Tinnitus

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Kiran Singh, M.D. [2] Sabeeh Islam, MBBS[3]

Overview

Tinnitus is derived from the Latin word tinnire, meaning to ring. Tinnitus can be classified as subjective and objective.  This classification not only explains the underlying etiology but also directs the management of tinnitus. In the normal functioning auditory pathway, there is ordered tonotopic frequency mapping from the cochlea to the auditory cortex via midbrain.  Conditions associated with cochlear damage result in altered tonotopic organization and ultimately tinnitus. The pathophysiology of tinnitus can be explained by the tinnitus model. Common causes of tinnitus include Ototoxicity, Presbycusis, noise induced hearing loss, late onset congenital hearing loss, meniere's disease, and Loop diuretics. The incidence rate of tinnitus increases with age and is more prevalent in older people. Tinnitus is more prevalent in men compared to women and smokers compared to non-smokers. If left untreated, patients may progress to functional impairment, insomnia, anxiety, and depression. TSI is used to rank the patient's based upon their severity. The score ranges from 0-45. Symptoms and history include sounds such as ringing, buzzing, pulsatile, roaring and humming and progressive hearing loss. An extensive neurological examination may rule out underlying brainstem damage or hearing loss. The Weber and Rinne test are done to establish sensorineural or conductive hearing loss. They are usually abnormal. MRI with contrast is followed by CT/CTA and ultimately interventional angiography, if needed. Initial audiometric tests are done to identify asymmetries between the ears and to locate the site of abnormality such as middle ear, cochlea, and brainstem.  These tests include: pure-tone audiogram, tympanometry, auditory reflex testing, determination of speech discrimination abilities, otoacoustic emissions testing and auditory brainstem response testing (ABR). Tinnitus is a symptom and not a disease itself.  It is a chronic condition that can be managed by treating the underlying etiology. The treatment of tinnitus is usually directed towards improvement in the quality of life by decreasing awareness or desensitizing towards tinnitus.  It is usually achieved by identifying the underlying pathology or the associated disease. It is recommended to treat underlying insomnia and depression (Grade 1B). Cochlear implants may be considered for tinnitus associated with severe sensorineural hearing loss. Other therapies include: tinnitus retraining therapy (TRT) (Grade 1C), biofeedback (Grade 2C), and cognitive behavioral therapy (CBT) as an adjunct to TRT (Grade 2C). Acupuncture and electrical stimulation are considered equally effective as placebo, no significant role established so far.

Historical Perspective

• In the early 19th century, Frenchman and Jean Marie Gaspard Itard introduced the concept of masking.  They were the first ones to differentiate between subjective and objective tinnitus.
• Later in the 19th Century, with the introduction of germ theory and anesthesia, surgical therapy such as incudectomy was established.
• Tinnitus is derived from the Latin word tinnire, meaning to ring.

Classification

Tinnitus can be classified as subjective and objective.  This classification not only explains the underlying etiology but also directs the management of tinnitus.

Subjective tinnitus:

• It is only experienced by the affected individual in the absence of any auditory stimulation
• More common, usually described as continuous ringing, high pitch sound

Objective tinnitus:

• It is experienced not only by the affected individual but also by anyone else
• Relative rare, usually described as intermittent venous hum, low pitch sound
• It has an underlying vascular (abnormality of the carotid artery, jugular bulb or jugular vein) or muscular etiology (degenerative conditions such as amyotrophic lateral sclerosis) and usually caused by sound produced in ear, head or neck.
  

Pathophysiology

In the normal functioning auditory pathway, there is ordered tonotopic frequency mapping from the cochlea to the auditory cortex via midbrain.  Conditions associated with cochlear damage result in altered tonotopic organization and ultimately tinnitus. The pathophysiology of tinnitus can be explained by the tinnitus model.

Lesion projection zone (LPZ):

This zone is defined as the area in the auditory cortex that represents the damaged cochlear input.  The neurons in the LPZ zone show 2 main changes:

• Accelerated spontaneous firing rate
• Increased representation of neurons that represent the damaged cochlear region also known as lesion edge frequencies in the LPZ

Tinnitus model:

This model explains 2 major phenomena in the auditory cortex caused by lack of sensory peripheral auditory input (cochlea)

• Hyperactivity in the lesion projections zone (LPZ)
• Increased cortical representation of the lesion-edge frequencies in the LPZ

Causes of subjective tinnitus

Sensorineural hearing loss:

• Ototoxicity
• Presbycusis
• Noise induced hearing loss
• Late onset congenital hearing loss
• Idiopathic

Cochlear injury:

• Meniere's disease
• Loop diuretics
• Platinum based chemotherapy
• Antibiotics
• Salicylate
• Trauma

Vascular causes:

• Systemic hypertension
• Sickle cell anemia
• Small vessel disease
• Hypercholesterolemia
• Hypercoagulable state
• Diabetic vasculopathy

CNS causes:

• Pseudotumor cerebri
• Stroke
• Vascular malformations
• Tumor
• Sarcoid
• Multiple sclerosis

Infections:

• Rubella
• Cytomegalovirus
• Chronic otitis media
• Neurosyphilis
• Measles
• Lyme disease
• Meningitis

Bone disease:

• Otosclerosis
• Fibrous dysplasia
• Osteogenesis imperfecta
• Paget's disease

Metabolic disorders:

• Hyperparathyroidism
• Chronic renal failure
• Diabetes mellitus
• Thyroid disease

Autoimmune diseases:

• Autoimmune inner ear disease
• SLE
• Rheumatoid arthritis

Medications:

• ACE inhibitors
• Antimalarial medications
• Aminoglycosides
• Dapsone
• Doxazosin
• Calcium channel blockers
• Benzodiazepines
• Cisplatin
• Clarithromycin
• COX-2 inhibitors
• Loop diuretics
• Tricyclic antidepressant
  

Differential Diagnosis of Tinnitus

Diseases	Clinical manifestations					Para-clinical findings		Gold standard	Additional findings
	Symptoms				Physical examination
						Lab Findings	Imaging
	Acute onset	Recurrency	Nystagmus	Hearing problems, tinnitus
Peripheral
HSV oticus	+	+/−	−	+/−	loss of tastein the front two-thirds of the tongue Acute facial nerve paralysis Vesicles in the ear canal, the tongue, and/or hard palate	+ VZV antibody titres	MRI with gadolinium contrast may show enhancement of the facial nerve and vestibulocochlear nerve	History/ Physical exam	May be associated with otalgia, dry mouth and dry eyes
Meniere disease	+/−	+	+/−	+ (Progressive)	Sensorineural hearing loss	−	CT scan may show small or invisible vestibular aqueduct	History/ Physical exam Ruling out other CNS and ear pathologies.	May be associated with nausea, vomiting, and tinnitus
Labyrinthine concussion	+	−	−	+	high frequency hearing loss	−	CT scan may show evidence of head trauma or temporal bone fracture	History/ Physical exam	Follows blunt head trauma May be associated with dizziness or tinnitus
Perilymphatic fistula	+/−	+	−	+	Tullio phenomenon	−	CT scan may show fluid around the round window recess	History/ Physical exam/Imaging	Complication of stapedectomy, head injury, or heavy lifting It may be provoked by activities such as sneezing, lifting, straining, coughing, and loud sounds. (Tullio phenomenon)
Semicircular canal dehiscence syndrome	+/−	+	−	+ (air-bone gaps on audiometry)	Tullio phenomenon	−	CT scan may show defect in the arcuate eminence of the superior semicircular canal	History/ Physical exam/Imaging	It may be provoked by Valsalva maneuver, coughing, and sneezing
Cogan syndrome	−	+	+/−	+	Interstitial keratitis Oscillopsia Absent vestibular function on caloric test Systemic vasculitis (Aortitis)	Increased ESR and cryoglobulins	CT scan may show calcification or soft tissue attenuation obliterating the intralabyrinthine fluid spaces	History/ Physical exam	It may cause Ménière-like attacks
Vestibular schwannoma	−	+	+/−	+	Sensorineural hearing loss + Rinne test Lateralization of Weber test to the normal ear	−	CT scan we may show erosion, and widening of the internal acoustic meatus T1-weighted MRI may show a hypointense mass lesion where as T-2 weighted MRI shows a hyperintense mass lesion	Imaging	Gadolinium-enhanced MRI scan is the definitive diagnostic test for acoutic neuroma
Otitis media	+	−	−	+/−	Fever Presence of effusion in the middle ear	Increased acute phase reactants	Opacification of the middle ear	History/ Physical exam	Patient may show other signs and symptoms of upper respiratory infection such as cough, nasal discharge, and fever
Aminoglycoside toxicity	+	−	−	+	Oscillopsia	−	−	History/ Physical exam	May be associated with nausea, vomiting, and ataxia possibly irreversible Gentamicin is the most common one
Central
Vestibular migraine	–	+	+/−	+/−	History of migraine headaches	−	MRI may show white-matter hyper-intensities (WMHs)	ICHD-3 criteria	It may be associated with anxiety and depression
Multiple sclerosis	−	+	+/−	+/−	Lhermitte's sign Spasticity Hyperreflexia Internuclear ophthalmoplegia Optic neuritis Gait disturbance	Elevated concentration of CSF oligoclonal bands	CT scan shows brain atrophy and contrast enhanced demyelinating plaques MRI showing cerebral plaques disseminating in time and space.	History and physical examination Imaging CSF analysis	MS is twice as prevalent in women as compared to men The onset of symptoms is mostly between the age of fifteen to forty years and rarely before the age of fifteen or after the age of sixty years
Brain tumors	+/−	+	+	+	Papilledema Focal neurological deficits	Cerebral spinal fluid (CSF) may show cancerous cells	On CT scan most of the brain tumors appears as a hypodense mass lesions On T1- weighted MRI most of the brain tumors appears as a hypointense or Isointense whereas on T2-weighted MRI they appear as hyperintense lesions	Imaging Biopsy	May experience headache, seizures, visual changes and changes in personality, mood and concentration
Cerebellar infarction/hemorrhage	+	−	++/−	+/−	Limb ataxia Gait disturbance Dysarthria	−	Based on the time interval lapsed between the onset of stroke and imaging performed there may be different presentations	Imaging	Posterior inferior cerebellar artery is the most common artery that causes vertigo
Brain stem ischemia	+	−	+/−	+/−	Contralateral body weakness Visual field deficits Oculomotor abnormalities Bulbar findings	−	Based on the time interval lapsed between the onset of stroke and imaging performed there may be different presentations For more information click here	Imaging	It may be associated with subclavian steal syndrome

ABBREVIATIONS

VZV= Varicella zoster virus, MRI= Magnetic resonance imaging, ESR= Erythrocyte sedimentation rate, EEG= Electroencephalogram, CSF= Cerebrospinal fluid, GPe= Globus pallidus externa, ICHD= International Classification of Headache Disorders

Epidemiology and Demographics

• Tinnitus affects 10 to 15% of the population.
• 85% of the population presenting with ear symptoms/disorders report tinnitus as an associated symptom.
• The incidence rate of tinnitus increases with age and is more prevalent in older people.
• Tinnitus is more prevalent in men compared to women and smokers compared to non-smokers.

Risk Factors

Common risk factors of tinnitus include

• Age
• Sensorineural hearing loss
• Loud noise exposure
• Vestibular schwannoma
• Ototoxic medication
• History of anxiety and depression
• History of head trauma
• History of multiple sclerosis

Natural History, Complications and Prognosis

• Early clinical features may include ear fullness, huming or ringing sensations in the ear
• If left untreated, patients may progress to functional impairment, insomnia, anxiety, and depression.

Diagnosis

Diagnostic criteria:

Tinnitus severity index (TSI)

• TSI is used to rank the patient's based upon their severity
• The score ranges from 0-45

Tinnitus handicap questionnaire:

• This questionnaire includes 27 questions and is used to estimate the social, physical and emotional handicap severity

Tinnitus handicap inventory:

• This questionnaire has 4 categories to classify severity
• None, mild,  moderate, and severe.

History and Symptoms:

• Sounds such as ringing, buzzing, pulsatile, roaring and humming
• Progressive hearing loss
• Recent exposure to excessive or loud noise or head trauma
• Poor hygiene leading to cerumen impaction
• Ear pain
• History of certain medication exposure

Physical Examination:

• The ear examination may show signs of cerumen impaction, underlying infection or tympanic membrane perforation.
• Auscultation of neck, orbits and periauricular areas as helpful in establishing the diagnosis of vascular causes
• An extensive neurological examination may rule out underlying brainstem damage or hearing loss
• The Weber and Rinne test are done to establish sensorineural or conductive hearing loss. They are usually abnormal.

Laboratory Findings:

• There are no specific lab findings associated with tinnitis.

Imaging:

• MRA and CTA are the gold standard diagnostic tests for arteriovenous fistula related tinnitus.
• MRI with contrast is the initial preferred diagnostic test of choice for suspected vascular tinnitus.
• MRI with contrast is followed by CT/CTA and ultimately interventional angiography, if needed.

Other Diagnostic Testing:

• Initial audiometric tests are done to identify asymmetries between the ears and to locate the site of abnormality such as middle ear, cochlea, and brainstem.  These tests include:
  • Pure-tone audiogram
  • Tympanometry
  • Auditory reflex testing
  • Determination of speech discrimination abilities
  • Otoacoustic emissions testing
  • Auditory brainstem response testing (ABR)

Treatment

• Tinnitus is a symptom and not a disease itself.  It is a chronic condition that can be managed by treating the underlying etiology.
• The treatment of tinnitus is usually directed towards improvement in the quality of life by decreasing awareness or desensitizing towards tinnitus.  It is usually achieved by identifying the underlying pathology or the associated disease.
• It is recommended to treat underlying insomnia and depression. (Grade 1B)

Medical Therapy

Following medications have minimal to modest role in relieving tinnitus.

• Misoprostol
• Lidocaine (intratympanic or intravenous)
• Benzodiazepine (alprazolam)
• Steroids such as dexamethasone (intratympanic)
• Carbamazepine

Following medications have been studied for tinnitus but are not found to be effective and have no role in the treatment of tinnitus

• Anticonvulsants
• Melatonin
• Ginkgo biloba
• Niacin

Surgery

• Cochlear implants may be considered for tinnitus associated with severe sensorineural hearing loss.

Other therapies:

• Tinnitus retraining therapy (TRT) (Grade 1C)
• Biofeedback (Grade 2C)
• Cognitive behavioral therapy (CBT) as an adjunct to TRT (Grade 2C)
• Acupuncture and electrical stimulation are considered equally effective as placebo, no significant role established so far.

Prevention

• Tinnitus may be been prevented by limiting the exposure to loud noise.