Predicting spinal neurological prognosis in patients with surgical treatment for thoracic spinal stenosis based on neurological and neurophysiological evaluation.

OBJECTIVE: We aim to investigate the spinal neurological outcomes in patients who have undergone surgery for thoracic spinal stenosis (TSS) and to identify high-risk factors for poor spinal neurological prognosis.  METHODS: Patients were categorized into four subgroups based on TSS causes: thoracic disk herniation (TDH), ossification of the posterior longitudinal ligaments (OPLL), ossification of the ligamentum flavum (OLF), and OPLL + OLF. The following data were collected: (1) demographic and clinical data; (2) neurological evaluation; and (3) neurophysiological evaluation by combining somatosensory- and motor- evoked potential (SSEP and MEP) baseline at both legs. The spinal neurological function was assessed by modified Japanese Orthopedic Association (mJOA) score at three time-point: before surgery, one-month and six-month after the surgery; Univariate and multivariate logistic regression analyses were performed to identify independent high-risk factors associated with poor spinal neurological prognosis.  RESULTS: A total of 236 patients were diagnosed with TSS. The mean mJOA scores before and six months after the surgery were 7.0 and 7.9, respectively. The number of patients with declined spinal neurological outcomes during the short- and long- term follow-ups were 17 and 8, respectively. Based on multivariate logistic analysis, risk factors for poor spinal neurological prognosis were as follows: preoperative severe myelopathy [OR = 5.65, 95% CI (2.12, 13.04), p = 0.001], abnormal SSEP and/or MEP baseline [OR = 3.93, 95% CI (1.44, 8.22), p = 0.007], and OPLL and/or OLF [OR = 3.06, 95% CI (1.01, 7.36), p = 0.039]. A decision tree that includes the risk factors can be used to screen patients.  CONCLUSIONS: Surgical treatment for TSS can improve spinal neurological function. Risk factors for poor prognosis were identified. Preoperative neurological evaluations and neurophysiological baseline signals can help predict poor prognosis of the TSS patients.