What are the possible causes of unilateral pulsatile tinnitus in the right ear, particularly in a patient with potential idiopathic intracranial hypertension (IIH)-like symptoms without papilledema, and a clean magnetic resonance venography (MRV) result?

Unilateral Right-Sided Pulsatile Tinnitus with IIH-Like Symptoms and Normal MRV

Your unilateral pulsatile tinnitus lasting one year with IIH-like symptoms but no papilledema and a clean MRV most likely represents either sigmoid sinus wall abnormalities (diverticulum/dehiscence), venous anatomic variants, or early/atypical IIH that requires additional imaging beyond MRV alone. 1

Why Your Clean MRV Doesn't Rule Out Venous Causes

Standard MRV can miss critical venous pathology that causes pulsatile tinnitus. The most common oversight is sigmoid sinus wall abnormalities (diverticulum or dehiscence), which require dedicated high-resolution CT temporal bone imaging to visualize—MRV simply doesn't have the spatial resolution to detect these bony defects. 1, 2 Additionally, MRV may not adequately demonstrate:

• Sigmoid sinus diverticulum or dehiscence (commonly associated with intracranial hypertension even without papilledema) 1
• Jugular bulb abnormalities including high-riding jugular bulb or dehiscence of the sigmoid plate 1
• Aberrant venous anatomy such as persistent petrosquamosal sinus or abnormal emissary veins 1

The IIH Connection Without Papilledema

IIH is the second most common cause of pulsatile tinnitus (after atherosclerotic carotid disease), and crucially, you can have IIH without papilledema. 1, 3 Your constellation of symptoms strongly suggests this:

• IIH can cause both pulsatile AND non-pulsatile tinnitus 4
• Pulsatile tinnitus from IIH responds dramatically to treatment (venous stenting or CSF diversion) in nearly 100% of cases when truly pulsatile 5
• Non-pulsatile tinnitus in IIH patients responds poorly to intervention (only 1 of 7 patients improved in one study) 5

The absence of papilledema does NOT exclude IIH—some patients have elevated intracranial pressure without optic nerve swelling, particularly early in the disease course. 1

Complete Differential Diagnosis for Your Right-Sided Pulsatile Tinnitus

Venous Causes (Most Likely Given Your Profile)

• Sigmoid sinus diverticulum/dehiscence - requires CT temporal bone to diagnose 1, 2
• High-riding jugular bulb or jugular bulb dehiscence - visible on CT temporal bone 1
• Persistent petrosquamosal sinus or abnormal emissary veins - anatomic variants that can cause pulsatile tinnitus 1
• IIH with sigmoid sinus wall abnormalities - the combination is extremely common 1

Arterial Causes (Must Be Excluded)

• Atherosclerotic carotid artery disease - most frequent overall cause (17.5% of cases), creates turbulent flow 1, 3
• Arterial dissection - life-threatening, requires urgent identification 1
• Fibromuscular dysplasia - can affect carotid arteries 6

Arteriovenous Causes (Life-Threatening If Missed)

• Dural arteriovenous fistula (AVF) - accounts for 8% of pulsatile tinnitus cases, can lead to hemorrhagic or ischemic stroke if untreated 1, 2
• Arteriovenous malformations - high-flow vascular lesions 1

Structural/Tumor Causes

• Paragangliomas (glomus tympanicum/jugulare) - highly vascularized skull base tumors accounting for 16% of cases, appear as vascular retrotympanic mass on otoscopy 1, 2
• Superior semicircular canal dehiscence - bony defect allowing transmission of vascular sounds 1

Your Next Diagnostic Steps

You need high-resolution CT temporal bone (non-contrast) as your next imaging study. 4, 1 This is the ACR-recommended first-line test for suspected:

• Sigmoid sinus diverticulum or dehiscence
• Jugular bulb abnormalities
• Superior semicircular canal dehiscence
• Aberrant venous anatomy

If CT temporal bone is negative, proceed to CT angiography (CTA) of head and neck with contrast to evaluate for: 1

• Dural arteriovenous fistulas (life-threatening if missed)
• Arterial dissection
• Atherosclerotic carotid disease
• Arteriovenous malformations

Consider lumbar puncture with opening pressure measurement if imaging remains negative but IIH symptoms persist, as you can have elevated intracranial pressure without papilledema or abnormal MRV. 1

Critical Clinical Maneuvers You Can Try Now

Perform jugular/carotid compression test: If your pulsatile tinnitus is relieved by gentle compression of the ipsilateral (right) jugular vein or carotid artery, this strongly suggests venous etiology (sigmoid sinus abnormalities, jugular bulb variants) or arterial dissection. 1

Confirm the tinnitus is truly pulsatile: Verify it synchronizes exactly with your heartbeat—this distinction is critical because truly pulsatile tinnitus has an identifiable structural or vascular cause in over 70% of cases. 1, 6

Why Something Was Likely Missed

MRV alone is insufficient for evaluating pulsatile tinnitus. 4, 1 The ACR Appropriateness Criteria explicitly state that for pulsatile tinnitus evaluation:

• CT temporal bone is the preferred initial study for venous and bony causes 4, 1
• CTA head and neck is the preferred initial study for arterial and arteriovenous causes 1
• MRV is not listed as a first-line study for pulsatile tinnitus evaluation 4

Your imaging workup was incomplete—you had the wrong test for this symptom.

Common Pitfalls to Avoid

Do not dismiss your symptoms as benign without completing the imaging workup. Pulsatile tinnitus almost always requires imaging evaluation due to identifiable causes in >70% of cases, and missing dural AVF is life-threatening (can present with isolated pulsatile tinnitus before catastrophic hemorrhage). 1

Do not assume normal papilledema excludes IIH. Some patients have elevated intracranial pressure without optic nerve swelling, and IIH is the second most common cause of pulsatile tinnitus. 1, 3

Ensure you had adequate otoscopic examination. Inadequate otoscopy can lead to delayed diagnosis of vascular retrotympanic masses (paragangliomas), which account for 16% of pulsatile tinnitus cases. 1, 2