Neuroimaging in Ataxias

Abstract

Primary ataxias are a heterogenic group of disorders mostly characterized by progressive incoordination of gait, speech, and eye movement. The mode of inheritance is diverse and authors use it to facilitate classification. Spinocerebellar ataxia (SCA) refers to autosomal dominant forms in which SCA3 (Machado-Joseph disease) is the most common followed by SCA1, SCA2, and SCA6. Recessive ataxias as Friedrich ataxia are also relatively prevalent, while x-linked and mitochondrial disorders are less frequent forms. Despite each type of ataxia has its own peculiarities, most of the symptoms overlap among them, making the diagnosis difficult when considering only the clinical picture. In this context, neuroimaging has become a valuable tool to help the diagnosis but also to better understand the affected brain areas and the pathophysiology of these conditions. Techniques as voxel-based morphometry, diffusion tensor imaging, and surface-based analyses have brought to light the structural differences between the ataxic patients and controls and also helped to differentiate the diagnosis. Functional MRI and spectroscopy have detected changes in functionality and in chemical ratios. Here, we describe the most promising neuroimaging methods that were used to evaluate ataxias and also revise and report the results of the main studies published so far.