The correlation between motor evoked potential and BBB score of spinal cord injury in rats

Abstract

Objective To investigate the correlation between motor evoked potential (MEP) and Basso-Beattie-Bresnahan (BBB) scores in evaluating spinal cord injury function in rats. Methods Sixteen adult female SD rats were randomly divided into control group and experimental group with 8 rats in each group. The animals of control group were only operated without external force, and the animals of experimental group were made the spinal cord injury (SCI) model used PSI-IH device. The spinal cord motor evoked potential (scMEP) and muscle motor evoked potential (mMEP) were recorded and analyzed before injury and 3 h, 1 d, 3 d, and the 1st, 2nd, 3rd, 4th, 5th, 6th weeks after injury. The motor function of hind limbs was evaluated by BBB score. The histological changes of spinal cord were observed 6 weeks after SCI. Results After SCI, the amplitude of scMEP in the experimental group decreased to 32.69%±0.83% of the normal amplitude at 3 hours, and it reached 52.93%±2.23% of the normal amplitude at 2 weeks later, which was stable, but was lower than that of control group (all P values<0.01); the mMEP waveform disappeared at 3 hours after SCI, and it reached to 1.16%±0.17% of the normal amplitude after one day of injury. 4th week after SCI, the amplitude of mMEP was 48.20%±3.70% of normal amplitude and was stable, but it was lower than that of the control group (all P values<0.01). The BBB score in the experimental group were 0 at 3 hours and 1 day after SCI. The BBB scores were 1.38±0.52 after 3 days and which were 11.50±0.93 after 4 weeks, reaching a stable state, but they were lower than those of the control group (all P values<0.01). In the experimental group, there was a significant correlation between scMEP and BBB score (r 0.732-0.908, all P values<0.05) from 3 h to 6th week after SCI. There was a moderate or high correlation between mMEP and BBB score in the experimental group from 1st to 6th week after SCI (r 0.718-0.951, all P values<0.05). There were no significant changes in the above indexes of the control group. Conclusions After SCI in rats, scMEP, mMEP and BBB scores will be recovered sequentially, and are correlated to some extent. In addition, scMEP and mMEP are more sensitive indicators of SCI than BBB scores. Key words: Spinal cord injuries; Evoked potentials, motor; Behavior detection; Basso-Beattie-Bresnahan scores; Models, animal; rats