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==Introduction==
==Introduction==
[[Deafness]] is a partial or total inability to hear. WHO defines deafness as hearing threshold of 20dB or better in both ears.


==Classification==
==Classification==
[Deafness] may be classified according to WHO into 5 subtypes/groups:
*Mild- Hearing losses between 26 and 40 dB
*Moderate- Hearing losses between 41 and 55 dB
*Moderately severe- Hearing losses between  56 and 70 dB
*Severe - Hearing losses between 71 and 90 dB
*Profound - Hearing losses greater than 91 dB


==Pathophysiology==
==Pathophysiology==
In general, sound waves reaching outer ear are conducted down the ear canal to vibrate [[eardrum]], which in turn, transmitted to inner ear via 3 tiny bones. The fluid in the inner ear moves the hair cells which generate impulses that is conducted to brain via cochlear nerve. Any alteration or obstruction in these pathways can lead to hearing loss.
Often, hearing loss is caused by long-term exposure to loud noises, that damage the hair cells.


==Causes==
==Causes==
Common causes of hearing loss include: Based on location
*External Ear
**Congenital [[atresia]] of external auditory meatus (EAC)
**[[Infection]]- Otitis externa
**[[Trauma]]
**[http://Tumour Tumour]
**[[Benign]] [[Polyp]]
**[[Cerumen]]
*Middle Ear
**[[Atresia]] or [[malformation]] of ossicular chain
**[[Eustachian]] tube [[dysfunction]]
**[[Infection]]- Otitis media
**[[Cholesteatoma]]
**[[Otosclerosis]]
**Jugulotympanic paragangliomas ([[glomus]] tumors)
**Middle ear barotrauma-sudden, large change in ambient pressure, often during diving or flying
*Inner Ear
**Congenital malformation of cochlea
**Presbycusis- old age related hearing loss
**Infection- Viral cochleitis
**Meniere disease
**Noise exposure
**Inner ear barotrauma
**Ototoxic drugs
**Systemic diseases- diabetic vasculopathy can cause cochlear ischemia
**Tumors- acoustic neuroma


==Differential Diagnosis==
==Differential Diagnosis==
Labyrinthitis must be differentiated from other diseases that cause [[Vertigo causes|vertigo]] along with [[Gait ataxia|gait]] impairment such as:
{| class="wikitable"
{| class="wikitable"
!Disease/Variable
!Conductive hearing loss
!Presentation
!Sensory hearing loss
!Causes
!Neural hearing loss
!Risk factors
!Central hearing loss
!Imaging
|-
|[[Brainstem infarction]]
|
*[[Neurological disorders|Neurological]] sign and symptoms such as [[hemiplegia]], cranial nerve deficits, [[ataxia]] may be present in brainstem
*[[infarction]] ([[vs labyrinthitis]]- no any neurological deficits in labyrinthitis)
*Sustained [[dizziness]] and [[vertigo]] observed in [[Brain stem|brainstem]] infarction.
 
|
*Occlusion of the blood vessels supplying to [[Brainstem stroke|brainstem]] ( [[vs labyrinthitis]]- secondary to viral infection/idiopathic)
|
*[[Hypertension, systemic|Hypertension]] and cardio-aortic diseases are found in the majority of patients with cerebellar infarction
|
*Brain stem infarction can reliably be visualized by a combination of DW-MRI and T2-weighted images beginning 12 hours after the [[Ischemic stroke|ischemic]] attack( [[vs labyrinthitis]]- brainstem is normal in imaging studies)
|-
|-
|[[Cerebellar Stroke]]
|[[Acute causes]]
|
*cerumen impaction
*Frequently present with sudden [[headache]], [[Nausea and Vomiting causes|nausea]] and vomiting, dizziness, and a striking difficulty walking and loss of consciousness in most cases.
*Tympanic effusion
*Eardrum perforation (traumatic)
*Acute infection of ear
[[Chronic causes]]
*Cholesteatoma
*Otosclerosis
*tympanosclerosis
*Defect in eardrum or ossicular chain disruption due to chronic infection
*Malformation
|
|
*Usually caused by a blood clot that obstructs blood flow to the [[cerebellum]].
[[Acute causes]]
* Loud noise induced(blast trauma, explosion trauma)
* Bacterial/Viral Labyrinthitis
*Idiopathic sudden sensorineural hearing loss
[[Permanent causes]]
*Occupational noise exposure
*Ototoxic drugs
*Hereditary inner ear malformation
*Presbycusis
|
|
*[[Hypertension]], small vessel disease and old ages are common risk factors for cerebellar stroke.
*Acoustic neuroma
*Tumors of cerebellopontine angle(meningioma,chordoma)
*Compression syndrome
|
|
*Cerebellar [[stroke]] can be diagnosed earlier by MRI and CT scanning.
*Hemorrhage
*Infarctions
*Intracranial tumor
*Multiple sclerosis
|}
|}


==Epidemiology and Demographics==
==Epidemiology and Demographics==
The incidence of hearing loss increases with age.
In the Beaver Dam cohort in the United States, the prevalence of hearing loss, defined by audiometry:


==Risk Factors==
●3 percent ages 21 to 34
There are no established risk factors for labyrinthitis. However, viral infection, [[allergies]] or ototoxic drugs may be responsible for development of labyrinthitis in some cases.


==Natural History, Complications and Prognosis==
●6 percent ages 35 to 44
Labyrinthitis is self limiting disorder, often becomes acutely symptomatic for 1 to 2 days. The symptoms gradually improve over 2 weeks. Recurrence is rare.
If left untreated, 15% of patients with labyrinthitis may progress to develop [[Benign Paroxysmal Positional Vertigo (BPPV)]] and around 10% may progress to develop [[panic disorder]] over 2 years.


==Diagnosis==
●11 percent ages 44 to 54
The diagnosis of labyrinthitis is based on clinical evaluation, rather than any test. The viral of preceding viral illness and acute onset symptoms like [[Dizziness causes|dizziness]],nausea and vomiting with gait impairment suggestive of labyrinthitis. No any specific diagnostic test are available.


===Diagnostic Study of Choice===
●25 percent ages 55 to 64
Neuroimaging, generally MRI is done to rule out other acute causes for symptoms that includes cerebellar [[Hemorrhage intracranial|hemorrhage]] and brainstem infraction. If MRI not available, CT scan can be done to look for alternative diagnosis.
===History and Symptoms===
The hallmark feature of labyrinthitis is sudden onset severe vertigo. A positive history of preceding viral infection and vertigo with gait instability is suggestive of labyrinthitis. The  common symptoms of labyrinthitis include dizziness, gait abnormality, nausea and vomiting.


===Physical Examination===
●43 percent ages 65 to 84
Common physical examination findings of labyrinthitis include [[nystagmus]] (unilateral-horizontal mostly), positive head impulse test(unable to maintain visual fixation on rapid turning of head towards the side of lesion), gait instability( tends to fall on side of lesion) and absence of neurological sign and symptoms. Unilateral hearing loss might be present in some cases.


===Laboratory Findings===
World Health Organization estimates that hearing loss affects 538 million people worldwide.
There are no diagnostic laboratory findings associated with [[Labyrinthitis (paitent information)|labyrinthitis]].


===CT scan===
==Risk Factors==
The most potent risk factor in the development of hearing loss is aging. Other risk factors include hereditary causes, occupational noises such as noises from factories, recreational noises such loud noises from firearm or jet engine, ototoxic drugs and illness such as meningitis or diabetes. Some other risk factors for hearing loss could be due to  head trauma and viral infections.


There are no CT scan findings associated with labyrinthitis. However, a CT scan may be helpful to rule out [[differential diagnosis]] like cerebellar hemorrhage/infarction and brainstem infarction.
==Natural History, Complications and Prognosis==


===MRI with contrast===
==Diagnosis==
MRI of inner ear may be helpful in the diagnosis of labyrinthitis. Findings on MRI suggestive of labyrinthitis include abnormal enhancement in membranous [[Labyrinth (inner ear)|labyrinth]] on post-contrast T1WI scan.
The diagnosis of hearing loss is based on the inability to hear sound( louder than 20dB) based on audiometer test.


==Treatment==
==Treatment==
 
Patients with infective aetiology for hearing loss are treated with Antibiotics and analgesics, whereas patients with non-infective/ structural causes are managed with hearing aids and cochlear implants .
The majority of cases of labyrinthitis are self-limited and require only supportive care during acute symptoms.
 
Supportive therapy for labyrinthitis includes anti-emetics, [[anti-histamines]], anti-[[cholinergics]] and [[benzodiazepines]]. [[Glucocorticoids]] and anti-viral drugs are the mainstay of treatment for labyrinthitis. Vestibular [[Physical medicine and rehabilitation|rehabilitation]] therapy also recommended among all patients who develop labyrinthitis.


==References==
==References==

Latest revision as of 16:10, 25 May 2021


Practice here

Introduction

Deafness is a partial or total inability to hear. WHO defines deafness as hearing threshold of 20dB or better in both ears.

Classification

[Deafness] may be classified according to WHO into 5 subtypes/groups:

  • Mild- Hearing losses between 26 and 40 dB
  • Moderate- Hearing losses between 41 and 55 dB
  • Moderately severe- Hearing losses between 56 and 70 dB
  • Severe - Hearing losses between 71 and 90 dB
  • Profound - Hearing losses greater than 91 dB

Pathophysiology

In general, sound waves reaching outer ear are conducted down the ear canal to vibrate eardrum, which in turn, transmitted to inner ear via 3 tiny bones. The fluid in the inner ear moves the hair cells which generate impulses that is conducted to brain via cochlear nerve. Any alteration or obstruction in these pathways can lead to hearing loss. Often, hearing loss is caused by long-term exposure to loud noises, that damage the hair cells.

Causes

Common causes of hearing loss include: Based on location

  • External Ear
  • Middle Ear
  • Inner Ear
    • Congenital malformation of cochlea
    • Presbycusis- old age related hearing loss
    • Infection- Viral cochleitis
    • Meniere disease
    • Noise exposure
    • Inner ear barotrauma
    • Ototoxic drugs
    • Systemic diseases- diabetic vasculopathy can cause cochlear ischemia
    • Tumors- acoustic neuroma

Differential Diagnosis

Conductive hearing loss Sensory hearing loss Neural hearing loss Central hearing loss
Acute causes
  • cerumen impaction
  • Tympanic effusion
  • Eardrum perforation (traumatic)
  • Acute infection of ear

Chronic causes

  • Cholesteatoma
  • Otosclerosis
  • tympanosclerosis
  • Defect in eardrum or ossicular chain disruption due to chronic infection
  • Malformation

Acute causes

  • Loud noise induced(blast trauma, explosion trauma)
  • Bacterial/Viral Labyrinthitis
  • Idiopathic sudden sensorineural hearing loss

Permanent causes

  • Occupational noise exposure
  • Ototoxic drugs
  • Hereditary inner ear malformation
  • Presbycusis
  • Acoustic neuroma
  • Tumors of cerebellopontine angle(meningioma,chordoma)
  • Compression syndrome
  • Hemorrhage
  • Infarctions
  • Intracranial tumor
  • Multiple sclerosis

Epidemiology and Demographics

The incidence of hearing loss increases with age. In the Beaver Dam cohort in the United States, the prevalence of hearing loss, defined by audiometry:

●3 percent ages 21 to 34

●6 percent ages 35 to 44

●11 percent ages 44 to 54

●25 percent ages 55 to 64

●43 percent ages 65 to 84

World Health Organization estimates that hearing loss affects 538 million people worldwide.

Risk Factors

The most potent risk factor in the development of hearing loss is aging. Other risk factors include hereditary causes, occupational noises such as noises from factories, recreational noises such loud noises from firearm or jet engine, ototoxic drugs and illness such as meningitis or diabetes. Some other risk factors for hearing loss could be due to head trauma and viral infections.

Natural History, Complications and Prognosis

Diagnosis

The diagnosis of hearing loss is based on the inability to hear sound( louder than 20dB) based on audiometer test.

Treatment

Patients with infective aetiology for hearing loss are treated with Antibiotics and analgesics, whereas patients with non-infective/ structural causes are managed with hearing aids and cochlear implants .

References

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