Our regular Friday roundup of research abstracts that have not already appeared on the website.
The science of fibromyalgia.
Clauw DJ, Arnold LM, McCarberg BH; FibroCollaborative.
Department of Anesthesiology, University of Michigan, Ann Arbor, MI 48106, USA. firstname.lastname@example.org
Fibromyalgia (FM) is a common chronic widespread pain disorder. Our understanding of FM has increased substantially in recent years with extensive research suggesting a neurogenic origin for the most prominent symptom of FM, chronic widespread pain.
Neurochemical imbalances in the central nervous system are associated with central amplification of pain perception characterized by allodynia (a heightened sensitivity to stimuli that are not normally painful) and hyperalgesia (an increased response to painful stimuli). Despite this increased awareness and understanding, FM remains undiagnosed in an estimated 75% of people with the disorder.
Clinicians could more effectively diagnose and manage FM if they better understood its underlying mechanisms. Fibromyalgia is a disorder of pain processing. Evidence suggests that both the ascending and descending pain pathways operate abnormally, resulting in central amplification of pain signals, analogous to the “volume control setting” being turned up too high. Patients with FM also exhibit changes in the levels of neurotransmitters that cause augmented central nervous system pain processing; levels of several neurotransmitters that facilitate pain transmission are elevated in the cerebrospinal fluid and brain, and levels of several neurotransmitters known to inhibit pain transmission are decreased.
Pharmacological agents that act centrally in ascending and/or descending pain processing pathways, such as medications with approved indications for FM, are effective in many patients with FM as well as other conditions involving central pain amplification. Research is ongoing to determine the role of analogous central nervous system factors in the other cardinal symptoms of FM, such as fatigue, nonrestorative sleep, and cognitive dysfunction.
PMID: 21878603 [PubMed – indexed for MEDLINE] FULL TEXT available on payment of US$11 at the Mayo Clinic Proceedings website.
BMC Public Health (open access online journal), 27 May 2011, 11:402
The functional status and well being of people with myalgic encephalomyelitis/chronic fatigue syndrome and their carers.
Nacul LC, Lacerda EM, Campion P, Pheby D, Drachler Mde L, Leite JC, Poland F, Howe A, Fayyaz S, Molokhia M.
Department of Nutrition and Public Health Interventions Research, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. email@example.com
Diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome or ME/CFS is largely based on clinical history, and exclusion of identifiable causes of chronic fatigue. Characterization of cases and the impact of interventions have been limited due to clinical heterogeneity and a lack of reliable biomarkers for diagnosis and outcome measures. People with ME/CFS (PWME) often report high levels of disability, which are difficult to measure objectively. The well being of family members and those who care for PWME are also likely to be affected. This study aimed to investigate the functional status and well being of PWME and their lay carers, and to compare them with people with other chronic conditions.
We used a cross sectional design to study 170 people aged between 18 and 64 years with well characterized ME/CFS, and 44 carers, using SF-36 v2™. Mean physical and mental domains scores (scales and component summaries) were calculated and compared internally and externally with reference standards for the general population and for population groups with 10 chronic diseases.
SF-36 scores in PWME were significantly reduced, especially within the physical domain (mean norm-based Physical Component Summary (PCS) score = 26.8), but also within the mental domain (mean norm-based score for Mental Component Summary (MCS) = 34.1). The lowest and highest scale scores were for “Role-Physical” (mean = 25.4) and “Mental Health” (mean = 36.7) respectively. All scores were in general lower than those for the general population and diseased-specific norms for other diseases. Carers of those with ME/CFS tended to have low scores in relation to population norms, particularly within the mental domain (mean = 45.4).
ME/CFS is disabling and has a greater impact on functional status and well being than other chronic diseases such as cancer. The emotional burden of ME/CFS is felt by lay carers as well as by people with ME/CFS. We suggest the use of generic instruments such as SF-36, in combination of other objective outcome measurements, to describe patients and assess treatments.
PMID: 21619607 [PubMed – indexed for MEDLINE]