Sphenoid Wing Meningiomas

40 Sphenoid Wing Meningiomas
James E. Conway and Alfredo Quinones-Hinojosa


♦ Preoperative


Operative Planning


Imaging



  • Gadolinium-enhanced brain magnetic resonance imaging (MRI): determine lesion location along the medial, middle, or lateral third of the sphenoid ridge; determine extent of disease affecting optic nerve, optic chiasm, optic canal, orbit, superior orbital fissure, cavernous sinus, carotid artery, and middle cerebral artery (MCA) branches
  • Computed tomography (CT): evaluate for hyperostosis or erosion
  • Acquire preoperative gadolinium-enhanced MRI scan for intraoperative image guidance
  • Consider preoperative cerebral angiography and embolization if large flow voids are identified on MRI; this permits a better understanding of the anatomy of large vessels in relation to the tumor

Classification



  • Based on location along sphenoid wing (clinoidal, middle, or lateral)
  • Clinoidal lesions subdivided by Al-Mefty1 into group I (origin: inferior clinoid), II (origin: lateral or superior clinoid), or III (origin: optic foramen)
  • Group I lesions adhere to the adventitia of the carotid artery preventing dissection of tumor from the vessels; group II lesions possess an arachnoid plane between vessels and the tumors permitting dissection from vessels; group III lesions present early secondary to their location
  • Resection of tumor that has invaded the cavernous sinus significantly increases the risk of cranial nerve deficits

Extent of Resection



  • Extent of resection based on Simpson grade correlates with recurrence of disease
  • Postoperative radiation therapy significantly decreases recurrence and progression

Neuro-ophthalmology



  • Preoperative evaluation to document existence of visual field and cranial nerve deficits

Routine Equipment



  • Major craniotomy tray
  • Microsurgery tray
  • Mayfield head holder
  • High-speed drill
  • Operating microscope
  • Fibrin glue
  • Bipolar cautery

Special Equipment



  • Image guidance system
  • Leyla bar or Greenberg system for self retaining retractors
  • Ultrasonic aspirator (Cavitron ultrasound surgical aspirator)
  • Intraoperative monitoring: somatosensory evoked potentials, electroencephalography
  • Aneurysm clips

Operating Room Set-up



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

Anesthetic Issues



  • Antibiotics: cefazolin, 2 g intravenous (IV) at least 30 minutes prior to incision and then every 4 hours, or vancomycin, 1 g IV 30 minutes prior to incision and then every 12 hours
  • Dexamethasone (10 mg IV) preoperative
  • Antiepileptic medication (phenytoin 15 mg/kg IV during surgery to achieve therapeutic level)
  • Mannitol (1 g/kg IV infusion at incision)
  • Arterial line and either good peripheral venous or central venous access

♦ Intraoperative


Positioning



  • After intubation, the patient is positioned supine. The Mayfield clamp is applied as for a pterional craniotomy. A small shoulder roll is placed under the ipsilateral shoulder.
  • The head is slightly extended and then rotated 30 degrees to the side contralateral to the lesion

Preparation of Operative Field



  • An incision is marked as for a pterional craniotomy

Incision



  • Incise the skin as in a pterional craniotomy; preserve the superficial temporal artery (STA)

Craniotomy (Fig. 40.1)



  • Meningiomas involving the middle or lateral third of the sphenoid wing: a frontotemporosphenoidal craniotomy is completed. Extradural drilling of the sphenoid ridge and hyperostotic bone is completed. This extradural drilling aids devascularization of the tumor.
  • Clinoidal meningiomas: a frontotemporosphenoidal craniotomy with an orbitozygomatic extension is completed. Removal of the posterior orbital roof, posterolateral orbital wall, and optic canal unroofing is completed.
    image
    < div class='tao-gold-member'>

    Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Jul 11, 2016 | Posted by in NEUROSURGERY | Comments Off on Sphenoid Wing Meningiomas

Full access? Get Clinical Tree

Get Clinical Tree app for offline access