Multiple Sclerosis Symptoms
Symptoms of multiple sclerosis vary by individual, depending on the area of the brain or spinal cord affected, and occur over time. The symptoms are caused by demyelination—destruction of the insulating myelin sheath that protects nerve fibers and helps to conduct the electrical impulses that control muscle action and sensation. When demyelination occurs in nerves that send messages to muscles, it causes problems with mobility (motor symptoms). Demyelination along nerves that carry sensory messages to the brain causes disturbances in sensation (sensory symptoms). The most common early symptoms of MS are tingling, numbness, loss of balance, weakness, and blurred or double vision. Less common symptoms include slurred speech and lack of coordination.
Symptoms fall into three categories and can also be characterized by the bodily functions they affect. This section contains more information on:
Categories of Symptoms
Symptoms of MS fall into three categories: primary, secondary, and tertiary.
Primary symptoms are a result of demyelination, the destruction of the nerve cells' protective myelin sheath. As the electrical impulses that control muscles and organ function are disrupted, people with MS experience weakness, tremors, tingling, numbness, loss of balance, vision impairment, paralysis, impaired thinking, neuropathic pain, and bladder or bowel problems.
Secondary symptoms result from primary symptoms. For example, paralysis can cause bedsores or pressure sores. Bladder dysfunction can cause urinary tract infections. The goal is to avoid secondary symptoms by treating primary symptoms.
Tertiary symptoms are the social, psychological, and vocational complications caused by primary and secondary symptoms. Depression is a common tertiary problem among MS patients but can also be a primary symptom.
Sometimes symptoms will seem to worsen or increase in frequency after an illness, a fever, a hot bath, exercise, or a hot day. This does not necessarily mean that the disease is worsening.
Bodily Functions Affected
Symptoms can be characterized by the bodily functions that they affect:
Sensory symptoms include numbness, tingling, and other abnormal sensations such as pain, visual disturbances, sexual disturbances, and dizziness. Many people are unusually sensitive to heat.
Motor symptoms are those that involve muscle coordination, such as weakness, difficulty walking, tremor, and stiffness. Fatigue is very common.
Mental fatigue is common, too; many MS patients report cognitive changes such as slowed thinking and an inability to concentrate. Emotional upset, including depression, may result from all of the other symptoms.
An important symptom of MS is spasticity, involuntary muscle contractions that result in muscle spasms or stiffness. Spasticity interferes with voluntary muscle movement and usually involves the muscles of the legs and/or arms. Spasticity is the result of an imbalance in the central nervous system that causes hyperactive muscle stretch reflexes, which lead to involuntary contractions and increased muscle tone. In the long term, severe spasticity may cause decreased range of motion in the affected limbs.
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