Abstract
Introduction
Changes in the central nervous system (CNS) pathways controlling trunk and leg muscles in patients with low back pain and radiculopathy have been observed and this study investigated whether surgery impacts upon these changes.
Methods
Parameters of corticospinal control were examined on 3 occasions in 22 patients prior to, at 6 and 26 weeks following lumbar decompression surgery and in 14 control subjects at the same intervals. Electromyographic 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.
Results
In the surgical group, asymmetries in the size of motor evoked potentials (MEPs) in TA (P=0.001) and in the cortical silent periods (cSP) were found between the left and right sides in SOL (P=0.005) and ES at L4 (P=0.014) prior to surgery. This was not observed at 6 or 26 weeks. Abdominal responses could be evoked in 12 patients and there was a significant reduction in the cSP contralateral to the pain in EO (P=0.034) and RA (P=0.041) at 6 weeks. These parameters remained stable in controls over time.
Discussion
The fact that changes appear to stabilise at 6 weeks is of interest as this parallels clinical outcome studies. Current work is ongoing to examine these excitability changes in both inhibitory and excitatory cortical pathways in these patients, and to what extent they may be related to clinical outcome.
Conflicts of interest: None
Sources of funding: Funded by 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
