Superior Semicircular canal dehiscence (SSCD)

🧪 Objective Testing

In addition to bedside testing, several objective measures provide support for SSCD.

Vestibular Evoked Myogenic Potentials (VEMP):
Often over-responsive, with lower thresholds and larger amplitudes due to increased sensitivity from the third window (Ward et al., 2021; Castellucci et al., 2021).

Audiometry:
May show an air–bone gap despite normal middle ear function. Bone conduction thresholds can be unusually sensitive (better than 0 dB), consistent with third-window physiology (Ward et al., 2021; Naert et al., 2018).

vHIT:
Assesses the vestibulo-ocular reflex during rapid head movements. VOR gain in the superior canal may be mildly reduced, as the third window allows energy to dissipate, resulting in less effective cupula deflection. Findings are often subtle or variable and should be interpreted alongside other clinical data (Castellucci et al., 2021).

🖥️ Imaging

• High-resolution CT of the temporal bone is required to confirm the diagnosis
• Thin slice imaging (≤0.5 mm) with appropriate reformats improves the ability to accurately detect a dehiscence (Ward et al., 2021; Cloutier et al., 2008).

⚖️ Balance and Functional Findings

Balance testing in SSCD is often variable and non-specific.

Some individuals may demonstrate unsteadiness or gait instability, particularly in more complex or visually challenging environments. However, these findings are not consistent and are not used to diagnose SSCD (Naert et al., 2018; Ward et al., 2021).

In select or more complex cases, balance impairment may be more noticeable, but findings vary widely and are not well standardized across patients (Carender et al., 2018; Khalili et al., 2026).

👉 Overall, balance testing may help describe functional impact, but does not provide specific diagnostic information for SSCD.