Assessment of the corticospinal fiber integrity in mirror movement disorder

Anarchy in the brain: Behavioural and neuroanatomical core of the anarchic hand syndrome

An individual's inability to control the movements of their own hand is known as the Anarchic Hand Syndrome. The hand may perform apparently purposeful actions but acts as if it has a will of its own. Although the syndrome was first described over a century ago, the nature of the condition remains, for the most part, obscure, in particular in terms of the definition of the main symptoms and the underlying neural networks. The present study compares the results from in-depth assessments, made at repeated intervals (2, 4 and 7 months from the lesion onset) of the anarchic hand symptoms in three patients suffering from various different forms of brain damage. An investigation of direct grey matter damage and structural connectivity allowed us to compare the grey matter lesions and white matter disconnections in the three patients. A "core" characteristic relating to anarchic hand symptoms was identified, involving, in particular, both apparently purposeful movements (i.e., magnetic apraxia, grasping, bimanual incoordination, disorders in manual dexterity and action sequencing) and non-purposeful movements (i.e., levitation, synkinesis and mirror movements). Furthermore, ideomotor apraxia may also be associated with this syndrome. No overlapping areas of grey matter lesions were found in the three patients. In contrast, a pattern of common white matter disconnections was found, which involves inter-hemispheric disconnections (via corpus callosum), the long intra-hemispheric tracts (via SLF, IFOF and Arcuate) and the descendent tracts (corticospinal tract). These results are discussed in terms of awareness of motor intention.

Paroxysmal Dystonic Posturing Mimicking Nocturnal Leg Cramps as a Presenting Sign in an Infant with DCC Mutation, Callosal Agenesis and Mirror Movements

Background/Objectives: Pathogenic variants in the deleted in colorectal cancer gene (DCC), encoding the Netrin-1 receptor, may lead to mirror movements (MMs) associated with agenesis/dysgenesis of the corpus callosum (ACC) and cognitive and/or neuropsychiatric issues. The clinical phenotype is related to the biological function of DCC in the corpus callosum and corticospinal tract development as Netrin-1 is implicated in the guidance of developing axons toward the midline. We report on a child with a novel inherited, monoallelic, pathogenic variant in the DCC gene. Methods: Standardized measures and clinical scales were used to assess psychomotor development, communication and social skills, emotional and behavioural difficulties. MMs were measured via the Woods and Teuber classification. Exome sequencing was performed on affected and healthy family members. Results: The patient's clinical presentation during infancy consisted of paroxysmal dystonic posturing when asleep, mimicking nocturnal leg cramps. A brain magnetic resonance imaging (MRI) showed complete ACC. He developed typical upper limb MMs during childhood and a progressively evolving neuro-phenotype with global development delay and behavioural problems. We found an intrafamilial clinical variability associated with DCC mutations: the proband's father and uncle shared the same DCC variant, with a milder clinical phenotype. The atypical early clinical presentation of the present patient expands the clinical spectrum associated with DCC variants, especially those in the paediatric age. Conclusions: This study underlines the importance of in-depth genetic investigations in young children with ACC and highlights the need for further detailed analyses of early motor symptoms in infants with DCC mutations.