Driving plasticity in the motor cortex in recurrent low back pain.

The sensory and motor systems can reorganise following injury and learning of new motor skills. Recently we observed adaptive changes in motor cortical organisation in patients with recurrent low back pain (LBP), which are linked to altered motor coordination. Although changes in motor coordination can be trained and are associated with improved symptoms and function, it remains unclear whether these training-induced changes are related to reorganisation of the motor cortex. This was investigated using the model of a delay in postural activation of the deep abdominal muscle, transversus abdominis (TrA) in 20 individuals with recurrent LBP. Subjects were allocated to either motor skill training that involved isolated voluntary contractions of TrA, or a control intervention of self-paced walking exercise for 2 weeks. Electromyographic (EMG) activity was recorded from TrA bilaterally using intramuscular fine-wire electrodes. Motor cortical organisation using transcranial magnetic stimulation (TMS) and postural activation associated with single rapid arm movements were investigated before and after training. Motor skill training induced an anterior and medial shift in motor cortical representation of TrA, towards that observed in healthy individuals from our previous study. This shift was associated with earlier postural activation of TrA. Changes were not observed following unskilled walking exercise. This is the first observation that motor training can reverse reorganisation of neuronal networks of the motor cortex in people with recurrent pain. The observed relationship between cortical reorganisation and changes in motor coordination following motor training provides unique insight into potential mechanisms that underlie recovery.