Sensorineural Hearing Loss
 

Introduction to Hearing Loss
Anatomy and Physiology of Hearing
Audiology
Conductive Hearing Loss
Sensorineural Hearing Loss
Sudden Sensorineural Hearing Loss
Other Types of Hearing Loss
Reference

Table of Contents

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Sensorineural Hearing Loss

Caused by a disorder of the inner ear,cochlea,or VIII nerve

Range from mild to total,ie,greater than 120 dB HL

Nerve deafness or nerve loss

 

Etiology

Developmental & Hereditary disorder

  • Congenital nerve deafness c loss at birth (endogenous, exogenous)
  • Heriditary nerve deafness
  • Heriditary disorder of adult deafness (Alports ,Waardenburgs, Ushers syndrome)
  • Inner ear abnormality (large vesibular aqueduct syndrome)

Toxic nerve deafness

  • Toxic febrile nerve deafness
  • Phamacological toxicity

Infectious disorder

  • Syphilis : congental, acquired
  • labyrinthitis : serous, supperative
  • Viral : mump, measels, herpes zoster, CMV)
  • Others : Rocky mountain, Spotted fever, Lyme disease

Trauma

  • Noise induced HL & Acoustic trauma
  • Head injury
  • Barotrauma & perilymphatic fistula
  • Irradiation

Meneires disease (Endolyphatic hydrops)

Central origin (Multiple sclerosis)

Bone disorder (cochlear otospongiosis)

Neoplesm (acoutic neuroma)

Endocrine (DM, congenital hypothyroid , hyperthyroid, hyperlipidemia)

disorder of unknown etiology(Presbyosis)

Others : vascular, immune disorder, renal, psycologic deafness)

 

Developmental & Hereditary disorder

Congenital nerve deafness c loss at birth

  • Endogenous : FHx+ve, inheritary cochler defect
  • Exogenous : During intrauterine life eg.Rubella, quinine, erytroblastosis, hypoxia)

Hereditary nerve deafness

  • Uncommon progressive symmetrical high tone SHNL in late childhood (same as presbycusis)

Clinical : FH+, delay speech, G&D

 

High-risk Indicators of Hearing Loss : Birth to 28 days

  • Family history of SNHL,
  • presumably congenital In utero infection associated with SNHL (e.g., toxoplasmosis, rubella, cytomegalovirus, herpes, syphilis)  
  • Ear and other craniofacial abnormalities  
  • Hyperbilirubinemia at levels requiring exchange transfusion 
  • Birth weight less than 1,500 g  
  • Bacterial meningitis  
  • Low Apgar scores: 0 to 3 at five minutes; 0 to 6 at 10 minutes  
  • Respiratory distress (e.g., meconium aspiration)  
  • Prolonged mechanical ventilation for more than 10 days  
  • Ototoxic medication (e.g., gentamicin) administered for more than five days or used in combination with loop diuretics  
  • Physical features or other stigmata associated with a syndrome known to include SNHL (e.g., Down syndrome, Waardenburg's syndrome)

 

High-risk Indicators of Hearing Loss : 29 days to 24 months

  • Parental or caregiver concern about hearing, speech or language, and/or developmental delay
  • Any of the newborn risk factors listed above 
  • Recurrent or persistent otitis media with effusion for at least three months  
  • Head trauma with fracture of temporal bone  
  • Childhood infectious disease associated with SNHL (e.g., meningitis, mumps, measles)
  • Neurodegenerative disorders (e.g., Hunter syndrome) or demyelinating diseases (e.g., Friedreich's ataxia, Charcot-Marie-Tooth syndrome)

 

Toxic nerve deafness

Most often found in childhood post acute febrile illness stage of severe general infection eg. Measle, scarlet fever, influenza, pneumonia etc.

Typical Hx: normal hearing->sudden loss

Usually bilateral high frequency symmetrical and spontaneous(normal) resolution

 

Pharmacologic toxicity

Aminoglycosides

most common caused, usually c nephrotoxic

Almost cochleotoxic (hair cell damage )> Vesibulotoxic except steptomycin & gentamicin)

Antimalarial :SHNL

Quinine : tinnitus, nausea, visual-> Cinchonism

Chlroquine:macular degeneration

Large dose may be permanent HL

Salicylates

hearing return to normal in 72 hr

 

Infectious disorder

Congenital Syphilis n. deafness

Rapid progressive asymetric SHNL+/- vestibular symptom occurring several to many years after chidhood interstitial keratitis

Hx,serology,VDRL,FTA-Ab

Rx:2sy benzathian PGs 2.4 mU IM,3 month c prednisolone40-80 mg/d daily then decrease 10 mg q 2 day

Aquired syphilis n. deafness

often in late tertiry Sy positive blood serology Rx PGS IV

Labyrinthitis (serous/supperative)

Unilateral depression of cochlear function c vertigo and diplacusis

Young and middle aged

Recovery depends on severity

Serous labyrinthitis : secondary to ASOM or CSOM or surgical trauma

Supperative : with infection

 

Trauma

Noise induced HL

Prolong exposure to industrial or aircraf noise common progressive notching bilateral at 4000 Hz from audiogram

Acoustic trauma

Single sharp sound of high intensity produce sudden unilateral permanent or temporary high frequency SHNL

 

 

Meniere s disease

Endolymphatic hydrops

Common disorder of endolymphatic labyrinth of inner ear

Unknown etiology

Fluctuating SHNL, roaring tinnitus, vertigo, sense of fullness in the ear, recruitment and diplacusis

Low-pitched frequencies in early stage

Unilateral, 30-50 YO

Diagnosis :

  • Hx
  • otoscope, tunning fork
  • neurological exam
  • balance system and coornination
  • water or air caloric stimulation
  • electronystagmography

Management

  • Low salt diet:<2,000 mg/day
  • Medication
    • Diuretics
    • Antivertigo and antiemetic drugs
    • Tranquillizer and sedatives
    • Vasodilator
    • Aminoglycoside injection when failure

Surgical treatment

  • Hearing conservative surgery
    • endolymphatic sac surgery (mastoid/ subarachnoid shunt)
    • vestibular nerve neurotomy
  • Hearing destructive surgery
    • labyrinthectomy

General management

  • Decrease stress
  • Exersise especially Vestibular exercises
  • Rest
  • Avoidant : tea, coffee, alcohol, smoking, sunlight, environment

 

Central origin(Multiple sclerosis)

Chronic demyelination & inflammatory disease

Interruption of the auditory pathway

Various clinical manifestation but the common is sudden unilateral SNHL

Recovery days or weeks

 

Bone disorder : Cochlear otospongiosis

Unknown etiology

Progressive SNHL

Early or middle adult life

Positive FHx : stapes fixation

Related to the time of onset or degree fixation

Typical high tone loss

 

Neoplesm(acoutic neuroma)

Vestibular schwannoma

m/c neoplasm -> SNHL (earliest presentation)

Incidence 8-10 % of intracranial neoplasm

Unilateral slow progressive high frequency loss

Dizziness, tinnitus

May involve CN V, VII, cerebellar, brain stem

X-ray evidence of bone erosion or around IAM

Bilateral in von Recklinghausens multiple neurofibromatosis

Rx : surgery

 

Presbycusis

Progressive, bilateral, symmetrical

Degenerative disorder

Old aged

Sloping high tone loss to flatter audiogram with a loss for all frequency, with variable impairment of speech discrimination

 

 

 

Summarized By Thirayost Nimmanon

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Ѻاش 15/06/2010

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