Effects of experimental pain and local anesthesia on motor cortex excitability and its relationship with muscle sensitivity

• Grant number: 18/00614-2
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: April 15, 2018
• End date: July 14, 2018
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal Investigator: Leonardo Rigoldi Bonjardim
• Grantee: Yuri Martins Costa
• Supervisor: Peter Svensson
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil
• Institution abroad: Aarhus University, Denmark
• Associated to the scholarship: 15/09913-4 - The effect of cutaneous afferents in the mechanical somatosensory profile of masticatory myofascial pain., BP.PD

Abstract

The precise relationship between pain and jaw motor function is still not totally clear and different and debatable models were proposed to explain such relationship. Transcranial magnetic stimulation (TMS) uses electromagnetic induction to elicit neuronal responses and has been widely applied to assess the functional integrity of top-down pathways related to motor control. The primary aim of this study is to investigate the representation and modulation of motor cortical activity under the effect of experimental muscle pain and local anesthesia and the secondary aim is to assess the possible relationship between motor cortical representation and excitability and muscle sensitivity. Sixty healthy participants will be divided into three groups according to the type of injection that will be applied into the right masseter: 1) experimental pain group (NGF group) where the participants will receive an injection of nerve growth factor (5 micrograms in 0.2 ml) to induce muscle sensitization; 2) experimental nerve block group (nerve block group) where the participants will receive 1 mL of lidocaine 0.5%; 3) control group, where the participants will receive 1 mL of sterile solution of isotonic saline. The outcomes masseter motor evoked potential (MEP), masseter entropy, i.e., mechanical pain sensitivity (MPS) to pressure stimuli and referral pattern will be assessed at two time points: baseline (before injection) and post-injection, which will occur 10 min after the injection for the nerve block and the control groups and 48 hours for the NGF group. Mixed ANOVA models will be performed to assess the mean differences of the outcome variables. The significance level was set at 5% (p = 0.050).

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

COSTA, YURI M.; EXPOSTO, FERNANDO G.; KOTHARI, MOHIT; CASTRILLON, EDUARDO E.; CONTI, PAULO CESAR R.; BONJARDIM, LEONARDO R.; SVENSSON, PETER. Masseter corticomotor excitability is decreased after intramuscular administration of nerve growth factor. EUROPEAN JOURNAL OF PAIN, v. 23, n. 9, JULY 2019. (15/09913-4, 18/00614-2)

COSTA, YURI M.; EXPOSTO, FERNANDO G.; CASTRILLON, EDUARDO E.; CONTI, PAULO CESAR R.; BONJARDIM, LEONARDO R.; SVENSSON, PETER. Local anaesthesia decreases nerve growth factor induced masseter hyperalgesia. SCIENTIFIC REPORTS, v. 10, n. 1, p. 11-pg., 2020-09-22. (15/09913-4, 18/00614-2)