What is the cause of daily pressure in the head and a difficult-to-describe sensation in a patient with a history of well-controlled hypertension, polycythemia vera (PV), sarcoidosis, and lymphoma in remission, who recently underwent a medial lumbar branch block?

Diagnostic Approach to Daily Head Pressure in a Patient with Polycythemia Vera and Recent Lumbar Procedure

This patient requires urgent MRI brain and orbits with contrast to evaluate for spontaneous intracranial hypotension (SIH), given the temporal relationship between symptom onset and the medial lumbar branch block, combined with the difficult-to-describe orthostatic pressure sensation. 1

Primary Diagnostic Consideration: Spontaneous Intracranial Hypotension

The timing of symptoms starting concurrently with the lumbar procedure is highly suspicious for iatrogenic CSF leak leading to intracranial hypotension. 1

Key Clinical Features Supporting SIH:

• Daily pressure sensation upon rising suggests orthostatic component, which is pathognomonic for intracranial hypotension when combined with appropriate imaging findings 1
• Difficulty describing the sensation (not quite lightheaded, not quite dizzy, but definitely pressure) is characteristic of SIH, as patients frequently struggle to articulate these symptoms 2
• Temporal relationship to spinal procedure (medial lumbar branch block) raises concern for dural puncture or CSF leak 1

Critical Diagnostic Workup:

• MRI brain with IV contrast AND MRI complete spine should be ordered immediately to confirm intracranial hypotension features and localize any spinal CSF leak source 1, 3
• Look for diffuse pachymeningeal enhancement on brain MRI, which occurs through compensatory venodilation in response to decreased CSF volume 1
• Do not exclude SIH based on normal CSF opening pressure if obtained - over half of SIH patients have normal lumbar puncture opening pressure 2, 1

Secondary Diagnostic Consideration: Elevated Intracranial Pressure

Given the patient's complex hematologic history, elevated ICP must also be considered in the differential.

Risk Factors Present:

• Polycythemia vera increases blood viscosity and predisposes to thrombosis, including cerebral venous thrombosis 4, 5
• History of sarcoidosis can cause secondary pseudotumor cerebri through various mechanisms 3
• History of lymphoma (even in remission) could cause leptomeningeal involvement 3

MRI Findings to Assess for Elevated ICP:

• Empty or partially empty sella (56% sensitivity, 100% specificity for high ICP) 3, 6
• Posterior globe flattening (56% sensitivity, 100% specificity) 3, 6
• Optic nerve sheath dilatation on coronal fat-saturated T2-weighted sequences 3
• Horizontal tortuosity of optic nerves (68% sensitivity, 83% specificity) 3, 6

Critical Red Flags Requiring Urgent Evaluation:

• Any abnormal neurological finding significantly increases likelihood of clinically significant intracranial pathology 3
• Headaches awakening from sleep suggest increased intracranial pressure 3
• Headaches worsened by Valsalva maneuver indicate elevated ICP 3
• Visual changes or papilledema require immediate ophthalmologic evaluation 3, 6

Polycythemia Vera-Specific Considerations

The hyperviscosity from PV predisposes to thrombosis, making cerebral venous thrombosis a critical diagnosis to exclude. 4, 5

Additional Imaging Required:

• MR venography or CT venography should be performed to exclude cerebral sinus thrombosis, which can present with head pressure and is a rare but life-threatening complication of both SIH (2% of cases) and PV 1, 6
• Venography is mandatory within 24 hours if any concern for venous thrombosis exists 6

Laboratory Assessment:

• Verify current hemoglobin/hematocrit levels - elevated red cell mass increases thrombotic risk 5
• Ensure adequate phlebotomy management of PV, as untreated hyperviscosity can cause neurologic symptoms 5

Algorithmic Diagnostic Approach

Step 1: Immediate Imaging

• Order MRI brain and orbits with IV contrast 1, 3
• Order MRI complete spine 1
• Include MR venography to exclude venous thrombosis 1, 6

Step 2: Interpret Imaging Results

If diffuse dural enhancement present:

• Diagnosis is SIH 1
• Proceed to early epidural blood patch as first-line treatment 1
• Non-targeted EBP is appropriate initially; reserve myelography for cases that fail to respond 1

If signs of elevated ICP present (empty sella, globe flattening, optic nerve changes):

• Perform lumbar puncture with opening pressure measurement in lateral decubitus position 3, 6
• Opening pressure >200 mm H₂O indicates elevated ICP 6
• Opening pressure >250 mm H₂O requires urgent intervention 3

If venous thrombosis identified:

• Initiate anticoagulation immediately
• Hematology consultation for PV management optimization

If imaging is normal:

• Do not exclude SIH - at least 25% of SIH patients have normal imaging 2
• Consider empiric epidural blood patch if clinical suspicion remains high 1
• Evaluate for other causes: medication side effects (antihypertensives), cervical spine pathology, postural hypotension 7, 3

Step 3: Ophthalmologic Evaluation

• Fundoscopic examination to assess for papilledema 6
• Visual field testing if any visual symptoms present 3

Common Pitfalls to Avoid

• Do not dismiss symptoms because they are difficult to describe - this is characteristic of intracranial pressure disorders 2
• Do not rely on normal CSF opening pressure to exclude SIH - 66% of SIH patients have opening pressure above the diagnostic threshold of ≤60 mm CSF 2
• Do not assume well-controlled hypertension excludes all diagnoses - measure blood pressure to exclude malignant hypertension as a cause of symptoms 6
• Do not overlook the temporal relationship to the spinal procedure - this is the most important clue pointing toward iatrogenic CSF leak 1

Management Priorities Based on Diagnosis

For confirmed SIH:

• Epidural blood patch should be performed as soon as possible after diagnosis 1
• Conservative measures include bed rest, hydration, and caffeine while awaiting definitive treatment 1

For confirmed elevated ICP:

• Weight loss if patient is overweight 3, 6
• Acetazolamide for medical management 3
• Surgical intervention if evidence of declining visual function 3, 6

For PV optimization:

• Phlebotomy remains mainstay to reduce hyperviscosity 5
• Consider aspirin and cytoreductive therapy based on thrombotic risk stratification 5