The Establishment Of Lateral Hemisection Of Cervical Spinal Cord Injury Model In Rhesus Monkey

Spinal cord injury (SCI) is often seen in clinical work with high disability and lethality, which has been a focus of laboratory and clinical research. In recent years, tremendous research work has been carried out to explore the repair mechanism of SCI and lots of valuable results have been found. Meanwhile improvement has been achieved in animal model research and many kinds of animal models are widely used in laboratory research. But the evaluation of SCI differs greatly in different models. The establishment of lateral hemisection of cervical SCI model is fundamental for the research of the nervous repair and motor improvement as well as the mechanism. This will make a breakthrough in basal research and offer valuable data for the clinical treatment. We established standard and reliable animal model in rhesus monkey to mimic the pathological reaction and clinical manifestation.In this experiment, the spinal cord of C3.5 centrum was exposed through a dorsal midline incision in the neck. The left hemispinal cord of the C4 was split for 0.5cm and the amplitude of somatosensory evoked potential (SEP) dropped by 50% in SEP monitoring. SEPs were measured 24h and 7d after surgery. The movement of left limbs were observed, scored and analyzed by digital camera screen. Our results showed that the left limbs were paralyzed and motor score dropped to 1 from 6 after surgery.SEP monitoring demonstrated that the latency of forelimb (median nerve) was 15.54±2.69 ms before surgery, 22.36±4.19ms at 24hand 23.14±3.89ms at 7d, which was delayed significantly (P<0.01) .Similarly the amplitudes were 13.04±4.95 uV before surgery, 5.28±3.02 uV at 24h and 5.32±2.75 uV at 7d, which dropped dramatically (PO.01) . And the latency of hindlimb(tibial nerve) was 22.84±3.59 ms before surgery, 33.02±3.80 ms at 24h and 35.02±3.44ms at 7d, which was delayed significantly (P<0.0\) .Similarly the amplitudes were 20.88±3.25uV before surgery, 4.28±2.25uV at 24h and 4.70±1.77uV at 7d, which also dropped dramatically P<0.0\). The post-operative muscle strength of left side correlated with the SEP amplitudes positively (Pearson r=1.00, P=0.01) and with the latency negatively (Pearson r=-0.99, i>=0.05).In conclusion, in the monitoring of SEP, microsurgical cross hemisecition of spinal cord will split the cortex-spinal cord and result in paralysis easily and reliably. The establishment of the lateral hemisection of cervical spinal cord injury model in rhesus monkey will make an ideal model for the research of nervous repair in SCI.