Corticomotor excitability of back muscles is affected by intervertebral disc lesion in pigs

摘要: Morphological and behavioural changes in back muscles are common pain injury. Recent data indicate a rapid reduction the size of multifidus, deep muscle, within 3 days experimental intervertebral disc (IVD) injury pigs. A reduced neural drive may contribute to this. We investigated corticomotor excitability following IVD lesion by evaluation response electrical stimulation motor cortex. Motor evoked potentials (MEPs) were studied 12 Swedish landrace pigs before injury, immediately after abdominal incision, L3-4 with scalpel, 15 min later. In two animals, responses also descending volleys excited at level mastoid processes (cervicomedullary potentials) without cortex activation. five sham procedure was followed lesion. MEPs recorded short (deep) long (superficial) fibres multifidus L3-5 on lesioned side L4 contralaterally intramuscular wire electrodes. Although MEP amplitude increased several only [36% (SD 15%), P < 0.05]. There no adjacent or contralateral levels. The cervicomedullary slightly. This suggests that due cortical excitability. These induces localized increases, not decreases, inputs paraspinal cross disc.