In hemimegalencephaly, MR imaging often reveals mid-sagittal band-like structures between the lateral ventricles. We describe the clinical presentation, morphologic abnormalities, conventional MR imaging, diffusion tensor MR and fiber tract (FT) reconstruction in a 14-year-old boy with unilateral hemimegalencephaly. We retrospectively examined MR images to determine whether these structures are aberrant mid-sagittal fibers.

Acute cerebellitis is an inflammatory process commonly involving both cerebellar hemispheres. Bilateral cerebellar hemispheres involvement is the most common finding. It typically occurs as a primary infectious, post-infectious or post-vaccination disorder, but is also a disease entity with heterogeneous pathogenesis including paraneoplasia. Acute cerebellitis is usually a benign, self-limiting and rarely fatal disease. Typically, cerebellar atrophy is a late consequence of the syndrome. We describe the radiological features of a case of pseudotumoural hemicerebellitis with emphasis on MRI and spectroscopy findings as non-invasive diagnostic tools to avoid unnecessary surgical procedures.