Multiple Sclerosis is one of a broad category of DeMyelinating Diseases. Affecting the CNS - the Brain and Spinal Cord. Myelin is a fatty material that insulates nerves, acting much like the covering of an electric wire and enabling the nerve to transmit its impulses
rapidly.
It is the speed at which these impulses are conducted that permits smooth, rapid and coordinated movements, performed with little conscious effort. In MS, the loss of Myelin is accompanied by a loss of the ability to perform these movements.
The sites where Myelin is lost appear as hardened sclerotic (scar) areas and because
there tends to be many such areas within the CNS, the term Multiple Sclerosis (literally, many scars) seems appropriate.
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There are really three fairly distinct Nervous Systems in the human body. The CNS lies centrally in the body and has two major parts, the Brain and Spinal Cord, which in turn have several sub-divisions, each with its own unique role in regulating the body's
functions.
The portion of the Brain referred to as the Cerebrum acts as a master control system, and is responsible for initiating all thought and movement. Memory, personality, vision, hearing, touch and muscle tone are also housed within the Cerebrum.
Behind it sits the Cerebellum, which coordinates movement and smooths muscle activity. It permits balance when walking and the smooth use of hands and arms.
Beneath the cerebrum and Cerebellum is the BrainStem. It contains the nerves that control the eyes as well as the vital centers that are involved in breathing, heart rate, etc.
Coming directly from the BrainStem is the Spinal Cord, which functions very much like a large electric cord carrying messages from the Brain centers above to and from the targets (body parts) below.
While numerous biochemical reactions occur in the Brain and Spinal Cord, their major effect is to produce electrical activity that stimulates and regulates the parts of the body.
This electricity is brought to the target structures very efficiently and effectively, with little loss from top to bottom.
This can be accomplished so well because the entire system is well insulated and shielded by a fatty substance called Myelin, which surrounds the conducting systems and allows the electrical nervous impluses to literally skip down the line with little loss.
Myelin in the Brain and Spinal Cord is produced by a specific type of cell called an Oligodendrocyte (Oligo). Both the oligo and the Myelin appear to be injured in MS.
The oligos disappear as the affected Myelin becomes hardened and scarred, forming what is called a plaque, and causing a short-circuiting of electrical transmission.
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Spasticity
In the normal Nervous System, muscle groups work together such that one contracts as its opposing muscle relaxes. This coordination of movements make them smooth and strong.
In MS, this balance system can be disturbed so that opposing muscles contract and
relax at the same time, producing Spasticity.
Spasticity tends to occur most frequently in a specific group of muscles that are responsible for maintaining our upright posture, referred to as anti-gravity or postural muscles.
These include the calf (Gastrocnemius), thigh (Quadriceps), buttock (Gluteus Maximus),
groin (Adductor) and occasionally the back (Erector Spinae) muscles.
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When Spasticity is present the increased stiffness in the muscles means that a great deal of energy is required to perform everyday activities.
Reducing the Spasticity produces greater freedom of movement and strength, frequently accompanied by less fatigue and increased coordination. The major means of reducing Spasticity include stretching exercises, physical therapy, and the use of medications.
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Tremor
The term tremor refers to an oscillating movement of the extremities or ocassionally the head. As is true of all MS symptoms, Tremor may come and go. It is one of the most frustrating symptoms to treat in MS.
There are many different kinds of Tremors; some have wide (gross) Oscillations, while others are barely perceptible (fine); some occur at rest, while others occur only with purposeful movement; some are fast, others are slow; some of the limbs, while others may involve the head, trunk or speech; some are disabling, while others are merely a nuisance; and some are treatable, while others are not.
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The most common tremor seen in MS and the most difficult to treat, occurs as the result of DeMyelination in the Cerebellum. This is the area of the Brain responsible for balance, sending its connections through the back of the BrainStem and the Spinal Cord.
DeMyelination in this area often results in a gross tremor which is relatively slow and which occurs with purposeful movement of the arm or leg. This type of tremor is almost always exaggerated at times of stress and anxiety. This exaggeration by stress is true of most of the neurological synptoms of MS.
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Fatigue
Fatigue is one of the most common and annoying problems for MSers. It is a difficult one to understand for others, since it is not manifested by a highly visible symptom. It can often be treated very effectively once its cause has been determined.
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Fatigue or Lassitude is unique to MS, and the type that is meant by the term "MS fatigue". It is an overwhelming fatigue that can come on at any time of the day without warning.
So that suddenly, one feels extremely sleepy and could go right to sleep. The drug
Symmetrel (Amantidine) has been found to effectively manage this type of fatigue.
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Adapting
Very occasionally, the bulk of the DeMyelination occurs within the Brain, and intellect actually decreases. Memory, planning, and foresight, diminish, and the personality changes.
Initially these changes are subtle, but they increase with time. Emotional lability is the hallmark of this type of disease, with inappropriate episodes of crying and/or laughing.
Older memories are lost last in MS remembering recent events presents the most difficulty. These changes are the result of DeMyelination rather than psychological causes. Thus counselling for this problem must be focused on understanding and adjustment.
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