Mirror movement disorder: corticospinal tracts

Abstract

Mirror movement disorder (MMD) is a rare neurological condition characterized by involuntary movements on one side of the body that mirror intentional movements on the opposite side. Understanding the pathophysiology of this condition requires a comprehensive assessment of corticospinal tract integrity through multimodal approaches. This mini review includes our previously published case of a patient with MMD, and reviews recent advances reported in the literature. As MMD is a complex neurological disease, it needs a detailed evaluation. We have evaluated our case using whole-exome sequencing, computed tomography (CT), diffusion tensor imaging (DTI), and transcranial magnetic stimulation (TMS) to elucidate the underlying mechanisms. Whole-exome sequencing analysis prioritized variants in neurologically expressed genes using a predefined logarithm of odds (LOD) score threshold; variants of uncertain significance were further assessed through in silico predictive modeling tools (SIFT, PolyPhen-2, and CADD) to determine likely pathogenicity. Furthermore, recent studies in the field expand our findings by contextualizing them within the broader literature on axon guidance molecules, genetic underpinnings, and emerging therapeutic strategies. The multidisciplinary approach can provide insight into the complex interplay between structural abnormalities and functional motor output in this rare disease, while highlighting the critical role of the corticospinal fiber decussation in normal bimanual coordination.