What causes tinnitus and hearing loss?

Causes of Tinnitus and Hearing Loss

Tinnitus is primarily a symptom, not a disease itself, that most often occurs in the setting of concomitant sensorineural hearing loss (SNHL), particularly among patients with bothersome tinnitus and no obvious ear pathology. 1

Primary Causes of Tinnitus and Hearing Loss

• Sensorineural hearing loss (SNHL) is the most common underlying cause of tinnitus, with various etiologies: 1, 2

  • Age-related hearing loss (presbycusis) 2
  • Noise exposure (occupational or recreational) 1
  • Ototoxic medications (including certain antibiotics, cancer drugs like cisplatin, loop diuretics such as furosemide) 2, 3
  • Menière's disease 4, 5
  • Sudden sensorineural hearing loss 1

• Cochlear synaptopathy ("hidden hearing loss") - moderate noise exposure can trigger irreversible degeneration of auditory nerve fibers without affecting outer hair cells or permanent threshold shifts, leading to difficulty understanding speech in noisy environments 1

Secondary Causes of Tinnitus

• Conductive hearing loss causes: 5

  • External ear infection
  • Cerumen impaction (ear wax)
  • Middle ear effusion
  • Otosclerosis 1

• Vascular abnormalities (often causing pulsatile tinnitus): 2

  • Arterial dissection
  • Dural arteriovenous fistulas
  • Arteriovenous malformations
  • Carotid cavernous sinus fistulas
  • Paragangliomas (glomus tumors)

• Bony abnormalities: 2

  • Superior semicircular canal dehiscence
  • Sigmoid sinus wall dehiscence
  • High jugular bulb

• Neurologic causes: 2

  • Intracranial hypertension
  • Neurodegeneration
  • Vestibular schwannoma (acoustic neuroma) - particularly important in unilateral tinnitus 4, 5

• Psychogenic factors: 2

  • Anxiety
  • Depression

Classification of Tinnitus

• Subjective tinnitus - perceived only by the patient, most common type 2
• Objective tinnitus - audible to the examining healthcare provider, requires evaluation for underlying vascular abnormality 2
• Pulsatile tinnitus - repetitive sound coinciding with heartbeat, often vascular in origin 2
• Non-pulsatile tinnitus - continuous or constant non-synchronous sound 2

Important Clinical Considerations

• Tinnitus can be perceived as coming from within or outside the head, and can occur unilaterally or bilaterally 1
• The quality of tinnitus varies, with patients describing ringing, buzzing, clicking, pulsations, and other sounds 1
• Approximately 10-15% of adults experience tinnitus, with prevalence increasing with age (1.6% in ages 18-44,4.6% in ages 45-64, and 9.0% in those over 60) 1
• Around 20% of adults with tinnitus require clinical intervention 1
• Patients with tinnitus accompanied by severe anxiety or depression require prompt identification and intervention due to increased suicide risk 1, 2
• Unilateral tinnitus, especially with hearing loss, should raise suspicion for acoustic neuroma 4, 5
• Pulsatile tinnitus requires thorough evaluation for vascular abnormalities 2

Risk Factors for Developing Tinnitus and Hearing Loss

• Advanced age 1
• Occupational noise exposure 1
• Recreational noise exposure (concerts, firearms, etc.) 1
• Use of ototoxic medications 2, 3
• Dehydration and reduced drug elimination (especially renal failure) increase risk of drug-related hearing loss 3
• Co-administration of multiple ototoxic drugs 3

Understanding the specific cause of tinnitus and hearing loss is crucial for determining appropriate management strategies and potentially addressing underlying conditions that may be treatable.