What causes tinnitus?

Causes of Tinnitus

Hearing loss is the most common cause of tinnitus, particularly sensorineural hearing loss from noise exposure, aging, and ototoxic medications. 1

Primary Causes of Tinnitus

Hearing Loss-Related Causes

• Sensorineural hearing loss - Most common underlying etiology 1, 2
  • Noise-induced hearing loss
  • Age-related hearing loss (presbycusis)
  • Sudden sensorineural hearing loss

Medication-Related Causes

• Ototoxic medications 1
  • Certain antibiotics
  • Salicylates and NSAIDs
  • Loop diuretics
  • Chemotherapeutic agents
  • Tricyclic antidepressants (e.g., amitriptyline) 3

Other Common Causes

• Ear-specific conditions 4

  • External ear infection
  • Cerumen impaction
  • Middle ear effusion
  • Meniere's disease
  • Otosclerosis

• Vascular abnormalities (typically cause pulsatile tinnitus) 4

  • Carotid artery abnormalities
  • Jugular venous system abnormalities
  • Vascular tumors

• Neurologic causes 1, 5

  • Vestibular schwannoma (acoustic neuroma)
  • Neural plasticity changes in the auditory system
  • Abnormal neural activity in central auditory pathways

Classification of Tinnitus Types

By Perception

• Subjective tinnitus - Heard only by the patient (most common) 1, 5
• Objective tinnitus - Can be heard by an examiner (rare) 4

By Pattern

• Pulsatile vs. non-pulsatile 1
• Unilateral vs. bilateral 1, 5
• Recent onset vs. persistent 1

Risk Factors and Associations

• Noise exposure - Strong correlation between years of work-related noise exposure and tinnitus prevalence 6

  • Occupational noise exposure increases risk by 3.3 times 6
  • Recreational noise exposure increases risk by 2.6 times 6

• Other associated conditions 7

  • Head injury
  • Depression and anxiety
  • Metabolic disorders

Clinical Pearls and Pitfalls

Red Flags Requiring Urgent Evaluation

• Pulsatile tinnitus (possible vascular abnormality) 1
• Unilateral tinnitus (possible vestibular schwannoma) 1, 2
• Tinnitus with sudden hearing loss 1
• Tinnitus with focal neurological symptoms 1
• Visible abnormality on otoscopic examination 1

Common Pitfalls to Avoid

• Failing to remove cerumen before assessment 1
• Overlooking non-otologic causes 1
• Not performing comprehensive audiologic evaluation 1
• Delayed referral for unilateral tinnitus 1
• Missing red flags that warrant urgent evaluation 1

Pathophysiological Mechanisms

The anatomical location of the physiological abnormality in chronic subjective tinnitus is rarely in the ear itself but more often in the auditory nervous system 5. Neural plasticity plays a central role in many forms of chronic subjective tinnitus by:

• Altering the balance between excitation and inhibition in the nervous system 5
• Promoting hyperactivity in auditory pathways 5
• Causing reorganization of specific parts of the nervous system 5

Since there are many different forms of tinnitus with varying underlying mechanisms, the search for a single cure is unlikely to be successful 5.