Definition And Mechanism

• Prosthetic device designed to bypass injured organ of Corti.
• Directly stimulates residual cochlear nerve cells located within spiral ganglion.
• Converts environmental auditory stimuli into digital radiofrequency impulses.
• Replaces normal physiologic transmission involving hair cell sound vibration, ion release, and neurotransmitter activation.

Device Components

• System combines externally worn and surgically implanted internal components.

Indications And Candidacy

• Indicated for bilateral severe to profound sensorineural hearing loss exceeding 70 decibels.
• Requires documented unsatisfactory benefit from conventional hearing aids after 3 to 6 month trial.
• Minimum age approved by United States Food and Drug Administration reduced to 9 months.
• Off-label utilization demonstrates efficacy in younger infants and children retaining residual hearing.
• Early intervention before 2 years of age optimizes outcomes, enabling over 90 percent of children to enter mainstream education.

Preoperative Evaluation

• Requires comprehensive audiologic testing to establish baseline deficits.
• High-resolution computed tomography assesses bony temporal bone and inner ear anatomy.
• Magnetic resonance imaging confirms presence and structural integrity of cochlear nerve.

Surgical Management

• Procedure performed under general anesthesia.
• Involves mastoidectomy coupled with widening of facial recess to access inner ear.
• Internal stimulator package fastened securely within mastoid process.
• Cochlea opened typically via round window to insert multielectrode array into scala tympani.
• Extreme caution exercised to prevent cochlear fluid contamination by bone dust or blood.
• Intraoperative audiologist testing immediately verifies device functional integrity via cranial nerve VIII electrophysiologic responses.
• Intraoperative plain radiograph confirms precise electrode array placement.

Postoperative Rehabilitation

• Initial healing period spans 3 to 4 weeks, during which child remains without auditory input.
• Initial stimulation establishes baseline programming for first sound access.
• Program modification relies on behavioral testing and observed vocalization changes.
• Demands intensive, long-term commitment to speech and language therapy.
• Bilateral implantation preferred over unilateral procedure to improve sound localization and speech understanding in noisy environments.

Complications And Special Considerations