The Operation for Supratentorial Ependymomas in Children

Patient Positioning

The patient is positioned on the basis of tumor location.

• Supine: Usually this is the position used, with the head turned so that the side of the tumor is uppermost.
• Prone or lateral position may be used for tumors in posterior parietal or occipital locations.
• Head frame: The head can be immobilized with the Mayfield or Sugita frame in older children, but a head frame is generally avoided in children younger than 3 years (use horseshoe head rest instead).

Surgical Approach

Craniotomy

• Size: Create an adequate-sized bone flap over site of tumor.
• Eloquent brain: Avoid eloquent areas of brain.
• Venous drainage: Preserve cortical veins and avoid damage to the sagittal sinus.

Intervention

• Goal of surgery: The goal of surgery is maximum tumor resection with avoidance of or minimal neurologic damage.

Tumor biopsy and resection

• Frozen section: Frozen section can be helpful to determine the nature of the tumor early during the resection.
• Centrally decompress, then separate: Bipolar diathermy, microsuction, and microinstruments are used to resect the tumor, working internally to decompress the tumor and dissecting the capsule away from normal brain.
• Tumor features: Tumor consistency can be like meat, sometimes with soft areas of necrosis and areas of calcifications. Cysts are frequent, with fluid being thick and dark. Cystic spaces within the tumor should be opened to drain out thick cystic fluid.
• Pseudocapsule: Usually, there is a pseudocapsule that demarcates tumor from normal brain tissue.
• Hemorrhage: Hemorrhage may be encountered during resection.  Control is easier if feeding vessels are cauterized, especially on the outer part of the tumor capsule.  If hemorrhage is profuse (especially in young children with low blood volumes), consider stopping the resection and doing a second- stage surgery at a later time.

Closure

Bone flap

• Replace: It is the author’s preference to replace the bone flap unless there is severe brain edema or the likelihood of postoperative tumor hemorrhage.
• Secure: Bone flap is secured with sutures or plates and screws.
• Resorbable plates and pins: If plates are used in younger children, the author prefers to use bio-resorbable plates and pins.

Scalp closure

• Routine: Galea closed with resorbable stitches and skin with suture or staples.