To report the spectrum of clinical presentation, neuroimaging findings and clinical outcomes for diffusion-restricting splenial lesions. 

Restricted diffusion lesions in the corpus callosum (CC) can represent a multitude of etiologies, leading to clinical dilemma in workup and management. There is limited data on their clinical characteristics, associated neuro-imaging findings and outcomes.

In this retrospective clinical cohort study, we reviewed clinical characteristics and neuroimaging data of 3490 individuals (1/1/2009–8/1/2020) who underwent brain MRI with suspected CC lesions. We identified those with diffusion restriction in the splenium and excluded those with prior neurosurgical procedures, recent cardiac procedures, hemorrhage-associated diffusion restriction, and diffuse anoxic brain injury. 200 patients met these criteria. Restricted diffusion lesions were defined as increased signal intensity on MRI FLAIR and DWI sequences with decreased signal intensity on ADC. We obtained data on socio-demographic, clinical presentation, and radiographic features. Etiologies of lesions were ascertained, as well as rates of inpatient mortality and one year re-admission.

In this study, 53% of the patients were male and mean age of patients was 57 years old. 80% of patients had at least one vascular risk factor. In 123 (61.5%) patients splenial diffusion restriction was from vascular origin. Malignancy-related, toxic/metabolic/drug-related, trauma, infectious and inflammatory processes were other major etiologies. Isolated splenial diffusion restriction was found in 31 (15.5 %) of the population. Only 5% had the typical midline, ovoid appearance consistent with a cytotoxic lesion of the corpus callosum (CLOCC). The inpatient mortality rate was 8.5%, and 46.5% of patients were re-admitted to the hospital within 1 year.

The majority of diffusion-restricting splenial lesions were of vascular etiology. Though CLOCCs are classically reversible, they accounted for a small percentage of cases. Nearly half of all cases were re-admitted to the hospital within a year.