Reversible splenial lesion with restricted diffusion in a wide spectrum of diseases and conditions: Report of eight additional cases and literature review

Objective: Reversible lesion in the central area of the splenium of the corpus callosum (SCC) is a unique phenomenon occurring particularly in patients with encephalitis or encephalopathy and in patients receiving antiepileptic drugs (AED). We report MR imaging findings, clinical courses, and outcomes in eight patients with various diseases and conditions. Materials and methods: Eight patients with a reversible SCC lesion with transiently restricted diffusion were reviewed retrospectively. Diseases and conditions that were associated with a reversible lesion included epilepsy receiving AED (n=1), seizure from eclampsia receiving AED (n=1), mild infectious encephalitis (n=2), hypernatremia resulting in osmotic myelinolysis (n = 1), and neoplasm (n=3) such as acute lymphocytic leukemia, spinal meningeal melanocytoma, and esophageal cancer. We evaluated MR imaging findings and clinical findings. Results: Seven patients had isolated SCC lesions; one patient with osmotic myelinolysis showed additional parenchymal lesions. The reversible SCC lesion shape was oval (n=6) or extended (n=2). The mean apparent diffusion coefficient value of the splenial lesion was 0.40±0.16×10^-3mm²/s, ranging from 0.22 to 0.64×10^-3mm²/s. In a patient with osmotic myelinolysis, additional white matter lesions, shown as restricted diffusion, were revealed as not reversible on follow-up MR imaging. Neurological courses and outcomes were good in seven patients with isolated SCC lesions, but poor in one with osmotic myelinolysis. Conclusion: Reversible SCC lesion with restricted diffusion is apparent in a wide spectrum of diseases and conditions. Neurological courses and outcomes are good, particularly in patients with isolated SCC lesions. Knowledge of MR imaging findings and the associated spectrum of diseases and conditions might prevent unnecessary invasive examinations and treatments.