About 400,000 Americans have multiple sclerosis, and 10,000 new cases are diagnosed every year. Multiple sclerosis (MS) is a chronic autoimmune disorder affecting movement, ensation, and bodily functions. It iscaused by destruction of the myelin insulation covering nerve fibers (neurons) in the central nervous system (brain andspinal cord). MS is a nerve disorder caused by destruction of the insulating layer surrounding neurons in the brain and spinal cord.This insulation, called myelin, helps electrical signals pass quickly and smoothly between the brain and the rest of thebody. When the myelin is destroyed, nerve messages are sent more slowly and less efficiently. Patches of scar tissue,called plaques, form over the affected areas, further disrupting nerve communication. The symptoms of MS occur whenthe brain and spinal cord nerves no longer communicate properly with other parts of thebody.
Multiple sclerosis causes a wide varietyof symptoms and can affect vision, balance, strength, sensation, coordination, and bodily functions.
Multiple sclerosis is an autoimmune disease, meaning its cause is an attack by the body’s own immune system. For unknown reasons, immune cells attack and destroy the myelin sheath that insulates neurons in the brain and spinal cord. This myelin sheath, created by other brain cells called glia, speeds transmission and prevents electrical activity in one cell from short-circuiting to another cell. Disruption of communication between the brain and other parts of the body prevent normal passage of sensations and control messages, leading to the symptoms of MS. The demyelinated areas appear as plaques, small round areas of gray neuron without the white myelin covering. The progression of symptoms in MS is correlated with development of new plaques in the portion of the brain or spinal cord controlling the affected areas. Because there appears to be no pattern in the appearance of new plaques, the progression of MS can be unpredictable. Despite considerable research, the trigger for this autoimmune destruction is still unknown. At various times, evidence has pointed to genes, environmental factors, viruses, or a combination of these. The risk of developing MS is higher if another family member is affected, suggesting the influence of genetic factors. In addition, the higher prevalence of MS among people of northern European background suggests some genetic susceptibility.
MS can present itself with multiple symptoms as we mentioned above. These are few of the most common ones.
-Fatigue. Occurs in about 80% of people, can significantly interfere with ability to function at home and work, and may be the most prominent symptom in a person who otherwise has minimal activity limitations.
-Numbness or tingling. Numbness of the face, body, or extremities (arms and legs) is often the first symptom experienced by those eventually diagnosed as having MS.
-Sexual problems. Very common in the general population including people with MS. Sexual responses can be affected by damage in the central nervous system, as well by symptoms such as fatigue and spasticity, and by psychological factors.
-Pain. Pain syndromes are common in MS. In one study, 55% of people with MS had “clinically significant pain” at some time, and almost half had chronic pain.
-Emotional changes. Can be a reaction to the stresses of living with MS as well as the result of neurologic and immune changes. Bouts of depression, mood swings, irritability, and episodes of uncontrollable laughing and crying pose significant challenges for people with MS and their families.
There is no single test that confirms the diagnosis of multiple sclerosis, and there are a number of other diseases withsimilar symptoms. While one person’s diagnosis may be immediately suggested by her symptoms and history, another’smay not be confirmed without multiple tests and prolonged observation. The distribution of symptoms is important: MSaffects multiple areas of the body over time. The pattern of symptoms is also critical, especially evidence of therelapsing- remitting pattern, so a detailed medical history is one of the most important parts of the diagnostic process. Athorough search to exclude other causes of a patient’s symptoms is especially important if the following features arepresent: 1) family history of neurologic disease, 2) symptoms and findings attributable to a single anatomic location, 3)persistent back pain, 4) age of onset over 60 or under 15 years of age, or 5) progressively worsening disease.
In addition to the medical history and a standard neurological exam, several lab tests are used to help confirm or rule outa diagnosis of MS:
Magnetic resonance imaging (MRI) can reveal plaques on the brain and spinal cord. Gadolinium enhancement candistinguish between old and new plaques, allowing a correlation of new plaques with-new symptoms. Plaques may beseen in several other-diseases as well, including encephalomyelitis, neurosarcoidosis, and cerebral lupus. Plaques onMRI may be difficult to distinguish from small strokes, areas of decreased blood flow.
A lumbar puncture, or spinal tap, is done to measure levels of immune proteins, which are usually elevated in thecerebrospinal fluid of a person with MS. This test may not be necessary if other tests are diagnostic.
Evoked potential tests, electrical tests of conduction speed in the nerves, can reveal reduced speeds consistent withthe damage caused by plaques. These tests may be done with small electrical charges applied to the skin (somatosensory evoked potential), with light patterns flashed on the eyes (visual evoked potential), or with soundspresented to the ears (auditory evoked potential).