deafness for medical finals (based on newcastle university learning outcomes)

8/14/2019 Deafness for Medical Finals (based on Newcastle university learning outcomes)

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Autosomal recessive syndromes. Pendred.

Sensorineural deafness.Goitre.

UshersSensorineural deafness.Retinitis pigmentosa

Jewell Lange Neilson.Sensorineural deafness.Long QT interval.

Acquired. In utero.

Maternal infections. Rubella CMV Influenza Syphilis

Ototoxic drugs.Metabolic upset, eg. Maternal diabetes.

Perinatal.AnoxiaBirth traumaCerebral palsyKernicterus

Post natal.

Meningitis Main cause

Ototoxic drugsLeadSkull fractures.

Universal newborn hearing screening Screening within hours of birth is the best way to ensure deafness is detected and managed.

Management should be implemented before 6 months of age. The main focus is to avoid language delay. The best test is by detecting otoacoustic emissions (OAE)

Microphone in external meatus detects tiny choclear sounds made by movement inthe basilar membrane.Abnormal or equivocal in 3 8% of neonates.

84% of abnormal results on OEA are due to external ear canal obstruction.In these patients test audiological brainstem responses (ABR).

Prevalence.0.9 3.24/1000 have permanent, bilateral heading loss of > 35 dBIncreases to 5.95/1000 have when unilateral and moderate hearing loss is included.


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Subjective hearing loss in the older child. Distraction test.

Can be used when patient 6 months or more.Tester in front of patient attracts their attention.

Tester to the side tries to distract the patient with a rattle or conversational voice. Conditioned response audiometry.

Can be used from 2 years.Child trained to put pegs in a hole or give toys to a parent in response to a particular auditory cue.

Speech discriminatation.Can be used from 2 years.Patient touches selected objects, cued by acoustically similar phrases, eg. Key/tree.

Pure tone audiogram.Can be used from 5 years.

Treatment. Once hearing loss is detected, aim to provide as good hearing as possible to help speaking and

education. Teachers of the deaf make arrangements of fitting hearing aids and help monitor progress.

Children tend to need higher gain on their hearing aids than adults.Ear moulds may need regular changing to maintain a good fit.

Encourage parents of deaf children to talk as much as possible to the child. Children may be educated at

Mainstream schools, with visits from teachers or the deaf.I n schools for the deaf or partially hearing.In special units of mainstream schools.

Cochlear implants may be suitable.The shorter the duration of deafness, the better the prognosis.Funding decisions should not be delayed.Give pneumococcal vaccine 2 weeks before insertion, or asap if implant already insitu.

Implants may be damaged by. Direct trauma. MRI Surgical diathermy Dental pulp testers Therapeutic diathermy, used in physiotherapy departments.

Ethical issues. Expensive intervention.

Cost per QALY is about 11400 Debate over what level of deafness should be the cut off for implantation.

In the UK, we implant patients with deafness of > 110 dB In the USA, they implant when deafness is > 95 dB

There is no good research looking at whether patients feel that they benefitfrom the implant, only whether those around them feel that there is animprovement.


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Deafness in Adults. 10% of UK adults are hearing impaired. Can be a frustrating and isolating disability.

Management. Determine type of deafness.

Conductive. Impaired sound transmission via external canal and middle ear ossicles to

foot of stapes. Has a variety of causes.

External canal obstruction.Impacted waxDicharge from otitis externaForeign bodyDevelopmental abnormalities.

Drum perforation.TraumaBarotraumaInfection

Problems with ossicular chain.OtosclerosisInfectionTrauma

Inadequate Eustachian tube ventilation of middle ear with effusion present.

Eg. Secondary to nasopharyngeal cancer.Sensorineural.

Results from defects to central area of oval window (sensory) or cochlear nerve (neural).

Occasionally due to pathology of more central pathways. Causes include.

Ototoxic drugs.StreptomycinAminoglycosides.

Especially gentomycin. Post infective.

Meningitis

MeaslesMumpsFluHerpesSyphilis

Cochlear vascular disease. Menieres disease Trauma Presbyacusis.

Rare causes include. Acoustic neuroma

B12 deficiency MS


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Secondary brain CA.

Exclude dangerous causes.Be especially concerned if deafness is unilateral or asymmetric.Acoustic neuromaCholesteatomaEffusion from nasopharyngeal carcinoma

Definitive management may be required.Surgery for perforations or otosclerosisFitting of suitable hearing aidsFitting of cochlear implants.

For profound sensorineural deafness. Stimulates residual neural tissue. Takes about 2 hours to fit under GA. An external device processes sound and transits it across the skin to a

subcutaneous receiver coil. an electrode in the cochlear via round window. Directly stimulates auditory nerve.

The received signal is not normally sound. Rehabilitation is needed to understand the new signals.

Benefits include. Improved lip reading Recognition of environmental sounds. Relieved isolation.

Sudden hearing loss. Sensorineural.

Defined as loss of 30 dB in 3 contiguous pure tone frequencies over < 72 hours.Incidence of 5 20/100000/year.Partial or complete spontaneous recovery occurs in 30 65%.Detailed evaluation reveals underlying disease in 10%

Noise exposure. Gentamicin toxicity. Mumps Acoustic neuroma MS

Vasculopathy TB

Investigations. INR TSH Blood glucose Cholesterol ESR FBC LFT

Viral titres Audiology


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Evoked response audiometry CXR/ MRI pANCA Lymph node & nasopharyngeal biopsy.

Malignancy & TBManagement.

Refer promptly to ENT. Idiopathic causes often respond well to high dose steroids and hyperbaric

oxygen. Have to give promptly.

High dose steroids are no more effective when combined with antivirals Intratympanic dexamethasone may have salvage role.

Prognosis better if. Early presentation Mild Unilateral No vertigo.

Conductive.Cause is almost always identified..

Infective Trauma Occlusive Fracture.

Otosclerosis.

Prevelence of:0.5 2% clinically10% subclinically.

Cause is mainly Autosomal dominant.Incomplete penetration50% have a family history85% are bilateral.

Female:Male ratio of 2:1 Pathology.

Vascular spongy bone replaces normal lamellare bone of otic capsule. Particularly around oval window which fixes the stapes footplate.

Symptoms usually appear late in adult life.Made worse by pregnancy, menstruation and the menopause.There is conductive deafness.

Hearing often improved by presence of background noise. Complications.

75% have tinnitusMild and transient vertigo is common.10% have Schwartzs sign.

Pink tinge to tympanic membrane Audiometry with masked bone conduction shows dip at 2 kHz.

Caharts notch.


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Treatment.Fluoride.

ContraversialHearing aids.Surgery.

Stapedectomy. Stapedotomy. Replacing adherent stapes with an implant helps in 90% of cases.

Many prefer surgery to wearing a hearing aid. 1 4% risk of dead ear.

Presbyacusis. Age related hearing loss from accumulated environmental noise toxicity. Loss of high frequency sounds starts before 30 years. Rate of loss is progressive thereafter. Deafness due to loss of hair cells is gradual and often not noticed until it is difficult to hear

speech.Constanants at 3 4 Hz are needed for speech discrimination.

Hearing is most affected in presence of background noise. Hearing aids are the usual treatment.

deafness for medical finals (based on newcastle university learning outcomes)

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