What are the 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 tinnitus through cochlear damage, with prevalence increasing dramatically with cumulative exposure 1
• Sudden sensorineural hearing loss requires prompt identification as it represents a treatable cause of acute tinnitus 1
• Cochlear synaptopathy ("hidden hearing loss") triggers irreversible auditory nerve fiber degeneration without affecting outer hair cells, leading to tinnitus and 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 that can lead 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 has an identifiable structural or vascular cause in over 70% of cases and requires 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 Malformations

• Dural arteriovenous fistulas (AVF) 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 that generate turbulent blood flow audible to the patient 2

Venous Etiologies

• Idiopathic intracranial hypertension (pseudotumor cerebri) is the second most common cause of pulsatile tinnitus, particularly in young overweight women 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
• Transverse sinus stenosis causes venous turbulence leading to pulsatile tinnitus 1
• Prominent mastoid or condylar emissary veins represent aberrant venous anatomy that 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 2
• Adenomatous middle ear tumors are less common vascular masses that can cause pulsatile tinnitus 2

Structural/Bony Abnormalities

• Superior semicircular canal dehiscence is a bony defect that allows transmission of vascular sounds, causing pulsatile tinnitus 2
• Sigmoid sinus wall dehiscence creates abnormal sound transmission 1
• Paget disease affecting temporal bone can cause tinnitus through bony abnormalities 1

Neurologic Causes

• Intracranial hypertension causes tinnitus through increased intracranial pressure affecting venous drainage 1
• Neurodegeneration is a neurologic cause of tinnitus 1
• Spontaneous intracranial hypotension can cause tinnitus 1
• Temporal bone fracture or head trauma with vascular injury can cause tinnitus 1

Otologic Disorders

• Menière's disease is a secondary cause of tinnitus requiring identification 1
• Ototoxic medications can cause tinnitus 1, 3

Psychogenic Factors

• Anxiety and depression are psychogenic factors that can both contribute to and result from tinnitus 1
• Severe psychiatric illness with tinnitus carries suicide risk and requires prompt intervention 1

Critical Clinical Distinctions

Objective vs. Subjective Tinnitus

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

Unilateral vs. Bilateral

• Unilateral tinnitus raises concern for acoustic neuroma and requires MRI evaluation 4
• Bilateral tinnitus is typical for primary tinnitus related to sensorineural hearing loss 4

Important 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 modifiable risk factor 1
• Recreational noise exposure (concerts, firearms) contributes to tinnitus development 1

Critical Red Flags Requiring Urgent Evaluation

• Pulsatile tinnitus requires imaging in nearly all cases due to high likelihood of identifiable vascular or structural cause 2
• Unilateral or asymmetric hearing loss demands investigation for acoustic neuroma 1
• Tinnitus that wakes patient from sleep is highly unusual and should raise suspicion for objective tinnitus with vascular or neuromuscular etiology 1
• Focal neurologic abnormalities with tinnitus require urgent imaging for stroke, hemorrhage, or mass lesions 1
• Severe anxiety or depression with tinnitus requires prompt intervention due to increased suicide risk 1