Possible retrocochlear pathology: asymmetric SNHL, left worse than right. There is deficiency of bone overlying the left superior semicircular canal. The other left inner ear structures are unremarkable. The right inner ear structures, including the cochlea, vestibule, endolymphatic duct, and semicircular canals, appear unremarkable. The bilateral cranial nerve 7 and 8 complexes are intact. There is no evidence of mass lesions. The bilateral mastoid air cells and middle ears also appear unremarkable. There is extension of cerebrospinal fluid into the bilateral geniculate fossae, which is an anatomic variant.
Apparent left superior semicircular canal dehiscence. A temporal bone CT may be useful for confirmation.