The impact of surgery to relieve leg pain on cortical control of trunk and leg muscles

All current chronic low back pain (LBP) treatments have variable long-term efficacy. Changes in the central nervous system pathways controlling trunk and leg muscles (T&L) in LBP have been reported, and this thesis investigated whether surgery (n=24) or conservative management (spinal injections [SIs;n=12] or no treatment [NT;n=18]), impact upon these changes in the long term. 19 healthy controls and 54 LBP patients were recruited. 45 of the LBP patients also had leg pain distal to the knee (LBPLP), 12 of which had radicular pain/radiculopathy at L5 and 12 at S1. Transcranial magnetic stimulation (TMS) was used to evoke a number of outcome measures in electromyographic activity. The first long term TMS T&L reliability study established suitable parameters to assess corticomotor excitability (CE) (i.e. motor evoked potential (MEP) threshold (MTh)) and intracortical inhibition (ICI: i.e. the cortical silent period (cSP)) on 4 occasions, prior and up to 1 year following treatment. LBPLP patients had pain-lateralised and markedly prolonged leg cSPs, which, unlike in SI patients, were gradually normalised in high functional responders to surgery. Significant reductions in leg MThs occurred in high functional responders ... (continues)