Congenital Mirror Movements: Behavioral, Neural, Genetic, and Clinical Issues

Abstract

Non-syndromic congenital mirror movements (CMM) is a rare neurological condition, either inherited or sporadic, in which affected individuals lack independent dexterity of hand and finger movements. With all volitional movements of the hands and fingers, unintentional mirroring occurs in the opposite-side homologous effectors. A hallmark neural mechanism of CMM is abnormal, active, extra ipsilateral corticospinal tracts. Mutations in four different causal genes have been identified so far. The present review considers the physiology underlying CMM, including its implicated neural mechanisms and clinical relevance. The heterogeneous nature of the condition is highlighted, particularly in terms of the clinical importance of factors associated with the mirroring phenotype or phenotypes. Speculation about the possible effects of CMM on the somatosensory system is also included as a prospective direction for further study. Despite some inconvenience and occasional discomfort associated with CMM, the potential for highly positive life outcomes is illuminated. Lastly, CMM management is discussed as a key goal toward which future research should stride.