Motor neglect: theoretical and clinical aspects

Neglect is a disabling and complex neuropsychological condition, often conceived as a syndrome. Neglect has received a considerable amount of attention in the scientific literature over the past quarter of a century. In humans, neglect typically affects the left side of space, opposite to right-hemispheric lesions. Neglect is present, on average, in 50% of cases in the acute phase following right-hemisphere stroke. Behaviorally, patients fail to attend, orient, process, and respond to stimuli presented in the contralateral side of their body and fail to explore that space through body movements. Neglect can affect several modalities and can be distinguished into different subtypes, resulting from a variety of ipsilesional and contralesional deficits. The motor subtype of neglect is among the most important and, probably, the least understood neuropsychological disorders of motor intention. Motor neglect is very frequent after right-hemisphere injury, with a high number of patients presenting the disorder in the acute phase post stroke. Motor neglect manifests as the failure of patients to use or act with their contralesional hemibody in the absence of sensorimotor deficits; anosognosia is a crucial feature of these patients’ behavior. Motor neglect doubly dissociates from deficits affecting motor production and deficits responsible for a directional motor bias. Nevertheless, in severe cases, distinguishing motor neglect from these deficits becomes a problematic and challenging task. The present thesis aimed to introduce the main theories and clinical aspects of motor neglect. Chapter 1 focused on the neglect syndrome, explaining its subtypes and manifestations, theoretical models, neuroanatomical correlates, assessment procedures, and rehabilitation approaches. In Chapter 2, an in-depth description of motor neglect was presented. Special efforts were made to analyze motor neglect features and related deficits, examine the underlying mechanisms, present the neuroanatomy of the disorder, and describe current therapeutic techniques. In the final chapter (i.e., Chapter 3), general comments regarding the limitations influencing the assessment and rehabilitation procedures were discussed, and future directions for research were proposed.