Hearing Loss

Hearing Loss

Congenital Sensorineural Deafness

·        Irreversible

·        Pathology: problems with nerve or cochlear

·        Profound hearing loss at birth: 2 per 1,000

·        Most often detected by parents (ie believe them!)

·        Aetiology: genetic or acquired, etc:

o  Idiopathic 60%

o  Genetic: most are spontaneous mutations rather than family history

o  Low birth weight

o  Infection (fairly rare now), eg Rubella, also toxoplasmosis, CMV, syphilis

o  Maternal drugs: eg aminoglycosides, alcohol

o  Lots of others, eg hypoxia, high bilirubin

Sudden Onset Sensorineural Hearing Loss

·        =Uni/bilateral sudden onset within 3 days.  May also get dizzy, tinnitis

·        Could be inflammatory, infective, ototoxicity, acoustic neuroma (Þ always investigate)

·        Urgent specialist referral within 24 hours

·        Spontaneous remission likely, poor prognosis if elderly, diabetic, vascular disease (Cochlear artery is an end artery – if blocked no collateral flow)

Presbycusis

·        = Age related hearing loss, especially at higher frequencies

·        Bilateral, symmetrical. May get recruitment (some sounds sound louder – eg toilet flushing, doing dishes)

·        M > F, 24% of 64 – 74 year olds, 40% of over 75s

·        May have ¯word discrimination: hard to help, ­volume doesn‟t help

·        Aetiology: age, noise, hypertension, genetic predisposition

·        Pathology: degenerative changes, eg of cochlea and also of central procession (this part won‟t respond to ­ volume) 

·        Clinical: progressive deafness, „social‟ deafness, especially 1 KHz, tinnitis. Often judged worse by spouse/partner

·        Exclude: wax impaction, otosclerosis, Paget‟s disease of the middle ear bones, acoustic neuroma

·        Management:

o  Screen elderly people (eg questionnaires or audiometry)

o  Hearing aid: only ¼ who would benefit use one, although there are many barriers to use (including cost)

o  Speaking facing the person, clearly, slowly, not too loud, paraphrasing sentences that aren‟t heard rather than repeating them (also give this advice to spouse and caregivers),

o  Aids (telephone boosters, lights that flash when the doorbell rings, etc)

o  Rehabilitative services available through the Hearing Association

Noise Induced Hearing Loss

·        Commonest cause of hearing loss < 60

·        Usually industrial noise exposure: factories, builders, firearms, jack hammers

·        Safe limit: 80 db for not more than 4 hours

·        Classic damage at 4 & 6 KHz on audiogram.  Usually bilateral

·        Treatment: Prevention, hearing aids not much help

Meniere’s Disease

·        Diagnostic triad: tinnitus (usually low pitched), deafness, vertigo, (+ feeling of aural fullness) 

·        Clinical: acute onset of triad, disabling vertigo (world spinning, vomiting) for 6 – 12 hours then low frequency hearing loss

·        30 – 55 years, M > F

·        Stages:

o  Early: occasional attacks

o  Later: fluctuating low tone deafness

·        End stage: low tone deafness, imbalance but no vertigo

·        Pathology: endolymphatic hydrops: distension of endolymphatic space

·        Aetiology: unknown.  ?­Production of endolymph

·        Diagnosis: possibly nystagmus, fluctuating SN loss

·        Treatment: Supportive, low Na diet (¯endolymph), thiazides, antivertigo, antiemetic and histamine medication

Acoustic Neuroma

·        Progressive loss of hearing in one ear with tinnitus.

·        Not usually associated with ¯vestibular function – slow enough to compensate (ie CNS adjusts so world doesn‟t seem on a tilt). But, everyone with acute vertigo should have a pure tone audiogram to screen for the (rare) possibility of acoustic neuroma

·        MRI is definitive, CT is unreliable and should not be done

Aural Rehabilitation

·        When hearing loss cannot be corrected, use hearing aids, listening devices and communication strategies

·        1 in 500 has significant permanent hearing loss ® receptive and/or expressive language delay

·        All infants babble, even hearing impaired

·        Suspect deafness when:

o   Parental concern

o   At risk babies (should be routinely screened):

§  Family history

§  Inter-uterine infection: rubella, CMV

§  Defects of ENT: cleft palate, external ear

§  Low birth weight

§  Neonatal distress

o   Poor response to sound

o   Not using words by 15 months

o   General developmental delay

o   Poor speech, comprehension and hearing failure

o   Following brain trauma, infection, neurotoxic drugs

o   Recurrent or persistent ear infections

·        Normal development:

·        History:

o   Can he hear – how do you know?

o   Previous development: first word, use of consonants, etc.  Check Well Child Book

o   Ear infections

o   Antenatal: rubella, prematurity, jaundice, drugs

o   Family history of hearing problems, developmental delay, neuro problems

·        Exam:

o   Dysmorphic features: cleft palate, external ear, skin, heart murmurs, liver enlargement, normal genitalia

o   Basic neuro exam, gait, symmetry of movement (including face), eye movement

·        Investigations:

o   Tympanogram

o   Don‟t do distraction testing – hard unless you‟re well trained.  Send straight for audiology

o   Others depending on clinical findings: eg if regression then EEG, brain scan, check stressors, chromosome problems, CK for Duchenne‟s

·        Differential of language delay:

o   End of normal range

o   Deafness

o   Isolated language delay (usually expressive more delayed than receptive – but not necessarily)

o   General delay or mild intellectual handicap ® formal cognitive testing

o  Autism

o  Epilepsy: absence seizures – especially if fluctuates or regressive

o  Possibly poor environment with little stimulation – but would also expect ¯socialisation and ¯self care

o  Congenital problems: cleft palate, macroglossia (eg Down‟s)

o  Rare isolated CNS or motor problems

·        Management: Speech language therapist, early intervention service, multidisciplinary team if problems over other domains. GP to support and co-ordinate, anticipate problems – especially at transitions (eg school, moving) and checking for comorbidity (eg behavioural problems, ¯self esteem)

·        Prognosis: Good if early intervention – but maybe problems with higher language function (eg essay writing)

·       Down Syndrome

·        Trisomy 21: 47XY + 21

o  Accounts for 95% of presentations of Down Syndrome. Usually (80%) non-disjunction at first meiotic division

o  5% have different karyotypes:

§  Mosaic Down: 3 %

§  Robertsonian translocation t14:21: 4.8%

·        Epidemiology:

o  Overall incidence is 1 in 700

o  At least 20% still born

o  Incidence increases with ­maternal age: at 16/40 gestation, 1 in 300 at 35 years, 1 in 22 at 45 years

o  Accounts for 25% of children with IQ < 50

o  ¼ of all chromosomal abnormalities. Chromosomal anomalies represent 15% of congenital anomalies

o  Risk:

·        Maternal age at birth  Down in live births

·        25 - 29     1:1100

·        30 1: 900

·        35 1:350

·        37 1:200

·        40 1:100

·        43 1:50

·        45 and over       1:25

·        Neonatal Screening:

o  Only 30% of children with Down are born to women over 35. Widespread screening of those > 35 will have only minor increase in detection rate

o  Screening with the triple test will increase detection, but at the expense of significantly higher rates of invasive testing as there is a high false positive given the low incidence in younger women

·        Neonatal signs:

o  Hypotonia

o  ¯Moro reflex

o  Joint hyper-extensibility

o  Excess skin at the back of the neck

o  Flat facial profile

o  Misshapen low set ears

o  Protruding tongue

o  Blunt inner eye angle

o  Single palmer crease in 50%

o  Clinodactyly (incurving) of little fingers in 50%

o  Big „saddle‟ gap between big and 2^nd toe

·        Complications:

o  IQ generally from 45 – 55

o  Congenital heart malformations in ~50%: VSD, ASD, patent ductus

o  Susceptible to respiratory infections

o  Duodenal atresia

o  Also cataracts (2%), epilepsy (10%), hypothyroidism (3%), acute leukaemia (1%)

·        Development:

o   Most will walk and develop simple language

o   Puberty is often delayed and incomplete

o   Average adult height is 150 cm

o   Pre-senile dementia (similar to Alzheimer‟s disease) supervenes after age 40

o   8% live past 40 years

·       Autism

·        Onset before age 3 of:

o   ¯Ability to form social relationships: slow to smile, don‟t enjoy being cuddled, indifferent eye contact

o   ¯Use of both verbal and non-verbal communication: slow onset, echolalia, no use of gesture, poor pragmatics (eg turn taking and eye contact in conversation). If it was isolated language delay you would expect compensation in other areas (eg social) but here that‟s affected as well

o   Restrictive and repetitive behavioural repertoire – dislike change

·        May start from birth, or regress after normal development

·        Other behavioural problems: outbursts, sleep problems, distractibility, poor toileting

·        Rare: 2 – 4/10,000. Boys = 3 * girls

·        75% show some degree of general intellectual impairment

·        Asperger‟s Syndrome:

o   Symptoms overlap with autism

o   Social interaction and behavioural problems similar to autism but not associated with significant language or intellectual delay