Preparation for Surgery for Cerebellar Astrocytoma in Children
Indications for Surgery
Presence of tumor: A newly diagnosed cerebellar tumor requires surgery both for confirmation of histological diagnosis and to alleviate hydrocephalus and presenting symptoms.
Admission to ICU: Generally a child is kept in an ICU environment with close monitoring for neurological changes until surgery is performed, particularly when hydrocephalus is present.
Steroids: Dexamethasone or a similar steroid is started on admission after imaging demonstrates a tumor, is continued until surgery, and is tapered slowly after surgery.
MRI of brain: MRI is the preoperative imaging study of choice. For a tumor with imaging findings consistent with a pilocytic astrocytoma, MRI of the total spine preoperatively may be considered.
Timing of surgery: Surgery generally is performed within 24 hours after MRI of the brain is obtained. Patients with lethargy or rapidly progressive symptoms may require immediate operative intervention, and those without hydrocephalus and an indolent presentation may be treated more electively.
Mild hyperventilation with target end-tidal pC02 of approximately 30 mm Hg is desired.
Normovolumia: IV fluids are controlled during the surgery to keep input/output roughly balanced.
Vascular access anticipates possible large blood loss: All patients should have an arterial line and appropriate venous access to prepare for blood loss, which may be rapid and life-threatening during dural opening, especially in young children. Blood loss during the surgery for a pilocytic astrocytoma is not expected to be extensive.
Coagulopathy and thrombocytopenia: These should be ruled out and aggressively corrected in the event of extensive blood loss.
Devices to Be Implanted
Intraoperative neurophysiological monitoring: Intraoperative monitoring is not necessary for patients with cerebellar hemispheric tumors. It may be more useful for tumors adherent to the brainstem or lateral tumors involving the cerebellopontine angle, but this is controversial.
Intraoperative ultrasound: This is useful for identifying echogenic tumor prior to resection and then confirming absence of echogenic tumor at the conclusion of tumor resection.
Operative microscope: Magnification of the surgical field and good illumination are highly desirable for safe tumor resection. The use of the operative microscope will address these needs.
Ultrasonic aspirator: This is useful for resection of solid tumor.