Conventional microsurgical techniques are applied to approach the sellar region regardless of which transcranial route is used. The operating microscope and micro-instruments are employed, and the approach is performed along anatomic tissue planes using as little retraction as possible.
Most authorities recommend starting high-dose steroids before surgery. In our unit, we give 8 mg dexamethasone intravenously with induction of anesthesia where there are no prior contraindications for its use. Pituitary tumors are usually operated on as elective cases and acutely raised intracranial pressure is not commonly present. Nevertheless, the sella is well concealed beneath the frontotem-poral region and a relaxed brain is required, especially in younger patients with small extracerebral cerebrospinal (CSF) spaces. Further relaxation can be achieved by generous removal of CSF. A lumbar drain may be used, but in the authors' experiences, opening the basal cisterns early in the procedure to allow CSF drainage is a satisfactory alternative. Mannitol can be given to produce additional relaxation of the frontal lobes, if required.
The treatment of the optic apparatus requires particular care. The surgeon should resist the temptation to "strip" the tumor from the optic apparatus at craniotomy. The stretched optic nerves are extremely vulnerable, and the compressed vasa vasorum may be damaged, causing optic nerve ischemia (19). Van Alphen went so far as to say: "Touching the optic nerve may cause a permanent visual defect" (20).
We believe that the vulnerability of the optic nerves limits the usefulness of the cavitron ultrasonic surgical aspirator (CUSA), which becomes hot and is a potential cause of optic nerve injury, and also of the laser, which is also best avoided in this region. Piecemeal microsurgical tumor removal is always preferable.
In summary, suprasellar lesions can safely be approached and removed transcranially by careful adherence to microsurgical principles and with minimal technologic assistance.
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