What could be causing my pulsatile tinnitus, pressure, and dizziness/balance issues despite a normal Magnetic Resonance Venography (MRV) scan?

Normal MRV with Persistent Pulsatile Tinnitus, Head Pressure, and Dizziness

A normal MRV does not exclude significant pathology causing your symptoms—you need additional imaging with CT angiography (CTA) of the head and neck with contrast and high-resolution CT temporal bone, as MRV has poor sensitivity (<50%) for detecting pressure gradients and misses many arterial, structural, and bony causes of pulsatile tinnitus. 1

Why MRV Alone Is Insufficient

MRV has critical limitations that explain your normal result despite ongoing symptoms:

• MRV sensitivity is less than 50% for detecting hemodynamically significant venous stenosis associated with pressure gradients, meaning it misses over half of cases where venous obstruction is causing symptoms 1
• Flow-related artifacts limit MRV's ability to evaluate transverse sinus stenosis and sigmoid sinus abnormalities, and arachnoid granulations can mimic stenosis, leading to false negatives 1
• MRV provides no bony detail to evaluate sigmoid wall dehiscence, jugular foramen dehiscence, superior semicircular canal dehiscence, or high-riding jugular bulb—all common causes of pulsatile tinnitus 1
• MRV cannot evaluate arterial causes including atherosclerotic carotid disease (17.5% of pulsatile tinnitus cases), arterial dissection, dural arteriovenous fistulas (8% of cases, life-threatening), or arteriovenous malformations 2, 3, 4

What Could Be Causing Your Symptoms

Your symptom triad of pulsatile tinnitus, head pressure, and dizziness/balance issues suggests several possibilities that MRV cannot detect:

Venous Causes (Require Catheter Angiography with Manometry)

• Idiopathic intracranial hypertension (IIH) is the second most common cause of pulsatile tinnitus and presents with head pressure, dizziness, and venous sinus stenosis that may have normal appearance on MRV but elevated pressure gradients on direct measurement 1, 2
• 65% of patients with venous abnormalities on catheter venography had normal or equivocal findings on prior MRV/CTV, demonstrating the inadequacy of non-invasive venous imaging 1
• Sigmoid sinus diverticulum or dehiscence commonly associated with intracranial hypertension, requires CT temporal bone for diagnosis 2, 5

Arterial Causes (Require CTA)

• Atherosclerotic carotid artery disease accounts for 17.5% of pulsatile tinnitus cases and creates turbulent flow 2, 3
• Arterial dissection is life-threatening and requires urgent identification 2
• Dural arteriovenous fistulas account for 8% of cases and can lead to hemorrhagic or ischemic stroke if untreated—this is a critical diagnosis that cannot be missed 2, 4

Structural/Bony Causes (Require High-Resolution CT Temporal Bone)

• Superior semicircular canal dehiscence causes pulsatile tinnitus and vestibular symptoms (dizziness/balance issues) by allowing transmission of vascular sounds and pressure changes 2, 5
• Sigmoid sinus wall dehiscence or jugular bulb abnormalities (high-riding jugular bulb, dehiscence of sigmoid plate) cause pulsatile tinnitus 2, 5
• Paragangliomas (glomus tumors) account for 16% of pulsatile tinnitus cases and are highly vascularized skull base tumors 2, 4

Recommended Diagnostic Algorithm

Step 1: Order CT angiography (CTA) of head and neck with contrast immediately 1, 2

• This single study evaluates arterial causes (dissection, atherosclerosis, dAVF, AVM) and venous anatomy in one acquisition 2
• CTA source images can be reconstructed to create temporal bone CT without additional radiation 2

Step 2: Order dedicated high-resolution CT temporal bone (non-contrast) if not adequately visualized on CTA reconstruction 1, 2

• Essential for detecting bony dehiscences (superior semicircular canal, sigmoid plate, jugular foramen) and vascular variants 1, 5

Step 3: If CTA and CT temporal bone are negative, proceed to catheter angiography with manometry 1

• This is the gold standard for detecting venous pressure gradients that cause symptoms despite normal-appearing anatomy on MRV 1
• It is reasonable to perform diagnostic catheter angiography on patients who continue to have symptoms while on medical therapy or who are intolerant of medical therapy, even with normal non-invasive imaging 1

Step 4: Consider MRI brain with contrast and MRA if above studies are negative but suspicion remains high 1, 2

• Evaluates for cerebellopontine angle lesions, vascular loops compressing CN VIII (80 times more common in pulsatile tinnitus patients), and subtle vascular malformations 1

Critical Clinical Pitfalls to Avoid

• Never dismiss pulsatile tinnitus as benign based on normal MRV alone—over 70% of pulsatile tinnitus cases have identifiable causes, and missing dural AVF can result in catastrophic hemorrhage 2, 6
• Dizziness/balance issues with pulsatile tinnitus raise concern for superior semicircular canal dehiscence, which requires high-resolution CT temporal bone for diagnosis and is completely invisible on MRV 2, 5
• Head pressure with pulsatile tinnitus suggests IIH, which requires lumbar puncture with opening pressure measurement and may need catheter venography with manometry despite normal MRV 1, 2
• Unilateral symptoms have higher likelihood of structural/vascular cause requiring aggressive workup 2

Additional Evaluation

While imaging is being arranged, obtain:

• Comprehensive audiologic examination (pure tone audiometry, speech audiometry, acoustic reflex testing) to document any asymmetric hearing loss that would change the differential diagnosis 2, 7
• Otoscopic examination to exclude vascular retrotympanic mass (paraganglioma) that would change first-line imaging to CT temporal bone 1, 2