Tag Archives: sudden sensorineural hearing loss

Noise and Ear

On International Noise Awareness Day, 28th April 2010

The Center for Hearing and Communication founded International Noise Awareness Day to promote awareness of the dangers of long-term exposure to noise.

Everything you need to know about the noises you’re exposed to every day. Discover which noises could be damaging to your hearing and learn steps you can take to prevent hearing loss due to noise at http://www.chchearing.org/noise-center-home/facts-noise

Noise and ear:

Excessive noise exposure is the most common cause of hearing loss.

Too loud noise damages sensitive nerve endings in the inner ear (delicate cells called cillia) and causes sensorineural hearing loss. It can be reduced or prevented all together.

Sudden exposure to loud noise may cause temporary sensorineural hearing loss which usually recovers over 24 to 48 hours.

But if sound is too loud, or loud sound is too close or loud sound is exposed over a long period of time (more than 85 db), permanent sensorineural hearing loss can occur.

And 85 decibels is not as loud as you will think.  Sound from an iPod shuffle is usually 115 db, and with fireworks it goes at 150 db. Not only Large bore guns and artillery But even cap guns and firecrackers can damage your hearing if the explosion is close to your ear.

What is Dangerous level of noise?

Sensitivity to sound is different for each person.

Noise may damage your hearing if you have to shout over background noise to make yourself heard, the noise hurts your ears, it makes your ears ring, or you have difficulty hearing for several hours after exposure to the noise.

Approx. Decibel Level Example
0 Faintest sound heard by human ear.
30 Whisper, quiet library.
60 Normal conversation, sewing machine, typewriter.
90 Lawnmower, shop tools, truck traffic; 8 hours per day is the maximum exposure to protect 90% of people.
100 Chainsaw, pneumatic drill, snowmobile; 2 hours per day is the maximum exposure without protection.
115 Sandblasting, loud rock concert, auto horn; 15 minutes per day is the maximum exposure without protection.
140 Gun muzzle blast, jet engine; noise causes pain and even brief exposure injures unprotected ears. Maximum allowed noise with hearing protectors.

Occupational exposure to noise

People with occupations involving exposure to noise above 85 decibel over an 8 hour period daily are also at risk. These include industries like mining, construction, drilling and agriculture.

For unprotected ears, the allowed exposure time decreases by one-half for each 5 dB increase in the average noise level. For instance, exposure is limited to 8 hours at 90 dB, 4 hours at 95 dB, and 2 hours at 100 dB

The highest permissible noise exposure for the unprotected ear is 115 dB for 15 minutes/day. Any noise above 140 dB is not permitted.

Noise exposure is cumulative. So the noise at home or at play must be counted in the total exposure during any one day.

If you must work in an excessively noisy environment, you should wear protectors.

* Person working in noise above 85 db should use noise protection devices-ear plugs and ear muffs. It is as simple a concept as using goggles to protect your eyes from UV rays of sun. It should also be used by musicians and when using power tools, noisy yard equipment, or firearms.

Do periodic hearing check ups with annual hearing test (pure tone Audiometry).

Ear Protectors

Hearing protection devices decrease the intensity of sound that reaches the eardrum. They come in two forms: earplugs and earmuffs.

Earplugs are small inserts that fit into the outer ear canal. They must be snugly sealed so the entire circumference of the ear canal is blocked. They are available in a variety of shapes and sizes and can be custom made.

Earmuffs fit over the entire outer ear to form an air seal so the entire circumference of the ear canal is blocked, and they are held in place by an adjustable band.
Properly fitted earplugs or muffs reduce noise 15 to 30 dB. Simultaneous use of earplugs and muffs usually adds 10 to 15dB more protection than either used alone. Combined use should be considered when noise exceeds 105 dB.

Cotton balls or tissue paper wads stuffed into the ear canals are very poor protectors.

On earliest sign of noise trauma like irritability, buzzing sound in ear or difficulty in hearing, trouble understanding what people say;  especially when you are in a noisy place such as in a crowd or at a party. This could be the beginning of high-frequency hearing loss; a hearing test will detect it.
visit your physician.

Few more tips

  • Turn down volume of MP3 player/television.
  • Do not stand directly near to the source of noise.
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Management of sudden sensorineural Hearing Loss

Previous Post:- Causes and evaluation of sudden sensorineural hearing loss

Sudden sensorineural hearing loss is an otologic emergency and challenge to otolaryngologist.

Thorough history, physical examination, appropriate laboratory and radiologic investigations including gadolinium enhanced MRI, and Audiometry tests should be carried out to find out known cause such as: – Infection (bacterial-meningitis/viral-mumps, herpes), Tumor, Trauma, Acoustic trauma, Ototoxic drugs (amino glycoside antibiotics), and Systemic diseases (hypothyroidism, Diabetes mellitus).

If an etiology is apparent, appropriate treatment may be initiated such as antibiotics for infection, withdrawal of ototoxic drugs.

In most cases cause remains unknown (idiopathic) thus existent treatment aims at improving blood flow.

Optimal treatment is still under research and controversies exist but treatment versus non-treatment and early initiation of treatment is proved to give better result.

1. Antivirals– Because of common association with viral infection antiviral medication is prescribed by some clinicians.

2. Steroids- Most widely accepted treatment option studies shows improved recovery rate with use of steroid. It can be given orally, or by injection, or Trans tympanic by means of middle ear instillation or round window micro catheter which is more effective than oral administration.

3. Vasodilator to improve blood flow or oxygenation to inner ear. Clinical studies shows mixed results. Carbogen inhalation, Papaverin, Histamine, Nicotin and Niacin have been used.

4. Immunosuppressant- Wang et al etanercept in experimental animal study improves hearing result.

5. Ginkgo Biloba-

6. General measures-

  • Low salt diet,
  • Avoid caffeine, nicotine and alcohol,
  • Avoid noise exposure,
  • Avoid heavy physical activity,
  • Well balanced diet,
  • Alpha-lipoic Acid, Antioxidants, Co-enzyme Q10.
  • Zinc, Magnesium, Calcium,
  • Vitamin D, B -Complex, Vitamin C

Prognosis of sudden sensorineural hearing loss-

50-65% spontaneous recovery within first 4-6 weeks.

Symptoms of ear blockage or deceased hearing is often considered as wax or middle ear infection and person delays visit to an otolaryngologist. A delay in initiating treatment may decrease the chances of recovery.

Negative factors in prognosis-

  • Age more than 65 years or less than 15 years
  • Severe hearing loss specially affecting high frequency
  • Hearing loss in opposite ear
  • Associated vertigo
  • Elevated ESR

Treatment protocol should be carefully applied and potentially harmful treatment should be avoided. A thorough evaluation to be done on emergency basis and all efforts should be taken to find out known causes. Steroids are most widely accepted treatment options.

Sudden Sensorineural hearing loss

  • It should be regarded as an otologic emergency.
  • Patient should be evaluated by otolaryngologist.
  • A thorough history, physical examination, appropriate laboratory and radiologic investigations including gadolinium enhanced MRI, and Audiometry tests should be carried out to find out known cause.
  • A tapering course of prednisolone/methyle prednisone is prescribed.
  • Antiviral medication may be considered.

Sudden Sensorineural Hearing Loss: Causes and Evaluation

Sudden Sensorineural Hearing Loss (SSNHL) is defined as a hearing reduction greater than 30 db, over at least 3 consecutive frequencies (on pure tone audiogram), occurring over or less than 3 days. It usually affects one ear, there may be mild to sever reduction of hearing, and there may be tinnitus and dizziness.

Most People (30-65%) may have a spontaneous recovery; others may have permanent hearing difficulties.

Causes of sudden sensorineural hearing loss-

There is no conclusive evidence as why it happens but some theories are suggested-

1. Generally 90% cases are idiopathic where cause is not known. Viral diseases appears to be most common cause (about 60% cases) as shown by association with herpes.

2. There may be partial or complete blockage of circulation or vascular spasm to inner ear and nerves of hearing.

3. There may be rupture of delicate inner ear membrane after strong physical activity or sudden change in barometric pressure (flying/scuba diving).

4. Immune theory may ply a role, because of its association with Cogan syndrome, SLE, Lupus and AIDS.

In most cases reason remains unclear.

Diagnosis of SSNHL requires thorough investigation to determine any known causes of sudden hearing loss. Some of the causes are following-

* CONGENITAL –

  • Rubella Syndrome
  • Atresia of the External ear canal
  • Congenital Cytomegalovirus
  • Congenital Perilymphatic Fistula
  • Fetal Methyl Mercury Effects
  • Fetal Iodine Deficiency Effects

* MEDICATIONS (Ototoxic Drugs)-

  • Aminoglycoside Antibiotics-streptomycin, kanamyin, neomycin, amikacin, gentamicin, tobramicin and netilmicin
  • Loop diuretics, ethacrynic acid
  • Antimalarial (quinine, chloroquine),
  • Salicylates
  • NSAIDS
  • Vancomycin
  • Erythromycin
  • Cisplatinum

* INFECTIOUS DISEASES-

Bacterial infection:

  • Otitis media
  • Labyrinthitis
  • Encephalitis
  • Meningitis

Viral infections:

Evidence is circumstantial, with the possible exception of mumps parortitis and herpes zoster, the clinical diagnosis of viral infection is unreliable.

  • Common Colds
  • Adenovirus
  • Cytomegalovirus (Cmv)
  • Infectious Mononucleosis
  • Influenza
  • Parainfluenza
  • Ear Infection (Otitis Media)
  • Mumps
  • Measles
  • Rubella
  • Herpes Simplex Virus Type 1

Others:

Rocky Mountain spotted fever-tick borne infection

Lyme disease- tickborne especially in endemic areas (mostly causes facial palsy)

Syphilis and AIDS

* IMMUNOLOGIC DISEASES-

Immunologic activity within the cochlea may be the cause as suggested by finding of antibodies and response to steroid therapy in many patients. Hearing loss in certain autoimmune diseases is documented.

  • Cogan’s Syndrome
  • Systemic Lupus erythomatosus
  • Fibromyalgia
  • Temporal arteritis

* TRAUMATIC-

Direct trauma (temporal bone fracture) or blunt head injury (concussion to labyrinth) can cause SSNHL.

  • Traumatic ear drum Perforation
  • Head Injuries
  • Skull Fracture (Temporal Bone)

* ACOUSTIC TRAUMA

  • Explosions
  • Fireworks,
  • Gunfire
  • Rock Concerts/Mp3 Players
  • Jets
  • Occupational Work Noise

* BAROTRAUMA and perilymphatic fistula

Barotraumas is caused by unequalized pressure differentials in middle ear and external ear such as in scuba diving, air travellingor blow to ear. If the pressure is severe, eardrum can rupture.

Barotrauma can cause acquired perilymphatic fistula (communication between inner ear and middle ear) leading to SSNHL and vertigo. Other causes of acquired perilymphatic fistula are direct or indirect trauma to temporal bone, heavy lifting or straining and complication of stapes surgery.

* TUMORS-

  • Acoustic Neuroma or Vestibular Schwannoma – SSNHL may be initial manifestation
  • Temporal Bone Metastases
  • Neoplasm of CPA or IAC

* OTHER SYSTEMIC DISEASES-

  • Leukemia
  • Diabetes
  • Hypothyroidism
  • Multiple Sclerosis
  • Ménière’s Disease
  • Syphilis

Evaluation  of sudden sensorineural Hearing loss (searching for cause)-

A thorough and detailed history of associated symptoms, noise exposure, any trauma, fever, medication and family history of hearing loss is necessary to determine the diagnosis.

Ear examination by otoscopy and pneumotoscopy is critical step.

Hearing assessment by Tunning fork test, pure tone audiometry (PTA) and speech audiometry should be done. Tympanometry, Auditory Brainstem Response and Otoacoustic emission may be useful.

Electronystagmogram (ENG)

Radiologic study should be done especially for patients with unilateral sensorineural hearing loss, such as MRI with gadolinium/CT temporal bone to investigate IAC/CPA tumors.

Laboratory investigations-

FTA-antibodies for syphilis

ANA, RA Factor, ESR for autoimmune disease

Coagulation profile

CBC for infection

TH for thyroid function

RBS/PPBS for Diabetes

Cholesterol/triglycerides for hyperlipidemia

Sudden Sensorineural hearing loss-

  • It should be regarded as an otologic emergency.
  • Patient should be evaluated by otolaryngologist.
  • A thorough history, physical examination, appropriate laboratory and radiologic investigations including gadolinium enhanced MRI, and Audiometry tests should be carried out to find out known cause.

Next Post– Management of sudden sensorineural hearing loss