence, surgical repair through either middle fossa craniotomy or transmastoid approach using plugging or capping techniques is recommended, with overall success rates of 94%. 1, 2

Initial Management Strategy

Conservative Management

• Patients with mild symptoms should be managed conservatively without surgical intervention. 2, 3
• Observation is appropriate when symptoms do not significantly impact quality of life or daily functioning. 2

Indications for Surgical Intervention

Surgery should be reserved for patients experiencing debilitating symptoms that include: 2, 3, 4

• Severe vertigo or oscillopsia induced by loud sounds (Tullio phenomenon)
• Disabling autophony (hearing one's own voice or bodily sounds excessively)
• Vertigo triggered by pressure changes in the external auditory canal or middle ear
• Significant functional impairment affecting work or daily activities

Surgical Approaches

Middle Fossa Craniotomy

• Provides superior visualization of the dehiscence and is considered the most common and standard surgical approach. 2, 3
• Allows direct access to the superior semicircular canal from above. 2
• Associated with higher morbidity compared to transmastoid approach. 2
• Endoscopic assistance during middle fossa approach may improve visualization. 2

Transmastoid Approach

• Offers lower morbidity than middle fossa craniotomy. 2
• Provides adequate access for canal repair with less invasive technique. 2
• No statistically significant difference in success rates compared to middle fossa approach. 1

Repair Techniques

Plugging and capping techniques are preferred over resurfacing alone, as they achieve higher success rates without increased risk of hearing loss. 2

• Plugging: Occlusion of the canal lumen at the site of dehiscence. 1, 2
• Capping: Covering the dehiscence without occluding the canal. 1, 2
• Resurfacing: Covering the bony defect with tissue or bone graft. 1, 2
• Combined plugging with resurfacing: May be used for more extensive defects. 1

Expected Outcomes

Success Rates

• Overall surgical success rate: 94% (95% CI: 87%-97%). 1
• Statistically significant improvement in autophony index score (p = 0.02), symptom severity score (p < 0.001), and sound hypersensitivity (p = 0.01). 5

Persistent Symptoms

• Dysequilibrium may persist post-operatively despite improvement in other symptoms. 5
• Headache and concentration difficulties are common symptom themes that may continue after surgery. 5

Diagnostic Confirmation Before Surgery

Imaging Requirements

• High-resolution CT temporal bone scans with fine-cut (0.5-0.6 mm) collimation reformatted parallel and orthogonal to the plane of the superior canal are the standard for confirming SSCD. 6, 4
• Oblique reformats in Pöschl and Stenver planes are essential to avoid overestimation of dehiscence. 6
• MRI FIESTA sequences may also be used for imaging SSCD. 3

Functional Testing

• Vestibular evoked myogenic potential (VEMP) testing serves as a useful screening tool. 3, 4
• Audiometry should be performed to document conductive hearing loss pattern. 3, 4

Critical Pitfalls to Avoid

• Do not operate on asymptomatic patients with radiographic evidence of SSCD alone—surgery should only be performed in patients with clinical manifestations. 4
• Avoid resurfacing as the sole repair technique—plugging or capping provides superior outcomes. 2
• Do not assume all symptoms will resolve—counsel patients that dysequilibrium may persist despite successful anatomic repair. 5
• Ensure proper imaging technique—standard CT without oblique reformats may overestimate the presence or extent of dehiscence. 6