Hearing Impairment Dr Ahmad Alamadi FRCS Consultant Otolaryngologist Al Baraha Hospital

Objectives  Basic anatomy  Types of hearing losses  History & Examination  Etiology  Investigations  Management

Introduction

Effects of Hearing Impairment on Development Has life long effect on  Language Delay  Literacy  Educational achievement  Vocational Opportunities  Academic difficulties  Psychosocial adjustments and/or difficulties

Anatomy External Ear 1.concha 2.crus helix 3.helix 4.scaphoid fossa 5.antihelix 6.antitragus 7.tragus lobule not labeled

Middle Ear

Inner Ear

Organ of corti

Pathophysiology  Sound waves to the auricle through the external auditory canal to the tympanic membrane. When they strike the tympanic membrane, the waves cause it to vibrate, setting off a chain of vibrations along the ossicles (malleus, incus, and stapes) to the membrane of the oval window at the entrance to the cochlea. This process amplifies the environment sound by approximately 20-fold.  The cochlea is the end organ of hearing and is shaped like a snail shell with 2.5 turns. Inside, 2 membranes longitudinally divide the cochlea into 3 sections: the scala tympani, the scala vestibuli, and the scala media. All 3 are filled with fluid of various ion concentrations (similar to intracellular and extracellular constituents).  Along one of the membranes in the scala media, or cochlear duct, lie the internal and external hair cells. Movement of the stapes on the oval window creates a wave or vibration in the perilymph fluid of the cochlea. This fluid movement, which opens ion channels in the hair cells, displaces the hair cells, triggering an action potential and causing a nerve in the cochlea to fire to the brain.  Thousands of nerves representing more than 20,000 frequencies are located along the length of the cochlea; these nerves account for the hearing range. The microscopic nerves culminate in the cochlear portion of the eighth cranial nerve. The location of the vibration in the cochlea is correlated with the frequency of the original pitch. Low-frequency sounds are near the apex, and high-frequency sounds are near the base.

Types of Hearing Losses  Conductive hearing loss  Sensori-neural hearing loss  Mixed hearing loss  Central Auditory disorders or Neural hearing loss

Conductive Hearing Loss  The loss of sound sensitivity produced by abnormalities of the outer or middle ear i.e, conducting mechanism

Sensori-Neural Hearing Loss  The loss of sound sensitivity produced by abnormalities of the inner ear.

Mixed Hearing Loss  The sum of the hearing losses produced by abnormalities in both the conductive and sensorineural mechanism of hearing.

Central OR Neural Hearing Loss  The loss or impairment in processing of information produced by abnormality in neural system i.e, Nerve fiber or central auditory cortex.

Clinical history  Hearing loss  Age of onset  Severity  Risk factors Family history of congenital or early SNHL Congenital infection known to be associated with SNHL Craniofacial anomalies Birth weight of less than 1500 g (<3.3 lb) Hyperbilirubinemia over the exchange level Exposure to ototoxic medications Bacterial meningitis Low Apgar scores at birth Prolonged mechanical ventilation Findings of a syndrome associated with SNHL

Syndromic Deafness  DiGeorge sequelae  CHLYesBranchio-oto-facial syndrome  Townes-Brocks syndrome  Miller syndrome  Bixler syndrome  CHARGE syndrome  Jervell Lange-Nielson  Limb-oto-cardiac syndrome  Alport syndrome  Branchio-oto-renal syndrome  Kearns-Sayre syndrome  Epstein syndrome  Barakat syndrome  Noonan syndrome  Killian/Teschler-Nicola syndrome

Clinical history  Hearing Impairment  Pain  Discharge  Tinnitus  Vertigo

Examination  Otoscopy  Nose  PNS  Facial nerve  Free field test  Tuning fork tests  Weber Test  Rinne Test

Investigations  Lab Studies TFT, BUN, CR ECG ESR, Rhf, ANA Connexin 26  Imaging Studies  Tests for Hearing Loss PTA ABR ASSR OAE

Etiology  Genetic causes connexion 26  Syndromic associations  Congenital infections  cytomegaloviral  herpes  Rubella  Syphilis  Toxoplasmosis  varicella  Postnatal  Prematurity  low birth weight  anoxia  hyperbilirubinemia  sepsis  meningitis  mumps  ototoxic medications  aminoglycosides  furosemide  major head injury

Management  Medical: antibiotics  Surgical: Ventilation tubes, reconstruction of middle ear  Amplification Technology: Analog & digital hearing aids + Speech and language therapy.  Surgical+ Amplification Technology: Cochlear Implants (Severe Sensorineural loss or greater)