Are Fibromyalgia Patients More Sensitive to Sound?

Fibromyalgia is characterized by widespread tenderness, including sensitivity to touch. But do fibromyalgia patients also more sensitive to other stimuli, such as sound? In their article A Psychophysical Study of Auditory and Pressure Sensitivity in
Patients With Fibromyalgia and Healthy Controls, researchers at the Chronic Pain and Fatigue Research Center at the University of Michigan, Ann Arbor, discuss their recent research into this question [Journal of Pain, 2008 Feb 14]. Because past studies reported that people with fibromyalgia are sensitive to other stimuli, such as auditory tones, they hypothesized "that subjects with [fibromyalgia] would display greater sensitivity to both pressure and auditory tones and report greater sensitivity to sounds encountered in daily activities" and that fibromyalgia involves a global central nervous system amplification of sensory information.

The study administered auditory tones and physical pressure to 30 fibromyalgia patients and 28 healthy controls. They used the same psychophysical methods to deliver the stimuli and a similar way of scaling responses. Subjects also completed a self-report questionnaire regarding sensitivity to everyday sounds.

Participants with [fibromyalgia] displayed significantly greater sensitivity to all levels of auditory stimulation (Ps < .05). The magnitude of difference between [fibromyalgia] 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 [fibromyalgia]... patients also were more sensitive to everyday sounds (t = 8.65, P < .001).

The research team suggests that these findings support the concept that fibromyalgia is "associated with a global central nervous system augmentation in sensory processing." They suggest further research to examine which neural substrates are associated with this abnormality of sensory processing and its role in the etiology of fibromyalgia. The research findings may also help explain why fibromyalgia patients frequently display a number of other physical symptoms besides pain.

Cost-Effectiveness of Aquatic Training for Women with Fibromyalgia

The results of a randomized controlled trial were published in the most recent issue of Arthritis Research and Therapy [2008 Feb 22;10(1):R24]. Knowing that physical therapy in warm water has been shown to be highly effective for fibromyalgia patients, the study was designed to evaluate whether it is an efficient investment for patients or health care managers. The research aimed to "assess the cost-utility of adding an aquatic exercise programme to the usual care of women with fibromyalgia."

The study evaluated costs to the health care system and to society. It included 33 participants, all women with fibromyalgia. Seventeen participants were randomly assigned to an experimental group and sixteen to a control group.

The intervention in the experimental group consisted of a one-hour, supervised, water-based exercise sessions, three times per week for 8 months. The main outcome measures were the health care costs and the number of quality-adjusted life-years (QALYs) using the time trade-off elicitation technique from the EQ-5D. Sensitivity analyses was performed for variations in the staff salary, number of women attending sessions and time spent going to the pool. The cost-effectiveness acceptability curves were created using a non-parametric bootstrap technique.

The mean incremental treatment costs for fibromyalgia patients participating in this aquatic therapy program exceeded those for usual care per patient by 517 Euros for health care costs and 1032 Euros for societal costs. The researchers conclude that "the addition of an aquatic exercise programme to the usual care for fibromyalgia in women, is cost-effective in terms of both health care costs and societal costs." However, the fact that appropriate facilities (warm water pools) are often far from patients' homes and cannot accommodate many patients per session is something that must be considered before investing in such a program.

Study Suggests Fibromyalgia Pain is Neuropathic

In the March issue of the journal Pain Medicine [2008 Mar;9(2):149-160] researchers at three institutions in Florida conducted a study to determine whether the neuropathic pain scale (NPS) can be used to classify chronic pain patients (CPPs) as having primarily neuropathic vs non-neuropathic pain, as well as to determine whether there is a cut-off score that can be used reliably to make this distinction between types of pain. This study evaluated 305 chronic pain patients (CPPs) admitted to The Rosomoff Pain Center (Miami, FL). All were administered the NPS, a diagnostic tool designed to assess the distinct pain qualities associated with neuropathic pain, and were given a diagnosis on the basis of a physical examination and all available test results.

Using patients known to have neuropathic or non-neuropathic pain conditions as a reference, esearchers were able to derive "an NPS cut-off score above which CPPs would be classified as having neuropathic pain." Patients who had diagnoses of myofascial pain syndromes, spinal stenosis, epidural fibrosis, fibromyalgia, complex regional pain syndromes, and failed back surgery syndrome, a predicted NPS score was calculated and compared with the cut-off score.

The NPS appeared to be able to separate CPPs into neuropathic pain vs non-neuropathic pain subtypes. The cut-off score the researchers derived was 5.53 on the NPS. Myofascial pain syndrome and spinal stenosis had scores lower than this cut-off score at 3.81 and 4.26, respectively - Therefore they did not meet the criteria for neuropathic pain. Epidural fibrosis, fibromyalgia, complex regional pain syndromes, and failed back surgery syndrome had predictive scores higher than the cut-off score at 6.15, 6.35, 6.87, 9.34, and 7.19, respectively. Thus, these syndromes did meet the qualifications for neuropathic pain according to this study's criteria. The researchers conclude that the NPS does appear to be able to discriminate between patients experiencing neuropathic and non-neuropathic pain.

A debate is currently raging as to whether diagnoses, such as fibromyalgia and complex regional pain syndrome 1, can be classified as neuropathic. Our NPS cut-off score results suggest that these diagnoses may have a neuropathic pain component. The reliability and validity of our NPS method will need to be tested further in other neuropathic pain models, such as diabetic peripheral neuropathic pain.

Immunological Changes in Fibromyalgia & Other Chronic Pain Conditions?

The newest issue of the medical journal Neuroimmunomodulation [2008 Feb 1;14(5):272-280] includes the results of a study conducted by Department of Anesthesiology of Ludwig Maximilians University, Munich, Germany. The study address immunological changes in chronic pain patients, specifically complex regional pain syndrome (CRPS) and fibromyalgia (FMS), both of which the researchers describe as "chronic pain syndromes occurring in highly stressed individuals."

Despite the known connection between the nervous system and immune cells, information on distribution of lymphocyte subsets under stress and pain conditions is limited. Lymphocytes are white blood cells that play a critical role in the body's defenses. They include T cells, B cells, and natural killer cells. They also modulate the activities of other cells.

The researchers performed a comparative study of 15 patients with CRPS, 22 patients with FMS and 37 age- and sex-matched healthy controls. Their aim was to investigate the influence of pain and stress on lymphocyte number, subpopulations and the Th1/Th2 cytokine ratio in T lymphocytes.

Lymphocyte numbers did not differ between the groups studied. However, when the subtypes of lymphocytes were studied using quantitative analyses, it became evident that there was "a significant reduction of cytotoxic CD8+ lymphocytes in both CRPS... and [fibromyalgia]... patients as compared with healthy controls. Additionally, CRPS patients were characterized by a lower percentage of IL-2-producing T cell subpopulations reflecting a diminished Th1 response in contrast to no changes in the Th2 cytokine profile."

The article concludes that future studies are necessary in order to answer "whether such immunological changes play a pathogenetic role in CRPS and [FMS] or merely reflect the consequences of a pain-induced neurohumoral stress response, and whether they contribute to immunosuppression in stressed chronic pain patients."

Effects of the Drug Pyridostigmine Along with Exercise in Treatment of Fibromyalgia

A subset of fibromyalgia patients are known to have a dysfunctional hypothalamic-pituitary-insulin-like growth factor 1 (IGF-1) axis, which is diagnosed by low blood serum levels of IGF-1 and a reduced growth hormone (GH) response to physiologic stimuli. There is evidence that the drug pyridostigmine (PYD) can improve the acute response of growth hormone to exercise in fibromyalgia patients. Researchers at Oregon Health & Science University in Portland, OR, conducted a 6-month randomized controlled trial of pyridostigmine in conjunction with exercise, in order to evaluate the effectiveness of this treatment on fibromyalgia treatment.

The purpose of this study was to evaluate the clinical effectiveness of 6 months of PYD and group exercise on [fibromyalgia] symptoms. The researchers randomized patients into one of four groups: PYD PYD plus exercise, PYD without exercise but with diet recall, placebo plus exercise, and placebo plus diet recall but no exercise. To assess the results of the treatments, they used the visual analog scale (VAS) score for pain, tender point count, and total myalgic score. They also used other secondary outcome measures including the Fibromyalgia Impact Questionnaire (FIQ) and scores for individual symptoms (fatigue, poor sleep, stiffness, and anxiety), as well as quality of life (QOL) evluation and level of physical fitness (lower body strength/endurance, upper and lower body flexibility, balance, and time on the treadmill).

A total of 165 [fibromyalgia] patients completed baseline measurements; 154 (93.3%) completed the study. The combination of PYD and exercise did not improve pain scores. PYD groups showed a significant improvement in sleep and anxiety in those who completed the study and in QOL in those who complied with the therapeutic regimen as compared with the placebo groups. Compared with the nonexercise groups, the 2 exercise groups demonstrated improvement in fatigue and fitness. PYD was generally well tolerated.

The research team concluded that "neither the combination of PYD plus supervised exercise nor either treatment alone yielded improvement in most fibromyalgia symptoms." However, they noted that pyridostigmine (PYD) did improve anxiety and sleep, and exercise improved fatigue and fitness. They speculate that pyridostigmine (PYD) "may have improved vagal tone, thus benefiting sleep and anxiety; this notion warrants further study."