The Operation for Supratentorial Pleomorphic Xanthoastrocytomas in Children

Patient Positioning

• Approach dependent: Depending on the approach used, the patient will be positioned supine, in a lateral decubitus position, or prone.
• Head fixation: Young children, especially those with hydrocephalus, cannot be pinned in a Mayfield or Sugita frame, but the head can be stabilized on a horseshoe headrest or with the use of a gel pad system.

Surgical Approach

• Dictated by tumor location: As a general principle, the shortest route to a tumor is the best approach. It will be determined by the location of the tumor and the presence of eloquent cortex in the vicinity, as well as whether or not the tumor is in the dominant hemisphere.

Nondominant hemisphere

• Direct approach: The shortest distance to the tumor needs to be determined. In addition, in the nondominant hemisphere the tumor should be approached with a temporal cortical incision anterior to the vein of Labbe to decrease the risk of hemianopia or with a parietal incision behind the angular gyrus (but with increased risk of hemianopia).

Dominant hemisphere

• Approach avoids angular gyrus and speech centers: The shortest distance to the tumor needs to be determined. In addition, in the dominant hemisphere language is typically located on T1 at 6–7 cm from the pole, as well as around the angular gyrus; therefore, an anterior incision, or a posterior incision (for parietal lesions) is recommended to avoid language deficits. Although a cortical lesion in the inferior parietal location can lead to a Gerstmann syndrome (dysgraphia, alexia, dyscalculia, finger agnosia, and left-right disorientation) in adults, it has rarely been described in children due to plasticity of the brain. An awake craniotomy can be performed in older children to decrease the risk for language deficit.

Intervention

• Enter the cyst: By decompressing the cyst, the surgeon gains a better view of the tumor and decreases the risk for injury to the adjacent cortex.
• Fragment large tumors: In small tumors, an “en bloc” removal can be tried at that point, whereas larger tumors need some fragmentation/debulking
• Goal is complete resection: Total removal of the tumor has been reported to have the best outcome (16).

Closure

• Irrigate the cavity: Irrigation of the cavity helps the hemostasis by identifying possible bleeders.