Transient Probst Bundle Diffusion Restriction: An Acute Encephalopathy Equivalent to Clinically Mild Encephalopathy with a Reversible Splenial Lesion.

Probst bundles are selectively seen in patients with agenesis of the corpus callosum (CC) and are thought to be homologous to the CC. We herein report a 19-year-old woman with partial agenesis of the CC. She developed acute encephalopathy during Bordetella pertussis infection. Brain magnetic resonance imaging (MRI) showed restricted diffusion of bilateral Probst bundles. She was treated with anti-epileptics and azithromycin and recovered with no neurological sequelae. Follow-up MRI showed the resolution of the diffusion abnormality. The characteristics of diffusion-weighted images on brain MRI and clinical course mimicked those in cases of clinically mild encephalopathy/encephalitis with reversible splenial lesion.