Imaging

• Contrast enhanced head computed tomography with sagittal and coronal reconstructions: evaluate for bony erosion of floor of the anterior fossa, sinus cavities, and orbits
  
• Contrast enhanced brain magnetic resonance imaging: determine the extent of soft tissue disease, intracranial and orbital involvement
  
• Consider acquiring preoperative scan for intraoperative image guidance

Operative Planning

Interdisciplinary Approach Required

Fig. 53.1 Dissection corridors allowed by fronto-orbital approaches: transbasal, extended frontal, and transfacial.

Biopsy

• Required prior to definitive therapy; acquired by otolaryngologist

Preoperative Adjuvant Therapy

• Preoperative radiation therapy: considered for all stages of disease
  
• Preoperative chemotherapy: considered for Kadish stage C lesions

Routine Equipment

• Major craniotomy tray
  
• Mayfield head holder or horseshoe headrest
  
• High-speed drill
  
• Lumbar drain set-up
  
• Operating microscope
  
• Fibrin glue

Special Equipment

• Ear, nose, and throat transfacial/transnasal tray and endoscopic set-up per otolaryngology
  
• Image guidance system
  
• Leyla bar for self retaining retractors
  
• Tarsorrhaphy set-up

• Headlights
  
• Loupes
  
• Bipolar and monopolar cautery
  
• Endoscopy equipment
  
• Image guidance equipment

Anesthetic Issues

• Antibiotics (cefazolin: 2 g intravenously at least 30 min prior to incision and then every 4 hours or vancomycin: 1 g intravenously 30 min prior to incision and then every 12 hours)
  
• Dexamethasone (10 mg intravenously) preoperative
  
• Antiepileptic medication (phenytoin 15 mg/kg intravenously during surgery to achieve therapeutic level)
  
• Mannitol (1 g/kg intravenously at incision)
  
• Precordial Doppler to monitor for air embolism (superior sagittal sinus exposed with bifrontal craniotomy)
  
• Anticipate 2 to 4 liters of blood loss
  
• Arterial line and either good peripheral venous or central venous access

Spinal Drain

• Five to 10 mL of cerebrospinal fluid (CSF) are removed periodically to facilitate brain relaxation and reduce frontal lobe retraction.

Positioning

• After intubation, the patient is placed in a lateral decubitus position for spinal drain insertion via L4–L5 interspace.
  
• The patient is then positioned supine. The neck is slightly extended. The head is placed on a horseshoe headrest or pinned in a Mayfield head holder if self retaining retractors or image guidance is utilized for resection of intracranial disease.

Tarsorrhaphies

• Performed bilaterally

Preparation of Operative Fields

• Sterile preparation of the head and face are performed. The abdomen is sterilely prepared for harvesting of a fat graft.

Bifrontal Craniotomy

Tumor Resection

• If present, intracranial tumor is resected with involved dura. Dura is replaced with allograft, fascia, or pericranium.
  
• Additional osteotomies are performed to access tumor if required.
  
• The otolaryngologists perform the transfacial procedure to resect tumor. This may involve a lateral rhinotomy incision or transnasal endoscopy. Nasal, ethmoidal, or maxillary osteotomies may be required. The medial canthal tendon and lacrimal system may require sectioning.
  
• Specimens are sent to verify pathology and margin status.

Reconstruction

• The anterior cranial base is reconstructed. Pericranium is isolated from the scalp flap. This vascularized pedicled flap is layered over the defect in the anterior cranial fossa and secured to dura with several sutures. A split-thickness calvarial bone graft that covers the bone defect in the floor of the anterior cranial fossa is inserted between the leaves of the pericranial graft. Fibrin glue is generously applied. Fat graft harvested from the abdomen may be used to occupy dead space.
  
• The medial canthal tendon is repaired if sectioned.
  
• Dacryocystorhinostomy is completed if the lacrimal duct has been sectioned.

• Significant intraoperative fluid resuscitation may have occurred. Extubation may be delayed secondary to pulmonary and airway edema.
  
• Spinal drainage may be continued at 5 to 10 mL/hr for 2 to 3 days.
  
• Antibiotics are continued for 24 hours.
  
• Antiepileptic medication is continued for 5 days if intracranial tumor resected.
  
• Nasal packing is removed after 5 days by otolaryngologists, if utilized.