Surgical Tips on Removing a Supratentorial Ependymoma in Children – Keith Goh, M.D.

  • Preservation of gliotic pseudocapsule: As these tumors usually have a “capsule” that demarcates tumor from brain, it is preferable to try to keep the capsule intact during the resection. In this way, as complete a resection as possible can be attempted.
  • Bipolar cautery dissection: The author uses bipolar diathermy to coagulate the capsule wall, which often has visible blood vessels. This will develop a “plane of cleavage” (as illustrated below).
Using bipolar diathermy forceps to coagulate capsule of tumor:

 

  • Tumor cyst: Sometimes, if the tumor has a large cystic component, the wall may be inevitably opened, and the cyst fluid will be drained out. This can be seen in the illustration below, where the cyst wall has been opened in the superior aspect of the tumor.
Tumor cyst wall opened, and fluid drained out:

 

  • Sharp dissection needed: The tumor capsule can be fairly thick and may be fibrous in texture. The author often uses microscissors to sharply dissect and remove the tumor (as illustrated below).
Sharp dissection, using microscissors, to excise firm parts of tumor:

 

  • Ultrasonic aspirator used with care: Some surgeons use an ultrasonic aspirator to debulk the tumor tissue. If this is done, it is important to remain within the tumor and not extend into normal brain.
  • Prefer combination of bipolar dissection and suction: Generally the author uses a combination of bipolar diathermy (to coagulate the tumor) and suction (to remove the tumor pieces which have been fragmented), so as to always remain within the tumor or at the capsule. With this technique, it is usually possible to get a complete or near-total resection.
  • Neuronavigation helpful in differentiating external pseudocapsule from intratumoral cyst walls: One has to be aware that the tumor can sometimes have various compartments. It may appear that the resection has followed the capsule but is actually following one compartment. Careful examination of the operation site is needed to correctly identify the edge of the tumor and normal adjacent brain tissue. The author finds it helpful to use a neuro-navigation system if the tumor structure looks complex in the preoperative scans, e.g., multiple solid-cystic compartments.
  • Cortical mapping and monitoring helpful: If the adjacent brain is eloquent (e.g., motor cortex), the author often uses cortical mapping or nerve stimulation to identify these areas and stop further resection so as to try to preserve function.