Preparation for Surgery for Pineal Region Tumors in Children
Indications for Surgery
Histological verification: Due to the histological variation of tumors in the pineal region, histological data can be valuable. Germinomas , which may be treated with radiotherapy alone, can be identified on the basis of tumor markers and radiographic appearance without need for tissue diagnosis. In cases where the diagnosis is not certain, histological verification is needed to determine an appropriate treatment plan. Stereotactic biopsy of pineal region tumors has emerged as a valuable tool for diagnosis and management.
Maximum cytoreduction: Surgical resection is indicated in cases of pineal tumors that are not responsive to radiation and chemotherapy (non-germ cell tumors). In the case of aggressive malignant tumors of the pineal region (e.g., pineoblastomas), gross total resection is the surgical goal. Tumor resection should also be considered in cases of significant mass effect and obstruction of CSF pathways.
Restoration of CSF pathways: When obstructive hydrocephalus is created by a lesion of the pineal region, it may be resolved through either tumor mass reduction or CSF diversion. If persistent obstruction at the aqueduct of Sylvius precludes prompt resolution of hydrocephalus (for example, patients with staged tumor resections or those treated medically with gradual decrease in tumor mass), ETV or shunting may be considered.
Imaging studies: MRI of the brain should be obtained with and without gadolinium enhancement, including thin-cut sequences and fiducial placement for use with intraoperative stereotactic guidance systems.
EVD: The EVD should be opened to drain to a pressure of 10 cm of water. If an interhemispheric approach to the third ventricle is planned, EVD clamping may be considered prior to surgery to facilitate the approach.
Medications: We typically use Dexamethasone, 4 mg PO every 6 hours.
Supratentorial approach: If a supratentorial approach is planned, antiepileptics may be given. Proper anesthetic agents should be chosen to ensure that the seizure threshold is not decreased.
Sitting position: If a sitting position is used for the infratentorial supracerebellar approach, there is the attendant increased risk of venous air embolism. These cases require strict monitoring of end-tidal CO2 and the availability of precordial Doppler ultrasound.