Patients with fibromyalgia show increased beta connectivity across distant networks and microstates alterations in resting-state electroencephalogram.

Fibromyalgia (FM) is a chronic condition characterized by widespread pain of unknown etiology associated with alterations in the central nervous system. Although previous studies demonstrated altered patterns of brain activity during pain processing in patients with FM, alterations in spontaneous brain oscillations, in terms of functional connectivity or microstates, have been barely explored so far. Here we recorded the EEG from 43 patients with FM and 51 healthy controls during open-eyes resting-state. We analyzed the functional connectivity between different brain networks computing the phase lag index after group Independent Component Analysis, and also performed an EEG microstates analysis. Patients with FM showed increased beta band connectivity between different brain networks and alterations in some microstates parameters (specifically lower occurrence and coverage of microstate class C). We speculate that the observed alterations in spontaneous EEG may suggest the dominance of endogenous top-down influences; this could be related to limited processing of novel external events and the deterioration of flexible behavior and cognitive control frequently reported for FM. These findings provide the first evidence of alterations in long-distance phase connectivity and microstate indices at rest, and represent progress towards the understanding of the pathophysiology of fibromyalgia and the identification of novel biomarkers for its diagnosis.

Evaluation of the accuracy of several symptoms and domains in distinguishing patients diagnosed with fibromyalgia from healthy controls.

OBJECTIVES: To assess the discriminative power of several symptoms and domains that may assist in the diagnosis of subjects with Fibromyalgia (FM). METHODS: 79 individuals with FM and 66 healthy controls participated in the study. The potential domains proposed by the American College of Rheumatology (ACR) criteria were considered (Wolfe et al., 1990). Binary logistic regression and area under a ROC curve (AUC) were used to rank the importance of the variables in distinguishing patients from pain-free controls. Z values were then calculated to compare the AUC values obtained for each variable with that which yielded the highest AUC (reference standard). For each measure, the cut-offs that maximise sensitivity and specificity were also calculated. RESULTS: The mean pressure pain threshold (PPT) yielded the highest discriminative power (AUC, 0.991) and was therefore chosen as the reference standard; considering an optimal cut- off ≤3.97, it correctly classified 95% of patients and 97% of controls. The discriminative powers of tender point count (cut-off ≥9), health-related quality of life (cut-off ≤63.27) and vitality (cut-off ≤46.97) were as good as that of the reference standard. Finally, items related to physical role and function, body pain, fatigue and memory loss showed adequate discriminative power, although slightly lower than that of the reference. CONCLUSIONS: In addition to pain, health-related quality of life and fatigue/vitality were confirmed as the best predictors of individuals with FM. The study findings indicate that tender point count and especially pressure pain threshold (measured with an algometer) continue to be key issues in the clinical assessment of subjects with FM relative to pain-free controls.

Low intensity magnetic field influences short-term memory: A study in a group of healthy students.

This study analyzes if an external magnetic stimulus (2 kHz and approximately 0.1 µT applied near frontal cortex) influences working memory, perception, binary decision, motor execution, and sustained attention in humans. A magnetic stimulus and a sham stimulus were applied to both sides of the head (frontal cortex close to temporal-parietal area) in young and healthy male test subjects (n = 65) while performing Sternberg's memory scanning task. There was a significant change in reaction time. Times recorded for perception, sustained attention, and motor execution were lower in exposed subjects (P < 0.01). However, time employed in binary decision increased for subjects exposed to magnetic fields. From results, it seems that a low intensity 2 kHz exposure modifies short-term working memory, as well as perception, binary decision, motor execution, and sustained attention.

Suicidality in chronic pain: predictors of suicidal ideation in fibromyalgia.

OBJECTIVES: Fibromyalgia (FM) has been associated with a higher prevalence of suicidal behavior. Nevertheless, much remains unknown about suicide risk factors for this chronic pain disorder. In the present study, the relationship of suicidal ideation in FM with a number of sociodemographic, clinical, and psychological variables was analyzed. METHODS: One hundred seventeen women with Fibromyalgia were assessed. The procedure included the exploration of sleep problems (Pittsburgh Sleep Quality Index), depression (Beck Depression Inventory [BDI]), health-related quality of life (SF-36 and Fibromyalgia Impact Questionnaire), the core symptoms of FM (visual analogue scales), and algometry of tender points. Suicidal ideation was evaluated by item 9 of the BDI. Patients with presence vs. absence of suicidal ideation were compared in all the variables studied. RESULTS: The prevalence of suicidal ideation among FM patients was 32.5%. Significant differences between patients with vs. without suicidal ideas emerged mainly for the various indices of depression. Patients with suicidal ideation also reported higher levels of anxiety, more day dysfunction due to sleepiness and more limitations due to emotional and physical problems. Logistic regression analysis revealed that cognitive depression symptoms such as BDI Self-Blame cluster are the more closely related to suicide ideation. CONCLUSIONS: The presence of suicidal ideation in FM patients is closely related to comorbid depression, anxiety and to a higher impact of the disease in daily life.

Profiles in fibromyalgia: algometry, auditory evoked potentials and clinical characterization of different subtypes.

The heterogeneity found in fibromyalgia (FM) patients has led to the investigation of disease subgroups, mainly based on clinical features. The aim of this study was to test the hypothesis that clinical FM subgroups are associated with different underlying pathophysiological mechanisms. Sixty-three FM patients were classified in type I or type II, according to the Fibromyalgia Impact Questionnaire (FIQ), and in mild/moderate versus severe FM, according to the severity of three cardinal symptoms considered in the American College of Rheumatology (ACR) 2010 criteria (unrefreshed sleep, cognitive problems and fatigue). To validate the subgroups obtained by these two classifications, we calculated the area under the receiver operating characteristic curves for various clinical variables and for two potential biomarkers of FM: Response to experimental pressure pain (algometry) and the amplitude/intensity slopes of the auditory evoked potentials (AEPs) obtained to stimuli of increasing intensity. The variables that best discriminated type I versus type II were those related to depression, while the indices of clinical or experimental pain (threshold or tolerance) did not significantly differ between them. The variables that best discriminated the mild/moderate versus severe subgroups were those related to the algometry. The AEPs did not allow discrimination among the generated subsets. The FIQ-based classification allows the identification of subgroups that differ in psychological distress, while the index based on the ACR 2010 criteria seems to be useful to characterize the severity of FM mainly based on hyperalgesia. The incorporation of potential biomarkers to generate or validate classification criteria is crucial to advance in the knowledge of FM and in the understanding of pathophysiological pathways.

Subjective symptoms related to GSM radiation from mobile phone base stations: a cross-sectional study.

OBJECTIVES: We performed a re-analysis of the data from Navarro et al (2003) in which health symptoms related to microwave exposure from mobile phone base stations (BSs) were explored, including data obtained in a retrospective inquiry about fear of exposure from BSs. DESIGN: Cross-sectional study. SETTING: La Ñora (Murcia), Spain. PARTICIPANTS: Participants with known illness in 2003 were subsequently disregarded: 88 participants instead of 101 (in 2003) were analysed. Since weather circumstances can influence exposure, we restricted data to measurements made under similar weather conditions. OUTCOMES AND METHODS: A statistical method indifferent to the assumption of normality was employed: namely, binary logistic regression for modelling a binary response (eg, suffering fatigue (1) or not (0)), and so exposure was introduced as a predictor variable. This analysis was carried out on a regular basis and bootstrapping (95% percentile method) was used to provide more accurate CIs. RESULTS: The symptoms most related to exposure were lack of appetite (OR=1.58, 95% CI 1.23 to 2.03); lack of concentration (OR=1.54, 95% CI 1.25 to 1.89); irritability (OR=1.51, 95% CI 1.23 to 1.85); and trouble sleeping (OR=1.49, 95% CI 1.20 to 1.84). Changes in -2 log likelihood showed similar results. Concerns about the BSs were strongly related with trouble sleeping (OR =3.12, 95% CI 1.10 to 8.86). The exposure variable remained statistically significant in the multivariate analysis. The bootstrapped values were similar to asymptotic CIs. CONCLUSIONS: This study confirms our preliminary results. We observed that the incidence of most of the symptoms was related to exposure levels-independently of the demographic variables and some possible risk factors. Concerns about adverse effects from exposure, despite being strongly related with sleep disturbances, do not influence the direct association between exposure and sleep.