Preparation for Surgery For Supratentorial Dysembryoplastic Neuroepithelial Tumors in Children

Indications for Surgery

• Diagnosis: Obtaining tissue for pathologic examination and arriving at a definite histological diagnosis is one of the main goals to be accomplished when operating on these tumors.

• Treatment of presenting symptoms: The reduction of tumor volume should result in symptomatic relief for patients with epilepsy.

• Treatment of the tumor: Cytoreduction is one of the hallmarks in managing tumors in the CNS, and oncological cure is a function of resection.  A maximal but safe resection should be a goal for surgery on these tumors. 

Preoperative Orders

• No special orders: Preoperative orders for a child with DNET are analogous to those for any low- grade glioma.

Steroids

• No established guidelines: The use of steroids in surgery for DNET has not been investigated. In most cases, there is no or minimal brain edema. In selected cases of large DNETs close to highly eloquent regions, a short course of steroids may be given (dexamethasone or methylprednisolone). No clear guidelines can be given, and the dose is chosen in analogy to similar situations in glioma surgery.

Anesthetic Considerations

• Agents tailored to electrophysiological needs: It is well known that general anesthesia (both intravenous and inhalation anesthesia) has an effect on electrocorticography (ECOG) and the mapping of eloquent areas. No randomized studies have been done, however, to compare the effects of different drugs. The choice of anesthetic medication will therefore have to be decided by the anesthesiologists, on the basis of personal and center experience and on the literature.

• Awake surgery: In selected cases, awake surgery must be considered (e.g., in older children and adults with a large DNET in the dominant temporal lobe) when fMRI and DTI have shown the speech areas and arcuate fascicle to be in the close vicinity of the tumor.

Ancillary/Specialized Equipment

• Intraoperative ECOG: The need for ECOG should be considered and the appropriate equipment and personnel scheduled. It can be of value to resect not only the tumor but also epileptic foci in the vicinity (19). ECoG led to a more extensive resection in 10 of 17 cases reported by Sandberg et al (36) and in 10 of 11 cases described by Spalice et al. (38).

• Computer-assisted image-guided surgery: Resection of these tumors is facilitated by use of image guidance. Neuronavigation can be useful to find small lesions and to resect normally appearing areas that have been shown to be epileptic foci on SISCOM images. The appropriate equipment should be scheduled.