Diagnosis

Toxic demyelination from methotrexate therapy

Findings

Image #1 8-18-2000 T2 axials - show diffuse confluent white matter high signal

Image #2 11-12-2000 T2 axials - white matter high signal which is vastly improved

Image #3 11-12-2000 T1 axials - normal appearance

Discussion

Toxic demyelination can be caused by various endogenous or exogenous toxins which can result in temporary or permanent damage. Endogenous toxins result from inborn errors of metabolism. Exogenous toxins are usually from various drugs. Some toxins like methotrexate and XRT affect mainly the myelin and white matter causing toxic demyelination. This patient had leukemia and received methotrexate thereapy. The first MRI shows extensive high signal in the white matter on the T2 images which vastly improve on the follow-up study 3 months later.

Causes of toxic demyelination:

Chronic alcoholism (common)

Inherited leukodystrophies

Hydrocarbons

Cyclosporin

Methotrexate

Radiation therapy (uncommon)

Lead,Mercury (rare)

Differential considerations: Dysmyelinating disease , ADEM (usually patchy), MS, PML(immunosuppresed, XRT/drug toxicity, vasculitis

Discussion of Multiple Choice Question:

MBD is an uncommon disease originally described in poorly nourished Italian men who drank excessive crude red wine. Corpus callosum demyelination and necrosis is the characteristic pathologic finding which causes focal cystic areas to form in the corpus callosum (genu, body, splenium).

Diagnostic Neuroradiology, Osborn