Neurophysiological characterization of the 'new anatomy' and motor control that results from neurological injury or disease.

Following injury or disease, the central nervous system (CNS), to varying degrees, loses neurons, synaptic connections and conduction-promoting myelin insulation altering the neural circuitry assembled during development. This "New Anatomy" changes neural processing, bringing spasticity, paresis and paralysis to motor function and altered sensation, numbness and pain to sensory function. Focusing on the effects of CNS damage on the motor subsystems, this review offers a neurophysiological assessment perspective developed within the study of human spinal cord injury and extends it to other CNS disorders. It puts forward the concept that there are essential domains of CNS processing, altered by most neurological disorders, that are temporal, the speed of activation and deactivation, and spatial, the distribution across multiple muscles of motor units selected and activated. Measured through multiple-muscle recordings of selected motor-task performance, these domains can be useful in quantifying the severity of CNS damage and changes achieved through recovery or treatment.