Sensorineural hearing deficit: a systematic approach based on imaging findings.

Sensorineural hearing loss (SNHL) can be classified audiometrically into two varieties: sensory (cochlear) and neural (retrocochlear). Individuals with sensory SNHL have damage to the "end organ" (the cochlea) at a macroscopic or microscopic level. When present, imaging manifestations may involve the bony labyrinth or membranous labyrinth. Abnormalities of the bony labyrinth are demonstrable primarily with computed tomography and include demineralization, congenital deformities, traumatic lesions, and erosive or destructive lesions. Abnormalities of the membranous labyrinth include enhancement and hemorrhage, which are demonstrable with magnetic resonance (MR) imaging, and obliteration, which may be diagnosed with either modality. Individuals with neural (retrocochlear) SNHL have involvement of the remainder of the auditory pathway exclusive of the cochlea. This type of SNHL requires study of the internal auditory canal, cerebellopontine angle, brain stem, thalamus, and temporal lobe. The entirety of this type of examination is best performed with high-resolution MR imaging in virtually all cases.