Primary somatosensory cortex and periaqueductal gray functional connectivity as a marker of the dysfunction of the descending pain modulatory system in fibromyalgia

Background@#Resting-state functional connectivity (rs-FC) may aid in understanding the link between painmodulating brain regions and the descending pain modulatory system (DPMS) in fibromyalgia (FM). This study investigated whether the differences in rs-FC of the primary somatosensory cortex in responders and non-responders to the conditioned pain modulation test (CPM-test) are related to pain, sleep quality, central sensitization, and the impact of FM on quality of life. @*Methods@#This cross-sectional study included 33 females with FM. rs-FC was assessed by functional magnetic resonance imaging. Change in the numerical pain scale during the CPM-test assessed the DPMS function. Subjects were classified either as non-responders (i.e., DPMS dysfunction, n = 13) or responders (n = 20) to CPM-test. A generalized linear model (GLM) and a receiver operating characteristic (ROC) curve analysis were performed to check the accuracy of the rs-FC to differentiate each group. @*Results@#Non-responders showed a decreased rs-FC between the left somatosensory cortex (S1) and the periaqueductal gray (PAG) (P < 0.001). The GLM analysis revealed that the S1-PAG rs-FC in the left-brain hemisphere was positively correlated with a central sensitization symptom and negatively correlated with sleep quality and pain scores. ROC curve analysis showed that left S1-PAG rs-FC offers a sensitivity and specificity of 85% or higher (area under the curve, 0.78, 95% confidence interval, 0.63–0.94) to discriminate who does/does not respond to the CPM-test. @*Conclusions@#These results support using the rs-FC patterns in the left S1-PAG as a marker for predicting CPM-test response, which may aid in treatment individualization in FM patients.

Potency of descending pain modulatory system is linked with peripheral sensory dysfunction in fibromyalgia: An exploratory study.

Fibromyalgia (FM) is characterized by chronic widespread pain whose pathophysiological mechanism is related to central and peripheral nervous system dysfunction. Neuropathy of small nerve fibers has been implicated due to related pain descriptors, psychophysical pain, and neurophysiological testing, as well as skin biopsy studies. Nevertheless, this alteration alone has not been previously associated to the dysfunction in the descending pain modulatory system (DPMS) that is observed in FM. We hypothesize that they associated, thus, we conducted a cross-sectional exploratory study.To explore small fiber dysfunction using quantitative sensory testing (QST) is associated with the DPMS and other surrogates of nociceptive pathways alterations in FM.We run a cross-sectional study and recruited 41 women with FM, and 28 healthy female volunteers. We used the QST to measure the thermal heat threshold (HTT), heat pain threshold (HPT), heat pain tolerance (HPT), heat pain tolerance (HPTo), and conditional pain modulation task (CPM-task). Algometry was used to determine the pain pressure threshold (PPT). Scales to assess catastrophizing, anxiety, depression, and sleep disturbances were also applied. Serum brain-derived neurotrophic factor (BDNF) was measured as a marker of neuroplasticity. We run multivariate linear regression models by group to study their relationships.Samples differed in their psychophysical profile, where FM presented lower sensitivity and pain thresholds. In FM but not in the healthy subjects, regression models revealed that serum BDNF was related to HTT and CPM-Task (Hotelling Trace = 1.80, P < .001, power = 0.94, R = 0.64). HTT was directly related to CPM-Task (B = 0.98, P = .004, partial-η = 0.25), and to HPT (B = 1.61, P = .008, partial η = 0.21), but not to PPT. Meanwhile, BDNF relationship to CPM-Task was inverse (B = -0.04, P = .043, partial-η = 0.12), and to HPT was direct (B = -0.08, P = .03, partial-η = 0.14).These findings high spot that in FM the disinhibition of the DPMS is positively correlated with the dysfunction in peripheral sensory neurons assessed by QST and conversely with serum BDNF.

Avaliação de fatores associados ao diagnóstico de queimação bucal: um estudo preliminar / Evaluation of factors associated to diagnosis of burning mouth: a preliminary study

Objetivo: avaliar fatores associados ao diagnóstico de ardência bucal como xerostomia, hipossalivação, sintomas depressivos, ansiedade, transtornos de sono, doenças sistêmicas e uso contínuo de medicamentos. Métodos: foram avaliados 22 pacientes atendidos em nível ambulatorial através de escalas validadas e questionário sociodemográfico, seguido de medidas de fluxo salivar espontâneo e estimulado através do método de expectoração salivar. Na análise estatística descritiva foi utilizado SPSS 16.0. Resultados: a amostra foi composta por 4 homens e 18 mulheres com idade média de 61,6+2,83 anos. As médias de fluxo salivar espontâneo e estimulado foram 0,27+0,06 ml/min e 0,84+0,08 ml/min, respectivamente. A hipossalivação esteve presente em 54,5% dos casos, sendo que a xerostomia foi referida por 31,3% dos pacientes. Sintomas depressivos leves foram observados em 22,7% da amostra. Na avaliação de ansiedade-traço 31,8% apresentaram sintomas de ansiedade moderada, 63,6%, sintomas de ansiedade elevada e 4,5%, ansiedade muito elevada. Quanto à avaliação de ansiedade-estado 27,3% apresentaram sintomas de ansiedade moderada e 72,7% sintomas de ansiedade elevada. Setenta e sete por cento apresentaram alterações de sono. Os exames sorológicos não apresentaram alterações significativas. Conclusão: estes resultados sugerem associação entre os parâmetros comportamentais avaliados e os sintomas bucais, sendo necessário o aumento da amostra para que possamos confirmar estatisticamente essa tendência.

Aim: to evaluate factors associated with the diagnosis of burning mouth, such as dry mouth, hyposalivation, depressive symptoms, anxiety, sleep disorders, systemic diseases, and continuous use of medications. Methods: twenty-two patients recruited from outpatient clinics were assessed using validated scales and a sociodemographic questionnaire. Patients’ spontaneous and stimulated salivary flow rates were also measured using saliva expectoration. SPSS 16.0 was used in the descriptive statistical analysis. Results: the sample consisted of 4 men and 18 women whose mean age was 61.6±2.83 years. The mean of spontaneous and stimulated salivary flow rates were 0.27+0.06 mL/min and 0.84+0.08 mL/min, respectively. Hyposalivation was present in 54.5% of cases, and dry mouth was reported by 31.3% of patients. Mild depressive symptoms were observed in 22.7% of the sample. When assessing anxiety-trait, we found that 31.8% had moderate symptoms of anxiety, 63.6% had symptoms of high anxiety, and 4.5% had very high anxiety. The assessment of anxiety-status showed that 27.3% and 72.7% had moderate and elevated anxiety symptoms, respectively. Seventy-seven percent had sleep disorders. Serological tests showed no significant changes. Conclusion: Our findings suggest an association between the behavioral parameters evaluated and the oral symptoms, indicating the need for a larger sample to confirm this trend using statistical analysis.