What are the causes of tinnitus?

Causes of Tinnitus

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

Primary Auditory System Causes

Sensorineural Hearing Loss (Most Common)

• 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 direct damage to cochlear structures, leading to both hearing loss and tinnitus 1
• Sudden sensorineural hearing loss is an otologic emergency that frequently presents with acute-onset tinnitus 1
• Cochlear synaptopathy ("hidden hearing loss") triggers irreversible auditory nerve fiber degeneration without affecting outer hair cells or causing permanent threshold shifts, resulting in difficulty understanding speech in noise despite normal audiograms 1
• Ototoxic medications (particularly platinum-based chemotherapy, aminoglycosides, loop diuretics, and high-dose aspirin) can cause permanent or reversible cochlear damage 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 progressive 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 present with tinnitus as an early symptom 1

Vascular Causes (Pulsatile Tinnitus)

Pulsatile tinnitus has an identifiable structural or vascular cause in over 70% of cases and should never be dismissed without imaging evaluation. 2

Arterial Etiologies

• Atherosclerotic carotid artery disease is the most frequent cause of pulsatile tinnitus (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 that generate turbulent blood flow audible to the patient 2
• Carotid-cavernous sinus fistulas create abnormal arteriovenous connections causing pulsatile tinnitus 1

Venous Etiologies

• Idiopathic intracranial hypertension (pseudotumor cerebri) is the second most common cause of pulsatile tinnitus, particularly in young overweight women with headaches 2
• Transverse sinus stenosis associated with intracranial hypertension causes venous turbulence 1
• Sigmoid sinus diverticulum or dehiscence is commonly associated with intracranial hypertension 2
• High-riding jugular bulb or dehiscence of the sigmoid plate can transmit vascular sounds 2
• Prominent mastoid or condylar emissary veins represent aberrant venous anatomy causing 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 and can cause pulsatile tinnitus 2
• Sigmoid sinus wall dehiscence creates abnormal sound transmission 2
• Paget disease affecting the temporal bone can cause tinnitus through bony abnormalities 1
• Temporal bone fracture or head trauma with vascular injury can cause acute-onset tinnitus 1

Neurologic Causes

• Intracranial hypertension causes tinnitus through venous sinus abnormalities and increased intracranial pressure 1
• Neurodegeneration is a neurologic cause of tinnitus involving auditory cortex dysfunction 1
• Spontaneous intracranial hypotension can present with tinnitus as a symptom 1
• Traumatic brain injury is a precipitating factor for tinnitus involving disruption of brain-auditory circuitry 3
• Migraine is correlated with tinnitus as a comorbid condition 3

Psychogenic and Comorbid Factors

• Anxiety and depression are both causes and consequences of tinnitus, with bidirectional relationships 1
• Severe psychiatric illness with tinnitus carries increased suicide risk and requires prompt intervention 1
• Stress exposure and socioeconomic status are precipitating factors for tinnitus 3
• Insomnia is commonly correlated with tinnitus 3

Specific Disease Entities

• Menière's disease is characterized by episodic vertigo, fluctuating hearing loss, and tinnitus 1
• Small vessel disease has been correlated with tinnitus in recent research 3

Important Clinical Distinctions

Classification by Perception

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

Classification by Character

• Pulsatile tinnitus is repetitive sound coinciding with heartbeat, often vascular in origin, requiring imaging in nearly all cases 1
• Non-pulsatile tinnitus is continuous or constant non-synchronous sound, most commonly 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 modifiable risk factor for developing tinnitus and hearing loss 1
• Recreational noise exposure (concerts, firearms) contributes to noise-induced hearing loss and tinnitus 1
• Military service is correlated with increased tinnitus prevalence due to noise exposure and traumatic brain injury 3
• Smoking history has been identified as a risk factor for tinnitus 3

Common Clinical Pitfalls

• Dismissing pulsatile tinnitus as benign without imaging is dangerous, as treatable and life-threatening causes are common in over 70% of cases 2
• Missing dural arteriovenous fistula is a life-threatening error, as it can present with isolated pulsatile tinnitus before catastrophic hemorrhage 2
• Inadequate otoscopic examination can lead to delayed diagnosis of vascular retrotympanic masses (paragangliomas) and inappropriate imaging selection 2
• Overlooking intracranial hypertension in young overweight women with headaches can lead to vision loss if missed 2
• Failing to screen for severe anxiety or depression misses patients at increased suicide risk who require prompt psychiatric intervention 1
• Assuming all tinnitus patients have detectable hearing loss on standard audiometry ignores cochlear synaptopathy and "hidden hearing loss" 1