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Preoperative and Operative Approach

In patients with supratentorial tumors a craniotomy is performed. and a total gross resection may be done, depending upon the location and the extent of the tumor. The principle here is that of reducing the tumor burden (the number of tumor cells) as much as possible.

Most patients with infratentorial tumors present with hydrocephalus. This should be treated before any other operative procedure is done. In a few patients the hydrocephalus may revolve with the use of steroids preoperatively, however. Almost all patients, need VPS before the posterior fossa is opened so that the brain does not herniate downward. Usually the patient improves clinically to the point of reaching a plateau, then the tumor may be operated on. As these tumors can seed  via the CSF, incorporation of a filter device into the shunt  is desirable. Preoperative insertion of external drain is another option.

Infratentorial ependymomas  excision is preferred to be done in setting position with the use of Doppler. Midline incision with suboccipital approach with the performance of flap, reflected down or sometimes, laminectomy of C1 and even C2 is needed, when the extension of the tumor go down. The dura  is opened in Y-shaped fashion. Most of these tumors are midline, therefore the vermis is splitted and the tumor is exposed. Many of these tumors derive their blood supply from the brain stem, therefore, total gross resection of the tumor is often not possible.

At the time of exposure of the surface of the dura, in patients with supra- or infratentorial ependymomas, real-time ultrasound may be used to dynamically image the tumor. The precise location of the tumor can be obtained from this as well as the tissue characterization (solid tumor versus necrotic tumor vs. cyst), If a large cystic component is identified, a probe may be advanced with continuous ultrasound guidance and the cyst can be drained. The immediate reduction in the mass of the lesion and the resulting decrease in intracranial pressure lessen the risk of injury to the brain when the dura is opened. Depending upon the circumstances, an operating microscope and microinstruments may be of use with certain ependymomas. as may a laser for vaporization and an ultrasonic aspirator.

In general, the patients undergo treatment  with steroids (dexamethasone 4 to 12 mg q 6 h) preoperatively for a minimum of several days but always to the point where they have improved clinically and then have plateaued. The principle is that of improving brain function as much as possible before any operation. At the time of operation, if the dura is tight despite pretreatment with steroids and perhaps a CSF diversion procedure, mannitol ( 1.5 gm/kg) is given until there is a good urinary response. Usually at that time the dura becomes slack and pulsatile.


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