12/13/2009

Atrofia Muscular Esclerosis Lateral Amiatrofíca


Atrofia muscular

Es el desgaste o pérdida del tejido muscular.

Consideraciones generales

Existen dos tipos de atrofia muscular.
La atrofia por desuso ocurre por una falta de ejercicio físico. En la mayoría de las personas, la atrofia muscular es causada por no utilizar los músculos lo suficiente. Las personas que tienen trabajos sedentarios, que padecen afecciones que limitan el movimiento o que tienen una disminución en los niveles de actividad pueden perder tono muscular y sufrir atrofia. Este tipo de atrofia se puede contrarrestar con el ejercicio vigoroso o una mejor nutrición.
Las personas que están postradas en una cama pueden experimentar un desgaste muscular significativo. Los astronautas, que están lejos de la gravedad de la tierra, pueden desarrollar una disminución del tono muscular y descalcificación ósea tan sólo pocos días después de la ingravidez.
El tipo más grave de atrofia muscular es la neurógena, que ocurre cuando hay una lesión o enfermedad en un nervio. Este tipo de atrofia muscular tiende a ocurrir más repentinamente que la atrofia por desuso.
Algunos ejemplos de enfermedades que afectan los nervios que controlan los músculos serían:
Incluso la atrofia muscular menor generalmente ocasiona algo de pérdida de movilidad o de fuerza.







New Evidence is giving credence to this curious form of pain relief—and may be silencing long-time critics in the process.

Meet Magnet, P.I.







In 1993, a patient of Carlos Vallbona, M.D., told him that a cushion made with small magnets had cured his lower back pain. Vallbona was skeptical. “I thought it was a psychological effect,” he recalls. “There was nothing in the scientific literature that indicated magnets were helpful.”

At the time, most scientists would have agreed and some, like William Jarvis, Ph.D., executive director of the National Council Against Health Fraud, still do. “There’s a lot of huckstering going on,” Jarvis says. “Marketers are making extravagant claims for which there is no evidence.”

Physicians and scientists ridiculed magnet therapy with good reason. Until last year, there was not a speck of scientific evidence showing that magnets did what patients–and magnet manufacturers–claimed they did. In fact, one informal study, conducted at Lenox Hill Hospital in New York in 1991 by physical therapist Benjamin Gelfand, tracked a group of 24 patients suffering from bursitis, tendonitis, and lower back pain. The patients wore magnets 12 hours a day for up to six weeks and none experienced any pain relief that could be attributed to the magnets. Gelfand concluded that magnet therapy merited no further investigation.

But magnet therapy wouldn’t go away. Anecdotal evidence continued to mount, despite the inability of science to explain how magnets worked. Chronic pain sufferers like Vallbona’s patient, went on claiming that magnets worked for them. Consider these three stories:

Golfer Jim Colbert’s chronic back pain forced him to quit playing professionally. Then a fellow player recommended magnet therapy. “When you have the kind of back I have, you try anything,” says Colbert, who returned to professional golf four years later. He now straps several magnets to his back when he plays and sleeps on a magnetic mattress pad every night. Today he is one of the top–ranked players on the circuit.

Ryan Vermillion, physical therapist and athletic trainer for the Miami Dolphins, says he regularly treats football players with magnets, including quarterbacks Craig Erickson and Dan Marino. Vermillion says that although there’s no way to be sure magnets are helping the players’ injuries to heal more quickly, he has noticed differences since he started treating them with magnets three years ago.

“The players are saying they’re feeling better, but there are also objective things,” Vermillion explains. “After applying the magnets you will get some decrease in swelling, or changes in post–surgical swelling or hematomas. You can actually see the swelling decrease faster.”

Gail Banta of Weymouth, Mass., suffered from bursitis in her hips and arthritis in her back for 11 years. She had fibromyalgia, a painful neuro-muscular condition whose cause is unknown. When her husband told her what he had heard about magnets from a hunting guide in Canada, she decided to order a magnetic mattress pad. The result astonished her.

“In one week of sleeping on the pad, my backache was gone.” Banta says she had been taking 12 pills a day for pain since the onset of her condition and that she had stopped needing them within two weeks of purchasing the mattress pad. (She was so impressed that she became a distributor for a Japanese magnet company that sells products in the United States).

Facts in Favor

After hearing story after story like these from his patients, Vallbona, the director of the Post–Polio Clinic at the Institute for Rehabilitation and Research, affiliated withBaylor College of Medicine in Houston, was interested enough to attend a 1994 conference on the effects of magnetic fields. What he learned led him to suspect there might be something to magnet therapy after all. He and his colleague Carleton Hazelwood, M.D., designed a double–blind study to test the effect of magnets on 50 patients suffering from pain associated with post–polio syndrome. What he found piqued the interest of even the staunchest critics of magnet therapy.

In the study, Vallbona examined the effects of one specific type of magnet known as a “concentric circles” magnet. He had some subjects hold these permanent magnets (permanent magnets have a static magnetic field) on points where they felt the most intense pain, and others hold inactive magnets. All were told to keep them in place for 45 minutes. After the magnets were removed, seventy–five percent of the patients who used active magnets reported a significant reduction in pain. Only 19 percent of the patients in the control group, however, experienced even a small decrease in pain. No side effects were reported. Vallbona published these results in the November 1997 issue of the Archives of Physical Medicine and Rehabilitation.

Vallbona’s study did not explore how long this effect might last, but he has continued to follow the progress of participants, and the preliminary results look promising. “Many patients reported that the effect lasted not only hours, but days, weeks, even months in some cases,” he says. “So we have the impression that the relief brought about by the magnets is lasting longer than relief by painkilling drugs.”

Vallbona is no the only researcher finding promising results. In a controlled setting, neurobiologist Alvaro Pascual–Leone, M.D., Ph.D., and his colleagues at Harvard Medical School treated 17 severely depressed patients with a technique called “rapid–rate transcranial magnetic stimulation.” The treatment involves using an electromagnet–produced by running an electric current through a coil of wire–to stimulate the activities of certain areas of the brain. After five daily sessions of the treatment, 11 of the 17 patients showed a marked improvement that lasted for two weeks after the treatments and no on reported significant adverse effects. Pascual–Leone published his findings in the July 1996 issue of the Lancet.

Several related studies on electromagnetic brain stimulation, including one at the National Institutes of Health, are currently exploring the use of this technique to treat a range of neurological disorders, including epilepsy, Parkinson’s disease, and even learning disabilities. Ann Gill Taylor, director of the Center for the Study of Complementary and Alternative Therapies in Charlottesville, Virginia, has just begun a year–long study designed to investigate the effect of using static magnetic fields to treat 100 patients suffering from fibromyalgia.

Although intrigued by research results, Gelfand and Jarvis say they are still waiting for more scientific evidence that magnet therapy works. The Food and Drug Administration (FDA), which as not approved the use of permanent magnets to treat pain, has approved several independent review boards to track current research in the field.

Leading Theories 

No one knows for sure how magnetic fields interact with the human body. But there are a few leading theories:

Blood flow
Experts agree that magnets probably help increase blood flow to a painful area of the body, which carries more oxygen to the region, decreases inflammation, and relieves pain. According to biophysicist Marko Markov, Ph.D., magnets probably stimulate blood flow because blood is composed of positively and negatively charged particles. Markov recently conducted a study–which has not yet been published–that found a substantially increased blood flow to an area of a horse’s leg where a magnet was applied.

Pain perception 
Vallbona suggests that the magnetic field may affect pain receptors in the painful area, eliciting a slight anesthetic effect, or that the magnetic field might be transmitted via blood vessels to the brain, which then releases endorphins, chemicals that act as natural pain relievers.

Theories are one thing, facts are another, which is why Vallbona has plans for further research on magnets. In the meantime, since he completed his study with the post–polio patients, he has been successfully treating his own injured shoulder with two small magnets. And he now takes along several magnets whenever he travels–just in case he needs them.

The Polio Crusade

THE POLIO CRUSADE IN AMERICAN EXPERIENCE A GOOD VIDEO THE STORY OF THE POLIO CRUSADE pays tribute to a time when Americans banded together to conquer a terrible disease. The medical breakthrough saved countless lives and had a pervasive impact on American philanthropy that ... Continue reading..http://www.pbs.org/wgbh/americanexperience/polio/

Erradicación de La poliomielitis

Polio Tricisilla Adaptada