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== Introduction ==
==Introduction==
Labyrinthitis is self-limiting inner ear disorder, often secondary to viral infection. The infection of vestibular neuron and labyrinth primary affects balance and hearing. The condition is commonly called as vestibular neuritis/ vestibular neuronitis.
[[Deafness]] is a partial or total inability to hear. WHO defines deafness as hearing threshold of 20dB or better in both ears.
 
== Classification ==
 
== Pathophysiology ==
The major cause for labyrinthitis is known to be viral infection or post-viral inflammatory disorder that mainly affects the vestibular portion of eighth cranial nerve. The exact cause of labyrinthitis or vestibular neuronitis  is still not clear. MRI with contrast had shown enhancement of the vestibular nerve fibers within the internal auditory canal, suggesting inflammatory process.
 
== Causes ==
 
== Differential Diagnosis ==
Labyrinthitis must be differentiated from other diseases that cause vertigo along with gait impairment such as:
*Cerebellar hemorrhage/Infarction
*Brainstem Infarction
 
== Epidemiology and Demographics ==
 
== Risk Factors ==


== Screening ==
==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


== Natural History and Prognosis ==
==Pathophysiology==
Labyrinthitis is self limiting disorder, often becomes acutely symptomatic for 1 to 2 days. The symptoms gradually improve over 2 weeks. Recurrence is rare.
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.
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.
Often, hearing loss is caused by long-term exposure to loud noises, that damage the hair cells.


== Diagnosis ==
==Causes==
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,nausea and vomiting with gait impairment suggestive of labyrinthitis. No any specific diagnostic test are available.
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


=== Diagnostic Study of Choice ===
==Differential Diagnosis==
Neuroimaging, generally MRI is done to rule out other acute causes for symptoms that includes cerebellar hemorrhage and brainstem infraction. If MRI not available, CT scan can be done to look for alternative diagnosis.
{| class="wikitable"
=== History and Symptoms ===
!Conductive hearing loss
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.
!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
|}


=== Physical Examination ===
==Epidemiology and Demographics==
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.
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:


=== Laboratory Findings ===
●3 percent ages 21 to 34


●6 percent ages 35 to 44


=== CT scan ===
●11 percent ages 44 to 54


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.
●25 percent ages 55 to 64


=== MRI with contrast ===
●43 percent ages 65 to 84
MRI of inner ear may be helpful in the diagnosis of labyrinthitis. Findings on MRI suggestive of labyrinthitis include abnormal enhancement in membranous labyrinth on post-contrast T1WI scan.


=== Other Imaging Findings ===
World Health Organization estimates that hearing loss affects 538 million people worldwide.


=== Other Diagnostic Studies ===
==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.


== Treatment ==
==Natural History, Complications and Prognosis==
===Treatment===
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 rehabilitation therapy also recommended among all patients who develop labyrinthitis.


===Symptomatic treatment===
==Diagnosis==
*Anti-emetics
The diagnosis of hearing loss is based on the inability to hear sound( louder than 20dB) based on audiometer test.
*Anti-histamines
*Anti-cholinergics
*Benzodiazepines


===Vestibular rehabilitation===
==Treatment==
*Vestibular exercises/ physical therapy
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 ==
==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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