Función del sistema motriz del cerebro después de la lesión de la médula…(I)

"Función del sistema motriz del cerebro después de la lesión de la médula espinal completa y crónica."

Steven C. Cramer1, Lindsey Lastra3, Michael G. Lacourse3,4 and Michael J. Cohen2,3 1 Departments of Neurology, Anatomy and Neurobiology, Reeve-Irvine Research Center and 2 Psychiatry and Human Behavior, University of California, Irvine, 3 Neuroimaging Research Laboratory, Department of Veterans Affairs Long Beach Healthcare System and 4 Department of Kinesiology, California State University, Long Beach, CA, USA

Correspondence to: Steven C. Cramer, MD, University of California, Irvine, UCI Medical Center, 101 The City Drive South, Building 53, Room 203, Orange, CA 92868-4280, USA. E-mail: scramer@uci.edu

Most therapies under development to restore motor function after spinal cord injury (SCI) assume intact brain motor functions. To examine this assumption, 12 patients with chronic, complete SCI and 12 controls underwent functional MRI during attempted, and during imagined, right foot movement, each at two force levels. In patients with SCI, many features of normal motor system function were preserved, however, several departures from normal were apparent: (i) volume of activation was generally much reduced, e.g. 4–8% of normal in primary sensorimotor cortex, in the setting of twice normal variance in signal change; (ii) abnormal activation patterns were present, e.g. increased pallido–thalamocortical loop activity during attempted movement and abnormal processing in primary sensorimotor cortex during imagined movement; and (iii) modulation of function with change in task or in force level did not conform to patterns seen in controls, e.g. in controls, attempted movement activated more than imagined movement did within left primary sensorimotor cortex and right dorsal cerebellum, while imagined movement activated more than attempted movement did in dorsolateral prefrontal cortex and right precentral gyrus. These modulations were absent in patients with SCI. Many features of brain motor system function during foot movement persist after chronic complete SCI. However, substantial derangements of brain activation, poor modulation of function with change in task demands and emergence of pathological brain events were present in patients. Because brain function is central to voluntary movement, interventions that aim to improve motor function after chronic SCI likely also need to attend to these abnormalities of brain function.

Brain 2005 128(12):2941-2950; doi:10.1093/brain/awh648.