Described by Lloyd Minor in 1998, the dehissent superior semicircular canal syndrome is a relatively common cause of hearing and balance problems. Basically there is a “third window” in the otic capsule that dissipates sound energy. Clinically it presents with ill defined balance issues, oscillopsia, Tullio’s phenomenon, Hennebert’s sign as well as a low frequency hearing loss. Patients often report hearing their eyes move (like sandpaper) as well as amplfied autophonia to voice (“kazoo” like) with out autophonia to breathing (like patulous ETT). May also have amplified conductive hearing sensitivity, being able to hear a tuning fork on the malleolus of the ankle.
Can see on a thin cut CT scan. Will have abnormal VEMPS and a positive fistula test (Hennebert’s Sign). May be what we thought previously to be a PLF which is why Round window reinforcement works.