The risks of metastases from shunting in children with primary central nervous system tumors.

The authors reviewed the hospital charts of 415 pediatric patients treated for benign or malignant primary brain tumors over the past 20 years at the Children's Hospital Medical Center, Seattle. Patients' ages ranged from the neonatal period to 18 years. A shunt was placed in 152 patients (37%), 45 before and 94 after surgery. Confirmation of extraneural metastases was based on clinical and diagnostic examination. Factors analyzed as possibly influencing the occurrence of extraneural metastases were: 1) the shunt: type, valve, location, filter, and revisions; 2) extent of resection; 3) pathology; and 4) treatment regimen. Eight of the 415 patients developed extraneural metastases during life. All eight patients had a medulloblastoma (cerebellar primitive neuroectodermal tumor). These eight patients were separated into Group A (without a shunt) and Group B (with a shunt). In Group A (five patients), the mean interval from primary diagnosis to metastasis was 15 months. Two children had gross total resection of the tumor. The predominant location of metastases in Group A was: bone (two cases); cervical lymph nodes (one); lung/bone (one); and retroperitoneal pelvic mass (one). Three Group A patients had a simultaneous central nervous system (CNS) recurrence. Of the three Group B patients, two had a ventriculoperitoneal (VP) shunt and one a ventriculoatrial (VA) shunt; all were placed postoperatively. One Group B patient had a simultaneous CNS recurrence. No shunt revisions were performed in these three patients. The mean time from primary diagnosis to metastasis was 25 months. One patient had a total tumor resection. The predominant location of metastases was bone (one case), retroperitoneal pelvic mass (one), and abdominal cavity with ascites (one case). Only one patient in the entire series had a filter placed; this resulted in shunt obstruction and was removed 1 month following placement. It is concluded that cerebrospinal fluid shunts, regardless of type, location, revision rate, or filter insertion, do not predispose pediatric patients with brain tumors to develop extraneural metastases. A diagnosis of shunt-related metastases should be based on the development of intra-abdominal (VP shunt) or pulmonary (VA shunt) dissemination primarily with or without additional sites. The diagnosis of medulloblastoma is an important factor related to metastasis occurrence while the extent of resection and postoperative therapy are not influential.