Operative Planning

• Review imaging studies
  
  
  
  
  • Non-contrast head computed tomography (CT) essential for precise localization of subdural hematoma (SDH); most often located at the frontotemporo-parietal convexity from bleeding of injured parasagittal or cortical veins
    
  • Adjust window on CT scan to detect chronic appearing SDH, which may have similar density to brain

Equipment

• Mayfield head holder: clamp or horseshoe
  
• Basic craniotomy tray
  
• Burr hole tray
  
• High-speed drill with appropriate drill bits
  
• Bone flap fixation tray
  
• Hemostatic agents (Avitene, Gelfoam, Surgicel, bone wax)
  
• Intracranial pressure (ICP) monitor or external ventricular drain system if needed

Operating Room Set-up

• Headlight and loupes
  
• Bovie electrocautery
  
• Bipolar cautery

Anesthetic Issues

• Preoperative intravenous antibiotics administered within 30 min prior to incision (cefazolin 2 g intravenously or clindamycin 600 mg intravenously)
  
• Arterial line useful for blood pressure monitoring in acute SDH evacuation cases
  
• Load with phenytoin (15 to 18 mg/kg) administered slowly, or alternatively, levetiracetam 1000 to 1500 mg intravenously
  
• Communicate with anesthesiologist suspected degree of ICP elevation and if needed:
  
  
  
  
  • Hyperventilation to pCO₂ of 30 to 35 mm Hg
    
  • Mannitol 0.5 to 1 g/kg infusion starting at time of skin incision
    
  • Propofol (if indicated)
  
  
• Surgeon should warn anesthesiologist of potential hypotension at the time of clot evacuation as blood pressure is often supported by a sympathetic response to increased ICP

Intraoperative

Positioning

• In general, the patient should be semilateral with head neutral (since C-spine may not be cleared).
  
  
  
  
  • Mayfield skull pin sites are kept out of the field and behind hairline and away from any skull fractures.
  
  
• 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 utilized to ensure good jugular venous outflow.

Planning of Incision

• Especially in emergency situations, ensure CT scan showing acute SDH is available in operating room where correct side can be verified.
  
• With electric clippers, a strip of hair of approximately ~3 cm in width is shaved over the planned incision or widely over the entire frontotemporoparietal area.

Incision and Scalp Flap

• Reverse question mark incision is begun 1 cm anterior to tragus, curved superiorly and posteriorly over the pinna, and extended to the midline and terminating at the hairline.
  
• Raney clips and bipolar cautery are used to control scalp bleeding.
  
• Temporalis muscle is divided in line with the incision and reflected anteriorly with the scalp flap.

Burr Holes

• Temporal burr hole placed first
  
• Additional burr holes placed as needed based on size/location of planned craniotomy

Craniotomy

• Use Penfield no. 3 to free the underlying dura from the bone.
  
• Craniotome is used to cut the craniotomy being sure to stay at least 1 to 2 cm lateral to midline to avoid the superior sagittal sinus.
  
• The bone flap is elevated with a periosteal dissector or Penfield no. 3.

Preoperative

Equipment

• Burr hole tray
  
• Horseshoe or Mayfield

Planning of Shave and Preparation