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

Background: 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.

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

Patients And Methods: 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.

Results: 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.

Conclusions: 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.