SENSORINEURAL HEARING DEFICIT A SYSTEMATIC-APPROACH BASED ON IMAGING FINDINGS

Sensorineural hearing loss (SNHL) can be classified audiometrically in to two varieties: sensory (cochlear) and neural (retrocochlear), Indiv iduals with sensory SNHL have damage to the ''end organ'' (the cochlea ) at a macroscopic or microscopic level, When present, imaging manifes tations may involve the bony labyrinth or membranous labyrinth, Abnorm alities of the bony labyrinth are demonstrable primarily with computed tomography and include demineralization, congenital deformities, trau matic lesions, and erosive or destructive lesions, Abnormalities of th e membranous labyrinth include enhancement and hemorrhage, which are d emonstrable with magnetic resonance (MR) imaging, and obliteration, wh ich may be diagnosed with either modality. Individuals with neural (re trocochlear) SNHL have involvement of the remainder of the auditory pa thway exclusive of the cochlea, This type of SNHL requires study of th e internal auditory canal, cerebellopontine angle, brain stem, thalamu s, and temporal lobe, The entirety of this type of examination is best performed with high-resolution MR imaging in virtually all cases.