The IOM loss between CCM and TCM patients present obvious difference and the sudden MEPs loss associated with spinal decompression need to be taken seriously especially in TCM.

Background: Surgery is usually the treatment of choice for patients with cervical compressive myelopathy (CCM). Motor evoked potential (MEP) has proved to be helpful tool in evaluating intraoperative cervical spinal cord function change of those patients. This study aims to describe and evaluate different MEP baseline phenotypes for predicting MEP changes during CCM surgery. Methods: A total of 105 consecutive CCM patients underwent posterior cervical spine decompression were prospectively collected between December 2012 and November 2016. All intraoperative MEP baselines recorded before spinal cord decompression were classified into 5 types (I to V) that were carefully designed according to the different MEP parameters. The postoperative neurologic status of each patient was assessed immediately after surgery. Results: The mean intraoperative MEP changes range were 10.2% ± 5.8, 14.7% ± 9.2, 54.8% ± 31.9, 74.1% ± 24.3, and 110% ± 40 in Type I, II, III, IV, and V, respectively. There was a significant correlation of the intraoperative MEP change rate with different MEP baseline phenotypes (r = 0.84, P < 0.01). Postoperative transient new spinal deficits were found 0/31 case in Type I, 0/21 in Type II, 1/14 in Type III, 2/24 in Type IV, and 4/15 in Type V. No permanent neurological injury was found in our cases series. Conclusions: The MEP baselines categories for predicting intraoperative cervical cord function change is proposed through this work. The more serious the MEP baseline abnormality, the higher the probability of intraoperative MEP changes, which is beneficial to early warning for the cervical cord injury.

Background: To our knowledge, the exposed nerve roots in thoracic spine are usually sacrificed to facilitate osteotomy during posterior vertebral column resection (PVCR) for severe spinal deformity. Currently we report a case with severe spine deformity in which intraoperative neurological monitoring (IOM) loss after interrupting T8 nerve root finally led to spinal cord injury during PVCR surgery. Case presentation: The patient was a 14-year-old female with severe congenital kyphoscoliosis (CKS) without preoperative neurologic deficits. The IOM events (MEP loss and SSEP latency prolong) were showed when T8 nerve root at concave side was interrupted. And then we reduce the scope of osteotomy to control bleeding, raised blood pressure (MAP, 65-80) to increase blood supply for spinal cord, placed the bilateral rod to stabilized the spinal cord, used the methylprednisolone, explored the presence or absence of spinal cord compression, and prepared to change the surgical plan from PVCR to PSO. After that the IOM signals partial recovered from the lowest point. Postoperatively the patients showed transient motor function deficits of left lower limbs weak without somatosensory deficits, and come back to preoperative status 6 months later. Conclusions: Interrupting the thoracic spine nerve root is danger to trigger the spinal cord injury during PVCR procedure of severe CKS. That probably because the increasing tension of contralateral anterior horn area of spinal cord via the nerve root pulling.