The management of brainstem gliomas in patients with neurofibromatosis 1

The appropriate management of brainstem tumors in patients with neurofibromatosis 1 (NF1) has been problematic because the natural history of these lesions remains poorly defined. To formulate rational guidelines for the evaluation and treatment of these tumors, we reviewed the outcome of 21 patients with brainstem mass lesions followed in our NF clinic during the last 9 years. We subdivided the imaging features of these lesions into four groups: (1) diffuse enlargement of the brainstem with hypointensity on T1-weighted MR images and hyperintensity on T2-weighted images (n = 9); (2) focal enhancing masses (n = 7); (3) intrinsic tectal tumors (n = 5); and (4) focal nonenhancing areas of hypointensity on T1-weighted MR images (n = 2). Two cases exhibited two types of lesions. Twelve patients presented with, or developed, symptoms that were referable to the mass; in nine, the lesion was asymptomatic. A distinguishing feature of these tumors was their generally indolent biological behavior. With a median follow-up of 3.75 years, only 10 patients have had radiographic (n = 9) or clinical (n = 3) evidence of disease progression. In seven of these patients, the tumor subsequently stabilized in size or regressed without intervention. Only four patients, each with a focal enhancing tumor, received specific therapy for the tumor; this consisted of biopsy (n = 1), excision (n = 3), and adjuvant radiotherapy (n = 2). Each of these lesions was a low-grade glioma histologically and each remained stable in size after treatment (median follow-up = 4.25 years). Four patients with tectal tumors underwent insertion of a CSF shunt for hydrocephalus, but required no specific treatment for the tumor. None of the patients with diffuse brainstem lesions or focal areas of hypointensity required any intervention for the tumor. All 21 patients are presently alive and well. We conclude that the biological behavior of brainstem lesions in patients with NF1 differs significantly from that of lesions with a similar appearance in patients without this disorder. Although these lesions may at some time in their course exhibit clinical and radiographic progression, most do not require specific intervention. The lesions that are most likely to progress and require therapy are focal enhancing tumors; however, even lesions in this subgroup may stabilize in size or regress spontaneously without intervention. Based on these results, we recommend that intervention be limited to those lesions that exhibit rapid or unrelenting growth on serial images or that produce significant clinical deterioration.