Cerebellar Bottom-of-Fissure Dysplasia-a Novel Cerebellar Gray Matter Neuroimaging Pattern.

We report on seven patients with a novel neuroimaging finding that involves exclusively the cerebellar gray matter at the bottom of several fissures of both hemispheres but spares the vermis. The abnormal fissures were predominantly located in the lower and lateral parts of the cerebellar hemispheres. The affected cerebellar cortex was hypointense on T1-weighted and hyperintense on T2-weighted and fluid attenuation inversion recovery sequences. In some patients, the involved cerebellar gray matter was mildly thickened and the affected fissures slightly widened. In three of seven patients, the neuroimaging findings were unchanged on follow-up studies up to 6 years. The seven patients had various indications for the brain magnetic resonance imaging studies, and none of them had cerebellar dysfunction. Based on the similarity of the neuroimaging pattern with the cerebral "bottom-of-sulcus dysplasia," we coined the term "cerebellar bottom-of-fissure dysplasia" to refer to this novel neuroimaging finding. The neuroimaging characteristic as well as the unchanged findings on follow-up favors a stable "developmental" (malformative) nature. The lack of cerebellar dysfunction in the affected patients suggests that cerebellar bottom-of-fissure dysplasia represents most likely an incidental finding that does not require specific diagnostic investigation but allows a reassuring attitude.