Acute Methotrexate Neurotoxicity: Findings on Diffusion-Weighted Imaging and Correlation with Clinical Outcome

Patient 2 presented with nonfluent aphasia and left-sided hemiparesis and hemisensory loss.

A, Axial ADC map shows asymmetric areas of restricted diffusion in the centrum semiovale. Image distortion is due to orthodontia. Right-sided lesion is correlated with left-sided hemiparesis, whereas the left-sided white matter lesion was not accompanied by a motor deficit.

B, Axial FLAIR image obtained 8 weeks later shows large, confluent areas of presumed demyelination in the right centrum semiovale similar in size to the DW abnormality. Left cerebral white matter lesion that was clinically unapparent at presentation is smaller than the white matter lesion associated with neurologic deficit at presentation. Neurologic deficits had resolved.

Patient 3 had steroid-induced IDDM and presented during induction. Initial strokelike event was associated with aphasia and right hemiparesis and hemisensory loss, which resolved. Second event occurred 8 weeks later and was associated with aphasia, left hemiparesis, and focal seizure, all of which resolved.

A and B, DW image (A) and ADC map (B) at initial presentation show large areas of restricted diffusion in the centrum semiovale (arrows). Bilateral diffusion abnormalities were associated with unilateral hemimotor-sensory deficit.

C and D, Axial FLAIR images obtained 8 weeks later shows extensive presumed demyelination in deep white matter. Note absence of abnormal signal intensity in the right parietal region.

E and F, Axial DW image (E) and ADC map (F) show restricted diffusion in the right parietal cortex and subcortical white matter. Diffusion abnormalities were correlated with left hemiparesis and left focal seizure. Hyperintensity in the left anterior centrum semiovale (arrow in E) is due to T2 shine-through; ADC map shows a corresponding area of hyperintensity (arrow in F).

G, Axial FLAIR image obatined 28 months later when the patient was asymptomatic shows more-extensive white matter abnormalities. Note absence of gliosis in the right parietal region.

Patient 4 presented with nonfluent aphasia and alternating fluctuating hemiparesis and left facial droop.

A and B, Axial DW images show asymmetric regions of restricted diffusion in the anterior centrum semiovale that do not explain the motor neurologic deficits.

C, Follow-up MR image obtained 39 months later shows minimal scattered demyelination. The patient was neurologically intact.