What is the differential diagnosis for a patient presenting with tinnitus, considering potential underlying conditions such as hypertension, diabetes, and thyroid disorders?

Differential Diagnosis of Tinnitus

The differential diagnosis for tinnitus fundamentally depends on whether it is pulsatile or non-pulsatile, as pulsatile tinnitus has an identifiable structural or vascular cause in over 70% of cases and requires urgent imaging evaluation, while non-pulsatile tinnitus is most commonly associated with sensorineural hearing loss and rarely requires imaging unless unilateral or accompanied by red flags. 1

Critical Initial Classification

The first step is determining whether the tinnitus is pulsatile (synchronous with heartbeat) versus non-pulsatile, as this fundamentally changes both the differential diagnosis and urgency of evaluation 1, 2:

Pulsatile Tinnitus Differential (Requires Imaging in Nearly All Cases)

Arterial causes:

• Atherosclerotic carotid artery disease (most common cause at 17.5% of pulsatile tinnitus cases, from turbulent flow) 1
• Arterial dissection (life-threatening, requires urgent identification) 1
• Arteriovenous malformations (high-flow vascular lesions) 1

Arteriovenous shunts:

• Dural arteriovenous fistulas (8% of cases, can lead to hemorrhagic or ischemic stroke if untreated—this is a life-threatening cause that requires high index of suspicion) 1

Venous causes:

• Idiopathic intracranial hypertension/pseudotumor cerebri (second most common cause of pulsatile tinnitus, particularly in young overweight women with headaches—can cause vision loss if missed) 1
• Sigmoid sinus diverticulum or dehiscence (commonly associated with intracranial hypertension) 1
• Jugular bulb abnormalities (high-riding jugular bulb or dehiscence of sigmoid plate) 1
• Aberrant venous anatomy (persistent petrosquamosal sinus, abnormal condylar/mastoid emissary veins) 1

Vascular tumors:

• Paragangliomas/glomus tumors (16% of cases, appear as vascular retrotympanic masses on otoscopy) 1
• Adenomatous middle ear tumors (less common vascular masses) 1

Structural causes:

• Superior semicircular canal dehiscence (bony defect allowing transmission of vascular sounds) 1

Non-Pulsatile Tinnitus Differential (Imaging Rarely Indicated Unless Red Flags Present)

Otologic causes:

• Sensorineural hearing loss (most common association, particularly in bothersome tinnitus without obvious ear pathology) 3, 2
• Noise exposure (occupational or recreational) 2
• Age-related hearing loss/presbycusis 2
• Ototoxic medications 2, 4
• Temporomandibular joint dysfunction 5, 2
• Eustachian tube dysfunction 5, 2
• Menière's disease (excluded from primary tinnitus guidelines but important secondary cause) 3
• Sudden sensorineural hearing loss 3
• Otosclerosis 3

Retrocochlear pathology:

• Vestibular schwannoma/acoustic neuroma (particularly with unilateral presentation or asymmetric hearing loss) 5, 2

Systemic/metabolic causes:

• Hypertension (47% of tinnitus patients with systemic disease in one series) 4
• Diabetes mellitus (16% of tinnitus patients with systemic disease) 4
• Hypercholesterolemia (41% of tinnitus patients with systemic disease) 4
• Thyroid disorders 4
• Rheumatic diseases (22% of tinnitus patients with systemic disease) 4
• Kidney disease 4

Psychiatric/neurologic:

• Anxiety and depression (can be both cause and consequence—patients with severe anxiety or depression require prompt identification as suicide has been reported) 3

Key Clinical Distinctions That Guide Differential

Objective versus subjective tinnitus:

• Objective pulsatile tinnitus (audible to examiner) is rare and strongly suggests vascular pathology requiring immediate workup 1, 6
• Subjective tinnitus (patient only) is more common but pulsatile subjective tinnitus still warrants comprehensive imaging 1, 6

Unilateral versus bilateral:

• Unilateral tinnitus has higher likelihood of identifiable structural or vascular cause and warrants more aggressive investigation even without apparent hearing loss 1, 5
• Bilateral, symmetric, non-pulsatile tinnitus without localizing features rarely requires imaging 1, 2

Response to compression maneuvers:

• Tinnitus relieved by carotid or jugular compression suggests venous etiology (sigmoid sinus abnormalities, jugular bulb variants) or arterial dissection 1

Red Flags Requiring Urgent Evaluation

The following presentations demand immediate escalation and imaging 5, 2:

• Pulsatile tinnitus (any presentation)
• Sudden onset unilateral tinnitus with hearing loss
• Focal neurological deficits
• Severe anxiety or depression with suicidal ideation
• Asymmetric hearing loss
• History of malignancy or recent trauma

Common Pitfalls to Avoid

• Missing dural arteriovenous fistula: This life-threatening cause can present with isolated pulsatile tinnitus before catastrophic hemorrhage—requires high index of suspicion and appropriate vascular imaging 1
• Dismissing pulsatile tinnitus as benign: Pulsatile tinnitus almost always requires imaging evaluation due to identifiable causes in >70% of cases 1
• Inadequate otoscopic examination: Can lead to delayed diagnosis of vascular retrotympanic masses like paragangliomas 1
• Overlooking intracranial hypertension: Particularly in young, overweight women with headaches—can lead to vision loss if missed 1
• Ordering imaging for bilateral, symmetric, non-pulsatile tinnitus: This represents inappropriate resource utilization with no benefit 1, 2
• Missing subclinical hearing loss: Audiometry may reveal hearing loss even when patient doesn't perceive it 5