[Basal ganglia and movement disorders-Part 2: … and if it is not Parkinson's disease? : Nondegenerative causes and neuroradiological patterns].

Nondegenerative disorders involving the basal ganglia frequently do not present clinically as a primary parkinsonian syndrome, but rather in the context of acute or subacute neurological symptoms such as altered level of consciousness, epileptic seizures, encephalopathy, or newly emerging hyperkinetic movement disorders. In these clinical scenarios, neuroimaging is often performed without a clear etiological hypothesis and primarily serves as an initial diagnostic orientation. Due to their end-arterial vascular supply, high metabolic demand, and central role within distributed motor and cognitive networks, the basal ganglia are particularly vulnerable to vascular, metabolic-toxic, inflammatory, and genetic insults. Accordingly, nondegenerative disorders often exhibit characteristic-and in some cases highly specific-patterns of involvement, the systematic analysis of which allows for rapid etiological stratification. This article provides a structured overview of the most relevant nondegenerative causes of movement disorders with basal ganglia involvement and describes typical neuroradiological patterns observed in vascular, metabolic-toxic, genetic, neoplastic, and infectious-inflammatory conditions. In addition, current developments in magnetic resonance imaging are discussed with respect to their potential and inherent limitations. Neuroradiological imaging remains a central tool in the evaluation of nondegenerative movement disorders, guiding etiological classification, and directing further diagnostic work-up.