Chapter 8. General Principles of Sensory Processing, Touch, and Pain
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By Elizabeth Pennisi Four years ago, Igor Spetic lost his right arm in an industrial accident. Doctors outfitted him with a prosthetic arm that restored some function, but they couldn't restore his sense of touch. Without it, simple tasks like picking up a glass or shaking hands became hit-or-miss propositions. The lack of touch also robs Spetic of basic pleasures. “I would love to feel my wife’s hand,” he says. In time, he may regain that pleasure: Two independent research teams have now equipped artificial hands with sensors that send signals to the wearer’s nerves to recreate this missing sense. The sensing technologies work only in the lab, but they have proved durable, and amputees who have tried them, including Spetic, say that they are effective. One technology advances the range of touch sensations available, while the other promises to enable touch through a better way to attach the prosthesis. “All of these results are very positive,” says Mandayam Srinivasan, a neuroengineer at the Massachusetts Institute of Technology in Cambridge, who was not involved in either project. “Each of them fills a piece of the puzzle in terms of [prosthesis] development.” Almost 40 years ago, researchers tried to provide sensory feedback by adding pressure sensors to prostheses that relayed the sensation through electrodes attached to nerves. But for the most part, they just made it seem like the hand was tingling. And durability has been an issue in such efforts, too. In February, Silvestro Micera, a neuroengineer at the Sant'Anna School of Advanced Studies in Pisa, Italy, and the Swiss Federal Institute of Technology in Lausanne and his team showed that it was possible for sensor-equipped prosthetic arms to gently or powerfully grab objects and even to distinguish a round from a square object. But the study lasted just 4 weeks, in part because of the delicate interface with the body. © 2014 American Association for the Advancement of Science.
Aaron E. Carroll For a drug to be approved by the Food and Drug Administration, it must prove itself better than a placebo, or fake drug. This is because of the “placebo effect,” in which patients often improve just because they think they are being treated with something. If we can’t compare a new drug with a placebo, we can’t be sure that the benefit seen from it is anything more than wishful thinking. But when it comes to medical devices and surgery, the requirements aren’t the same. Placebos aren’t required. That is probably a mistake. At the turn of this century, arthroscopic surgery for osteoarthritis of the knee was common. Basically, surgeons would clean out the knee using arthroscopic devices. Another common procedure was lavage, in which a needle would inject saline into the knee to irrigate it. The thought was that these procedures would remove fragments of cartilage and calcium phosphate crystals that were causing inflammation. A number of studies had shown that people who had these procedures improved more than people who did not. However, a growing number of people were concerned that this was really no more than a placebo effect. And in 2002, a study was published that proved it. A total of 180 patients who had osteoarthritis of the knee were randomly assigned (with their consent) to one of three groups. The first had a standard arthroscopic procedure, and the second had lavage. The third, however, had sham surgery. They had an incision, and a procedure was faked so that they didn’t know that they actually had nothing done. Then the incision was closed. The results were stunning. Those who had the actual procedures did no better than those who had the sham surgery. They all improved the same amount. The results were all in people’s heads. © 2014 The New York Times Company
Keyword: Pain & Touch
Link ID: 20167 - Posted: 10.07.2014
By Lisa Sanders, M.D. On Thursday, we challenged Well readers to solve the mystery of a 62-year-old man with severe neck pain that spread down his arm, a facial droop, and numbness on his torso. Nearly 200 of you wrote in, and 20 of you correctly diagnosed the patient. The correct diagnosis is… Lyme disease. And more precisely, the early disseminated form of Lyme disease with neurological involvement The first person with the correct answer was Dr. Arielle Hay, a pediatric rheumatologist in Miami, who nailed it just half an hour after the case was posted. Dr. Hay said that the biggest clue was the UConn letterhead. When combined with the odd neurological symptoms, this reminder of where the case took place brought Lyme disease to mind. Lyme disease is one of those diseases that hardly needs an explanation. It was first described in 1977, in a case series of 51 children and parents who had mysterious episodes of joint pain and swelling. The children were initially diagnosed with juvenile rheumatoid arthritis, but the clustering of cases eventually led the investigators, Dr. Allen Steere and Dr. Stephen Malawista, to consider an infectious disease. The illness was named after the Connecticut town where most of the initial cases were located. The disease is caused by a spirochete, a spiral shaped bacterium carried by the Ixodes tick, and usually presents first with a distinctive, expanding red rash (called erythema migrans) that appears at the site of the bite in the early, localized stage of the disease. It is thought that the rash appears in up to 80 percent of Lyme infections. © 2014 The New York Times Company
By Kevin Hartnett You may have seen that deliberately annoying “View of the World from Ninth Avenue” map featured on the cover of the New Yorker a while back. It shows the distorted way geography appears to a Manhattanite: 9th and 10th avenues are the center of the world, New Jersey appears, barely, and everywhere else is just a blip if it registers at all. As it turns out, a similar kind of map exists for the human body — with at least some basis in neuroscience. In August I wrote a story for Ideas on the rise of face transplants and spoke to Michael Sims, author of the book, “Adam’s Navel: A Natural and Cultural History of the Human Form.” During our conversation Sims mentioned an odd diagram published in 1951 by a neurosurgeon named Wilder Penfield. The diagram is known as “Homunculus” (a name taken from a weird and longstanding art form that depicts small human beings); it shows the human body scaled according to the amount of brain tissue dedicated to each part, and arranged according to the locations in the brain that control them. In the diagram, the eyes, lips, nose, and tongue appear grotesquely large, indicating that we devote an outsized amount of brain tissue to operating and receiving sensation from these parts of the body. (Sims’s point was that we devote a lot of processing power to the face, and for that reason find it biologically disorienting that faces could be changeable.) The hand is quite large, too, while the toes, legs, trunks, shoulders, and arms are tiny, the equivalents of Kansas City and Russia on the New Yorker map. “Homunculus” seems like the kind of thing that would have long since been superseded by modern brain science, but it actually continues to have a surprising amount of authority, and often appears in neuroscience textbooks.
Keyword: Pain & Touch
Link ID: 20158 - Posted: 10.04.2014
|By Tanya Lewis and LiveScience Dolphins can now add magnetic sense to their already impressive resume of abilities, new research suggests. When researchers presented the brainy cetaceans with magnetized or unmagnetized objects, the dolphins swam more quickly toward the magnets, the new study found. The animals may use their magnetic sense to navigate based on the Earth's magnetic field, the researchers said. A number of different animals are thought to possess this magnetic sense, called "magnetoreception," including turtles, pigeons, rodents, insects, bats and even deer (which are related to dolphins), said Dorothee Kremers, an animal behavior expert at the University of Rennes, in France, and co-author of the study published today (Sept. 29) in the journal Naturwissenschaften. "Inside the ocean, the magnetic field would be a very good cue to navigate," Kremers told Live Science. "It seems quite plausible for dolphins to have a magnetic sense." Some evidence suggests both dolphin and whale migration routes and offshore live strandings may be related to the Earth's magnetic field, but very little research has investigated whether these animals have a magnetic sense. Kremers and her colleagues found just one study that looked at how dolphins reacted to magnetic fields in a pool; that study found dolphins didn't show any response to the magnetic field. But the animals in that study weren't free to move around, and were trained to give certain responses. © 2014 Scientific American
Keyword: Animal Migration
Link ID: 20140 - Posted: 10.01.2014
By Mo Costandi The nerve endings in your fingertips can perform complex neural computations that were thought to be carried out by the brain, according to new research published in the journal Nature Neuroscience. The processing of both touch and visual information involves computations that extract the geometrical features of objects we touch and see, such as the edge orientation. Most of this processing takes place in the brain, which contains cells that are sensitive to the orientation of edges on the things we touch and see, and which pass this information onto cells in neighbouring regions, that encode other features. The brain has outsourced some aspects of visual processing, such as motion detection, to the retina, and the new research shows that something similar happens in the touch processing pathway. Delegating basic functions to the sense organs in this way could be an evolutionary mechanism that enables the brain to perform other, more sophisticated information processing tasks more efficiently. Your fingertips are among the most sensitive parts of your body. They are densely packed with thousands of nerve endings, which produce complex patterns of nervous impulses that convey information about the size, shape and texture of objects, and your ability to identify objects by touch and manipulate them depends upon the continuous influx of this information. © 2014 Guardian News and Media Limited
Keyword: Pain & Touch
Link ID: 20051 - Posted: 09.09.2014
By JOHN MARKOFF STANFORD, Calif. — In factories and warehouses, robots routinely outdo humans in strength and precision. Artificial intelligence software can drive cars, beat grandmasters at chess and leave “Jeopardy!” champions in the dust. But machines still lack a critical element that will keep them from eclipsing most human capabilities anytime soon: a well-developed sense of touch. Consider Dr. Nikolas Blevins, a head and neck surgeon at Stanford Health Care who routinely performs ear operations requiring that he shave away bone deftly enough to leave an inner surface as thin as the membrane in an eggshell. Dr. Blevins is collaborating with the roboticists J. Kenneth Salisbury and Sonny Chan on designing software that will make it possible to rehearse these operations before performing them. The program blends X-ray and magnetic resonance imaging data to create a vivid three-dimensional model of the inner ear, allowing the surgeon to practice drilling away bone, to take a visual tour of the patient’s skull and to virtually “feel” subtle differences in cartilage, bone and soft tissue. Yet no matter how thorough or refined, the software provides only the roughest approximation of Dr. Blevins’s sensitive touch. “Being able to do virtual surgery, you really need to have haptics,” he said, referring to the technology that makes it possible to mimic the sensations of touch in a computer simulation. The software’s limitations typify those of robotics, in which researchers lag in designing machines to perform tasks that humans routinely do instinctively. Since the first robotic arm was designed at the Stanford Artificial Intelligence Laboratory in the 1960s, robots have learned to perform repetitive factory work, but they can barely open a door, pick themselves up if they fall, pull a coin out of a pocket or twirl a pencil. © 2014 The New York Times Company
Erin Allday It's well established that chronic pain afflicts people with more than just pain. With the pain come fatigue and sleeplessness, depression and frustration, and a noticeable disinterest in so many of the activities that used to fill a day. It makes sense that chronic pain would leave patients feeling weary and unmotivated - most people wouldn't want to go to work or shop for a week's worth of groceries or even meet friends for dinner when they're exhausted and in pain. But experts in pain and neurology say the connection between chronic pain and a lousy mood may be biochemical, something more complicated than a dour mood brought on from persistent, long-term discomfort alone. Now, a team of Stanford neurologists have found evidence that chronic pain triggers a series of molecular changes in the brain that may sap patients' motivation. "There is an actual physiologic change that happens," said Dr. Neil Schwartz, a post-doctoral scientist who helped lead the Stanford research. "The behavior changes seem quite primary to the pain itself. They're not just a consequence of living with it." Schwartz and his colleagues hope their work could someday lead to new treatments for the behavior changes that come with chronic pain. In the short term, the research improves understanding of the biochemical effects of chronic pain and may be a comfort to patients who blame themselves for their lack of motivation, pain experts said. © 2014 Hearst Communications, Inc.
By Sandra G. Boodman When the Philadelphia specialist gently tweaked a spot deep inside Heidi Gribble Camp’s back, she screamed, an expression of both anguish and elation.Camp’s vindication was fueled in large part by her persistence. In 2006, her complaints of severe abdominal pain early in her first pregnancy were brushed aside by her doctor — until she nearly bled to death from a ruptured ectopic pregnancy. That near-fatal hemorrhage was swiftly followed by her sudden lapse into unconsciousness and the discovery of large blood clots in her lung and abdomen, requiring additional emergency surgery. “I told him, ‘You found the pain, this is the best day of my life!’ ” Camp, 32, recalled saying during the June 18 procedure at the Hospital of the University of Pennsylvania. The fact that the interventional radiologist, an expert in minimally invasive surgical procedures, was able to pinpoint and replicate the stabbing pain she had suffered for more than eight years was sweet validation. It proved that Camp wasn’t exaggerating her pain and that it had an identifiable, physical cause, something a series of doctors had come to doubt. Months of recovery followed — as did the first episode of searing back pain. But doctors in Florida, Toronto and Northern Virginia, where Camp lived at various times with her husband, a recently retired professional baseball player — told her they could not find a reason for her agony. Some implied that she was dramatizing normal aches; others rebuffed her inquires about a potential cause that would later prove to be prescient.
Keyword: Pain & Touch
Link ID: 19992 - Posted: 08.26.2014
By GRETCHEN REYNOLDS Regular exercise may alter how a person experiences pain, according to a new study. The longer we continue to work out, the new findings suggest, the greater our tolerance for discomfort can grow. For some time, scientists have known that strenuous exercise briefly and acutely dulls pain. As muscles begin to ache during a prolonged workout, scientists have found, the body typically releases natural opiates, such as endorphins, and other substances that can slightly dampen the discomfort. This effect, which scientists refer to as exercise-induced hypoalgesia, usually begins during the workout and lingers for perhaps 20 or 30 minutes afterward. But whether exercise alters the body’s response to pain over the long term and, more pressing for most of us, whether such changes will develop if people engage in moderate, less draining workouts, have been unclear. So for the new study, which was published this month in Medicine & Science in Sports & Exercise, researchers at the University of New South Wales and Neuroscience Research Australia, both in Sydney, recruited 12 young and healthy but inactive adults who expressed interest in exercising, and another 12 who were similar in age and activity levels but preferred not to exercise. They then brought all of them into the lab to determine how they reacted to pain. Pain response is highly individual and depends on our pain threshold, which is the point at which we start to feel pain, and pain tolerance, or the amount of time that we can withstand the aching, before we cease doing whatever is causing it. © 2014 The New York Times Company
Keyword: Pain & Touch
Link ID: 19952 - Posted: 08.13.2014
|By Tori Rodriguez and Victoria Stern A growing number of people are seeking alternatives to antidepressant medications, and new research suggests that acupuncture could be a promising option. One new study found the traditional Chinese practice to be as effective as antidepressants, and a different study found that acupuncture may help treat the medications' side effects. In acupuncture, a practitioner inserts needles into the skin at points of the body thought to correspond with specific organs (right). Western research suggests the needles may activate natural painkillers in the brain; in traditional Chinese medicine, the process is believed to improve functioning by correcting energy blocks or imbalances in the organs. A study published last fall in the Journal of Alternative and Complementary Medicine found that electroacupuncture—in which a mild electric current is transmitted through the needles—was just as effective as fluoxetine (the generic name of Prozac) in reducing symptoms of depression. For six weeks, patients underwent either electroacupuncture five times weekly or a standard daily dose of fluoxetine. The researchers, the majority of whom specialize in traditional Chinese medicine, assessed participants' symptoms every two weeks and tracked their levels of glial cell line–derived neurotrophic factor (GDNF), a neuroprotective protein. Previous studies have found lower amounts of GDNF among patients with major depressive disorder, and in other research levels of the protein rose after treatment with antidepressant medication. © 2014 Scientific American,
Link ID: 19920 - Posted: 08.06.2014
By Sandra G. Boodman At first the rash didn’t bother her, said Julia Omiatek, recalling the itchy red bumps that suddenly appeared one day on her palm, near the base of her first and third fingers. It was January 2013 — the dead of winter in Columbus, Ohio — so when the area reddened and cracked a few weeks later, she assumed her problem was simply dry skin and slathered on some cream. Omiatek, then 35, had little time to ponder the origin of her problem. An occupational therapist who works with adult patients, she was also raising two children younger than 3. A few weeks later when her lips swelled and the rash appeared on her face, she decided it was time to consult her dermatologist. Skin problems were nothing new; Omiatek was so allergic to nickel that her mother had had to sew cloth inside her onesies to prevent the metal snaps from touching her skin and causing a painful irritation. Over the years she had learned to avoid nickel and contend with occasional, inexplicable rashes that seemed to clear up when she used Elidel, a prescription cream that treats eczema. But this time the perpetually itchy rash didn’t go away, no matter what she did. Over the course of 11 months, she saw four doctors, three of whom said they didn’t know what was causing the stubborn eruption that eluded numerous tests. The fourth specialist took one look at her hand and figured it out. “The location was a tip-off,” said Matthew Zirwas, an assistant professor of dermatology at the Ohio State University Wexner Medical Center who specializes in treating unexplained rashes. Omiatek’s case was considerably less severe than that of many of the approximately 300 other patients he has treated for the same problem.
Keyword: Pain & Touch
Link ID: 19900 - Posted: 07.30.2014
By Janice Lynch Schuster I have never been one to visit a doctor regularly. Even though I had accumulated my share of problems by age 50— arthritic knees, poor hearing — I considered myself to be among the mostly well. But 19 months ago I developed a perplexing problem that forced me to become not only a regular patient but also one of the millions of Americans with chronic pain who struggle to find relief, in part through treatment with opioids. The trouble began with a terrible and persistent pain in my tongue. It alternately throbbed and burned, and it often hurt to eat or speak. The flesh looked red and irritated, and no amount of Orajel or Sensodyne relieved it. My doctor suggested I see my dentist; my dentist referred me to an oral surgeon. The surgeon thought the problem was caused by my being “tongue-tied,” a typically harmless condition in which the little piece of tissue under the tongue, called the frenulum, is too short. It seems I have always had this condition but had never noticed, because it hadn’t affected my ability to eat or speak. Now things had changed. The doctor recommended a frenectomy, a procedure to remove the frenulum and relieve tension on the tongue. “Just a snip,” he promised. It sounded trivial, and I was eager to be done with it. Although I make a living writing about health care, I didn’t even bother to do a Web search on the procedure. It never occurred to me that “a snip” might entail some risks. I trusted the oral surgeon.
Keyword: Pain & Touch
Link ID: 19871 - Posted: 07.23.2014
James Gorman All moving animals do their best to avoid running into things. And most living things follow a tried and true strategy — Watch where you’re going! Flying and swimming animals both have to cope with some complications that walkers, jumpers and gallopers don’t confront. Not only do they have to navigate in three dimensions, but they also cope with varying air and water flow. Beyond that, they often do so without the same references points and landmarks we have on the ground. Christine Scholtyssek of Lund University in Sweden, and colleagues decided to compare how two species in different mediums, air and water, which pose similar problems, reacted to apparent obstacles as they were moving. What they found, and reported in Biology Letters in May, was that the two species they examined — bumblebees and zebra fish — have very different strategies. It was known that the bees’ navigation depended on optic flow, which is something like the sensation of watching telephone poles speed past from a seat on a moving train. They tend to fly away from apparent obstacles as they approach them. The question was whether fish would do something similar. So, in order to give both animals the same test, Dr. Scholtyssek and her colleagues devised an apparatus that could contain air or water. When one wall had vertical stripes and the other horizontal, the bees, not surprisingly, flew away from the vertical stripes, which would have appeared as one emerging obstacle after another as the bees flew past. Horizontal stripes don’t change as a creature moves past, so they provide no reference for speed or progress. The fish, however, swam closer to the vertical stripes, which wasn’t expected. “It is surprising that although fish and bees have the same challenge, moving with or against streams, they do not use the same mechanisms,” Dr. Scholtyssek said. © 2014 The New York Times Company
Keyword: Animal Migration
Link ID: 19778 - Posted: 07.01.2014
By Lori Aratani The placebo effect — the idea that a treatment works because a patient believes it does — has long been a footnote to the work of finding ways to counteract disease. Some physicians have dismissed placebos as mere hokum, a trick of the mind. But researchers have found that in some people, placebos elicit similar responses in the brain to actual drug treatments. In one experiment, researchers using a PET scanner found that the brain activity in test subjects who received placebos and reported less pain mirrored that of those who received actual treatment for their pain. As Erik Vance writes in “Why Nothing Works,” published in the July/August 2014 issue of Discover magazine, the work suggests we possess an “inner pharmacy” of some sort that, if harnessed correctly, could be used as a complement to traditional treatments. But as Vance’s overview of recent research on the topic shows, it’s complicated. A placebo’s impact is not universal. Certain individuals — and certain conditions (pain and depression, for example) — seem to respond better than others to placebos. Researchers think that something in a person’s physiological makeup makes him more sensitive to placebos, while others feel little or no impact. There are ethical considerations, too, since it’s considered wrong to mislead volunteers participating in a study. But there are ways to navigate this thicket. In one small study, researchers gave placebos to a group of people with irritable bowel syndrome — after telling them that the pills were just placebos; a second group received no treatment. Surprisingly, many more of those who received the placebos reported improvements in their symptoms than did people in the no-treatment group.
Migraines have been diagnosed in about eight per cent of Canadians, a quarter or more of whom say the severe headaches impact day-to-day life such as getting a good night’s sleep or driving, Statistics Canada says. The federal agency on Wednesday released its first report on the prevalence of migraine, saying an estimated 2.7 million Canadians, or 8.3 per cent, reported they had been diagnosed with the severe headaches in 2010-2011. Chronic migraines are frequent, severe, pulsating headaches accompanied by nausea, vomiting, and sensitivity to light and sound. "I think the key finding that was quite interesting was the impact of migraine," said report author Pamela Ramage-Morin, a senior analyst in Ottawa. "For three-quarters to say that it had an impact on their getting a good night sleep, over half said it prevented them from driving on some occasions, even people feeling left out of things because of their condition. There's some social isolation that could be occurring. It may be limiting on people's education and employment opportunities. That can have a long-term effect." The sleep findings are important given lack of sleep can impact other aspects of life, Ramage-Morin said, noting how the effects can extend beyond the individual to the larger community. For both men and women surveyed, migraines were most common at ages 30 to 49, a group represents 12 per cent of the population and the prime working years. © CBC 2014
Keyword: Pain & Touch
Link ID: 19745 - Posted: 06.19.2014
Haroon Siddique The forehead and fingertips are the most sensitive parts to pain, according to the first map created by scientists of how the ability to feel pain varies across the human body. It is hoped that the study, in which volunteers had pain inflicted without touching them, could help the estimated 10 million people in the UK who suffer from chronic pain by allowing physicians to use lasers to monitor nerve damage across the body. This would offer a quantitative way to monitor the progression or regression of a condition. Lead author Dr Flavia Mancini, of the UCL Institute of Cognitive Neuroscience, said: "Acuity for touch has been known for more than a century, and tested daily in neurology to assess the state of sensory nerves on the body. It is striking that until now nobody had done the same for pain." In the study, a pair of lasers were used to cause brief sensation of pinprick pain to 26 blindfolded healthy volunteers on various parts of their body without any touch, in order to define our ability to identify where it hurts, known as "spatial acuity". Sometimes only one laser would be activated, and sometimes both. The participants were asked whether they felt one sting or two, at varying distances between the two beams and researchers recorded the minimum distance between the beams at which people were able to accurately say whether it was one sting or two. © 2014 Guardian News and Media Limited
Keyword: Pain & Touch
Link ID: 19708 - Posted: 06.07.2014
Jessica Morrison Bees, like birds and butterflies, use the Sun as a compass for navigation, whereas mammals typically find their way by remembering familiar landmarks on a continuous mental map. However, the latest research suggests that bees also use this type of map, despite their much smaller brain size. The work adds a new dimension to complex bee-navigation abilities that have long captivated researchers. “The surprise comes for many people that such a tiny little brain is able to form such a rich memory described as a cognitive map,” says co-author Randolf Menzel, a neurobiologist at the Free University of Berlin. The research by Menzel and his team, published today in the Proceedings of the National Academy of Sciences1, demonstrates that bees can find their way back to their hives without relying solely on the Sun. Instead, they seem to use a 'cognitive map' that is made up of memorized landscape snapshots that direct them home. The cognitive map used by mammals is thought to originate in the brain’s hippocampus. Humans employ such maps on a daily basis; for example, even in a windowless office, many people can point towards their home, orienting themselves in space based on knowledge of their location relative to the outside world. “They can point to their home generally even though they can’t see it, even along a path through a wall that they haven’t travelled,” explains Fred Dyer, a behavioural biologist at Michigan State University in East Lansing, who was not involved in the research. The study authors argue that bees can do something similar, albeit on a much more rudimentary level. © 2014 Nature Publishing Group
Keyword: Animal Migration
Link ID: 19684 - Posted: 06.03.2014
|By Bret Stetka Skepticism around fibromyalgia stemmed in part from an elusive organic explanation. Symptoms appeared to arise out of nowhere, which didn't make any sense to empirically minded physicians. “I, too, have been assigned months of futility, long and weary nights of misery. When I go to bed, I think,`When will it be morning?' But the night drags on, and I toss till dawn...Depression haunts my days. My weary nights are filled with pain as though something were relentlessly gnawing at my bones.” Job suffered badly. And his Old Testament woes are considered by many to be one of the earliest descriptions of fibromyalgia, a painful, puzzling disorder that still has experts bickering and patients frustrated, bereft of relief. The Bible isn't exactly a paragon of medical accuracy, but Job’s ailment does sound an awful lot like the modern interpretation of fibromyalgia. The classic diffuse pain, aches and discomfort aren’t the half of it; depression, fatigue, stiffness, sleep loss and generally just feeling really bad are common too. Fibromyalgia patients — 2 percent to 8 percent of the population — have also endured decades of dismissals that it's all in their head — a psychosomatic conjuring, a failure of constitution. Skepticism around fibromyalgia stemmed in part from an elusive organic explanation. Symptoms appeared to arise out of nowhere, which didn't make any sense to empirically minded physicians. But over the past two decades, research has brought clinicians closer to deciphering this mysterious pain state, once thought muscular in nature, now known to be neurologic. Based on this recent work a new article in the Journal of the American Medical Association by chronic pain expert Dr. Daniel Clauw brings us up to speed on the understanding, diagnosis and management of fibromyalgia circa 2014. And the outlook for patients is rosier than you might expect given the condition’s perplexing reputation. © 2014 Scientific American
By C. CLAIBORNE RAY Q. WHY WOULD A PAIN MEDICATION LOSE ITS EFFICACY AFTER WORKING WELL FOR SEVERAL YEARS? A. The mechanism is complex, said Dr. Shakil Ahmed, a pain medicine specialist at NewYork-Presbyterian Hospital/Weill Cornell Medical Center. “It is due to a phenomenon called tolerance,” in which there is a decrease in response over time to repeated exposures of the body to pain medication, he said. “This might be due to alteration in the way the body disposes of the medication,” Dr. Ahmed suggested. Or it could occur because drug interactions or bodily changes add a substance that induces an enzyme responsible for disposing of the drug. Another explanation is that long-term administration of pain medications results in a reduction of the number of target drug receptors or a drop in their responsiveness, and in desensitization to the pain medication in question. There is also an increase in the function of other nervous system receptors, called NMDA receptors , which may lead to the development of the tolerance, Dr. Ahmed said. Dr. Ahmed’s practice and research include several alternatives to conventional drug treatment for pain, including spinal cord stimulation, use of radio frequency to interrupt the nerve pathways of pain, delivery of pain medication with a pump directly to the space around the spinal cord, and non-invasive laser therapy. © 2014 The New York Times Company
Keyword: Pain & Touch
Link ID: 19666 - Posted: 05.28.2014