Pediatric Acute Toxic Leukoencephalopathy: Prediction of the Clinical Outcome by FLAIR and DWI for Various Etiologies

Pediatric acute toxic leukoencephalopathy is a clinicoradiologic entity comprising various etiologies. This study aimed to identify the MR imaging appearance of pediatric acute toxic leukoencephalopathy from various etiologies and determine whether the etiology correlates with clinical outcome.

We retrospectively reviewed the electronic records of patients with pediatric acute toxic leukoencephalopathy younger than 19 years of age who had MR imaging within <2 weeks of presentation, including DWI and FLAIR sequences. Two neuroradiologists scored the DWI and FLAIR severity and measured the percentage ADC reduction within the visibly affected regions and normal-appearing WM. The percentage ADC reduction and DWI and FLAIR severity were correlated with clinical outcome using the Spearman correlation.

Of 22 children, 3 were excluded due to a nontoxic cause or incomplete examination. Regarding the included 19 children (mean age, 13 years), the etiologies of pediatric acute toxic leukoencephalopathy were the following: methotrexate (n = 6), bone marrow transplantation (n = 4), fludarabine (n = 3), cytarabine (n = 1), carboplatin (n = 1), vincristine (n = 1), cyclosporine (n = 1), uremia (n = 1), and bevacizumab (n = 1). Three subgroups were analyzed (chemotherapy, n = 12; immunosuppression, n = 5; others, n = 2). There was a strong correlation of FLAIR (r  = 0.773, P < .001) and DWI (r = 0.851, P < .001) severity with clinical outcome, and patients treated with fludarabine had the worst outcomes. High percentage ADC reduction values were associated with adverse outcomes, and lower percentage ADC reduction values were associated with favorable outcomes (r = 0.570, P = .011).

The DWI and FLAIR severity scores appear highly prognostic, whereas percentage ADC reduction is moderately prognostic for clinical outcomes in pediatric acute toxic leukoencephalopathy. Immunosuppressive pediatric acute toxic leukoencephalopathy tends toward favorable outcomes, and fludarabine tends toward worse outcomes.