IntroductionAt present, there is neither a laboratory test nor an imaging technique able to differentiate people with fibromyalgia (FM) from healthy controls. This lack of an objective biomarker has hampered FM recognition and research. Heart rate variability (HRV) analyses provide a quantitative marker of autonomic nervous system activity. Nighttime is a stable period in which most people are resting. Sleep is modulated by autonomic activity. Sleeping problems are prominent in FM. The objectives of this study are: 1) to explore different nocturnal HRV parameters as potential FM biomarkers and 2) to seek correlation between such HRV parameters and diverse FM symptoms.MethodsWe studied 22 women suffering from FM and 22 age-matched controls. All participants filled out several questionnaires related to FM symptoms. All participants used a Holter monitor over 24 hours while undertaking their routine activities during the day and while sleeping at their homes at night. Time-domain HRV parameters analyzed from 0000 to 0600 hours included, among others: mean normal-normal interbeat intervals (mean NN), standard deviation of the NN intervals (SDNN), and standard deviation of the successive NN differences (SDSD).ResultsNocturnal SDNN of less than 114 ms had the greatest predictive value to set apart patients from controls with an odds ratio of 13.6 (95% confidence interval: 3.9 to 47.8). In patients, decreased nighttime HRV markers indicative of sympathetic predominance had significant correlations with several FM symptoms: SDSD was associated with pain intensity (r = - 0.65, P = 0.001). SDNN correlated with constipation (r = - 0.53, P = 0.001), and mean NN with depression (r = - 0.53, P = 0.001). Controls displayed an opposite behavior. For them, increased nighttime SDNN correlated with Fibromyalgia Impact Questionnaire scores (r = 0.69, P = 0.001) and with other FM symptoms.ConclusionsNocturnal HRV indices indicative of sympathetic predominance are significantly different in FM women when compared to healthy individuals. In FM patients, these HRV parameters correlated with several symptoms including pain severity. Opposite associations were seen in controls. FM may not be just one end of a continuous spectrum of common symptoms. Nocturnal HRV analyses are potential FM biomarkers.

Objective. Fibromyalgia (FM) patients have signs of relentless sympathetic hyperactivity associated with hyporeactivity to stress. Adrenergic receptors (ARs) are parts of the sympathetic nervous system that are fundamental for maintenance of homeostasis. We undertook this study to correlate ␣-AR and ␤-AR gene polymorphisms with the presence of FM and with different domains of the FM syndrome as measured by the Fibromyalgia Impact Questionnaire (FIQ).Methods. We studied 78 Mexican FM patients and 48 age-matched controls as well as 78 Spanish FM patients and 71 controls. All subjects studied were women. Single-nucleotide polymorphisms (SNPs) of ␣ 1A -AR (rs574584, rs1383914, rs1048101, and rs573542), ␤ 2 -AR (rs1042713 and rs1042714), and ␤ 3 -AR (rs4994) were analyzed by 5 exonuclease TaqMan polymerase chain reaction. Polymorphic haplotypes were constructed after linkage disequilibrium analysis.Results. The ␤ 2 -AR AC haplotype was a risk factor for the presence of FM. This haplotype had an increased frequency in Mexican patients compared with Mexican controls (42.1% versus 30.5%; P ‫؍‬ 0.04). Similarly, 50.4% of Spanish patients had this haplotype compared with 40.0% of Spanish controls (P ‫؍‬ 0.05). In Spanish patients, the ␣ 1A -AR SNP rs1383914 was associated with the presence of FM (P ‫؍‬ 0.01), and the ␣ 1A -AR SNP rs1048101 was linked with FIQ disability (P ‫؍‬ 0.02). Mexican patients with the rs574584 GG genotype presented the highest FIQ score compared with Mexican patients with other genotypes (P ‫؍‬ 0.01), and in Mexicans SNP rs574584 was associated with FIQ morning stiffness (P ‫؍‬ 0.04) and with FIQ tiredness upon awakening (P ‫؍‬ 0.02).Conclusion. AR gene polymorphisms are related to the risk of developing FM and are also linked to different domains of the FM syndrome.

Background: A consistent line of investigation suggests that autonomic nervous system dysfunction may explain the multi-system features of fibromyalgia (FM); and that FM is a sympathetically maintained neuropathic pain syndrome. Dorsal root ganglia (DRG) are key sympathetic-nociceptive short-circuit sites. Sodium channels located in DRG (particularly Nav1.7) act as molecular gatekeepers for pain detection. Nav1.7 is encoded in gene SCN9A of chromosome 2q24.3 and is predominantly expressed in the DRG pain-sensing neurons and sympathetic ganglia neurons. Several SCN9A sodium channelopathies have been recognized as the cause of rare painful dysautonomic syndromes such as paroxysmal extreme pain disorder and primary erythromelalgia. The aim of this study was to search for an association between fibromyalgia and several SCN9A sodium channels gene polymorphisms. Methods: We studied 73 Mexican women suffering from FM and 48 age-matched women who considered themselves healthy. All participants filled out the Fibromyalgia Impact Questionnaire (FIQ). Genomic DNA from whole blood containing EDTA was extracted by standard techniques. The following SCN9A single-nucleotide polymorphisms (SNP) were determined by 5' exonuclease TaqMan assays: rs4371369; rs4387806; rs4453709; rs4597545; rs6746030; rs6754031; rs7607967; rs12620053; rs12994338; and rs13017637. Results: The frequency of the rs6754031 polymorphism was significantly different in both groups (P = 0.036) mostly due to an absence of the GG genotype in controls. Interestingly; patients with this rs6754031 GG genotype had higher FIQ scores (median = 80; percentile 25/75 = 69/88) than patients with the GT genotype (median = 63; percentile 25/75 = 58/73; P = 0.002) and the TT genotype (median = 71; percentile 25/75 = 64/77; P = 0.001). Conclusion: In this ethnic group; a disabling form of FM is associated to a particular SCN9A sodium channel gene variant. These preliminary results raise the possibility that some patients with severe FM may have a dorsal root ganglia sodium channelopathy.

Patients with FM have multiple nonpain symptoms related to different expressions of autonomic dysfunction. There is a correlation between a questionnaire that measures FM severity (FIQ) and an autonomic dysfunction questionnaire (COMPASS). Such correlation suggests that autonomic dysfunction is inherent to FM.

In this study, single and several combinations of bacterial DNA were identified in the synovial fluid of patients with long-term undifferentiated and definite juvenile onset SpA and adult onset SpA. Of relevance is that bacterial DNA corresponds to bacteria producing endemic disease in our population.