What are the primary considerations for a 26-year-old female presenting with orthostatic headache and diffuse dural enhancement on imaging?

Spontaneous Intracranial Hypotension (SIH) Due to Spinal CSF Leak

In a 26-year-old female presenting with orthostatic headache and diffuse dural enhancement, the primary diagnosis is spontaneous intracranial hypotension (SIH) caused by a spinal cerebrospinal fluid leak from a dural defect, leaking meningeal diverticulum, or CSF-venous fistula. 1

Primary Etiology

The combination of orthostatic headache and diffuse pachymeningeal (dural) enhancement is pathognomonic for intracranial hypotension, and in this age group without recent spinal procedures, the cause is spontaneous CSF leakage. 1

The three main anatomical causes of spontaneous CSF leaks are: 1, 2

• Dural defects (tears in the spinal dura)
• Leaking meningeal diverticula (outpouchings of dura that rupture)
• CSF-venous fistulas (abnormal connections between CSF space and venous structures)

The spine represents the anatomical source of most symptomatic CSF leaks—not the cranium—because hydrostatic pressure in the spine is positive relative to atmosphere while intracranial pressure is slightly negative in the upright position. 1

Pathophysiology of Dural Enhancement

Diffuse pachymeningeal enhancement occurs through two mechanisms: 1

• Compensatory venodilation and blood volume expansion as the body attempts to maintain stable intracranial volume in response to decreased CSF volume
• Downward traction on meninges, nerves, and brain parenchyma as the brain loses buoyancy and begins to sag

The dural enhancement, along with venous sinus engorgement, resolves with clinical improvement after successful treatment of the CSF leak. 1

Additional Imaging Features to Confirm Diagnosis

Beyond dural enhancement, look for these supportive intracranial findings on MRI: 1

• Engorgement of venous sinuses
• Midbrain descent (brain sagging)
• Subdural hygroma or hematoma
• Convex superior surface of the pituitary gland
• Superficial siderosis (in chronic cases)

The cumulative presence of these findings correlates with likelihood of finding a spinal leak source. 1

Risk Factors in Young Females

Consider these predisposing conditions in this demographic: 1, 2

• Collagen vascular disease (weakened ectatic dura, meningeal cysts)
• Spinal osteophytes that can perforate the dura
• History of bariatric surgery (rapid epidural fat loss weakens dura)
• Idiopathic intracranial hypertension (paradoxically associated with spontaneous CSF leaks)

Critical Diagnostic Workup

First-line imaging per ACR and multidisciplinary consensus guidelines: 1

• MRI brain with IV contrast (to confirm intracranial hypotension features)
• MRI complete spine (to localize the spinal CSF leak source)

These two studies should be performed together as complementary procedures, not as alternatives. 1

Spinal MRI findings indicating leak location include: 1

• Epidural fluid collections (direct evidence)
• CSF-venous fistula (direct evidence)
• Dilated epidural venous plexus (indirect sign)
• Spinal subdural hygromas (indirect sign)
• Spinal dural enhancement (indirect sign)

Important Clinical Pitfall

CSF opening pressure can be normal in patients with SIH, and absence of low CSF pressure should not exclude this diagnosis. 1 The diagnosis is based on clinical presentation (orthostatic headache) plus imaging findings, not solely on measured CSF pressure.

Differential Diagnoses to Exclude

While SIH is the primary consideration, briefly evaluate for: 1

• Postural orthostatic tachycardia syndrome (PoTS) - check for postural tachycardia >30 bpm increase on standing
• Orthostatic hypotension - measure blood pressure changes with standing
• Cervicogenic headache - provoked by cervical movement rather than posture
• Migraine - provoked by movement rather than posture, with migrainous features

Rare but Serious Complication

Cerebral venous thrombosis (CVT) occurs in approximately 2% of SIH cases and can be life-threatening. 1 This young female demographic is at particular risk. If neurological deterioration occurs (hemiplegia, seizures, altered consciousness), immediately obtain CT or MR venography to evaluate for CVT. 1 Among 31 reported patients with SIH-associated CVT, 81% recovered completely with appropriate management. 1

Treatment Implications

Early epidural blood patch (EBP) is first-line treatment and should be performed as soon as possible after diagnosis. 1 Non-targeted EBP is appropriate initially, with myelography reserved for cases that fail to respond or have persistent symptoms, to guide targeted therapy. 1

Most patients with SIH recover without sequelae with conservative or EBP treatment. 3, 4, 5 Clinical improvement typically occurs within 10 days to 3 weeks, though MRI findings may persist longer than symptoms. 4