[Neuroimaging study with morphometric analysis of hereditary and idiopathic ataxia]

Hereditary and idiopathic ataxias are neurodegenerative disorders affecting diverse neuronal systems, particularly the cerebellum and its tracts. They are currently classified according to clinical and genetic criteria. Neuroimaging is a useful tool to help diagnosis but studies using quantitative methodology are scarce.

To apply digital morphometry to cerebral MRI and define objective patterns for clinical evaluation and follow up.

The study was carried out on 48 patients of whom 17 were Friedreich ataxia (FA), 6 non-Friedreich early onset spinocerebellar ataxia (EOCA), 9 autosomal dominant cerebellar ataxia type 1 (ADCA 1), 7 ADCA 3 and 9 idiopathic late onset cerebellar ataxia (ILOCA); 35 controls were grouped on early (< 30 years-old) and late age. Morphometric measures were done on previously selected MRI planes by image analyser digital software.

Six out of 21 measurements and 3 ratios were significantly discriminant. By categories, the structures mainly involved were as follows: atrophy of cervical spinal cord (p = 0.001), cerebellum (p = 0.038) and protuberance (p = 0.002) in FA; atrophy of spinal cord (p = 0.009), cerebellum (p = 0.035) and widening of IV ventricle (p = 0.044) in EOCA; shrinkage of protuberance (p = 0.009), middle cerebellar peduncles (p = 0.004) and spinal cord atrophy (p = 0.001) in ADCA 1; cerebellar atrophy (p = 0.041) in ADCA 3; and cerebellar atrophy (p = 0.041) and shortening of middle cerebellar peduncles (p = 0.038) in ILOCA.

This quantitative morphometric study confirms the existence of different pattern of cerebral involvement that is closely related with the distints clinical forms of hereditary and idiopathic ataxias. Only a few measurements can be used to obtain a morphometric profile for diagnostic and follow up purposes.