Electroencephalogram (EEG)
An electroencephalogram (EEG) is a test that measures and records the electrical activity of your brain. Special sensors (electrodes) are attached to your head and hooked by wires to a computer. The computer records your brain's electrical activity on the screen or on paper as wavy lines. Certain conditions, such as seizures, can be seen by the changes in the normal pattern of the brain's electrical activity.
Electromyography (EMG) & Nerve Conduction Studies
An electromyogram (EMG) measures the electrical activity of muscles at rest and during contraction. Nerve conduction studies measure how well and how fast the nerves can send electrical signals. Nerves control the muscles in the body by electrical signals (impulses), and these impulses make the muscles react in specific ways. Nerve and muscle disorders cause the muscles to react in abnormal ways.
Measuring the electrical activity in muscles and nerves can help find diseases that damage muscle tissue (such as muscular dystrophy) or nerves (such as amyotrophic lateral sclerosis or peripheral neuropathies). EMG and nerve conduction studies are often done together to give more complete information.
Evoked Potentials
Evoked potentials are used to measure the electrical activity in certain areas of the brain and spinal cord. Electrical activity is produced by stimulation of specific sensory nerve pathways. These tests are used in combination with other diagnostic tests to assist in the diagnosis of multiple sclerosis (MS) and other disorders.
Evoked potentials test and record how quickly and completely the nerve signals reach the brain. Evoked potentials are used because they can indicate problems along nerve pathways that are too subtle to show up during a neurologic examination or to be noticed by the person. The disruption may not even be visible on MRI exam.
These tests can be helpful in making the diagnosis of MS and other disorders. In MS, signal transmission can slow down and the signal becomes weak. Evoked potentials are used to show abnormalities in the function of nerve pathways that can be caused by MS.
Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging (MRI) is an advanced diagnostic tool that provides a high level of anatomic detail for precisely locating the stroke and determining the extent of damage. Due to its high level of sensitivity, MRI is considered especially useful when the stroke involves small blood vessels. The technology involves use of a strong magnetic field, and is performed in a special room free of metallic equipment.
