In patients with bilateral severe-to-profound SNHL who receive cochlear implants, which of the following anatomical structures is the electrode array stimulating to restore hearing?
- A Outer hair cells of the organ of Corti via direct mechanical stimulation
- B Cochlear nerve fascicles in the internal acoustic canal
- C Stria vascularis to restore endocochlear potential
- D Spiral ganglion neurons (Type I auditory neurons) in the modiolus via electrical stimulation ✓
Explanation
A cochlear implant electrode array is inserted into the scala tympani of the cochlea and delivers electrical stimulation directly to the peripheral processes and soma of Type I spiral ganglion neurons located in Rosenthal's canal within the modiolus. These neurons survive even after complete outer and inner hair cell loss because they can be sustained by intact afferent auditory nerve fibres. Cochlear implants bypass the damaged hair cells entirely, which is why they work in profound SNHL. The prerequisite is a sufficient number of surviving spiral ganglion neurons and an intact auditory nerve.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.