Operative Planning

• Review imaging studies
  
• If using frameless stereotaxy, perform necessary image reconstruction

Equipment

• Mayfield head holder (Integra, Plainsboro, NJ): clamp or horseshoe; radiolucent clamp if intraoperative angiography is planned
  
• Basic craniotomy tray
  
• High-speed drill with appropriate drill bits
  
• Bone flap fixation tray
  
• Optional equipment
  
  
  
  • Microscope
    
  • Brain retractor systems: Greenberg (Codman, Raynham, MA), Budde Halo (Integra), Leyla
    
  • Stereotactic navigational system (BrainLab [Heimstetten, Germany]; Stealth [Medtronic, Louisville, CO])
    
  • Video monitors
    
  • Hemostatic agents (Avitene [Medchem Products, Woburn, MA], Gelfoam [Pfizer, New York, NY], Surgicel [Ethicon, Somerville, NJ])
    
  • Ultrasonic aspirator (CUSA [Integra])
    
  • Ultrasound
    
  • Doppler
    
  • Endoscope
    
  • Lumbar drain kit
    
  • Electrophysiological monitoring: somatosensory evoked potential, motor evoked potentials, electroencephalogram, and/or brain stem auditory evoked response recordings

Operating Room Set-up

• Headlight and loupes
  
• Bovie electrocautery (Bovie Medical Products, Clearwater, FL)
  
• Bipolar cautery (irrigating bipolar optional)
  
• Microscope
  
• Monitors for frameless stereotactic navigation

Anesthetic Issues

Positioning

• In general, the patient should be positioned so that the side of interest is away from the anesthesiologist and close to the surgeon.
  
  
  
  • Mayfield skull pin sites are kept out of the field and behind hairline
    
  • Operative area is highest point on the field; or, if brain retraction is expected, the patient is positioned so that gravity assists with retraction
    
  • For prone cases, the vertex points toward the anesthesiologist, or the table is turned 90° in the room
  
  
• Neck should be positioned to avoid compression of the jugular veins and kinking of the endotracheal tube.
  
• Ipsilateral shoulder elevation with a shoulder roll and head of bed elevation may be used to ensure good jugular venous outflow.
  
• Dependent pressure points (especially elbows to prevent ulnar neuropathies) are well-padded and eyes are covered to avoid corneal abrasions. If prone position, ensure adequate protection of female breasts and male genitalia.
  
• Compression stockings on lower extremities to prevent deep venous thrombosis (DVT)
  
• If the microscope will be used, the observer eyepiece is placed on the appropriate side and the microscope is balanced.

Planning of Incision and Minimal Shave

• A strip of hair ~1 to 2 cm in width over the planned incision is shaved with electric clippers
  
• General principles regarding incisions
  
  
  
  • Incisions should consist of continuous lines and curves that stay behind the frontal hairline
    
  • Avoid intersecting incision lines because of the potential for poor wound healing at these areas of intersection
    
  • Linear incisions are performed if possible
    
  • The length of the scalp flap should not exceed its width, if U-shaped
    
  • Frameless stereotaxy can be used to plan incision and identify location of major venous sinuses
    
  • If an extracranial/intracranial bypass may be necessary, then the incision should be planned to preserve superficial temporal arteries
    
  • If reoperation, use previous incisions when possible and extend as needed

Sterile Scrub, Prep, and Draping

Incision and Scalp Flap

• Incision is infiltrated with lidocaine with epinephrine (no epinephrine if craniotomy for ruptured aneurysm)
  
• Confirm that frameless stereotactic equipment is working properly
  
• Incision is performed down through galea
  
  
  
  • Areas over the superficial temporal artery are incised carefully to preserve this vascular supply to scalp
    
  • In general, incisions for supratentorial procedures should not extend below the level of the zygoma to avoid injury to the facial nerve
  
  
• Raney clips (Aesculap) and bipolar cautery are used to control scalp bleeding
  
• Fascial layers are incised sharply
  
• Muscle is incised with cautery but dissected from bone with minimal cautery to preserve blood supply
  
• Periosteal elevator is used for subperiosteal dissections
  
• Self retaining retractors or fishhooks are used for retraction of scalp flap, which is padded with wet sponge

Burr Holes

• For most procedures, a single burr hole with a round burr or perforator drill bit can be used to perform craniotomy.
  
  
  
  • Additional burr holes are used to allow further dissection of the dura if it is suspected to be extremely adherent to inner table of skull.
  
  
• For procedures in which the craniotomy will extend across a dural sinus, the following techniques may be used:
  
  
  
  • A burr hole is made directly over the sinus with a round cutting burr or
    
  • Two burr holes are made on either side of the sinus and dura in between the two holes is carefully dissected free
  
  
• Burr holes can be widened with a 3- or 4-mm Kerrison punch.
  
• Dura is dissected from bone flap with footplate craniotome attachment, Woodson dissector, or Penfield no. 3 instrument (Codman)

Craniotomy

Opening of Dura

• Using fine-toothed forceps or a 4–0 Nurolon suture to lift the dura, the dura is incised with a no. 15 blade.
  
• A ¼-inch Cottonoid is placed through the hole in the dura to separate the brain from the dura and protect the brain from the scissor tips.
  
• Fine scissors are then used to cut the dura overlying the ¼-inch Cottonoid, which is advanced as needed for the dural opening.
  
• In general, at least a ½ to 1 cm cuff of dura near the native bone should be left for dural closure.
  
• The dura can be opened in a cruciate manner with intersecting incisions if necessary, to maximize exposure.
  
• The dura is reflected and protected from desiccation with moist Cottonoids; the dura can be retracted with 4–0 Nurolon sutures weighted down by hemostats.
  
• Moist 4 × 4 gauze sponges and blue towels are placed along the craniotomy edges to wick epidural blood away from the operative field.

Closure of Dura

• Closure of dura proceeds after hemostasis of operative field has been ensured
  
• The dura is reapproximated with interrupted or running 4–0 Nurolon sutures while avoiding injury to cortical vessels or draining veins
  
• If watertight dural closure cannot be obtained:
  
  
  
  • Small holes can be closed with muscle and 4–0 Nurolon sutures
    
  • Large dural defects can be closed by patching with fascial, pericranial, or synthetic dural grafts
  
  
• Irrigation is placed into subdural space to confirm hemostasis prior to final closure
  
• A dural tack-up suture is placed in the middle of dural opening; large craniotomies may require several central dural tack-up sutures

Closure of Craniotomy and Skin

• If patient is unable to follow commands bilaterally after emergence from anesthesia then an emergent head computed tomographic scan is performed.
  
• Patient is monitored in neurosurgery intensive care unit for ~24 hours.
  
• Postoperative imaging is obtained depending on indication for craniotomy.
  
• Antibiotics are continued for 24 hours.
  
• Continuation of antiepileptic medication and steroids is based on nature of pathology and procedure.
  
• Head wrap is removed on postoperative day (POD) 1 to 2.
  
• DVT prophylaxis with subcutaneous heparin is started on POD 1.
  
• Staples are removed on POD 5 to 10.