Primary Degeneration of the Granular Layer of the Cerebellum. A Study of 14 Patients and Review of the Literature

Abstract

Primary degeneration of the granular layer of the cerebellum is an autosomal recessive disorder exhibiting characteristic clinical features: hypotonia, strabismus, delayed motor development, nonprogressive ataxia, delayed language development with dysarthria and mental retardation.

We studied fourteen children, seven of each gender. Neuroimaging tests including pneumoencephalography, computed tomography (CT) and magnetic resonance imaging (MRI) showed severe cerebellar atrophy in all. MRI best demonstrated the cerebellar lesion, revealing great uniformity amongst the cases. Vertebrobasilar angiography was performed in two cases and showed marked hypoplasia of the cerebellar arteries, predominantly the posterior inferior cerebellar artery (PICA) and its branches. Necropsy was performed in three cases; cerebellar atrophy with loss of granular cells and diverse abnormalities of the Purkinje cells was found in two. The third, the sister of one of the other two cases, had a similar but shorter clinical course and died at three months of age. Her sister, who died at 5 years of age, presented a severe cerebellar atrophy with typical changes in the granular cell layer and Purkinje cells. In the third patient, who lived three months, only focal cerebellar folial atrophy with no microscopic changes in the granular cell layers was present. Though this case cannot objectively be included in the cerebellar atrophy syndrome with granular cell loss, her family history and clinical picture suggest the same disease. The findings observed in our series and the study of cases described in the literature, suggest that there are several forms of this disease which differ mainly in severity and neurological evolution. The cerebellar lesion seems to be a progressive atrophic process with the most severe changes during the early years of life.

Key words

Cerebellum - Cerebellar atrophy - CT - MRI - Ataxia - Degeneration of the granular layer of the cerebellum - Norman disease