Superior canal dehiscence syndrome is due to a defect in the bone coverage of this canal. The presence of this « third window » alters the biomechanics of the inner ear and can induce cochleo-vestibular symptoms, most commonly bone conduction hyperacusis, autophony, pulsatile tinnitus, and pressure- or sound-induced vertigo. Although the etiology remains unknown, it could be congenital. Head trauma or a Valsalva maneuver may also trigger the symptoms. The diagnosis is based on the association of specific symptoms, a characteristic auditory and vestibular workup and the presence of a dehiscence on a high-resolution CT-scan. Management can be medical or surgical in selected cases.