Current Neurosurgical Treatment of Medulloblastomas in Children

Abstract

To determine the current neurosurgical treatment of children with medulloblastomas, we reviewed the operative reports and neurosurgical report forms from 141 children with posterior fossa medulloblastomas treated on two current Children’s Cancer Study Group (CCSG) protocols, CCG-921 for high-stage and CCG-923 for low-stage medulloblastoma. Most medulloblastoma operations were performed in major medical centers: 61% of the operations were performed in CCSG member institutions, 23% in CCSG affiliates and 16% in other institutions. The tumor T stage distribution was as follows: T1 – 4%, T2 – 15%, T3A – 35%, T3B – 36%, and T4 – 10%. Tumors infiltrated the brainstem in 38% of cases and were associated with hydrocephalus in 91% of cases. Hydrocephalus was managed by external ventricular drains in 50% and by shunts in 60%. Adjunctive instruments (e.g., microscope, ultrasonic aspirator) were used in 93% of the operations. Tumor removals were as follows: biopsy only 3%, partial removals 13%, subtotal removals 13%, near total removals 41% and gross total removals in 40%; 90% or more of the tumor was removed in 81% of the operations. Forty-seven percent of the operations were performed by pediatric neurosurgeons. Near total and gross total removals were performed significantly more often (p < 0.05) by pediatric neurosurgeons than by general neurosurgeons. Postoperative morbidity was reported in 46% of cases, including neurologic morbidity in 26% of cases. There was no significant difference in patient morbidity between pediatric and general neurosurgeons.

Prognostic Factors in Children with Supratentorial (Nonpineal) Primitive Neuroectodermal Tumors

“…The strong correlation between M stage and survival has been reported for chil dren with posterior fossa PNETs (medulloblastomas), although no previous studies consist of prospectively staged patients [16], The extent of resection for children with S-PNETs was less than that previously reported for children with me dulloblastomas. Approximately 65% of patients with SPNETs had a 90% or greater resection versus 80% of patients with medulloblastomas [21]. We attribute the difference to the fact that S-PNETs are often much larger tumors than medulloblastomas, and infrequently have an intraventricular location.…”

Medulloblastoma of the Cerebellopontine Angle-Case Report-

“…31) To achieve maximum cytoreduction, further aggressive tumor resection from the brainstem is not advised 31) and a high postoperative complication rate of up to 26% has been reported following tumor resection. 2) We performed only partial removal of the lesion because of the disappearance of the margins between the tumor and the brainstem. However, new postoperative neurological deficits related to the surgery still occurred in our patient.…”

MeduUoblastoma with Brain Stem Involvement: The Impact of Gross Total Resection on Outcome

“…The role of surgery in the treatment of medulloblasto ma has evolved with refinements in surgical techniques and improvements in instrumentation that permit more radical resection with a reduced risk of operative mortali ty and morbidity [4,10,23,24], Several earlier studies suggested that the extent of resection had prognostic impact in patients subsequently treated with craniospinal irradiation, and selected use of chemotherapy [6][7][8][9][25][26][27][28]. As a result, patients with otherwise favorable prog nostic features are now eligible for 'low-risk' treatment protocols only if there is minimal or no apparent local residual disease after initial surgery.…”

“…Recent reports, like most earlier studies, have not directly addressed the importance of gross total resection in patients with medulloblastoma invading the brain stem, with or without direct extension beyond the posterior fossa (modified Chang stages T3b_4). However, some authors contend that radical surgery in such cases increases the risk of surgical morbidity, without improving local tumor control [10,12].…”

“…Studies identifying the extent of resection as a significant outcome predictor have prompt ed neurosurgeons in pediatric oncology centers to attempt complete tumor resection whenever possible [6][7][8][9]. How ever, for patients with medulloblastoma involving the brain stem, the goal of gross total resection has been con troversial because of the potential for surgical morbidity and the absence of data indicating a clear impact on pro gression-free survival (PFS) [10][11][12],…”