General Description

The venous side of the cerebrovascular system has garnered minimal attention in the past, but advances in the understanding of how it contributes to pathologies (e.g., stenosis in idiopathic intracranial hypertension, drainage in arteriovenous malformations) have increased our need to access and evaluate the venous system. For many cerebral pathologies, the venous system can be adequately visualized on delayed phases of arterial injections; however, when precise detail and pressures are required, diagnostic venography becomes a vital piece of the armamentarium.

Indications

Diagnostic cerebral venography is most commonly used for direct evaluation of sinus stenosis, usually in patients with symptoms of idiopathic intracranial hypertension with evidence of stenotic segments on magnetic resonance venography. Diagnostic cerebral venography is also useful for assessing patency as smaller vessels and sinuses can be difficult to evaluate on late-phase arterial injections.

Neuroendovascular Anatomy

The femoral vein accompanies and lies medial to the femoral artery and nerve within the femoral triangle. The femoral vein drains the lower extremities superiorly into the external iliac vein, which continues as the inferior vena cava before entering the heart. The superior vena cava extends superiorly from the heart, draining the upper extremities, head, and neck. It splits to form the paired subclavian veins that drain the internal jugular veins, which are the main venous outflow from the head. The venous sinus is the most common cerebral vein interrogated by venography. It extends from the superior sagittal sinus (SSS) to the torcula into paired transverse and sigmoid sinuses that ultimately drain into the internal jugular veins.

Specific Technique and Key Steps

1. 
   

   After the groin is prepared and draped, the femoral artery pulse is palpated with the understanding that the vein should lie just medial to the palpated pulse.

   
   
2. 
   

   Local anesthetic is infused into the skin and subcutaneous tissues in the groin region.

   
   
3. 
   

   A microneedle (i.e., 21-gauge micropuncture kit) is connected to a saline-filled 10 mL syringe. Slight negative pressure is applied to the syringe as the needle is advanced into the femoral vein at a 45°angle with the bevel facing up ( Fig. 8.1 and Video 8.1 ).

   
   
4. 
   

   Once dark, nonpulsatile blood return is established through the micropuncture needle, a 0.010-inch microwire is advanced through the needle. Once the wire has been advanced several centimeters, fluoroscopy is used to confirm location. The needle is removed, and an intermediate 4–5 French (F) dilator is inserted. The introducer that comes with the dilator is thereafter removed, and a J-wire is inserted into the femoral vein. The dilator sheath is then exchanged for the procedural sheath of choice. For diagnostic procedures, typically a 5F sheath is chosen, but for venous sinus manometry, we typically use a 6F sheath for placement of a guide and microcatheter ( Fig. 8.1 and Video 8.1 ).

   
   
5. 
   

   Before proceeding with the case, we perform a femoral vein angiographic run to assess for patency, stenosis, dissection, and possible extravasation.

   
   
6. 
   

   The diagnostic or guide catheter with obturator are advanced into the venous system over a 0.035-inch Glidewire. We preferentially catheterize the right internal jugular vein given the relatively straight anatomy from the brachiocephalic vein to the superior vena cava. Venous valves can make navigation difficult. The tip of the catheter is brought close to the valve to provide additional support when crossing that valve ( Video 8.1 ).

   
   
7. 
   

   For venous sinus manometry, we position the guide catheter near the sigmoid sinus and remove the obturator and 0.035-inch Glidewire and introduce the microcatheter and J-shaped wire. The microcatheter and J-shaped wire are sequentially advanced through the sigmoid, transverse, and SSSs to the anterior one-third to one-half of the SSS. The J-shaped wire is then withdrawn and contrast material is injected to evaluate the venous anatomy.

   
   
8. 
   

   To document venous pressures, connect a flushed pressure transducer directly to the hub of the microcatheter, pulling back the catheter to periodically capture pressures at set locations within the sinuses, including distal, mid- and proximal SSS, torcula, distal, mid-, and proximal transverse sinus, distal, mid-, and proximal sigmoid sinus, and the internal jugular vein.

   
   
9. 
   

   With a patent torcula, the contralateral side may then be accessed with the microcatheter and J-shaped wire by directing them across the torcula and measuring venous pressures in a retrograde fashion starting from the contralateral jugular vein and proceeding toward the torcula.

   
   
10. 
    

    Once pressures and venograms have been obtained, the guide or diagnostic catheter is carefully withdrawn.