Muscle Spasms
Muscle spasms and cramps are spontaneous, often painful muscle contractions.
Muscle spasms and pain or "Trigger Points" as we commonly
refer to them, are the accumulation of products that build in muscles, particularly when
those muscles are used more frequently. Trigger points can be created by automobile
injuries, work activities, sporting events, or repetitive use. Any continued motion over a
prolonged period of time irritates the muscles and decreases function, causing a build-up
of metabolic byproducts. As these byproducts begin to build, the muscle goes through three
basic physiological changes:
1. It becomes shorter, which we feel as tightness, due to a decrease
blood flow to the muscle.
2. The muscle can't recover as fast as it used to due to the decreased
blood going to the muscle. The muscle then has a much greater chance of becoming injured
due to the tightness and shortening of the muscle fibers.
3. The muscle cannot and will not perform to the
maximum potential.
Description of Muscle Spasms
Most people are familiar with the sudden pain of a muscle cramp. The rapid,
uncontrolled contraction, or spasm, happens unexpectedly, with either no stimulation or
some trivially small one. The muscle contraction and pain last for several minutes, and
then slowly ease. Cramps may affect any muscle, but are most common in the calves, feet,
and hands. While painful, they are harmless, and in most cases, not related to any
underlying disorder. Nonetheless, cramps and spasms can be manifestations of many
neurological or muscular diseases.
The terms cramp and spasm can be somewhat vague, and they are sometimes used to include
types of abnormal muscle activity other than sudden painful contraction. These include
stiffness at rest, slow muscle relaxation, and spontaneous contractions of a muscle at
rest (fasciculation). Fasciculation is a type of painless muscle spasm, marked by rapid,
uncoordinated contraction of many small muscle fibers. A critical part of diagnosis is to
distinguish these different meanings and to allow the patient to describe the problem as
precisely as possible.
Causes of Muscle Spasms
- Some possible causes of local muscle spasms:
- Sudden movements
- Over-extending the muscle
- Neck spasm
- Back spasms
- Disc disorders - may cause back spasms
- Nerve disorders (see Nerve symptoms)
- See also cause of muscle cramps or muscle pain
Normal voluntary muscle contraction begins when electrical signals are sent from the
brain through the spinal cord along nerve cells called motor neurons. These include both
the upper motor neurons within the brain and the lower motor neurons within the spinal
cord and leading out to the muscle. At the muscle, chemicals released by the motor neuron
stimulate the internal release of calcium ions from stores within the muscle cell. These
calcium ions then interact with muscle proteins within the cell, causing the proteins
(actin and myosin) to slide past one another. This motion pulls their fixed ends closer,
thereby shortening the cell and, ultimately, the muscle itself. Recapture of calcium and
unlinking of actin and myosin allows the muscle fiber to relax.
Abnormal contraction may be caused by abnormal activity at any stage in this process.
Certain mechanisms within the brain and the rest of the central nervous system help
regulate contraction. Interruption of these mechanisms can cause spasm. Motor neurons that
are overly sensitive may fire below their normal thresholds. The muscle membrane itself
may be over sensitive, causing contraction without stimulation. Calcium ions may not be
recaptured quickly enough, causing prolonged contraction.
Interuption of brain mechanisms and overly sensitive motor neurons may result from
damage to the nerve pathways. Possible causes include stroke, multiple sclerosis, cerebral
palsy, neurodegenerative diseases, trauma, spinal cord injury, and nervous system poisons
such as strychnine, tetanus, and certain insecticides. Nerve damage may lead to a
prolonged or permanent muscle shortening called contracture.
Changes in muscle responsiveness may be due to or associated with:
- Prolonged exercise. Curiously, relaxation of a muscle actually requires energy to be
expended. The energy is used to recapture calcium and to unlink actin and myosin.
Normally, sensations of pain and fatigue signal that it is time to rest. Ignoring or
overriding those warning signals can lead to such severe energy depletion that the muscle
cannot be relaxed, causing a cramp. The familiar advice about not swimming after a heavy
meal, when blood flow is directed away from the muscles, is intended to avoid this type of
cramp. Rigor mortis, the stiffness of a corpse within the first 24 hours after death, is
also due to this phenomenon.
- Dehydration and salt depletion. This may be brought on by protracted vomiting or
diarrhea, or by copious sweating during prolonged exercise, especially in high
temperatures. Loss of fluids and salts--especially sodium, potassium, magnesium, and
calcium--can disrupt ion balances in both muscle and nerves. This can prevent them from
responding and recovering normally, and can lead to cramp.
- Metabolic disorders that affect the energy supply in muscle. These are inherited
diseases in which particular muscle enzymes are deficient. They include deficiencies of
myophosphorylase (McArdle's disease), phosphorylase b kinase, phosphofructokinase,
phosphoglycerate kinase, and lactate dehydrogenase.
- Myotonia. This causes stiffness due to delayed relaxation of the muscle, but does not
cause the spontaneous contraction usually associated with cramps. However, many patients
with myotonia do experience cramping from exercise. Symptoms of myotonia are often worse
in the cold. Myotonias include myotonic dystrophy, myotonia congenita, paramyotonia
congenita, and neuromyotonia.
Fasciculations may be due to fatigue, cold, medications, metabolic disorders, nerve
damage, or neurodegenerative disease, including amyotrophic lateral sclerosis. Most people
experience brief, mild fasciculations from time to time, usually in the calves.
Symptoms of Muscle Spasms
The pain of a muscle cramp is intense, localized, and often debilitating Coming on
quickly, it may last for minutes and fade gradually. Contractures develop more slowly,
over days or weeks, and may be permanent if untreated. Fasciculations may occur at rest or
after muscle contraction, and may last several minutes.
Diagnosis of Muscle Spasms
Abnormal contractions are diagnosed through a careful medical history, physical and
neurological examination, and electromyography
of the affected muscles. Electromyography records electrical activity in the muscle during
rest and movement.
Treatment of Muscle Spasms
Most cases of simple cramps require no treatment other than patience and stretching.
Gently and gradually stretching and massaging the affected muscle may ease the pain and
hasten recovery.
More prolonged or regular cramps may be treated with drugs such as carbamazepine,
phenytoin, or quinine. Fluid and salt replacement, either orally or intravenously, is used
to treat dehydration. Treatment of underlying metabolic or neurologic disease, where
possible, may help relieve symptoms.
Alternative treatment of Muscle Spasms
Cramps may be treated or prevented with Gingko (Ginkgo biloba) or Japanese
quince (Chaenomeles speciosa). Supplements of vitamin E, niacin, calcium, and
magnesium may also help. Taken at bedtime, they may help to reduce the likelihood of night
cramps. |
