What is the best course of action for a patient with isolated carcinomatous meningitis who is responding well to intrathecal methotrexate but now has MRI findings suspicious for methotrexate leukoencephalopathy?

Neurological toxicities of intrathecal methotrexate tend to be categorized by the timeline of onset after treatment. Acute MTX toxicity includes arachnoiditis, encephalitis, transverse myelopathy, and seizures. This tends to be readily reversible including neuroimaging findings. Subacute MTX toxicit...