A neurologic deficit is a functional abnormality of a body area due to a decrease in the function of the brain, spinal cord, muscles, or nerves.
Griggs RC, Jozefowicz RF, Aminoff MJ. Approach to the patient with neurologic disease. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 403.