What are the possible causes of tinnitus?

Causes of Tinnitus

Sensorineural hearing loss is the single most common underlying cause of tinnitus, particularly in patients with bothersome tinnitus and no obvious ear pathology. 1

Primary Auditory System Causes

Most Common Etiologies

• Presbycusis (age-related hearing loss) represents gradual, progressive decline in high-frequency hearing due to hair cell degeneration and is the most common cause in older adults 1
• Noise exposure (occupational or recreational) causes both tinnitus and hearing loss through cochlear damage 1
• Sudden sensorineural hearing loss requires prompt identification as it represents a treatable cause of tinnitus 1
• Cochlear synaptopathy ("hidden hearing loss") triggers irreversible auditory nerve fiber degeneration without affecting outer hair cells, leading to difficulty understanding speech in noise 1

Conductive Hearing Loss Causes

• Cerumen impaction is a simple, reversible cause identifiable on otoscopic examination 1
• Middle ear infection or effusion causes conductive hearing loss with associated tinnitus 1
• Otosclerosis causes conductive hearing loss leading to tinnitus 1

Retrocochlear Pathology

• Vestibular schwannoma (acoustic neuroma) almost always causes unilateral tinnitus with asymmetric hearing loss 1
• Cerebellopontine angle masses and auditory pathway lesions can cause tinnitus 1

Vascular Causes (Pulsatile Tinnitus)

Pulsatile tinnitus has an identifiable structural or vascular cause in over 70% of cases and requires urgent imaging evaluation. 2

Arterial Etiologies

• Atherosclerotic carotid artery disease is the most frequent cause of pulsatile tinnitus, accounting for 17.5% of cases, resulting from turbulent flow 2
• Arterial dissection is a potentially life-threatening condition requiring urgent identification 2
• Fibromuscular dysplasia of the carotid arteries can cause pulsatile tinnitus 2

Arteriovenous Shunting

• Dural arteriovenous fistulas account for 8% of pulsatile tinnitus cases and can lead to hemorrhagic or ischemic stroke if untreated 2
• Arteriovenous malformations are high-flow vascular lesions causing pulsatile tinnitus through abnormal arteriovenous shunting 2

Venous Abnormalities

• Idiopathic intracranial hypertension is the second most common cause of pulsatile tinnitus, associated with sigmoid sinus wall abnormalities 2
• Sigmoid sinus diverticulum or dehiscence is commonly associated with intracranial hypertension 2
• Jugular bulb abnormalities (high-riding jugular bulb or dehiscence of the sigmoid plate) can cause pulsatile tinnitus 2
• Aberrant venous anatomy including persistent petrosquamosal sinus and abnormal condylar/mastoid emissary veins 2
• Transverse sinus stenosis can cause pulsatile tinnitus 1

Vascular Tumors

• Paragangliomas (glomus tympanicum/jugulare) are highly vascularized skull base tumors accounting for 16% of pulsatile tinnitus cases, appearing as vascular retrotympanic masses on otoscopy 2
• Adenomatous middle ear tumors are less common vascular masses causing pulsatile tinnitus 2

Structural/Bony Abnormalities

• Superior semicircular canal dehiscence is a bony defect allowing transmission of vascular sounds 2
• Sigmoid sinus wall dehiscence allows abnormal sound transmission 2
• Paget disease affecting the temporal bone can cause tinnitus 1
• Temporal bone fracture or head trauma with vascular injury can cause tinnitus 1

Neurologic Causes

• Intracranial hypertension (both idiopathic and secondary) causes tinnitus through venous sinus abnormalities 1
• Spontaneous intracranial hypotension can cause tinnitus 1
• Neurodegeneration is a neurologic cause of tinnitus 1
• Traumatic brain injury is correlated with tinnitus development 3

Ototoxic Medications

Over 130 drugs and chemicals have been reported as potentially ototoxic. 4

Chemotherapeutic Agents (Highest Risk)

• Cisplatin elevates the risk of new tinnitus by 5.53 times over nonototoxic medications 5
• Carboplatin increases the risk by 3.75 times 5

Other Major Drug Classes

• Aminoglycosides and other antimicrobials carry borderline risk (2.81 times) for new tinnitus 5, 4
• Anti-inflammatory agents (particularly NSAIDs and aspirin) are associated with tinnitus 4
• Loop diuretics can cause ototoxicity 4
• Antimalarial drugs are potentially ototoxic 4

Psychogenic and Comorbid Factors

• Anxiety and depression are both contributing factors and consequences of tinnitus 1
• Stress exposure is correlated with tinnitus development 3
• Insomnia is associated with tinnitus 3
• Migraine is correlated with tinnitus 3

Specific Disease Entities

• Menière's disease is a secondary cause requiring identification 1, 6
• Small vessel disease is correlated with tinnitus 3

Important Clinical Distinctions

Subjective vs. Objective Tinnitus

• Subjective tinnitus is perceived only by the patient, comprises 70-80% of cases, and is typically related to sensorineural hearing loss 1
• Objective tinnitus is audible to the examining healthcare provider and should prompt evaluation for underlying vascular abnormality 1

Pulsatile vs. Non-Pulsatile

• Pulsatile tinnitus synchronizes with heartbeat, often has vascular origin, and requires thorough vascular evaluation in nearly all cases 1
• Non-pulsatile tinnitus is continuous or constant non-synchronous sound, typically associated with sensorineural hearing loss 1

Critical Risk Factors

• Advanced age is the strongest demographic risk factor, with prevalence increasing from 1.6% in adults aged 18-44 years to 9.0% in those over 60 years 1
• Occupational noise exposure is a major risk factor 1
• Recreational noise exposure (concerts, firearms) increases risk 1
• Military service is correlated with tinnitus development 3
• Smoking history is associated with tinnitus 3
• Lower socioeconomic status is correlated with tinnitus 3

Critical Clinical Pitfalls to Avoid

• Missing dural arteriovenous fistula is life-threatening, as it can present with isolated pulsatile tinnitus before catastrophic hemorrhage 2
• Dismissing pulsatile tinnitus as benign without imaging is dangerous, as identifiable causes exist in >70% of cases 2
• Overlooking intracranial hypertension particularly in young, overweight women with headaches can lead to vision loss 2
• Failing to identify severe anxiety or depression in tinnitus patients is critical, as they carry increased suicide risk and require prompt intervention 1
• Inadequate otoscopic examination can delay diagnosis of vascular retrotympanic masses (paragangliomas) 2