Description

• Tinnitus is the perception of sound in the absence of an acoustic stimulus; may be a buzz, ring, roar, chirp, whistle, or hiss. Tinnitus is derived from the Latin word tinnire meaning “to ring.”
• Subjective tinnitus: Heard only by the patient
• Objective tinnitus: Heard through a stethoscope placed near the patient's ear
• Tinnitus for >6 months is considered chronic.

Epidemiology

• Predominant age: 40–70 years (prevalence increases with age)
• Predominant sex: Males > Females; men traditionally have greater noise exposure in military, occupational, and recreational activities.
• ~16% of the US population, or ~50 million people in the US; 25–30% of US population >65 years of age have chronic tinnitus.
• Interferes with daily activities in 12 million people (~4%) in the US, and 25% of those with tinnitus consider it to be a significant problem.
• Rare in children with normal hearing; occurs in 33–64% of children who have severe hearing loss.

Risk Factors

• Advanced age
• Pregnancy
• Excessive noise exposure
• Hearing loss
• Use of ototoxic medications
• Renal/Hepatic impairment
• White
• Male sex

Genetics
Possibly a genetic predisposition, but a tinnitus gene has not yet been discovered. Genes have been identified for temporomandibular joint (TMJ) dysfunction, Ménière disease, and acoustic neuroma.

General Prevention

Avoid prolonged exposure to loud noises, wear hearing protection when loud noises cannot be avoided (e.g., lawn mower, power tools), and avoid overuse of ototoxic medications. Even occasional exposure to loud sounds can cause irreversible damage to the hair cells of the auditory nerve fibers and cochlea resulting in hearing loss and tinnitus (1).

Pathophysiology

• Moderate sounds cause tiny movements of the stereocilia, which are attached to hair cells in the cochlea. This triggers neuronal transmission in CN VIII. Loud sounds (≥85 dB) cause the stereocilia to bend more than they should. Hair cells that respond to higher-frequency sounds are located at the base of the cochlea and are the first to be damaged. This causes high-pitched ringing. If loud noise exposure is excessive, then stereocilia cannot recover and permanent damage occurs. This results in hearing loss and possibly tinnitus.
• Other causes of hearing loss/damage to the auditory system also can cause tinnitus.
• Tinnitus has many similarities with the symptoms of central neuropathic pain and paresthesias, and it may be related to these neurologic disorders.

Etiology

• Subjective tinnitus (My AAA NOISE PAIN):
  • Medications and heavy metals that cause or exacerbate tinnitus: Aspirin, aminoglycosides, benzodiazepines, calcium channel blockers, chloroquine, cisplatin, erythromycin, fluoroquinolones, lead, lidocaine, loop diuretics, mercury, methotrexate, NSAIDs, proton pump inhibitors, quinine, sertraline, tetracycline, tricyclic antidepressants, valproate, vancomycin
  • Ménière disease (estimated 1% prevalence in the US) or other forms of endolymphatic hydrops (abnormally high inner ear pressure)
  • Aging-related hearing loss (presbycusis)
  • Anemia
  • Arterial problems (hypertension [HTN], arteriosclerosis, cerebral aneurysm, cerebrovascular accident)
  • Noise (chronic exposure to loud noise/acoustic trauma due to acute exposure to very loud noise)
  • Otosclerosis and osteogenesis imperfecta
  • Infections (otitis, meningitis, Lyme disease, neurosyphillis, rubella) or impaction (cerumen)
  • Sclerosis (multiple sclerosis)
  • Endocrine (diabetes mellitus [DM], thyroid)
  • Psychogenic (depression, anxiety, psychosis)
  • Autoimmune disease of inner ear
  • Injury (head and neck) and idiopathic
  • Neoplasms (acoustic neuroma/cholesteatoma)
• Objective tinnitus (<1% of all cases of tinnitus; CAGED PETS):
  • Vascular abnormalities:
    • Carotid stenosis/CAD
    • Arteriovenous shunt/fistula
    • Glomus jugulare
    • Existing stapedial artery
    • Dehiscent jugular bulb/a vascular loop
  • Mechanical abnormalities:
    • Palatal myoclonus
    • Eustachian tube abnormally patent
    • TMJ disorder
    • Stapedial muscle spasticity

Commonly Associated Conditions

• Hearing loss (~90% of chronic tinnitus is associated with sensorineural hearing loss):
  • Causes of sensorineural hearing loss: Loud noise, presbycusis, ototoxic medications, Ménière disease, acoustic neuroma
  • Causes of conductive hearing loss: Cerumen, ear infection/effusion, trauma, tumor
• TMJ dysfunction
• Depression, anxiety, insomnia, fibromyalgia (40–60% of patients with tinnitus also have major depressive disorder)
• Psychological disorders can contribute to the distress of tinnitus. Some patients with severe tinnitus contemplate suicide.