What causes tinnitus?

Causes of Tinnitus

Tinnitus is not a disease but a symptom with multiple underlying causes, most commonly sensorineural hearing loss (SNHL), which is present in the majority of patients with bothersome tinnitus. 1, 2

Primary Causes

Sensorineural Hearing Loss (Most Common)

• SNHL is the most frequent underlying cause of tinnitus, particularly in patients with bothersome tinnitus and no obvious ear pathology 1, 2
• Age-related hearing loss (presbycusis) is a common etiology, with tinnitus prevalence increasing from 1.6% in adults aged 18-44 years to 9.0% in those over 60 years 1, 2
• Noise exposure (occupational or recreational) causes both tinnitus and hearing loss 2
• Sudden sensorineural hearing loss can trigger tinnitus 2
• Cochlear synaptopathy ("hidden hearing loss") can cause irreversible auditory nerve fiber degeneration without affecting outer hair cells, leading to difficulty understanding speech in noisy environments 2

Ototoxic Medications

• Certain antibiotics and platinum-based chemotherapy agents can cause tinnitus 2, 3
• Ototoxic drugs represent a significant risk factor for developing tinnitus 3

Trauma and Injury

• Head or cervical vertebra trauma can precipitate tinnitus 3, 4
• Traumatic brain injury is a recognized precipitating factor 4

Secondary Causes

Otologic Conditions

• Otosclerosis causes conductive hearing loss that can lead to tinnitus 2
• Menière's disease includes tinnitus as part of its symptom complex 5
• Vestibular schwannoma (acoustic neuroma) almost always presents with tinnitus 5
• Cerumen impaction can cause tinnitus 2

Vascular Causes (Pulsatile Tinnitus)

• Arterial dissection and fibromuscular dysplasia of carotids 2
• Dural arteriovenous fistulas and arteriovenous malformations 2
• Carotid cavernous sinus fistulas 2
• Transverse sinus stenosis and sigmoid sinus diverticulum 2
• Paragangliomas (glomus tumors) and vascular middle ear tumors 2

Bony Abnormalities

• Superior semicircular canal dehiscence 2
• Sigmoid sinus wall dehiscence and high jugular bulb 2
• Paget disease affecting the temporal bone 2

Neurologic Causes

• Intracranial hypertension 2
• Neurodegeneration 2
• Spontaneous intracranial hypotension 2

Psychiatric and Psychological Factors

• Anxiety and depression are both risk factors for developing tinnitus and can contribute to its severity 2, 3, 6
• Depression is recognized as a significant risk factor 6
• Stress exposure correlates with tinnitus development 4

Important Clinical Distinctions

Subjective vs. Objective Tinnitus

• Subjective tinnitus (most common) is perceived only by the patient and represents a phantom sensation from abnormal neural activity 1, 2
• Objective tinnitus is audible to the examining healthcare provider and should prompt evaluation for underlying vascular abnormality 2

Pulsatile vs. Non-Pulsatile

• Pulsatile tinnitus is repetitive and coincides with heartbeat, often vascular in origin, and requires thorough evaluation for vascular abnormalities 2
• Non-pulsatile tinnitus is continuous or constant and non-synchronous 2

Critical Clinical Considerations

Patients with tinnitus accompanied by severe anxiety or depression require prompt identification and intervention, as suicide has been reported in tinnitus patients with coexisting psychiatric illness. 1, 2

• Tinnitus can be unilateral or bilateral, and perceived as coming from within or outside the head 1, 2
• The quality varies widely, with patients describing ringing, buzzing, clicking, pulsations, and other sounds 1, 2
• Approximately 10-15% of adults experience tinnitus, with around 20% requiring clinical intervention 1, 2
• The anatomical location of chronic subjective tinnitus is rarely in the ear but more often in the auditory nervous system 5

Pathophysiologic Mechanisms

• Expression of neural plasticity plays a central role in chronic subjective tinnitus development 5
• Abnormal activities in the central nervous system include elevated spontaneous neuronal firing rate and increased neuronal synchronization caused by auditory deprivation 3
• Changes in tonotopic mapping, auditory cortical reorganization, and dysregulation of the limbic system contribute to tinnitus 3
• Tinnitus involves both auditory and nonauditory cortical areas of the brain, affecting brain-auditory circuitry 4