Hearing impairment Hearing impairment and rehabilitationand rehabilitation

OUTLINEOUTLINE

Types of hearing loss

Classification of hearing loss Diagnosing and managing different kinds of hearing loss; e.g

congenital hearing loss otosclerosis, presbyacusis, noise Induced Hearing Loss ,Meniers disease ,ototoxicity

Performing and interpreting various subjective and objective hearing tests

Tuning fork test

Pure Tone Audiometry

Impedance Audiometry

Brain Stem Evoked Response Audiometry

HEARING IMPAIRMENTHEARING IMPAIRMENT

Hearing impairment, also called deafness or hearing loss, occurs when there’s a problem with or damage to one or more parts of the ear.

U.S. population 270+ million2 million Deaf 26 million Hard of Hearing

1 of every 10 people has a hearing loss Over age 65, 1 in every 3 persons has some degree of hearing loss 80% of hearing people are in denial

TYPES OF HEARING LOSSTYPES OF HEARING LOSS

1. Conductive Hearing Loss (CHL)

• the conduction of sound to the cochlea is impaired

• can be caused by external and middle ear disease

2. Sensorineural Hearing Loss (SNHL)

• due to a defect in the conversion of sound into neural signals or in the transmission of those signals to the cortex

• can be caused by disease of the cochlea, acoustic nerve ( CN Vlll), brainstem, or cortex

TYPES OF HEARING LOSSTYPES OF HEARING LOSS

3. Mixed Hearing Loss

• the conduction of sound to the cochlea is impaired, as well as transmission through the cochlea to the cortex

DIFFERENTIAL DIAGNOSIS OF HEARING DIFFERENTIAL DIAGNOSIS OF HEARING LOSSLOSS

DIFFERENTIAL DIAGNOSIS OF HEARING DIFFERENTIAL DIAGNOSIS OF HEARING LOSSLOSS

APPROACH

HISTOHISTORYRY

HPI:

Onset (sudden or gradual)

Duration

Unilateral/ bilateral

Continuous / Intermittent

HISTOHISTORYRY

HPI:

Exposure- noise, drugs, viral illness

History of ear of head trauma

History of surgeries

Associated symptoms- pain, discharge, tinnitus, vertigo

HISTORYHISTORY

PMH: Chronic illness: DM, HTN, Hypothyroidism Previous surgeries

Rx: Ototoxic drugs

Amino glycosides, diuretics, quinine, aspirin

Social history: Occupation Tobacco Alcohol Cocaine Marijuana

PHYSICAL PHYSICAL EXAMINATIONEXAMINATION

General assessment Ear exam:

Deformities of Pinna & EAC Pre & post-auricular region

Otoscopy - EAC, TM

Tuning Fork Test- Rinne

- Weber

Cranial Nerves

INVESTIGATIONSINVESTIGATIONS

Specific hearing tests

Tuning Fork Tests

Pure tone audiometry

Impedance audiometry

Brain stem evoked response audiometry

Radiology

- CT & MRI of skull & temporal bones

HEARING TESTSHEARING TESTS

Subjective Tonic Fork test

Pure tone audiometry (PTA)

Objective Tympanometry (impedance audiometry)

Electric response audiometry (ERA).

TUNING FORK TESTSTUNING FORK TESTSTest: Weber Technique: Tuning Fork placed at

midline forehead

Normal: Sound radiates to both ears equally

Abnormal: Sound lateralizes to one ear Ipsilateral Conductive Hearing Loss OR

Contralateral Sensorineural Hearing Loss

TUNING FORK TESTSTUNING FORK TESTSTest: Rinne’s

TechniqueFirst: Bone Conduction

Vibrating Tuning Fork held on Mastoid

Patient covers opposite ear with hand

Patient signals when sound ceases

Move the vibrating tuning fork over the ear canal

Near, but not touching the ear

Next: Air Conduction Patient indicates when the sound

ceases

TUNING FORK TESTSTUNING FORK TESTS

Test: Rinne’s Normal: Air Conduction is better than Bone Conduction

Air conduction usually persists twice as long as bone

Referred to as "positive test"

Abnormal: Bone conduction better than air conduction

Suggests Conductive Hearing Loss

Referred to as "negative test"

PURE TONE AUDIOMETRY (PTA)PURE TONE AUDIOMETRY (PTA)

PTA is the key hearing test used to identify hearing threshold level of an individual, enabling determination of the degree, types and configuration of hearing loss.

Provides the basis for diagnosis and management.

The symbols used on most audiograms are: x - left, air conduction

o - right, air conduction

] - left, bone conduction

[ - right, bone conduction

NORMAL AUDIOGRAMNORMAL AUDIOGRAM

TYMPANOMETRY (IMPEDANCE TYMPANOMETRY (IMPEDANCE AUDIOMETRY)AUDIOMETRY)

Assess the function of middle ear and Eustachian function of middle ear and Eustachian tube.tube.

Very useful when screeningscreening for middle ear effusion.

It is not a hearing testnot a hearing test, but rather a measure of energy transmission through the middle ear.

It can also assess the integrity of stapedius refluxstapedius reflux. .

NORMAL TYMPANOGRAMNORMAL TYMPANOGRAM

AUDITORY BRAINSTEM RESPONSE (ABR) AUDITORY BRAINSTEM RESPONSE (ABR) AUDIOMETRYAUDIOMETRY

An objective neurologic test of auditory brainstem function in response to auditory (click) stimuli.

Procedure: The stimulus either in the form of click or tone pip is transmitted to the ear via a transducer placed in the insert ear phone or head phone. The wave froms of impulses generated at the level of brain stem are recorded by the placement of electrodes over the scalp.

AUDITORY BRAINSTEM RESPONSE (ABR) AUDITORY BRAINSTEM RESPONSE (ABR) AUDIOMETRYAUDIOMETRY

These peaks are considered to originate from the following anatomical sites:

1. Cochlear nerves - waves I and II

2. Cochlear nucleus - wave III

3. Superior olivary complex - wave IV

4. Nulclei of lateral lemniscus - wave V

5. Inferior colliculus - waves VI and VII

CASES

CASE 1CASE 1

A 30 years old lady presented with 3 months history of progressive bilateral hearing loss that has worsend during present pregnancy, associated with tinnitus in both ears. Her sistert was having the same problem.

o/e:

Normal ears, no evidence of middle ear infection, normal TM ± pink blush (Schwartz's sign)

What is next?

CASE 1CASE 1

OTOSCLEROSISOTOSCLEROSIS

Fusion of stapes footplate to oval window so that it cannot vibrate.

Etiology autosomal dominant female> male, progresses during pregnancy (hormone responsive)

Symptoms include slowly progressive hearing loss,bilateral in 70% of cases.

Vertigo is uncommon.  Tinnitus may be present and often resolves after successful

surgical management

OTOSCLEROSISOTOSCLEROSIS

Conductive hearing loss

In 80-90% of patients, lesions are limited to the anterior oval window and affect its pathology by involving the stapes

sensorineural hearing loss

In 8% of patients, the process involves the cochlea and parts of the labyrinth (labyrinthine otosclerosis)

OTOSCLEROSISOTOSCLEROSIS

Tx: monitor with serial audio grams if coping with loss

hearing aid (air conduction, bone conduction, BAHA)

stapedectomy or stapedotomy (with laser or drill) with prosthesis is definitive treatment

CASE 2CASE 270 years old gentleman , a known

hypertensive, presented with gradual hearing loss in both ears, started to notice that since 5 months, hearing people like they are mumbling, associated with tinnitus and difficulty understanding speech, especially in noisy situations.

Otoscopy: normal external auditory canal & TM, no signs of middle ear infection

PRESBYCUSISPRESBYCUSIS

Sensorineural hearing loss associated with aging (staging in 5th and 6th decades).

Etiology hair cell degeneration

age related degeneration of basilar membrane

cochlear neuron damage

ischemia of inner ear

Accumulated exposure to noise

Drug and environmental chemical exposure

Stress

Genetics

Arteriosclerosis

Diet and metabolism

CAUSESCAUSES

The inability to hear or understand speech in a crowded or noisy environment

Difficulty understanding consonants

The inability to hear high pitched voices or noises

Tinnitus is often present

COMMON COMPLAINTSCOMMON COMPLAINTS

Tx: hearing aid if patient has difficulty functioning, hearing loss >30-

35 dB, and good speech discrimination

±lip reading, auditory training, auditory aids (doorbell and phone lights)

NOISE-INDUCED HEARING LOSSNOISE-INDUCED HEARING LOSS Constant exposure to loud

noises can cause high frequency sensorineural hearing loss

The mechanism by 1- Direct mechanical

damage of cochlear structures

2- Metabolic overload due to overstimulation

OTOTOXICITYOTOTOXICITY

Antibiotics

1-Aminoglycosides (gentamicin > tobramycin > amikacin > neomycin)

2-Erythromycin and tetracycline

Chemotherapeutic agents are known to cause hearing loss. The worst ototoxicity occurs with cisplatin.

High-dose aspirin.

Antimalarial medications such as quinine and chloroquine

MÉNIÈRE DISEASEMÉNIÈRE DISEASE

Endolymphatic hydrops refers to a condition of increased hydraulic pressure within the inner ear endolymphatic system.

Episodic attacks of tinnitus, hearing loss, aural fullness, and vertigo lasting minutes to hours.

peak incidence 40 to 60 years

Acute management:: Bed rest, antiemetics, antivertiginous drugs [e.g. betahistine].

Long term management may include: Medical:Medical:

low salt diet, Local application of gentamicin, betahistine

Surgical. Surgical. Decompressing the inner ear ( draining the endolymphatic sac) Vestibular neurectomy Labyrinthectomy

SUMMARYSUMMARY

Patients with hearing loss may have conductive, sensorineural, or mixed hearing loss.

Patients with hearing loss should undergo a directed history and examination.

Weber and Rinne tests to distinguish conductive from sensorineural hearing loss

Patients with conductive hearing loss should undergo physical examination of the auricle and external auditory canal (EAC) looking for evidence of blockage to explain the hearing loss.

Patients without an obvious etiology for hearing loss (such as external otitis or cerumen impaction) should undergo formal audiologic testing.

SUMMARYSUMMARY

Otoscelerosis is the second most common cause of conductive hearing loss in 15-50 years olds (eftar cerumen impation).

Presbycusis is the most common cause of SNHL

Short exposure to louder sounds can cause significant SNHL

Features of Ménière disease; tinnitus, hearing loss, aural fullness, and vertigo

QUIZQUIZ

Q.With negatives Renne’s test on the right side and Weber’s test lateralized to the right ear could be suffering from:

Bilateral chronic suppuratiove otitis media

Right CSOM

Bilateral otosclerosis

Right secretory otitis media and left Eustachian tube dysfunction

Left CSOM only

Q.A progressing conductive hearing loss in an adult with a normal appearing, mobile tympanic membrane is most likely due to:

a. serous otitis media

b. otosclerosis

c. acute otitis media

d. external otitis media

Q.Most common cause of conductive hearing loss in children:

C.S.O.M.

Acute O.M.

Chronie recurrent S.O.M

Otitis externa.

Q. Meniere's syndrome is a symptom complex characterized by:

a) conductive hearing loss and tinnitus.b) fluctuating Sensorineural hearing loss, tinnitus, and

constant vertigo.c) intermittent vertigo lasting several days each time.d) fluctuating Sensorineural hearing loss, vertiginous

episodes lasting 1-2 hours, and tinnitus.e) vertigo precipitated by lying down and turning over

to one side.

REFERENCESREFERENCES

Ear, nose and throat and head and neck surgery, R. S. Dhillon, C.A East, third edition.

Otolaryngology- head and neck surgery, Toronto notes 2011

http://www.ncbi.nlm.nih.gov

http://www.uptodate.com