Operative Planning

• Perform extensive neurologic exam and document to compare for postoperative changes
  
• Computed tomography (CT) scan
  
  
  
  • Without contrast: note density and calcification in peritumoral area; low density associated with low grade gliomas; compare these films to CT scan with contrast
    
  • With contrast: note degree of enhancement; no enhancement associated with low grade gliomas; patchy, nonuniform vivid enhancement associated with high grade gliomas
  
  
• Magnetic resonance imaging (MRI) with gadolinium contrast enhancement: best to visualize smaller tumors; improved anatomical localization and assessment of tumor extension; note degree of edema surrounding the lesion
  
• Identify proximity of lesion to central sulcus and frontal gyri and sulci
  
• Functional MRI (fMRI) to determine eloquent cortices for motor, speech, and short-term memory
  
  
  
  • Language mapping indicated for lesions occupying dominant frontal lobe, despite clinical absence of aphasia
    
  • Stimulation mapping indicated for patients with lesions proximal to the motor strip
  
  
• Perfusion-weighted MRI to determine surrounding blood volume; differentiates radiation necrosis from tumor recurrence
  
• Determine if bony opening needs to extend to or across midline; generally, crossing the midline with craniotomy is rarely needed for gliomas
  
• Note proximity to the superior sagittal sinus and/or any other venous structures surrounding the lesion
  
• Discuss extensively with the patient the potential risks of the procedures, including (but not limited to) potential risks to eloquent cortex and supplemental motor area if the tumor is in the vicinity.

Equipment

Frontal Approach

Tumor Resection

• Multiple burr holes should be used for the craniotomy in cases of high grade lesions or recurrence with significant amount of edema
  
• Use CT/MRI wand for low grade lesions with vague margins; also recommended for high grade lesions because it helps to plan the appropriate bone flap craniotomy
  
• Stereotactically aspirate cystic lesions for decompression and relief of mass effect prior to dissection
  
• Cortical incision should be made longitudinally away from the sulci to avoid unnecessary bleeding
  
• Debulk tumor starting from most central point and extending to its periphery. Following internal decompression with irrigating bipolar cautery and suction, a subpial-pial plane is developed in an effort to dissect around the tumor “margins” if possible.
  
• More aggressive resection is usually appropriate for lesions occupying the nondominant frontal lobe
  
• Diagnosis confirmed with intraoperative review of frozen section by neuropathologist
  
• Consider placement of adjuvant therapies, such as Gliadel wafers (Eisai Inc., Woodcliff Lake, NJ), for high grade lesions
  
• Avoid excessive bleeding primarily with use of bipolar cautery, assisted with placement of Avitene, Surgicel, Gelfoam, or hydrogen peroxide-soaked cotton balls. Avoid using hydrogen peroxide-soaked cotton balls if the resection has reached the ventricle because this may leave peroxide in the ventricular space and result in potential problems.
  
• Resection cavity is lined with Surgicel at the completion of tumor removal for complete hemostasis
  
• Avoid cerebrospinal leak, central nervous system infection, and decrement in Gliadel wafer durability with watertight dural closure
  
• Dural grafts required with extensive dural resection, recurrent tumor surgery, postradiation treatment; usefulness of muscle patch, fascia lata, pericranium, cadaveric dura mater, porcine lyophilized dura mater, suturable DuraGen
  
• Ensure that the patient maintains an adequate body core temperature (≥ 36°C) when conducting intraoperative cortical and subcortical motor and/or speech mapping

• Avoid excessive hydration in initial postoperative period
  
• Nurse with head of bed elevated at 20 to 30 degrees
  
• Mobilize patient as soon as possible with help of physiotherapist
  
• High grade lesions: start with steroid treatment with long taper period
  
• Low grade lesions: start with steroid treatment with short taper period
  
• Patients with significant comorbid conditions should be monitored in neurosurgery intensive care unit
  
• For clean neurosurgical procedures, prophylactic coverage of gram-positive skin bacteria using intravenous first or second generation cephalosporins prior to skin incision and redose as indicated if a long procedure. No data on the use of postoperative use of antibiotics in elective clean procedures.
  
• Complete neurological exam with particular attention to speech, motor strength, and conjugate gaze; compare with preoperative neurological exam
  
• Monitor anticonvulsant levels
  
• Obtain a postoperative MRI within 48 hours to assess extent of tumor resection and response to adjuvant therapy