Neuroimaging of Pediatric Cerebellum in Inherited Neurodegenerative Diseases

Abstract

In the study of cerebellar degenerative diseases, morphologic imaging (computed tomography, CT and magnetic resonance imaging, MRI) is the most common examination. From the clinical and genetic point of view, cerebellar degenerative diseases include heterogeneous conditions in which MRI may show isolated cerebellar atrophy or cerebellar atrophy associated with other cerebellar or supratentorial abnormalities. Neuroradiological progression is often observed. In congenital disorders of glycosylation (CDG), for example, MRI may be normal, may demonstrate mild cerebellar atrophy or, in the advanced stages of the disease, marked atrophy of the cerebellar hemispheres and vermis associated with the abnormal signal intensity of the cerebellar cortex and white matter and brainstem hypotrophy. In spinal cerebellar ataxias (SCAs), very rare in the pediatric population, MRI may demonstrate isolated cerebellar atrophy or cerebellar and brainstem atrophy. MRI shows characteristic findings in other diseases, strongly suggesting a distinct disorder, such as neuroaxonal dystrophy, ARSACS, ataxia-telangiectasia, or precise mitochondrial diseases. An example of neurodegenerative disorder with prenatal onset is pontocerebellar hypoplasia (PCH). PCH represents a group of neurodegenerative disorders characterized by microcephaly, early cerebellar hypoplasia, and variable atrophy of the cerebellum and ventral pons, genetically divided into several subtypes. Cerebellar hypoplasia visible on MRI is often the first sign that suggests the clinical diagnosis. In most cases, the PCH subtype may demonstrate a characteristic pattern distinguishable at MRI. Selective involvement of the cerebellum, sometimes accompanied by brainstem or supratentorial abnormalities in different combinations, may help restrict the differential diagnosis and may address the specific molecular screening.