Can the Assessment of the Circadian Rhythm of Pain Be Shortened? A Study of Community-Dwelling Participants with Chronic Pain.

Purpose: This study aimed to juxtapose the circadian rhythm of pain with the conventional 7-day assessment and ascertain the feasibility of condensing the evaluation of the circadian rhythm of pain into a 3-day timeframe. Patients and Methods: Seventy-three patients with pain persisting for a minimum of 3 months and a numerical rating scale (NRS) score of ≥2 were recruited from three medical centers. The circadian patterns of pain were appraised over a 7-day period by quantifying the intensity of pain at six temporal junctures each day using a 10-cm visual analog scale (VAS). Cluster analysis was performed using six standardized variables derived from the VAS score of each participant at six designated time points to identify cohorts with analogous circadian rhythms of pain. The clusters were discerned for the 7- and 3-day assessments (Tuesday-Thursday, Friday-Sunday, and Sunday-Tuesday), according to the research objectives. Cohen's kappa coefficient was calculated to gauge the intra-observer variability to assess the consistency between the outcomes of the cluster analysis for the 7-day assessment and each of the 3-day assessments. Results: The highest Cohen's kappa coefficient was observed for the 3-day evaluation spanning from Friday to Sunday, indicating a substantial concordance with the results of the 7-day assessment. Conclusion: Our results suggest that it may be prudent to consider implementing a condensed 3-day evaluation of the circadian rhythm of pain that is tailored to individual characteristics. This approach will allow a better understanding of the diurnal rhythms of chronic pain in patients and implement more targeted and specific pain management strategies. Furthermore, it will contribute to increased patient satisfaction through early intervention.

Prognosis of Pain after Stroke during Rehabilitation Depends on the Pain Quality.

OBJECTIVE: Pain after a stroke interferes with daily life and the rehabilitation process. This study aimed to clarify the prognosis of pain in subgroups of patients with pain after a stroke using pain quality data. METHODS: The study included 85 patients with pain after stroke undergoing exercise-based rehabilitation. Items of the Neuropathic Pain Symptom Inventory (NPSI) were used, and patients with pain after stroke were clustered according to their scores of NPSI. Other clinical assessments, such as physical and psychological conditions, were assessed by interviews and questionnaires, and then these were compared among subgroups in a cross-sectional analysis. Longitudinal pain intensity in each subgroup was recorded during 12 weeks after the stroke and the patients' pain prognoses were compared between subgroups. RESULTS: Four distinct subgroups were clustered: cluster 1 (cold-evoked pain and tingling), cluster 2 (tingling only), cluster 3 (pressure-evoked pain), and cluster 4 (deep muscle pain with a squeezing and pressure sensation). The cross-sectional analysis showed varying clinical symptoms among the subgroups, with differences in the prevalence of joint pain, limited range of motion, somatosensory dysfunction, and allodynia. There were no significant differences in pain intensity at baseline among the subgroups. A longitudinal analysis showed divergent prognoses of pain intensity among the subgroups. The pain intensity in cluster 4 was significantly alleviated, which suggested that musculoskeletal pain could be reduced with conventional exercise-based rehabilitation. However, the pain intensity of patients in clusters 1 and 2 remained over 12 weeks. CONCLUSION: The study classified patients into clinically meaningful subgroups using pain quality data and provided insight into their prognosis of pain. The findings could be useful for guiding personalized rehabilitation strategies for pain management. IMPACT: Assessment of pain quality in patients with pain after stroke leads to personalized rehabilitation for pain management.

Long-term physical therapy for neuropathic pain after cervical spinal cord injury and resting state electroencephalography: a case report.

INTRODUCTION: Neuropathic pain after spinal cord injury is difficult to treat, and it is associated with abnormalities in the function of the thalamus-to-cortex neural circuitry. Aerobic exercise provides immediate improvement in neuropathic pain and is associated with abnormal resting electroencephalography (EEG) findings in patients with spinal cord injury. This study aimed to investigate whether physical therapy, including walking, can improve neuropathic pain and EEG peak alpha frequency (PAF) in the long term in a patient with cervical spinal cord injury. CASE PRESENTATION: A 50-year-old man was admitted with a cervical spinal cord insufficiency injury sustained one week prior. The residual height was C5. Neuropathic pain was observed in the fingers bilaterally. A numerical rating scale (NRS) was evaluated to measure the weekly mean and maximum intensities of pain. Resting EEG was measured, and the PAF was calculated. Each time point was evaluated in 2-week intervals from the time of admission, and the rate of change (Δ) of PAF was calculated based on the initial evaluation. Interventions included 18 weeks of standard physical therapy focusing on gait, with additional intensive gait training (4-10 weeks). The NRS scores for the mean and maximum intensities of pain decreased significantly after 6 weeks, and ΔPAF increased significantly after 4 weeks. Improvement in PAF coincided with the start of intensive gait training. DISCUSSION: PAF shifts to a high frequency during intensive gait training, suggesting the effectiveness of aerobic exercise. Furthermore, there is a close relationship between PAF, pain, and the quantification of pain changes.

Pain quality of thermal grill illusion is similar to that of central neuropathic pain rather than peripheral neuropathic pain.

OBJECTIVES: Application of spatially interlaced innocuous warm and cool stimuli to the skin elicits illusory pain, known as the thermal grill illusion (TGI). This study aimed to discriminate the underlying mechanisms of central and peripheral neuropathic pain focusing on pain quality, which is considered to indicate the underlying mechanism(s) of pain. We compared pain qualities in central and peripheral neuropathic pain with reference to pain qualities of TGI-induced pain. METHODS: Experiment 1:137 healthy participants placed their hand on eight custom-built copper bars for 60 s and their pain quality was assessed by the McGill Pain Questionnaire. Experiment 2: Pain quality was evaluated in patients suffering from central and peripheral neuropathic pain (42 patients with spinal cord injury, 31 patients with stroke, 83 patients with trigeminal neuralgia and 131 patients with postherpetic neuralgia). RESULTS: Experiment 1: Two components of TGI-induced pain were found using principal component analysis: component 1 included aching, throbbing, heavy and burning pain, component 2 included itching, electrical-shock, numbness, and cold-freezing. Experiment 2: Multiple correspondence analysis (MCA) and cross tabulation analysis revealed specific pain qualities including aching, hot-burning, heavy, cold-freezing, numbness, and electrical-shock pain were associated with central neuropathic pain rather than peripheral neuropathic pain. CONCLUSIONS: We found similar qualities between TGI-induced pain in healthy participants and central neuropathic pain rather than peripheral neuropathic pain. The mechanism of TGI is more similar to the mechanism of central neuropathic pain than that of neuropathic pain.

Effectiveness of patient education focusing on circadian pain rhythms: A case report and review of literature.

BACKGROUND: Neuropathic pain management should aim at improving quality of life and daily living activities of patients; therefore, emphasis should be placed on pain management including understanding the pain patterns during daily activity. Therefore, lifestyle guidance should be based on a detailed understanding of pain; however, previous studies commonly evaluated pain intensity at a single point in time. We report a case on patient education intervention based on the relationship between pain circadian rhythms and detailed physical activity during the day. CASE SUMMARY: A man in his 60s, who suffered a brachial plexus injury in a traffic accident, presented with neuropathic pain. Early assessment of the importance of daily living activities to the patient, pain rhythmicity, and physical activity, was performed. The early assessments showed that the pain intensity was lower on days when more light-intensity physical activity (LIPA) was performed, than on days when less LIPA was performed. Consequently, patient education focused on methods to decrease the pain intensity that tended to worsen in the afternoon, and encouraged behavioral changes by suggesting the patient to take walks," which could be used to maintain LIPA in the afternoon. On reassessment, the afternoon LIPA, which had been the focus of attention, had increased and a change was noted in the circadian rhythm of pain. CONCLUSION: Patient education based on a composite assessment elicited positive results in relation to the pain circadian rhythm and physical activity.

Classification of circadian pain rhythms and pain characteristics in chronic pain patients: An observational study.

ABSTRACT: This study aimed to perform cluster analysis in patients with chronic pain to extract groups with similar circadian rhythms and compare neuropathic pain and psychological factors among these groups to identify differences in pain-related outcomes. A total of 63 community-dwellers with pain lasting at least 3 months and Numerical Rating Scale scores of ≥2 were recruited from 3 medical institutions. Their pain circadian rhythms were evaluated over 7 days by measuring pain intensity at 6-time points per day using a 10-cm visual analog scale. Cluster analysis was performed using 6 variables with standardized visual analog scale values at 6-time points for individual participants to extract groups with similar pain circadian rhythms. The results of the Neuropathic Pain Symptom Inventory and psychological evaluations in each group were compared using the Kruskal-Wallis test. The results revealed 3 clusters with different circadian rhythms of pain. The total and evoked pain subscale Neuropathic Pain Symptom Inventory scores differed among the 3 clusters. The results suggest that a thorough understanding of circadian pain rhythms in chronic pain patients may facilitate the performance of activities of daily living and physical exercise from the perspective of pain management.

The Effects of Transcranial Direct Current Stimulation Combined with Aerobic Exercise on Pain Thresholds and Electroencephalography in Healthy Adults.

OBJECTIVES: We examined whether transcranial direct current stimulation (tDCS) combined with aerobic exercise (AE) modulated the pressure pain threshold (PPT) and peak alpha frequency (PAF) measured via resting electroencephalography. DESIGN: Single-blind experimental study with a cross-over design. SETTING: Neuro Rehabilitation Research Center, Kio University. SUBJECTS: Ten healthy controls participated in this study. METHODS: Three types of sessions--(i) tDCS, (ii) Sham tDCS/AE, and (iii) tDCS/AE--were tested in this investigation. Anodal stimulation (2 mA, 20 minutes) was applied over the left primary motor cortex. Each session was 20 minutes long. We used the PPT and short-form Profile of Mood States-Brief, as well as PAF measured via resting-electroencephalography, to investigate the effects of tDCS and AE. Heart rate and scores on the Borg scale were used to confirm exercise intensity. PAF was calculated in four regions of interest: frontal, central, parietal, and occipital areas. RESULTS: The change ratio of PPT increased during each session. The maximum change ratio of PPT were tDCS: 40.7%, Sham tDCS/AE: 51.5%, and tDCS/AE: 83.4%. change ratio of PPT was earlier and higher in the tDCS/AE trials compared with the other sessions. Negative mood was improved after session completion. Significant differences in PAF were found in the occipital area in the Sham tDCS/AE and tDCS/AE sessions. CONCLUSIONS: The combined tDCS and AE intervention induced significant changes in PPT in a single session, with a PAF that was earlier and higher than those produced during the Sham tDCS/AE and tDCS sessions.

Correction to: Kinesiophobia modulates lumbar movements in people with chronic low back pain: a kinematic analysis of lumbar bending and returning movement.

In the figure 2, "CLBP Low fear" located at the right end of Time of Phase 1 is wrong. The correct statement is "CLBP High fear". The complete correct figure 2 is given below.

Kinesiophobia modulates lumbar movements in people with chronic low back pain: a kinematic analysis of lumbar bending and returning movement.

PURPOSE: We aimed to kinematically analyze lumbar bending and returning movements and clarify the relationship between fear of movement and kinematic output. METHODS: We recruited 45 participants with CLBP (i.e., > 6 months) and 20 healthy control (HC) participants with no history of CLBP. We used the numerical rating pain scale (NRS), Tampa Scale for Kinesiophobia (TSK-11), and Pain Self-Efficacy Questionnaire (PSEQ-2) as qualitative outcome measurements. CLBP participants were divided into two subgroups (high- and low-fear groups) based on the median split of the total TSK-11 score. In the kinematic recording session, a starting-cue beep signaled participants to bend forward using the lumbar region of their spine and then return to an upright posture, and we used a flexible twin-axis electrogoniometer to record the lumbar movements. The time series of lumbar movements was divided into four phases according to lumbar movement velocity, and we calculated the length (sec) of each phase. RESULTS: Phase 1 (duration prior to cue-induced movement initiation) and phase 3 (switch in the direction of lumbar movement from forward to backward) were significantly longer in the CLBP high-fear group compared with those in the CLBP low-fear group and HC group (p < 0.05). The increased lengths of these two phases were positively correlated with not only pain intensity but also TSK-11 scores (p < 0.05). CONCLUSIONS: These results represent evidence of a particular lumbar movement pattern associated with kinesiophobia. These results might help to identify psychological factors that impact lumbar movement patterns in individuals with CLBP. These slides can be retrieved under Electronic Supplementary Material.

Effects of wheelchair propulsion on neuropathic pain and resting electroencephalography after spinal cord injury.

OBJECTIVES: To investigate the effects of wheelchair propulsion on neuropathic pain and to examine resting electroencephalography pre- and post-wheelchair propulsion after spinal cord injury. DESIGN: Cross-sectional study. PARTICIPANTS: Eleven individuals with spinal cord injury and pain and 10 healthy controls. METHODS: Single-session 15-min wheelchair propulsion and measurement of resting electroence-phalography. Effects of wheelchair propulsion were investigated using numerical rating scale (NRS) for neuropathic pain and short-form Profile of Mood States-Brief for mood. Peak alpha frequency on electroencephalography was calculated in 4 regions of interest; frontal, central, parietal and occipital areas. These outcomes were compared between pre- and post-wheelchair propulsion. RESULTS: Ten participants with spinal cord injury and all healthy controls completed the wheelchair propulsion exercise. NRS scores and negative mood were significantly improved following the wheelchair propulsion exercise. Pre-wheelchair propulsion, parietal and occipital peak alpha frequencies were significantly lower in the spinal cord injury group compared with the healthy controls group. Post-wheelchair propulsion, central peak alpha frequency increased in the spinal cord injury group. CONCLUSION: Wheelchair propulsion exercise temporarily decreased neuropathic pain intensity, improved negative mood, and modified alpha activity in spinal cord injury.

Toxicidade aguda de herbicidas e inseticida utilizados na cultura do arroz irrigado sobre juvenis de carpa (Cyprinus carpio) / Acute toxicity of herbicides and insecticides applied in water-seeded rice to juvenile carp (Cyprinus carpio)

A cultura do arroz irrigado apresenta grande importância econômica e social nos Estados de Santa Catarina e no Rio Grande do Sul (Brasil) e destaca-se tanbém pelo uso intenso de agroquímicos, especialmente herbicidas e inseticidas. Experimentos foram conduzidos em laboratório para avaliar a toxicidade aguda de alguns agroquímicos utilizados em arroz irrigado, visando estabelecer as concentraçöes de risco bem como os possíveis efeitos que tais produtos possam apresentar dobre organismos näo alvo. A espécie empregada como indicadora foi a carpa-comum em funçäo da sua utilizaçäo em consórcios de arroz com peixe. Foram testados individualmente os herbicidas Ally (Metsulfuron), Gamit (Clomazone), Goal (Oxifluorfen), Ronstar (Oxadiazon) e Sirius (Pirazosulfuron) e o inseticida Furadan 9Carbofuran). Os resultados indicaram grande variaçäo entre os produtos quanto à toxicidade para a espécie testada. O índice de segurança, estimado pela relaçäo entre a CL 50 e a concentraçäo provável utilizada na lavoura, foi de 0,82; 2,76; 5,93; 8,87; 13,94; 4.000 e 7,878, respectivamente para os agroquímicos Furadan, Ronstar, Goal, Facet, Gamit, Sirius e Ally. Os resultados obtidos neste trabalho evidenciam que os produtos Furadan, Ronstar, Goal, Facet, e Gamit apresentam maiores riscos ambientais e cuidados devem ser adotados após a aplicaçäo no sentido de evitar o deslocamento dos mesmos para fora das lavouras. Os herbicidas Ally e Sirius apresentam valores elevados de CL50, demonstrnado baixa toxicidade para carpa.