brain, spinal cord, and nerve disorders
Brain Dysfunction by Location
Introduction
Because different areas of the brain control specific functions, the location of brain damage determines the type of dysfunction that results. Which side of the brain is affected is also important because the functions of the two halves of the cerebrum (cerebral hemispheres) are not identical. Some functions of the brain are performed exclusively by one hemisphere. For example, movement and sensation on one side of the body are controlled by the hemisphere on the opposite side. Other functions are performed mainly by one hemisphere, which is said to be dominant for that function, and the other hemisphere is said to be nondominant. For example, the left hemisphere mainly controls language in most people. This characteristic is called left-hemisphere language dominance. Damage to only one hemisphere of the brain may cause complete loss of such functions. However, most functions (such as memory) require coordination of several areas in both hemispheres. For such functions to be completely lost, both hemispheres must be damaged. Specific patterns of dysfunction can be related to the area of the brain that has been damaged. Usually, doctors can diagnose the type of dysfunction by examining the person. They ask questions designed to evaluate specific brain functions. Imaging tests, such as computed tomography (CT) and magnetic resonance imaging (MRI), are usually needed to identify the cause of the damage. 