Your inner ear is made up of a system of passages and canals. Within that system, two “window” openings are responsible for moving sound and air pressure in your ear. SCDS (sometimes called superior semicircular canal dehiscence) begins when a third window is created and redirects the pressure in this inner ear system. This window forms when the bony covering of the semicircular canal (near the top of the ear) doesn’t exist or is too thin. Without that covering, the extra opening leads to balance, vision, and hearing problems. Doctors don’t know for sure what causes the defect in the covering, but theories include failure to fully form in utero, thinning of the bone as part of aging, and head trauma.