Cochlear Implants

Useful in Severe to Profound Sensorineural Hearing Loss With Severe Degeneration Of Hair Cell Of Cochlea where Hearing Aids Are ineffective

2 Component

External

Internal

Speech Processor + Transmitter

Receiver / Stimulater With Electrode array

Principle / Mechanism

Speech Sound ➡️ Speech Processor ➡️ Coding of Sound into Electrical impulses ( Radiofrequency Waves )
Various Coding Strategies ➡️
1.Simultaneous analogue strategy (SAS)
2.Spectral Speak (SPEAK)
3.Advanced Combination Encoder (ACE)

Radifreuency waves ➡️ Transmitter Coil ➡️ Receiver / Stimulator ➡️ Linear erray of Electrodes placed in Scala Tympanic Of Cochlea

Stimulates Spiral Ganglion Cells ➡️ Stimulation of Auditory Nerve ➡️ Processed in Brain 🧠

Candidacy Profile
(Both Childdren & Adults )

Bilateral Severe to Profound Sensorineural Hearing
Loss

No medical contraindications to surgery

Family & Social Support

Adequate Cognitive Function

Prelingual ( Early indicated for proper speech development) & Postlingual Sensorineural Deafness

FACTORS that determine
Successful outcome of Implantation

Postlingual Deafness
Previous Use Of Hearing Aids

Neural Plasticity within Auditory system

Younger age of Children ( Prelingual Deafness)

Clinical Evaluation before Implantation

Vaccination against Meningitis ( H Influenzae , Pneumococcus & Meningococcus )

CT Scan & MRI for Evaluation Of
Anatomy of Temporal bone , Cochlea & Auditory Nerve

Audio logical Evaluation

Pure Tone Audiogram
SD Score
Tympanometry
Otoacoustic Emissions ( OAE)
Auditory Brainstem Responses (ABR)
Auditory Steady state Responses ( ASSR)

Hearing Aid Trial & Evaluation

Speech & Language Evaluation
Useful in Programming Of Implantable Device

Psychological Evaluationfor Cognitive status Of Patient & Counseling Of Parents

Surgery
For Placing the Electrode array
in close proximity with Spiral Ganglion cells & Dendrites

2 Surgical Approach

FACIAL RECESS Approach

1.Cortical Mastoidectomy

  1. Posterior Tympanotomy ➡️ Facial Recess is Opened
  2. Cochleostomy( Diameter 1 to 1.6 mm) anteroinferior to the Round window Membrane

PERICANAL Approach

1.Elevation Of Tympanomeatal Flap ( Veria or Suprameatal Approach )

  1. Cochleostomy ( Endaural or Postaural Approach)

Electrophysiological Testing Of Implant should be done before complete the surgery

Postoperative Care

Postoperative Mapping ( Programmimg Of Device ) After 3 -4 Weeks Of implantation.

Rehabilitation

Auditory-Verbal Therapy

Example
MED-EL , Nucleus &
Advanced Bionics Cochlear Implants