A Psychophysical Study of Auditory and Pressure Sensitivity in Patients With Fibromyalgia and Healthy Controls
Chronic Pain and Fatigue Research Center, Department of Internal Medicine, Division of Rheumatology, University of Michigan, Ann Arbor, Michigan 48108, USA. Journal of Pain
(Impact Factor: 4.01).
05/2008; 9(5):417-22. DOI: 10.1016/j.jpain.2007.12.006
Fibromyalgia (FM) is characterized by widespread tenderness. Studies have also reported that persons with FM are sensitive to other stimuli, such as auditory tones. We hypothesized that subjects with FM would display greater sensitivity to both pressure and auditory tones and report greater sensitivity to sounds encountered in daily activities. FM subjects (n = 30) and healthy control subjects (n = 28) were administered auditory tones and pressure using the same psychophysical methods to deliver the stimuli and a common way of scaling responses. Subjects were also administered a self-report questionnaire regarding sensitivity to everyday sounds. Participants with FM displayed significantly greater sensitivity to all levels of auditory stimulation (Ps < .05). The magnitude of difference between FM patients' lowered auditory sensitivity (relative to control subjects) was similar to that seen with pressure, and pressure and auditory ratings were significantly correlated in both control subjects and subjects with FM. FM patients also were more sensitive to everyday sounds (t = 8.65, P < .001). These findings support that FM is associated with a global central nervous system augmentation in sensory processing. Further research is needed to examine the neural substrates associated with this abnormality and its role in the etiology and maintenance of FM. PERSPECTIVE: Muscle tenderness is the hallmark of FM, but the findings of this study and others suggest that persons with FM display sensitivity to a number of sensory stimuli. These findings suggest that FM is associated with a global central nervous system augmentation of sensory information. These findings may also help to explain why persons with FM display a number of comorbid physical symptoms other than pain.
Available from: Marina López-Solà
- "In the current study, we have shown that SII is functionally connected with the major sensory cortical domains in healthy subjects, and that the functional connectivity of SII is reduced in fibromyalgia patients. Abnormal response to nonsomatic (visual, auditory, and olfactory) sensory stimulation has been reported in clinical and experimental studies in fibromyalgia     , which together suggest a poor integration of general sensory information. "
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ABSTRACT: Fibromyalgia typically presents with spontaneous body pain with no apparent cause and is considered pathophysiologically to be a functional disorder of somatosensory processing. We have investigated potential associations between the degree of self-reported clinical pain and resting-state brain functional connectivity at different levels of putative somatosensory integration. Resting-state functional MRI was obtained in 40 women with fibromyalgia and 36 control subjects. A combination of functional connectivity-based measurements were used to assess (i) the basic pain signal modulation system at the level of the periaqueductal gray (PAG), (ii) the sensory cortex with an emphasis on the parietal operculum/secondary somatosensory cortex (SII) and (iii) the connectivity of these regions with the self-referential "default mode" network. Compared with control subjects, a reduction of functional connectivity was identified across the three levels of neural processing, each showing a significant and complementary correlation with the degree of clinical pain. Specifically, self-reported pain in fibromyalgia patients correlated with (i) reduced connectivity between PAG and anterior insula, (ii) reduced connectivity between SII and primary somatosensory, visual and auditory cortices, and (iii) increased connectivity between SII and the default mode network. The results confirm previous research demonstrating abnormal functional connectivity in fibromyalgia and show that alterations at different levels of sensory processing may contribute to account for clinical pain. Importantly, reduced functional connectivity extended beyond the somatosensory domain and implicated visual and auditory sensory modalities. Overall this study suggests that a general weakening of sensory integration underlies clinical pain in fibromyalgia.
- "A mechanical regulator, in series with the electronic one, ensured that, in the event of a computer or electronic failure (which never occurred), excessive force would not inadvertently be applied to the finger. The design of this instrument was inspired by the hydraulic thumbnail stimulator developed by Gracely and colleagues (Geisser et al., 2008; Petzke, Clauw, Ambrose, Khine, & Gracely, 2003), but differed in the use of compressed air rather than water, and in the type of contactor and site of application of the noxious pressure. The stimulator was designed, built, and programmed by Michael Young and Oliver Monbureau of the UNC School of Dentistry. "
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ABSTRACT: Cutaneous vibration is able to reduce both clinical and experimental pain, an effect called vibratory analgesia. The traditional explanation for this phenomenon is that it is mediated by lateral inhibition at the segmental (spinal cord) level, in pain-coding cells with center-surround receptive fields. We evaluated this hypothesis by testing for two signs of lateral inhibition-namely (1) an effect of the distance between the noxious and vibratory stimuli and (2) an inhibition-induced shift in the perceived location of the noxious stimulus. The experiment involved continuous ratings of the pain from pressure applied to the back of a finger, alone and in the presence of vibration delivered to sites on the palm of the hand both near to and far from the site of painful stimulation. Neither prediction of the segmental hypothesis was supported. There was also little evidence to support the view (widely held by subjects) that distraction is the primary mechanism of vibratory analgesia. The results are more consistent with a recently proposed theory of interactions between two cortical areas that are primarily involved in coding pain and touch, respectively.
Available from: Jean Decety
- "Prior to performance of the fMRI experiment, pain threshold was assessed using a method described previously by Geisser et al., 2008. Pain stimuli were applied to the left thumbnail for five minutes using a hard rubber probe measuring 1 cm 2 . "
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ABSTRACT: Chronic widespread pain is a hallmark of fibromyalgia (FM). Previous neuroimaging studies have reported that the pain neuro-matrix in patients with FM showed augmented activation in response to actual pain. However, the effect of observing pain in others among patients with FM remains poorly understood. Both healthy female control subjects (n=24) and female patients with FM (n=23) underwent functional magnetic resonance imaging while observing a series of color pictures depicting others' hands and feet being injured, and a matched set of control pictures that did not show any painful events. Compared with healthy subjects, patients with FM showed a smaller neural response to pain-related versus neutral stimuli in several neural regions, including the thalamus, anterior cingulate cortex, dorsolateral prefrontal cortex, pre- and post-central gyrus, and supplementary motor area. In contrast to augmented pain processing in response to actual experimental pain, patients with FM did not show an enhanced pain response but generally showed lesser activation in cortical regions known to play a role in processing of pain. These hemodynamic alterations observed in patients with FM suggest that patients with chronic pain may empathize less with others in pain, possibly in order to lessen arousal and aversive self-oriented emotions.
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