Tinnitus

Description

• Tinnitus is a perceived sensation of sound in the absence of an external acoustic stimulus; often described as a ringing, hissing, buzzing, or whooshing
• Derived from the Latin word tinnire, meaning “to ring”
• May be heard in one or both ears or centrally within the head
• Two types: subjective (most common) and objective tinnitus
• Subjective tinnitus: perceived only by the patient; can be continuous, intermittent, or pulsatile
• Objective tinnitus: audible to the examiner; usually pulsatile; <1% cases (1)
• Primary tinnitus: idiopathic with or without sensorineural hearing loss (SNHL) (2)
• Secondary tinnitus: associated with a specific cause (other than SNHL)

Epidemiology

• Tinnitus reported by 35 to 50 million adults in United States; although underreported, 12 million seek medical care.
• Affects 10–15% of adults
• Prevalence increases with age and peaks in 6th decade.
• Prevalence of 13–53% in general pediatric population
• Ethnic: whites > blacks and Hispanics
• Gender: males > females

• Incidence increasing in association with excessive noise exposure
• Higher rates of tinnitus in smokers, hypertensives, diabetics, and obese patients

Etiology and Pathophysiology

• Precise pathophysiology is unknown; numerous theories have been proposed. Cochlear damage from ototoxic agents or noise exposure damage hair cells so that the central auditory system compensates, resulting in hyperactivity in cochlear nucleus and auditory cortex. Animal models have identified brain abnormalities resulting in increased firing and synchrony in auditory cortex.
• Causes of subjective tinnitus are the following:
  • Otologic: hearing loss, cholesteatoma, cerumen impaction, otosclerosis, Ménière disease, vestibular schwannoma
  • Ototoxic medications: anti-inflammatory agents (aspirin, NSAIDs); antimalarial agents, antimicrobial drugs (aminoglycosides); antineoplastic agents, loop diuretics, miscellaneous drugs (antiarrhythmics, antiulcer, anticonvulsants, antihypertensives); psychotropic drugs; anesthetics (1)
  • Somatic: temporomandibular joint (TMJ) dysfunction, head or neck injury
  • Neurologic: multiple sclerosis, spontaneous intracranial hypertension, vestibular migraine, type I Chiari malformation
  • Infectious: viral, bacterial, fungal
• Causes of objective tinnitus:
  • Vascular: aortic or carotid stenosis, venous hum, arteriovenous fistula or malformation, vascular tumors, high cardiac output state (anemia)
  • Neurologic: palatal myoclonus, idiopathic stapedial muscle spasm
  • Patulous eustachian tube

Genetics
Minimal genetic component

Risk Factors

• Hearing loss (but can have tinnitus with normal hearing)
• High-level noise exposure
• Advanced age
• Use of ototoxic medications
• Otologic disease (otosclerosis, Ménière disease, cerumen impaction)
• Anxiety and depression associated with increased odds of tinnitus

General Prevention

• Avoid loud noise exposure and wear appropriate ear protection to prevent hearing loss.
• Monitor ototoxic medications and avoid prescribing more than one ototoxic agent concurrently.

Commonly Associated Conditions

• SNHL caused by presbycusis (age associated hearing loss) or prolonged loud noise exposure
• Conductive hearing loss due to cerumen, otosclerosis, cholesteatoma
• Psychological disorders: depression, anxiety, insomnia, suicidal ideation
• Despair, frustration, interference with concentration and social interactions, work hindrance