High-frequency pseudo-hypofunction of the superior semicircular canal dehiscence syndrome: a vHIT - oVEMP dissociation explained by hydrodynamic energy loss

Superior semicircular canal dehiscence syndrome (SCDS) produces a wide spectrum of vestibular and auditory abnormalities due to the presence of a "third mobile window." While enhanced otolith-mediated responses are well recognized, the behavior of high-frequency semicircular canal function remains debated....

When vHIT shows apparent semicircular canal hypofunction alongside preserved or enhanced oVEMP responses in SCDS, clinicians should recognise this as pseudo-hypofunction caused by hydrodynamic energy loss rather than true canal pathology, and avoid misdiagnosis.

Understanding the mechanism behind vHIT–oVEMP dissociation in SCDS clarifies a known diagnostic pitfall and may prevent unnecessary further investigation or misclassification of vestibular function in these patients.

1. 01SCDS creates a 'third mobile window' in the inner ear that bleeds hydrodynamic energy at high frequencies.
2. 02This energy loss explains why vHIT (a high-frequency test) can appear abnormal while oVEMP remains normal or enhanced.
3. 03The apparent canal hypofunction in vHIT is termed 'pseudo-hypofunction'—not a true loss of vestibular function.
4. 04The dissociation between vHIT and oVEMP results is a useful diagnostic pattern for identifying SCDS.
5. 05Findings add mechanistic clarity to an existing clinical observation without requiring a change in diagnostic workup.

PMID

42228120

DOI

10.1007/s00405-026-10347-0.

Journal

European Archives of Oto-Rhino-Laryngology

Publication type

research_article

Evidence level

4

Population

Patients diagnosed with superior semicircular canal dehiscence syndrome (SCDS)

Intervention

Video head impulse testing (vHIT) and ocular vestibular-evoked myogenic potentials (oVEMP) in SCDS