The purpose of this study is to determine the qualitative and quantitative toxicity of intrathecal topotecan, a topoisomerase I inhibitor, in patients with meningeal malignancies refractory to conventional therapy (radiation therapy and chemotherapy). A safe dose of topotecan that can be recommended for intrathecal administration in subsequent phase II studies will be established in a limited dosage escalation schedule. The CSF pharmacokinetics of intrathecal topotecan will also be studied. Topotecan will be administered intrathecally on a bi-weekly basis for four to six weeks, followed by weekly administration for 1 month, twice monthly administration for four months and then monthly IT administration.