Abstract
Introduction
Changes in central nervous system (CNS) pathways controlling trunk and leg muscles in patients with low back pain(LBP) and lumbar radiculopathy have been observed and this study investigated whether surgery impacts upon these changes in the long term.
Methods
80 participants were recruited into the following groups: 25 surgery(S), 20 chronic LBP(CH), 14 spinal injection(SI), and 21 controls(C). Parameters of corticospinal control were examined before, at 6, 26 and 52 weeks following lumbar decompression surgery and equivalent intervals. Electromyographic(EMG) activity was recorded from tibialis anterior(TA), soleus(SOL), rectus abdominis(RA), external oblique(EO) and erector spinae(ES) muscles at the T12&L4 levels in response to transcranial magnetic stimulation of the motor cortex. Motor evoked potentials (MEP) and cortical silent periods(cSP) recruitment curves(RC) were analysed.
Results
Trunk muscles in all patients had reduced raw EMG (P<0.001), increased motor thresholds (MTh;P<0.001) and MEP RC slopes. MTh in ESL4 correlated with back pain in all patients (r=0.201, P=0.016) and soleus MTh laterality with disability in surgery patients (r=0.49, P=0.018). S&SI patients displayed bilaterally increased soleus cSP (p<0.001), MEP latencies on the painful side (P<0.001), and cSP asymmetry (cSPA;P<0.001). cSPA resulted from abnormal soleus late responses on the painful side, indicating compromised agonist-antagonist control in patients with radiculopathy. In contrast to SI, surgery significantly reduced soleus cSPA and MEP latencies at 6 weeks (P≤0.034).
Discussion
These results show long term changes in CNS control of trunk and leg muscles in radiculopathy and LBP, which are only partly reversed by surgery, and may provide future therapeutic targets to address the altered inhibitory processes within the brain.
No conflicts of Interest
Sources of funding: The DISCS foundation.
This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting.
