Secondary Movement Disorders: A Comprehensive Review of Drug-Related and Systemic Etiologies

Secondary movement disorders (SMDs) encompass a broad and clinically significant spectrum of motor abnormalities arising from diverse etiologies, including pharmacologic agents, metabolic imbalances, infections, vascular insults, and immune-mediated mechanisms. These disorders may present with hyperkinetic features such as chorea, dystonia, and myoclonus, or hypokinetic manifestations like parkinsonism, often mimicking primary neurodegenerative conditions and complicating diagnosis. This review synthesizes current knowledge on the pathophysiology, clinical presentation, and management of SMDs, with a particular focus on drug-induced syndromes, metabolic disturbances, infectious triggers, cerebrovascular events, and autoimmune phenomena. Advances in neuroimaging, pharmacogenomics, and biomarker development have enhanced diagnostic precision, while emerging therapies—including VMAT2 inhibitors, adaptive deep brain stimulation, and personalized pharmacologic strategies—offer new avenues for treatment. By integrating multidisciplinary insights, this review aims to improve early recognition, guide differential diagnosis, and support individualized care for patients with secondary movement disorders.