Somatosensory Profiling of Patients With Cluster Headache: A Systematic Review and Meta-analysis.

The objectives were 1) to synthesize quantitative sensory testing results in cluster headache (CH) patients and to identify somatosensory differences from healthy subjects (HS), and 2) between symptomatic and asymptomatic sides in CH patients. Two independent reviewers conducted a literature search in MEDLINE, EMBASE, Web of Science, and CINAHL databases. Studies with observational designs were included. Methodological quality and risk of bias were assessed with the Newcastle Ottawa Scale. The selected studies underwent qualitative and quantitative analyses. The qualitative analysis showed inconsistent findings among multiple studies. Meta-analysis showed lower pressure pain thresholds (PPTs) on the symptomatic side of CH patients than HS in V2 (standardized mean difference [SMD] -1.01 [95% confidence interval (CI) -1.79, -.23], P = .01, I2 = 73%, n = 114), V3 (SMD -1 [95% CI -1.54, .45], P < .01, I2 = 82%, n = 354), and cervical region (SMD -1.25 [95% CI -2.07, -.44], P < .01, I2 = 84%, n = 194). Furthermore, lower PPTs than those detected in HS were found on the asymptomatic side in V3 (SMD -.77 [95% CI -1.27, -.27], P < .01, I2 = 79%, n = 354) and in the cervical region (SMD -1.13 [95% CI -1.97, -.3], P < .01, I2 = 85%, n = 194). However, no differences were found in V1 or the extratrigeminal points between these groups. No significant changes were found between symptomatic and asymptomatic sides in trigeminal and extratrigeminal regions. Mechanical hyperalgesia in the trigemino-cervical region of patients with CH could suggest the presence of central pain mechanisms. These results are of clinical relevance because their presence could be associated with a poorer prognosis, chronification, and treatment response. PERSPECTIVES: This study provides consistent findings on the somatosensory profile characterizing patients with CH. Clinicians should assess PPTs and other quantitative sensory testing variables in the trigeminal and extratrigeminal (cervical) regions.

Hyperalgesia, Increased Temporal Summation and Impaired Inhibitory Mechanisms in Episodic and Chronic Cluster Headache: An Observational Study.

Cluster Headache (CH) is a primary headache that causes severe pain. Some evidence suggests that central mechanisms might be involved. The objective of this study was (1) to compare hyperalgesia signs, temporal summation and conditioned pain modulation among episodic (ECH) and chronic CH (CCH) patients and controls, (2) to compare these factors between sides in the patient groups and (3) to compare the psychophysical variables between the groups. This cross-sectional study included 71 subjects divided into three groups (ECH, CCH and controls). Pressure pain thresholds, temporal summation, conditioned pain modulation and other psychosocial variables were measured. The ANOVA showed differences for all physical outcome measures (p < 0.05). Bonferroni post hoc analyses showed differences when comparing the patient groups with the healthy subjects (p < 0.05), with large effect sizes (d > 0.8). No differences between the patient groups were found for almost all the variables (p > 0.05). Significant differences for all the variables were detected when comparing the symptomatic and non-symptomatic sides in both the ECH and CCH groups (p < 0.05). The ECH and CCH groups showed mechanical hyperalgesia, increased temporal summation and impaired inhibitory mechanisms compared to the controls. Side-to-side differences were also detected within the patient groups. Patients with CCH had poorer sleep quality and quality of life than the controls.

Dietary Nitrate Ingestion Does Not Improve Neuromuscular Performance in Male Sport Climbers.

Beetroot juice (BJ) is commonly used as an ergogenic aid in endurance and team sports, however, the effect of this supplement on climbing performance is barely studied. The purpose of the current study was to investigate the effect of acute BJ ingestion on neuromuscular and biochemical variables in amateur male sport climbers. Ten physically active sport climbers (28.8 ± 3.7 years) underwent a battery of neuromuscular tests consisting of the half crimp test, the pull-up to failure test, the isometric handgrip strength test, the countermovement jump (CMJ) and the squat jump (SJ). Participants performed the neuromuscular test battery twice in a cross-over design separated by 10 days, 150 min after having consumed either 70-mL of BJ (6.4 mmol NO3-) or a 70-mL placebo (0.0034 mmol NO3-). In addition, nitrate (NO3-) and nitrite (NO2-) saliva concentrations were analysed, and a side effect questionnaire related to ingestion was administrated. No differences were reported in particular neuromuscular variables measured such as the CMJ (p = 0.960; ES = 0.03), the SJ (p = 0.581; ES = -0.25), isometric handgrip strength (dominant/non dominant) (p = 0.459-0.447; ES = 0.34-0.35), the pull-up failure test (p = 0.272; ES = 0.51) or the maximal isometric half crimp test (p = 0.521-0.824; ES = 0.10-0.28). Salivary NO3- and NO2- increased significantly post BJ supplementation compared to the placebo (p < 0.001), while no side effects associated to ingestion were reported (p = 0.330-1.000) between conditions (BJ/placebo ingestion). Acute dietary nitrate supplementation (70-mL) did not produce any statistically significant improvement in neuromuscular performance or side effects in amateur sport climbers.