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Hypersensitivity to Non-Painful Events may be Part of Pathology in Fibromyalgia

by Anil Golani on  August 8, 2015 at 2:03 PM Health In Focus   - G J E 4
A new research conducted showed that patients suffering from fibromyalgia are hypersensitive to non-painful events. This was evident from the brain scan images that showed reduced activation in its primary sensory regions and augmented activation in its sensory integration areas.
 Hypersensitivity to Non-Painful Events may be Part of Pathology in Fibromyalgia
Hypersensitivity to Non-Painful Events may be Part of Pathology in Fibromyalgia
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This important finding was published in Arthritis and Rheumatology journal of American College of Rheumatology (ACR). It is further indicated that these brain abnormalities in response to non-painful sensory stimulation may lead to greater repulsiveness that patients experience in reply to every day visual, auditory and tactile stimulation.

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Fibromyalgia, a chronic, musculoskeletal syndrome is identified by pervasive pain and affects about 2% of world population. As per the ACR, there are 5 million people in the US alone known to have fibromyalgia and is more seen in women than men. Earlier studies reported that patients with fibromyalgia have reduced tolerance towards normal sensory stimulation (auditory, visual, olfactory, and tactile), besides to greater pain sensitivity.

The present study involved 35 women patients having fibromyalgia and 25 healthy age matched controls. Functional magnetic resonance imaging (fMRI) was used as a diagnostic test for assessing brain response to sensory stimulation. Average duration of the disease of patients in this study was 7 years with a mean age of 47.

As per the study, patients showed greater level of disagreeableness in reply to multisensory stimulation in daily life events. In addition, fMRI test presented abridged activation in sensory integration regions. These kind of brain abnormalities facilitated the increased disagreeableness to visual, auditory and tactile stimulation that patients conveyed experiencing in daily life.

In a statement issued by Dr. Marina López-Solā, a lead author from the Institute of Cognitive Science, University of Colorado Boulder stated that their study provides new evidence on patients suffering from fibromyalgia. These patients have altered central processing in regards to multisensory stimulation, that is linked to core fibromyalgia symptoms and which may be a part of disease pathology. This critical finding of decreased cortical activation in the visual and auditory brain areas of patients may provide new targets for neuro-stimulation treatments in fibromyalgia.

Fibromyalgia patients show higher level of pain after sensory stimulation, as evident tissue damage is normally lacking. This kind of extravagant pain could be also explained by hyperexcitability to central nervous system. A case control study involving 22 fibromyalgia patients was done to evaluate a spinal reflex, for understanding the excitability state of spinal cord neurons. Two types of transcutaneous electrical stimulation (single stimuli and 5 repeated stimuli at 2 hertz) of the sural nerve was applied on these patients. Electromyography was then recorded from biceps femoral muscle. Primary outcome measure was to check minimum current intensity causing a spinal reflex (reflex threshold). Spinal reflexes were comparatively lower than the control group after both single (P=0.001) and repeated stimulation (P= 0.046). This proved spinal cord hyperexcitability in fibromyalgia patients, which can cause inflated pain after low intensity nociceptive or innocuous peripheral stimulation. Spinal hypersensitivity can therefore explain to some extent, pain in absence of detectable damage to the tissue.

Hypersensitivity to nonnoxious sensory stimuli could also contribute to higher stress levels in daily life. To evaluate this a descriptive study was done on 27 women with fibromyalgia, which were compared with women with rheumatoid arthritis (n=28) and healthy pain-free women as controls (n=28). The participants in the study were asked if they were sensitive to sensations that had no effect on other people or they avoid activities or environments that can affect them. Significantly increased sensory sensitivities to both somatic (tactile) and nonsomatic (like auditory and olfactory) sensory stimuli was recorded in fibromyalgia patients as compared to rheumatoid arthritis and control groups. However, rheumatoid arthritis and control groups exhibited no difference in reported hypersensitivities. Hypersensitivity to nonnoxious sensory stimuli in daily life could thus experience an increased stress.

What is Hypersensitivity?

It is a condition in which there is an inflated immune response towards external stimuli. People suffering from fibromyalgia are likely to have intense and unpleasant response to things (bright light, loud noise, strong smell, and rough texture and body pressure) that affects senses. The unpleasant response may also be towards certain foods and chemicals. According to research conducted, pain in fibromyalgia is caused by malfunction, in the way body processes these pain. End result of this malfunction leads to hypersensitivity to stimuli, which are not really painful. Brain scans of people having fibromyalgia illustrates non-painful stimuli like sound and touch, inversely than the normal people. This therefore explains why fibromyalgia patients often complain of hypersensitivity towards sensations in their daily life.

What is Fibromyalgia?

Fibromyalgia is considered a disorder related to stress due to frequent onset and worsening of pain symptoms. It is a baffling condition, which predominantly affects women more than men and characterised by unexplained, chronic musculoskeletal pain. The disorder is also linked with increased fatigue, disturbances in sleep and elevated levels of stress reactivity and anxiety.

As no clear cause and effect relationship is established between brain and chemical activity (neurotransmitters) and pain or sensory perception. It could be that the disorder results due to effect of pain and stress on the central nervous system (CNS) that leads to changes in brain circuitry. This has clearly been depicted in brain imaging studies, which shows CNS disturbances occurring in response to brain stimulation. Abnormal increase in blood flow have also been indicated in brain scans that defines intensity of pain. A decreased blood flow is linked with emotional response to pain.

The origin and underlying mechanisms of this disorder is not yet well portrayed.

Managing Hypersensitivity

Fibromyalgia can affect senses at all levels and make life more complex. Managing hypersensitivity is the best way and avoid things that leads to botheration. Measures by which intensity and severity of symptoms can be reduced are: avoiding triggers, controlling environment, reducing stress, eating well to improve immune system and educating family and friends.

Conclusion

People suffering from fibromyalgia suffer from pain that is unbearable. Research indicates that fibromyalgia can be caused by a problem in how body processes pain, or more definitively, a hypersensitivity to stimuli which is non-painful. If things in daily life can cause sensory overload, it can only lead to struggle.

References

1. Hypersensitivity to Non-Painful Events May Be Part of Pathology in Fibromyalgia. Arthritis & Rheumatology. Updated September 15, 2014. Available from: http://www.wiley.com/WileyCDA/PressRelease/pressReleaseId-112105.html

2. Banic B, et.al. Evidence for spinal cord hypersensitivity in chronic pain after whiplash injury and in fibromyalgia.Pain. 2004 Jan; 107(1-2):7-15.

3. Wilbarger JL, Cook DB. Multisensory Hypersensitivity in Women With Fibromyalgia: Implications for Well Being and Intervention. Arch Phys Med Rehabil. 2011 Apr; 92(4): 653-656.

4. Fibromyalgia and Sensory Perception. Accessed July 29 2015. Available from: http://www.fibromyalgia-symptoms.org/heightened-sensory-perception-fibro.html

Source: Medindia
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