P06 The relationship between motor cortex organisation and motor variability in the transition to sustained muscle pain
Summers SJ, Chipchase LS[1, 2], Hirata R, Graven-Nielsen T, Cavaleri R, Schabrun SM
- Western Sydney University, School of Science and Health, Penrith, NSW, Australia.
- Faculty of Health, University of Canberra, ACT, Australia
- Laboratory for Musculoskeletal Pain and Motor Control, SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
- Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
Evidence to support a relationship between the reorganisation of the primary motor cortex(M1) and altered motor control in response to pain is limited.Here, we examined the relationship between M1 reorganisation and motor variability in response to sustained muscle pain. We hypothesized that sustained muscle pain would stimulate M1 reorganisation, and that changes in M1 would correlate with the magnitude of motor variability.Twenty-eight healthy individuals were injected with nerve growth factor(NGF) into right extensor carpi radialis brevis(ECRB) muscle on Days 0 and 2. Assessment of M1 organisation using transcranial magnetic stimulation and motor variability were performed on Days 0,2,4, and 14.Motor variability was assessed during a radial-ulna movement and quantified as variability of wrist flexion-extension and forearm pronation-supination (kinematic variability), and electromyography(EMG) activity of ECRB(EMG variability).Pain intensity, disability,and muscle soreness were assessed on each day.Pain intensity, disability,and muscle soreness increased at Day 2 and 4(P0.15).Discrete peaks and centre of gravity (CoG) were unchanged(P>0.55).Map volume reduced at Day 2 and 4(P0.13),nor between map outcomes and kinematic variability(P>0.15).These data indicate a decrease in map excitability in response to sustained muscle pain.Reduced map excitability was associated with reduced EMG variability during a wrist radial/ulna movement.These findings suggest a relationship between M1 reorganisation and motor variability in response to pain.
- Schabrun S, Christensen SW, Mrachacz-Kersting N, Graven-Nielsen T. Motor cortex reorganization and impaired function in the transition to sustained muscle pain. Cerebral Cortex. 2015