Operative Planing

• Review imaging: magnetic resonance imaging with or without gadolinium to evaluate cyst and rule out other pathology
  
• Middle cranial fossa is the most common location; others include suprasellar, posterior fossa (cerebellopontine angle), interhemispheric, intraventricular

Surgical Options

• Craniotomy for open fenestration
  
  
  
  • Consider for middle fossa cysts; best option for most cerebellopontine angle and other posterior fossa cysts
    
  • Advantages: likely definitive treatment if no associated hydrocephalus, avoidance of shunt hardware and associated complications
    
  • Disadvantages: more extensive operation than endoscopic approach
  
  
• Endoscopic fenestration
  
  
  
  • Best option for intraventricular cysts; consider for suprasellar region and other cysts adjacent to ventricular compartment; an option for middle fossa cysts
    
  • Advantages: less extensive operation than open fenestration
    
  • Disadvantages: more difficult to control bleeding and may be more technically difficult to achieve multiple wide fenestrations of cyst than with open approach
  
  
• Cyst shunting (or ventricular shunting if associated hydrocephalus)
  
  
  
  • A less optimal treatment than fenestration (either open or endoscopic) due to multitude of possible shunt complications
    
  • May be necessary if fenestration fails; ventricular shunting may be considered simultaneously with fenestration if hydrocephalus is present at presentation

• Padded horseshoe headrest
  
• Craniotomy tray for open procedures, rigid neuroendoscope with associated equipment for endoscopic procedures, shunt hardware and instruments for shunting procedures

Operating Room Set-up

• Operating microscope for open fenestration

Anesthetic Issues

• Arterial line for blood pressure monitoring for open fenestration
  
• Intravenous antibiotics 1 hour prior to skin incision (i.e., cefazolin or vancomycin)

Craniotomy for Open Fenestration

• Patient positioning: depends on cyst location; head typically positioned in a padded horseshoe headrest so that cyst is at highest point of the skull’s convexity
  
• Minimal shave; standard scrub, prep, and drape
  
• Infiltrate scalp with local anesthetic (1% lidocaine or 0.25% bupivacaine hydrochloride with epinephrine)
  
• Skin incision, muscle (i.e., temporalis) reflection as required for exposure
  
• Small craniotomy; large enough to provide adequate exposure to cyst
  
• Epidural tacking sutures in the periphery using 4–0 Nurolon suture
  
• Dural opening
  
• Sharp opening of outer cyst wall
  
• Multiple fenestrations of inner cyst wall into basal cisterns or other adjacent cerebrospinal fluid (CSF) spaces
  
• Watertight dural closure and standard craniotomy closure

Endoscopic Fenestration

• Patient positioning: depends on cyst location; head typically positioned in a horseshoe
  
• Minimal shave; standard scrub, prep, and drape
  
• Infiltrate scalp with local anesthetic (1% lidocaine or 0.25% bupivacaine hydrochloride with epinephrine)
  
• Small incision, muscle (i.e., temporalis) reflection as needed
  
• Create single burr hole
  
• If cyst comes to surface underneath dura, open outer cyst wall sharply and introduce endoscope; if cyst is intraventricular, introduce endoscope through cortex into lateral ventricle after minimal pial coagulation and incision with no. 11 blade
  
• Fenestrate cyst to ventricular compartment, basil cisterns, or other adjacent CSF spaces using monopolar electrode, grasping forceps, microscissors, and inflatable balloon

• Continue antibiotics for 24 hours postoperatively
  
• Mobilize patient slowly postoperatively to minimize chance of subdural hematoma