Infratemporal Fossa and Petrous Apex Approaches

Elizabeth H. Toh

• Infratemporal fossa (ITF) approaches are used to access tumors of the temporal bone extending inferiorly to or beyond the jugular foramen, tumors of the jugular foramen, tumors involving the petrous carotid artery, and tumors involving the deep lobe of the parotid gland with temporal bone involvement.
  
• Surgical access to the ITF may be obtained using a postauricular incision for primary temporal bone and jugular foramen lesions; a preauricular incision is used to access more anteriorly based lesions, which do not involve the petrous temporal bone.
  
• Preservation of neurovascular structures within and in the vicinity of the ITF remains the limiting factor in developing and modifying these surgical approaches.

• Computed tomography (CT) and magnetic resonance imaging (MRI) provide complementary anatomical information necessary for preoperative planning.
  
• MR angiography is useful in assessing tumor involvement of the petrous carotid artery. If tumor resection necessitates resection of the contiguously involved petrous carotid artery, preoperative angiography and balloon occlusion with xenon/CT imaging is required to assess the adequacy of collateral cerebral blood flow.
  
• Preoperative embolization is performed 24 to 48 hours prior to surgery for juvenile angiofibromas and paragangliomas.
  
• Reconstructive and rehabilitative options should be thoroughly assessed prior to surgery, and a multidisciplinary approach should be used to ensure optimal functional and cosmetic outcomes.

• This section describes the most commonly employed Fisch-type ITF approaches, which permit access to the ITF mostly through the temporal bone, with or without facial nerve rerouting.
  
• General anesthesia is employed without the use of muscle relaxants after induction. This is necessary because intraoperative neurophysiologic monitoring is routinely employed. The specific cranial nerves monitored will depend on the nerves likely to be involved by or adjacent to the tumor and surgical dissection site.
  
• The patient is positioned supine, with the head turned to the contralateral side.
  
• Preparation and draping should take into account the potential donor sites needed for reconstructive surgery.