What are the possible causes of tinnitus?

Causes of Tinnitus

Primary Mechanism: Auditory System Dysfunction

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

Common Auditory Causes

• Presbycusis (age-related hearing loss) represents the most common cause in older adults, resulting from progressive degeneration of hair cells and declining ability to perceive high-frequency tones 1
• Noise exposure (occupational or recreational including concerts, firearms) causes both tinnitus and permanent hearing damage through cochlear synaptopathy and outer hair cell damage 1
• Sudden sensorineural hearing loss requires prompt identification as it represents an otologic emergency that can cause persistent tinnitus 1
• Cochlear synaptopathy ("hidden hearing loss") triggers irreversible degeneration of auditory nerve fibers without affecting outer hair cells or causing permanent threshold shifts, leading to difficulty understanding speech in noisy environments 1

Conductive and Middle Ear 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 and requires MRI evaluation 1
• Cerebellopontine angle masses and auditory pathway lesions can cause tinnitus 1

Vascular Causes (Pulsatile Tinnitus)

Pulsatile tinnitus is vascular until proven otherwise and requires imaging evaluation, as identifiable structural or vascular causes exist in over 70% of cases. 2

Arterial Causes

• Atherosclerotic carotid artery disease is the most frequent cause of pulsatile tinnitus, accounting for 17.5% of cases, resulting from turbulent flow 2, 3
• Arterial dissection is a potentially life-threatening condition requiring urgent identification and immediate anticoagulation or antiplatelet therapy 1, 2
• Fibromuscular dysplasia of carotids can cause pulsatile tinnitus through altered flow dynamics 1

Arteriovenous Shunting

• Dural arteriovenous fistulas (AVF) account for 8% of pulsatile tinnitus cases and can lead to hemorrhagic or ischemic stroke if untreated, making this a life-threatening cause requiring urgent identification 1, 2, 3
• Arteriovenous malformations (AVMs) are high-flow vascular lesions that create abnormal arteriovenous shunting with turbulent flow patterns synchronized with the cardiac cycle 1, 2

Venous Causes

• Idiopathic intracranial hypertension (pseudotumor cerebri) is the second most common cause of pulsatile tinnitus, particularly in young overweight women, and is associated with sigmoid sinus wall abnormalities 2
• Transverse sinus stenosis causes venous turbulence leading to pulsatile tinnitus 1
• Sigmoid sinus diverticulum or dehiscence is commonly associated with intracranial hypertension 2
• Jugular bulb abnormalities including 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 and mastoid emissary veins can cause pulsatile tinnitus 2

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 1, 2
• Adenomatous middle ear tumors are less common vascular masses that can cause pulsatile tinnitus 2

Bony and Structural Abnormalities

• Superior semicircular canal dehiscence is a bony defect that allows transmission of vascular sounds and can cause pulsatile tinnitus 1, 2
• Sigmoid sinus wall dehiscence creates abnormal sound transmission 1
• High jugular bulb can cause pulsatile tinnitus through proximity to the cochlea 1
• Paget disease affecting temporal bone can cause tinnitus through bony abnormalities 1
• Temporal bone fracture or head trauma with vascular injury can cause tinnitus 1

Neurologic Causes

• Intracranial hypertension causes tinnitus through venous sinus abnormalities and increased intracranial pressure 1
• Neurodegeneration is a neurologic cause of tinnitus 1
• Spontaneous intracranial hypotension can cause tinnitus 1

Specific Otologic Disorders

• Menière's disease is an important secondary cause requiring identification, characterized by episodic vertigo, fluctuating hearing loss, and tinnitus 1
• Ototoxic medications can cause tinnitus through cochlear damage 1

Neuromuscular Causes (Objective Tinnitus)

• Palatal or tympanic myoclonus represents pulse-asynchronous objective tinnitus from rhythmic muscle contractions in the middle ear or palate, creating clicking sounds 2

Psychogenic and Psychiatric Factors

Anxiety and depression are both causes and consequences of tinnitus, and patients with severe anxiety or depression require prompt identification and intervention due to increased suicide risk. 1

Critical Clinical Distinctions

Objective vs. Subjective Tinnitus

• Subjective tinnitus (perceived only by the patient) accounts for 70-80% of cases and is typically related to sensorineural hearing loss 1
• Objective tinnitus (audible to the examining healthcare provider) is rare and strongly suggests vascular pathology requiring immediate workup 1, 2

Pulsatile vs. Non-Pulsatile

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

Unilateral vs. Bilateral

• Unilateral or asymmetric tinnitus demands investigation for acoustic neuroma, requiring MRI of the internal auditory canals with contrast to exclude vestibular schwannoma 1
• Bilateral, symmetric, non-pulsatile tinnitus without localizing features typically does not require imaging 1

Key Epidemiologic Considerations

• 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
• Approximately 10-15% of adults experience tinnitus, with prevalence increasing with age 1
• Around 20% of adults with tinnitus require clinical intervention, although most patients adapt to the phantom sound over time 1

Critical Red Flags Requiring Urgent Evaluation

• Tinnitus that wakes a patient from sleep is highly unusual and should immediately raise suspicion for objective tinnitus with a vascular or neuromuscular etiology 2
• Pulsatile tinnitus requires thorough evaluation for vascular abnormalities, as missing dural AVF or arterial dissection can result in catastrophic hemorrhage or stroke 2, 3
• Unilateral tinnitus with asymmetric hearing loss requires MRI to exclude vestibular schwannoma 1
• Tinnitus with focal neurological deficits requires immediate imaging for stroke, hemorrhage, mass lesions, or vascular malformations 2
• Tinnitus with severe anxiety or depression requires prompt intervention due to increased suicide risk 1