Differential efficiency of transcutaneous electrical nerve stimulation in dominant versus nondominant hands in fibromyalgia: placebo-controlled functional near-infrared spectroscopy study

Treating fibromyalgia with electrical neuromodulation: A systematic review and meta-analysis

OBJECTIVE

Several types of electrical neuromodulation (such as transcranial direct current stimulation, tDCS; transcutaneous electrical nerve stimulation) have been applied in the treatment of fibromyalgia. These trials had different outcome measurements, such as subjective pain, pain threshold, depression, anxiety, and functioning. We intended to integrate data from different trials into a meta-analysis to clearly present the clinical value of electrical neuromodulation in fibromyalgia.

METHODS

A systematic review and meta-analysis of randomized controlled trials comparing the effect of all types of electrical neuromodulation in patients with fibromyalgia was conducted. The main outcome was subjective pain; the secondary outcomes included depression, anxiety, and functioning.

RESULTS

Twenty-five studies and 1061 fibromyalgia patients were included in the quantitative analysis. Active electrical neuromodulation and active tDCS both showed significant effects on subjective pain, depression, and functioning. For different anode tDCS electrode positions, only F3-F4 revealed a significant effect on depression. Meta-regression tDCS effects on depression were significantly associated with age.

CONCLUSIONS

Electrical neuromodulation is significantly effective in treating pain, depression, and functioning in patients with fibromyalgia.

SIGNIFICANCE

The results may help clinicians to arrange effective treatment plans for patients with fibromyalgia, especially in those patients who reveal limited response to pharmacotherapy and psychotherapy.

Shedding light on pain for the clinic: a comprehensive review of using functional near-infrared spectroscopy to monitor its process in the brain

ABSTRACT

Pain is a complex experience that involves sensation, emotion, and cognition. The subjectivity of the traditional pain measurement tools has expedited the interest in developing neuroimaging techniques to monitor pain objectively. Among noninvasive neuroimaging techniques, functional near-infrared spectroscopy (fNIRS) has balanced spatial and temporal resolution; yet, it is portable, quiet, and cost-effective. These features enable fNIRS to image the cortical mechanisms of pain in a clinical environment. In this article, we evaluated pain neuroimaging studies that used the fNIRS technique in the past decade. Starting from the experimental design, we reviewed the regions of interest, probe localization, data processing, and primary findings of these existing fNIRS studies. We also discussed the fNIRS imaging's potential as a brain surveillance technique for pain, in combination with artificial intelligence and extended reality techniques. We concluded that fNIRS is a brain imaging technique with great potential for objective pain assessment in the clinical environment.

A Controlled Thermoalgesic Stimulation Device for Exploring Novel Pain Perception Biomarkers

OBJECTIVE

To develop a new device for identifying physiological markers of pain perception by reading the brain's electrical activity and hemodynamic interactions while applying thermoalgesic stimulation.

METHODS

We designed a compact prototype that generates well-controlled thermal stimuli using a computer-driven Peltier cell while simultaneously capturing electroencephalography (EEG) and photoplethysmography (PPG) signals. The study was performed on 35 healthy subjects (mean age 30.46 years, SD 4.93 years; 20 males, 15 females). We first determined the heat pain threshold (HPT) for each subject, defined as the maximum temperature that the subject can withstand when the Peltier cell gradually increased the temperature. Next, we defined the painful condition as the one occurring at temperature equal to 90% of the HPT, comparing this to the no-pain state (control) in the absence of thermoalgesic stimulation.

RESULTS

Both the one-dimensional and the two-dimensional spectral entropy (SE) obtained from both the EEG and PPG signals differentiated the condition of pain. In particular, the SE for PPG was significantly reduced in association with pain, while the SE for EEG increased slightly. Moreover, significant discrimination occurred within a specific range of frequencies, 26-30 Hz for EEG and about 5-10 Hz for PPG.

CONCLUSION

Hemodynamics, brain dynamics and their interactions can discriminate thermal pain perception.

SIGNIFICANCE

The possibility of monitoring on-line variations in thermal pain perception using a similar device and algorithms may be of interest to study different pathologies that affect the peripheral nervous system, such as small fiber neuropathies, fibromyalgia or painful diabetic neuropathy.

The relationship of cortical activity induced by pain stimulation with clinical and cognitive features of somatic symptom disorder: A controlled functional near infrared spectroscopy study

OBJECTIVE

The neurobiological correlates of Somatic Symptom Disorder (SSD) introduced in the DSM-5 has been the focus of a limited investigation. We aimed to examine the cortical response to painful stimuli and its relationship to symptom severity as well as cognitive and psychological characteristics in proposed models of somatoform disorders.

METHODS

We measured hemodynamic responses by 52-channel functional near-infrared spectroscopy. We compared the cortical response to painful stimuli in index patients with SSD (N = 21) versus age, and gender matched healthy control subjects (N = 21). We used brush stimulation as the control condition. We analyzed the relationship of cortical activity with SSD symptom severity as well as somatosensory amplification (SSA), alexithymia, dysfunctional illness behaviour, worry, and neuroticism.

RESULTS

Patients with SSD had higher somatic symptom severity, SSA, alexithymia, neuroticism, illness-related worry, and behaviour. Somatic symptom severity was predicted by a model including SSA and subjective feeling of pain in the index patients. Activity in the left-angular and right-middle temporal gyri was higher in the SSD subjects than the controls during pain stimulation. Positive correlations were detected between mean pain threshold levels and left middle occipital gyrus activity, as well as between SSA-scores and right-angular gyrus activity during pain condition in the index patients with SSD.

CONCLUSION

We present the first evidence that representation of pain in terms of cortical activity is different in subjects with SSD than healthy controls. SSA has functional neuroanatomic correlates and predicts symptom severity in SSD and therefore is involved as a valid intermediate phenotype in SSD pathophysiology.

Fibromyalgia: Recent Advances in Diagnosis, Classification, Pharmacotherapy and Alternative Remedies

Fibromyalgia (FM) is a syndrome that does not present a well-defined underlying organic disease. FM is a condition which has been associated with diseases such as infections, diabetes, psychiatric or neurological disorders, rheumatic pathologies, and is a disorder that rather than diagnosis of exclusion requires positive diagnosis. A multidimensional approach is required for the management of FM, including pain management, pharmacological therapies, behavioral therapy, patient education, and exercise. The purpose of this review is to summarize the recent advances in classification criteria and diagnostic criteria for FM as well as to explore pharmacotherapy and the use of alternative therapies including the use of plant bioactive molecules.

The effectiveness and safety of electrotherapy in the management of fibromyalgia

Treating fibromyalgia is a challenging task for physicians. With its multifaceted features, fibromyalgia requires a comprehensive management strategy focusing on both the pharmacological and non-pharmacological treatment options. During the last decades, there has been growing evidence regarding the role of electrotherapy in fibromyalgia treatment. In this regard, the present article aimed to review the recent literature on the effectiveness and safety of the electrotherapy in the treatment of fibromyalgia. A literature search was conducted through PubMed/MEDLINE and Scopus databases. Transcutaneous electrical nerve stimulation (TENS), non-invasive brain stimulation (transcranial direct current/magnetic stimulation), and light amplification by stimulated emission of radiation (LASER) emerged as the most commonly examined electrotherapy techniques in fibromyalgia. Currently, there is growing data regarding the effectiveness of electrotherapy in the management of fibromyalgia-related pain. Besides, non-invasive electrotherapy techniques are related to no/minor side effects. Further studies are warranted to identify the optimal treatment protocols for each electrotherapy modality.