General Description

Idiopathic intracranial hypertension (IIH) has traditionally been treated with shunt placement and weight loss, but mounting evidence has indicated that venous outflow restrictions can contribute to elevated intracranial pressure that can be reversed with stenting. Two types of stenosis exist: intrinsic, in which the size of a segment of the venous sinus is reduced (e.g., from scarring or congenitally), and extrinsic, in which elevated pressures or surrounding structures (e.g., arachnoid granulations) exert pressure on the venous wall that cause it to bow inward. Both stenosis types respond to stenting and the stenting helps to control the IIH symptoms.

Indications

Stenting may be considered when there are definite signs and symptoms of intracranial hypertension and evidence of elevated venous pressures. Evaluation includes a lumbar puncture to determine elevated intracranial pressure, an ophthalmology evaluation to assess for visual loss and changes to the optic nerve, and diagnostic venography with pressure sampling along the course of the major dural sinuses to identify hemodynamically significant stenosis. In practice, a pressure gradient of at least 8 mmHg and visual compromise are the strongest indications for stenting.

Neuroendovascular Anatomy

The most common locations for venous stenoses associated with symptomatic IIH are in the transverse and sigmoid sinuses. Stenosis of the posterior third of the superior sagittal sinus (SSS) can also cause symptomatology. Because the transverse and sigmoid sinuses are paired structures, it is critical to assess pressure gradients. Often, one side is sufficient for adequate drainage; and, as a corollary to this, when bilateral stenosis is observed, patients often derive relief from unilateral stenting. In practice, we measure pressures in every patient bilaterally starting at the middle SSS and proceeding proximally as follows: middle and posterior SSS; torcula; distal, middle, and proximal transverse sinus; transverse-sigmoid junction; distal, middle, and proximal sigmoid sinus; and jugular vein. In most patients, it is possible to access both sides from a unilateral approach by crossing the torcula with a microcatheter to access the contralateral circulation.

Specific Technique and Key Steps

1. 
   

   Review of noninvasive imaging studies and the previously performed diagnostic venogram to identify the optimal access route and the site of the pressure gradient.

   
   
2. 
   

   Femoral venous access is obtained, as previously described in Chapter 2, and a 6 French (F) short sheath is placed.

   
   
3. 
   

   A Benchmark (Penumbra) or similar distal access catheter is advanced through the venous system and into the sigmoid sinus ( Fig. 16.1, 16.2, Video 16.1, 16.2 ).

   
   
4. 
   

   A 3MAX (Penumbra) or similar microcatheter is advanced over a 0.014-inch microwire and pressures are measured to verify the location of the gradient.

   
   
5. 
   

   Once the location of the gradient is established and marked on a roadmap, the soft guide catheter is advanced over the microcatheter, past the location of the stenosis, and the microcatheter and microwire are withdrawn ( Video 16.1, 16.2 ).

   
   
6. 
   

   A 0.018-inch floppy-tipped microwire is backloaded into a self-expanding open-cell or closed-cell carotid or biliary stent, such as the Zilver (Cook Medical) or the Wallstent (Abbott).

   
   
7. 
   

   The microwire and stent are advanced into the guide catheter and positioned to span the stenosis. Then, unsheathing the stent in position across the stenosis, the guide catheter is withdrawn ( Video 16.1, 16.2 ).

   
   
8. 
   

   The stent is deployed in place across the stenotic region, and the stent and microwire are withdrawn ( Fig. 16.1, 16.2, Video 16.1, 16.2 ).

   
   
9. 
   

   Follow-up runs are obtained to assure patency and good distal flow.

   
   
10. 
    

    Pressure measurements are obtained across the stenotic region to verify that the gradient has improved.

    
    
11. 
    

    The guide catheter, microwire, and microcatheter are withdrawn after all images are determined to be satisfactory.

    
    
12. 
    

    The venous access site is closed with manual compression as the sheath is withdrawn.

Device Selection

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  Access:

  
  
  
  
  • 
    

    6F short femoral sheath.

    
    
  • 
    

    Benchmark or similar 6F distal access system with Berenstein select catheter (Cook Medical).

    
    
  • 
    

    0.035-inch angled Glidewire (Terumo).

    
    
  • 
    

    3MAX or similar microcatheter.

    
    
  • 
    

    0.014-inch microwire (Synchro 2, Stryker).

    
    
  • 
    

    Pressure transducer.

  
  
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  Stenting:

  
  
  
  
  • 
    

    Self-expanding carotid or biliary flexible (open-cell) stent.

    
    
  • 
    

    0.018-inch floppy-tipped microwire.

Pearls

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  The most worrisome complication of venous sinus stenting is intracranial hemorrhage. We avoid the use of balloons in the venous sinuses to minimize this risk.

  
  
• 
  

  Venous valves can make navigating the guide catheter within the sinuses challenging. Using a soft Glidewire is usually sufficient to “feel” one’s way through the valves, but occasionally it can be helpful to have arterial access to obtain a roadmap of the venous system ( Video 16.1, 16.2 ).