What is the workup and treatment for a patient with suspected Spontaneous Intracranial Hypotension (SIH)?

Diagnostic Workup and Treatment for Spontaneous Intracranial Hypotension (SIH)

The diagnostic workup for suspected Spontaneous Intracranial Hypotension (SIH) should begin with brain MRI with contrast followed by complete spine MRI with fluid-sensitive sequences to confirm diagnosis and identify potential CSF leak sources. 1, 2

Initial Clinical Evaluation

• Key clinical features that should prompt consideration of SIH:

  • Orthostatic headache (worsens when upright, improves when lying down)
  • Additional symptoms may include:
    • Neck pain/stiffness
    • Tinnitus
    • Hearing changes
    • Visual disturbances
    • Nausea/vomiting
    • Cognitive difficulties

• Important distinction: SIH occurs spontaneously without recent spinal intervention, unlike post-dural puncture headache 1

Diagnostic Imaging Algorithm

First-Line Imaging

1. Brain MRI without and with IV contrast (highest priority)

   • Look for characteristic findings:
     • Pachymeningeal enhancement
     • Venous sinus engorgement
     • Brain sagging/descent
     • Pituitary enlargement
     • Subdural fluid collections/hygromas
     • Convex superior surface of pituitary 1, 2

2. Complete spine MRI with fluid-sensitive sequences

   • Optimally with 3D T2-weighted fat-saturated sequences
   • Look for:
     • Epidural fluid collections
     • Meningeal diverticula
     • Dilated epidural venous plexus
     • Dural enhancement 1, 2

Second-Line Imaging (if initial imaging is negative but clinical suspicion remains high)

1. CT myelography of complete spine

   • Detects epidural contrast collections suggestive of dural defects or leaking meningeal diverticula 1

2. Dynamic CT myelography

   • Positioning based on initial findings:
     • Prone for suspected ventral dural defect
     • Decubitus for suspected meningeal diverticulum or CSF-venous fistula 1, 3

3. Digital subtraction myelography

   • For real-time visualization of subtle or intermittent leaks
   • Particularly useful for detecting CSF-venous fistulas 1, 3

Treatment Algorithm

Conservative Management (Initial Approach)

• Bed rest
• Hydration
• Caffeine supplementation
• Abdominal binder
• Symptomatic headache management 1, 4

First-Line Interventional Treatment

• Non-targeted epidural blood patch (EBP)
  • Indicated when conservative management fails after 1-2 weeks
  • Success rate: approximately 30-70% of patients show improvement 3
  • Volume: 20-30 mL of autologous blood
  • Location: typically at lower thoracic or lumbar level 1

Second-Line Interventional Treatment

• Targeted epidural blood patch or fibrin sealant
  • Indicated when non-targeted EBP fails
  • Guided by myelographic localization of leak
  • Higher success rate than non-targeted approach 1, 3

Surgical Management

• Indicated when:

  • Multiple targeted patches fail
  • Precise leak location identified
  • Large dural defects present
  • CSF-venous fistulas identified 1, 3

• Procedures:

  • Direct surgical repair of dural tears
  • Ligation of leaking nerve root sleeves
  • Repair of meningeal diverticula
  • For CSF-venous fistulas: surgical ligation or transvenous embolization 3

Post-Treatment Management

• Slow mobilization after blood patch (24-48 hours)
• Avoid straining, heavy lifting, or Valsalva maneuvers for 4-6 weeks
• Follow-up imaging if symptoms persist or recur 5

Common Pitfalls and Caveats

1. Normal CSF pressure does not exclude SIH

   • Up to 20% of patients may have normal opening pressure on lumbar puncture 1

2. Normal initial brain MRI does not exclude SIH

   • Approximately 20% of initial brain MRIs may be normal in SIH 1

3. Negative initial spine imaging does not exclude SIH

   • 46-67% of initial spine imaging may be normal in patients with clinically suspected SIH 1

4. CSF-venous fistulas and slow meningeal diverticular leaks

   • Often subtle and may require advanced imaging techniques 1, 3

5. Misdiagnosis is common

   • SIH is frequently misdiagnosed as migraine, tension headache, or sinusitis 6

By following this systematic diagnostic and treatment approach, clinicians can improve outcomes for patients with this challenging but treatable condition.