Clinical validity of MR based program for analysis of fluid/brain index of posterior cranial fossa structures in patients with spinocerebellar ataxia

Background: Spinocerebellar ataxia type 1 (SCA1) and type 2 (SCA2) belong to the group of neurodegenerative disorders of autosomal dominant inheritance, genetically and clinically heterogeneous, caused by CAG trinucleotide repeat expansion, which leads to productions of protein carrying the abnormal polyglutamine chain (polyQ). Molecular abnormalities cause degenerative changes - atrophy of posterior cranial fossa structures. The clinical symptoms typical of this disorder include progressive gait and limb ataxia, dysarthria, occulomotor disturbances, pyramidal tract and peripheral nerves involvement. The aim of the study is to evaluate the usefulness of a computer program prepared in our department for volumetric measurements of posterior cranial fossa structures (the pons, vermis and cerebellar hemispheres) in a group of SCA patients. Material/Methods: MR examinations of 22 patients suffering from SCA were used to calculate the value of fluid/brain index of posterior cranial fossa structures and compared with the results of group of 10 healthy volunteers. The degree of atrophy of posterior cranial fossa structures can be objectively evaluated by special volumetric measurements. Results: We found fluid/brain index (FBI) of posterior cranial fossa structures in group of SCA patients to vary from 0.1411 to 0.3929 (mean 0.2456 SD±0.601). Conclusions: 1. MR-based calculation of fluid/brain index of posterior fossa structures is a valuable tool for morphological assessment of SCA-related changes in brain structures. 2. The presented software enables objective evaluation of the course and stage of posterior fossa structures atrophy. 3. Our self-made computer program to calculate the fluid/brain index of posterior cranial fossa structures is easy to use on a personal computer - it is a good tool in everyday radiological practice.