Superior canal dehiscence syndrome (SCDS) is a rare medical condition of the inner ear, first described in 1998 by Dr. Lloyd B. Minor of Johns Hopkins University, Baltimore, USA, leading to hearing and balance disorders in those affected. The symptoms are caused by a thinning or complete absence of the part of the temporal bone overlying the superior semicircular canal of the vestibular system. This may result from slow erosion of the bone or physical trauma to the skull and there is evidence that the defect or susceptibility is congenital.
Patients with SCDS-related autophony report hearing their own voice as a disturbingly loud and distorted “kazoo-like” sound deep inside the head as if relayed through “a cracked loudspeaker.” Additionally they may hear the creaking and cracking of joints, the sound of their footsteps when walking or running, their heartbeat and the sound of chewing and other digestive noises. Some sufferers of this condition experience such a high level of conductive hyperacusis that a tuning fork placed on the ankle will be heard in the affected ear. The bizarre phenomenon of being able to hear the sound of the eyeballs moving in their sockets (e.g. when reading in a quiet room) “like sandpaper on wood” is one of the more distinctive features of this condition and is almost exclusively associated with SCDS.
