Superior canal dehiscence syndrome

Superior canal dehiscence syndrome (SCDS) occurs when thin or dehiscent bone over the superior semicircular canal, best demonstrated on CT, allows pressure transmission between the canal and the intracranial space. Vertigo and nystagmus may occur when the canal is stimulated by loud sounds or changes in middle ear or intracranial pressure. Hyperacusis to bone-conducted sounds can cause conductive hearing loss, pulsatile tinnitus, or autophony (hearing one’s own body sounds as loud or distorted). While the bony defect may be congenital, head trauma can be the final step that opens a functionally mobile labyrinthine window.