Association of anxiety with intracortical inhibition and descending pain modulation in chronic myofascial pain syndrome

• Autor(a) principal: Vidor, Liliane Pinto
• Data de Publicação: 2014
• Outros Autores: Torres, Iraci Lucena da Silva, Medeiros, Liciane Fernandes, Sarria, Jairo Alberto Dussán, Dall'Agnol, Letizzia, Deitos, Alícia, Brietzke, Aline Patrícia, Laste, Gabriela, Rozisky, Joanna Ripoll, Fregni, Felipe, Caumo, Wolnei
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/110151
• topic: Ansiedade; Síndromes da dor miofascial; Estimulação magnética transcraniana; Dor crônica; Transcranial magnetic stimulation; Chronic pain; Noninvasive brain stimulation; Neuromodulation; Anxiety; Myofascial pain syndrome

Background: This study aimed to answer three questions related to chronic myofascial pain syndrome (MPS): 1) Is the motor cortex excitability, as assessed by transcranial magnetic stimulation parameters (TMS), related to state-trait anxiety? 2) Does anxiety modulate corticospinal excitability changes after evoked pain by Quantitative Sensory Testing (QST)? 3) Does the state-trait anxiety predict the response to pain evoked by QST if simultaneously receiving a heterotopic stimulus [Conditional Pain Modulation (CPM)]? We included females with chronic MPS (n = 47) and healthy controls (n = 11), aged 19 to 65 years. Motor cortex excitability was assessed by TMS, and anxiety was assessed based on the State-Trait Anxiety Inventory. The disability related to pain (DRP) was assessed by the Profile of Chronic Pain scale for the Brazilian population (B:PCP:S), and the psychophysical pain measurements were measured by the QST and CPM. Results: In patients, trait-anxiety was positively correlated to intracortical facilitation (ICF) at baseline and after QST evoked pain (β = 0.05 and β = 0.04, respectively) and negatively correlated to the cortical silent period (CSP) (β = -1.17 and β = -1.23, respectively) (P <0.05 for all comparisons). After QST evoked pain, the DRP was positively correlated to ICF (β= 0.02) (P < 0.05). Pain scores during CPM were positively correlated with trait-anxiety when it was concurrently with high DRP (β = 0.39; P = 0.02). Controls’ cortical excitability remained unchanged after QST. Conclusions: These findings suggest that, in chronic MPS, the imbalance between excitatory and inhibitory descending systems of the corticospinal tract is associated with higher trait-anxiety concurrent with higher DRP.