Is a cerebral (cerebral angiogram) angiogram indicated in a patient with suspected idiopathic intracranial hypertension, hypoplastic left transverse sinus, and multiple collateral veins, without evidence of sinus thrombosis?

Cerebral Angiogram in Suspected Idiopathic Intracranial Hypertension with Hypoplastic Left Transverse Sinus

Cerebral angiography with manometry is indicated in this patient with suspected idiopathic intracranial hypertension (IIH), hypoplastic left transverse sinus, and multiple collateral veins, especially if the patient is medically refractory or has progressive visual symptoms. 1

Diagnostic Approach in IIH with Venous Abnormalities

Initial Non-Invasive Imaging

• MR venography (MRV) or CT venography (CTV) are typically performed first to identify venous sinus abnormalities
• However, these non-invasive methods have limitations:
  • MRV sensitivity is <0.5 in detecting significant stenosis associated with pressure gradients 1
  • Only 65% of patients with venous abnormalities on MRV/CTV demonstrate actual dural venous sinus abnormalities on catheter angiography 1
  • Non-invasive imaging cannot determine whether anatomical stenosis is associated with a physiologically significant pressure gradient

Role of Cerebral Angiography with Manometry

• Gold standard for diagnosing transverse sinus stenosis 2
• Provides critical information not available from non-invasive imaging:
  • Measures actual pressure gradients across stenotic segments
  • A pressure gradient ≥8 mmHg is considered significant for treatment 2
  • Can distinguish between a hypoplastic sinus and a thrombosed sinus
  • Can identify collateral venous pathways and their adequacy

Specific Indications for Cerebral Angiography in This Case

1. Presence of hypoplastic left transverse sinus with collaterals:

   • Requires evaluation of pressure gradients to determine hemodynamic significance
   • Collateral veins may indicate compensatory drainage that needs assessment

2. Medical management considerations:

   • If patient is refractory to medical therapy or intolerant of medications
   • Guidelines state: "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" 1

3. Potential for therapeutic intervention:

   • If significant pressure gradient is found, venous sinus stenting may be considered
   • Stenting can immediately eliminate pressure gradients and rapidly improve symptoms 2

Important Considerations and Caveats

• Ruling out sinus thrombosis: Although initial imaging shows no sinus thrombosis, cerebral angiography provides definitive evaluation
• Hypoplastic sinus assessment: Angiography can differentiate between congenital hypoplasia and acquired stenosis
• Collateral veins significance: Multiple collateral veins may indicate chronic venous outflow obstruction requiring pressure measurement
• Potential pitfalls:
  • Hypoplastic sinuses may be normal variants (found in 33% of normal population) 1
  • Not all stenoses are associated with significant pressure gradients 1

Conclusion

In this specific case with suspected IIH, hypoplastic left transverse sinus, and multiple collateral veins, cerebral angiography with manometry is indicated to:

1. Measure pressure gradients across the hypoplastic segment
2. Evaluate the hemodynamic significance of the venous outflow abnormality
3. Guide potential therapeutic interventions if medical management fails
4. Definitively rule out sinus thrombosis that might have been missed on non-invasive imaging

This approach aligns with current guidelines that recommend catheter angiography for patients with IIH who have venous abnormalities on non-invasive imaging, especially when medical therapy is ineffective or poorly tolerated.