Why is MRI important?
Because noticeable MS exacerbations are infrequent (usually fewer than one a year) and visible disability occurs slowly, a diagnosis based on symptoms and signs alone is difficult and often delayed. Thus, physicians have come to rely on MRI, which can provide 3-dimensional images of the brain, to detect MS and differentiate it from other illnesses that may have similar symptoms. It has also been shown that MRI is 7 to 10 times more sensitive for detecting MS progression than clinical assessment alone. Recently, doctors have started to use serial MRIs (performed over time) to monitor the course of illness and identify which MS patients will benefit most from early treatment.Evoked Potentials
The tests to diagnose Multiple Sclerosis (MS) are known as evoked potentials. These tests measure the electrical impulses produced by the nerves of the central nervous system in response to a stimulus supplied by the tester, hence "evoked." The tests show whether sensory nerve pathways are damaged. In an undamaged nerve cell, myelin is continuous and electrical impulses travel smoothly. In MS the myelin is damaged and movement of the electrical impulse is blocked or slowed.When a person touches, sees, or hears a stimulus, electrical messages are sent to the brain. During the test, electrodes placed on the head and body record electrical impulses and measure their intensity. A specialist can evaluate the graph produced by the test to see which nerve pathways are affected and to locate areas of myelin damage.
There are three types of Evoked Potential Tests:
- Visual evoked potentials (VEP): tests nerves involved in vision using a strobe flash or a checkerboard-patterned image to check for damage of the optic nerve or its pathways
- Brain stem auditory potentials (BAEP): tests nerves involved in hearing by using sounds to stimulate and evaluate lesions in the brain stem
- Sensory Evoked Potentials (SEP): tests skin sensations via a brief electrical stimulus applied to the wrist or ankle to check for lesions in sensory nerves
Spinal Tap
To help confirm a diagnosis of Multiple Sclerosis (MS), a small sample of the fluid surrounding the brain and spinal cord may be removed and tested. A small needle is placed in the lower back to remove a small sample of the clear cerebrospinal fluid, also known as lumbar puncture or spinal tap. A number of tests are typically performed to see if there are proteins, cells, and other components not usually found in this space, which would indicate that the protective blood-brain barrier has been broken.Increased antibody production and the presence of oligoclonal bands, which reflect antibodies made in the central nervous system, are often found in the spinal fluid of people with MS. However, the results of a spinal tap alone (whether normal or abnormal) neither prove nor disprove a diagnosis of MS. Although high levels of antibodies and the presence of oligoclonal bands may help confirm a diagnosis of MS, this information is usually used to supplement MRI and neurological exam findings. Spinal fluid analysis can also help rule out other diseases that may be causing similar symptoms.
Medical History
A complete medical history includes a detailed review of past medical problems and all current symptoms. The past medical history will include questions about past illnesses and their treatment, accidents, surgeries, allergies, and use of recreational drugs and alcohol. People being evaluated for Multiple Sclerosis (MS) will also be asked questions about their close family members, including their histories of illnesses (particularly nervous system diseases) and their causes of death.(published with permission in writing from:http://www.multiplesclerosis.com)
