Sickle cell disease chronic joint pain: Clinical assessment based on maladaptive central nervous system plasticity

Chronic joint pain (CJP) is among the significant musculoskeletal comorbidities in sickle cell disease (SCD) individuals. However, many healthcare professionals have difficulties in understanding and evaluating it. In addition, most musculoskeletal evaluation procedures do not consider central nervous system (CNS) plasticity associated with CJP, which is frequently maladaptive. This review study highlights the potential mechanisms of CNS maladaptive plasticity related to CJP in SCD and proposes reliable instruments and methods for musculoskeletal assessment adapted to those patients. A review was carried out in the PubMed and SciELO databases, searching for information that could help in the understanding of the mechanisms of CNS maladaptive plasticity related to pain in SCD and that presented assessment instruments/methods that could be used in the clinical setting by healthcare professionals who manage chronic pain in SCD individuals. Some maladaptive CNS plasticity mechanisms seem important in CJP, including the impairment of pain endogenous control systems, central sensitization, motor cortex reorganization, motor control modification, and arthrogenic muscle inhibition. Understanding the link between maladaptive CNS plasticity and CJP mechanisms and its assessment through accurate instruments and methods may help healthcare professionals to increase the quality of treatment offered to SCD patients.

Neurophysiological aspects of isotonic exercises in temporomandibular joint dysfunction syndrome

PURPOSE

The aim of the study was to investigate the electroneurophysiological aspects of volunteers with temporomandibular disorders before and after performing isotonic exercises for pain relief and self-care guidelines.

METHODS

The study was a parallel controlled randomized controlled trial under protocol 1,680,920. The inclusion criteria were age between 18 and 60 years, muscle temporomandibular dysfunction with or without limitation of mouth opening and self-reported pain with scores between 4 and 10. The individuals were randomized into experimental group and control. Twenty-three volunteers participated in the study, most of then were female. Control group had 11 and experimental group 12 individuals. Dropouts occurred in both groups, two in the experimental group and three in the control group. Since there were an intergroup imbalance the power density was analysed just in experimental group. Electroencephalographic recording was performed before and after the interventions, using the 32-channel apparatus, with sample frequency of 600 Hz and impedance of 5 kΩ. The data were processed through the MATLAB computer program. The individual records filtered off-line, using bandpass between 0.5 and 50 Hz. Epochs of 1,710 ms were created and the calculation of the absolute power density calculated by means of the fast Fourier transform. The statistical approach was inferential and quantitative.

RESULTS

The alpha power density analyzed presented a difference, but not significant, when compared in the two moments.

CONCLUSION

According to this study, isotonic exercises performed to reduce pain provided a small increase in alpha power density in the left temporal, parietal and occipital regions.

Does Transcranial Direct Current Stimulation Combined with Peripheral Electrical Stimulation Have an Additive Effect in the Control of Hip Joint Osteonecrosis Pain Associated with Sickle Cell Disease? A Protocol for a One-Session Double Blind, Block-Randomized Clinical Trial

Chronic pain in Sickle Cell Disease (SCD) is probably related to maladaptive plasticity of brain areas involved in nociceptive processing. Transcranial Direct Current Stimulation (tDCS) and Peripheral Electrical Stimulation (PES) can modulate cortical excitability and help to control chronic pain. Studies have shown that combined use of tDCS and PES has additive effects. However, to date, no study investigated additive effects of these neuromodulatory techniques on chronic pain in patients with SCD. This protocol describes a study aiming to assess whether combined use of tDCS and PES more effectively alleviate pain in patients with SCD compared to single use of each technique. The study consists of a one-session double blind, block-randomized clinical trial (NCT02813629) in which 128 participants with SCD and femoral osteonecrosis will be enrolled. Stepwise procedures will occur on two independent days. On day 1, participants will be screened for eligibility criteria. On day 2, data collection will occur in four stages: sample characterization, baseline assessment, intervention, and post-intervention assessment. These procedures will last ~5 h. Participants will be divided into two groups according to homozygous for S allele (HbSS) (n = 64) and heterozygous for S and C alleles (HbSC) (n = 64) genotypes. Participants in each group will be randomly assigned, equally, to one of the following interventions: (1) active tDCS + active PES; (2) active tDCS + sham PES; (3) sham tDCS + active PES; and (4) sham tDCS + sham PES. Active tDCS intervention will consist of 20 min 2 mA anodic stimulation over the primary motor cortex contralateral to the most painful hip. Active PES intervention will consist of 30 min sensory electrical stimulation at 100 Hz over the most painful hip. The main study outcome will be pain intensity, measured by a Visual Analogue Scale. In addition, electroencephalographic power density, cortical maps of the gluteus maximus muscle elicited by Transcranial Magnetic Stimulation (TMS), serum levels of Brain-derived Neurotrophic Factor (BDNF), and Tumor Necrosis Factor (TNF) will be assessed as secondary outcomes. Data will be analyzed using ANOVA of repeated measures, controlling for confounding variables.