Operative Planning

• Review imaging
  
  
  
  • Computed tomography (CT) scan: low yield with respect to operative planning, unless frame-based stereotaxis is used
    
  • Magnetic resonance imaging (MRI)
    
    
    
    • Absolutely critical: should be viewed as mass lesions (i.e., tumors); relationship to surrounding structures is critical
      
    • Helpful if using frameless stereotaxy for assistance with operative planning
      
    • Assess associated venous malformation
    
    
  • Angiogram
    
    
    
    • Not necessary for diagnosis, however is useful if there is concern as to whether lesion is a true arteriovenous malformation (AVM) and would thus change management (i.e., radiosurgery)
  
  
• Review relative risks with the patient and family
  
• Neuroanesthesiology, neurophysiology

Special Equipment

• Mayfield head holder
  
• Fishhooks and operating microscope
  
• Additional platinum-coated irrigating and nonirrigating cauteries in multiple lengths
  
• Fram eless stereo taxy

Anesthetic Issues

Positioning

• Highly variable depending on location of lesion and approach used

Do Not Shave

• Clip hair with electric razor
  
• Approximately 3-cm wide strip along length of proposed incision

Sterile Scrub and Prep

Craniotomy, Cortical Incision, and Resection

Craniotomy

• Depends on location of cavernoma (i.e., pterional, subfrontal)
  
• With or without stereotaxis
  
• Shortest trajectory should be undertaken

Cortical Incision

• Most malformations can be removed through an incision somewhat smaller than the largest diameter of the malformation
  
• Too small of an incision can result in increased trauma to the adjacent cortex

Resection of Lesion

• Initially enlarge the subcortical section to expose the breadth of the lesion
  
• Use minimal retraction with a self retaining retractor against the least eloquent border if needed; avoid retraction if possible
  
• Enter large caverns to internally decompress the lesion
  
• Using an irrigating cautery under low heat, dissect around the borders of the malformation
  
• “Roll” the malformation onto itself to identify the margins
  
• Mark each margin with Cottonoid and cauterize any small feeding vessels
  
• The most eloquent border of the malformation should be dissected last in an attempt to minimize the heat exposure
  
• Line the deep white matter with Surgicel
  
• Raise the blood pressure to 20 mm Hg over systolic to test for hemostasis
  
• Be careful not to resect the main trunk of the associated venous malformation

• Intensive care unit care and observation
  
• Control for systolic blood pressure between 120 to 140 mm Hg
  
• Antibiotics for 24 hours
  
• Steroid taper
  
• CT scan on postoperative day one for evaluation (i.e., hemorrhage, pneumocephalus)
  
• MRI eventually for assessment of residual cavernoma
  
• Remove staples/sutures on postoperative day 10