THE MANAGEMENT OF BRAIN-STEM GLIOMAS IN PATIENTS WITH NEUROFIBROMATOSIS-1

The appropriate management of brainstem tumors in patients with neurof ibromatosis 1 (NF1) has been problematic because the natural history o f these lesions remains poorly defined. To formulate rational guidelin es for the evaluation and treatment of these tumors, we reviewed the o utcome of 21 patients with brainstem mass lesions followed in our NF c linic during the last 9 years, We subdivided the imaging features of t hese lesions into four groups: (1) diffuse enlargement of the brainste m with hypointensity on T-1-weighted MR images and hyperintensity on T -2-weighted images (n = 9); (23 focal enhancing masses in = 7); (3) in trinsic tectal tumors (n = 5); and (4) focal nonenhancing areas of hyp ointensity on T-1-weighted MR images (a = 2). Two cases exhibited two types of lesions. Twelve patients presented with, or developed, sympto ms that were referable to the mass; in nine, the lesion was asymptomat ic. A distinguishing feature of these tumors was their generally indol ent biological behavior. With a median follow-up of 3.75 years, only 1 0 patients have had radiographic (n = 9) or clinical (n = 3) evidence of disease progression. In seven of these patients, the tumor subseque ntly stabilized in size or regressed without intervention. Only four p atients, 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 und erwent insertion of a CSF shunt for hydrocephalus, but required no spe cific treatment for the tumor. None of the patients with diffuse brain stem lesions or focal areas of hypointensity required any intervention for the tumor, All 21 patients are presently alive and well. We concl ude that the biological behavior of brainstem lesions in patients with NF1 differs significantly ii om that of lesions with a similar appear ance in patients without this disorder. Although these lesions may at some time in their course exhibit clinical and radiographic progressio n, most do not require specific intervention. The lesions that are mos t likely to progress and require therapy are focal enhancing tumors; h owever, even lesions in this subgroup may stabilize in size or regress spontaneously without intervention. Based on these results, we recomm end that intervention be limited to those lesions that exhibit rapid o r unrelenting growth on serial images or that produce significant clin ical deterioration.