Introduction Transcranial motor evoked potentials are routinely used at The Children’s Hospital at Westmead to monitor the spinal cord in spinal surgery. This study is a prospective review of all spinal cord monitoring procedures from 1999 to 2004 in patients undergoing elective spinal deformity correction surgery at The Children’s Hospital at Westmead and Westmead Hospital. Spinal cord monitoring with Somatosensory Evoked Potentials (SSEP) and MEP has been widely used in combination during spinal surgery with good sensitivity and specificity. The use of CMAP as the only modality has not been widely used and its efficacy has not been fully elucidated. Using MEP and CMAP only may increase the sensitivity of spinal cord monitoring compared with combined SSEP and MEP monitoring.

Methods The intra-operative monitoring outcomes were compared with patient’s post-operative clinical outcomes. The sensitivity and specificity were calculated and determined for our monitoring protocol.

Results Transcranial MEPs were measured in 146 patients in 175 procedures. In 2 patients (2 procedures) we were unable to record any CMAPS. There were 15 intra-operative monitoring changes (8.7%). There were no new post-operative neurological deficits. Our results compare favourably to the literature with respect to the false-negative rate or new neurological events.

Discussion Using our anaesthetic protocol and spinal monitoring criteria, we were able to successfully monitor patients undergoing elective spinal deformity correction surgery for a variety of diagnoses. The monitoring criteria are sufficiently strict to achieve a sensitivity of 1.0 (95%CI = 0.66–1.00) and a specificity of 0.97 (95%CI = 0.83–0.99). Monitoring of CMAPs alone has been adequate to avoid clinical neurological deficits.

Introduction A prospective cohort study was conducted to assess the incidence of venous thromboembolism (VTE) in 300 patients undergoing elective spinal surgery. Although this subject has been extensively studied in patients undergoing joint replacement surgery, the true incidence of VTE related to spinal surgery remains unknown. We also sought to assess the efficacy of various forms of VTE prophylaxis, another area which has not been adequately studied.

Methods Bilateral lower extremity venous duplex scans were performed pre-operatively, within one week postoperatively and at 4 to 6 weeks post-operatively. Information was collected regarding age, gender, body mass index, type and duration of surgical procedure, intra-operative blood loss and blood transfusion, pre- and post-operative mobility and other risk factors for VTE. All patients received vigorous mechanical prophylaxis with 56% of patients receiving pharmacological prophylaxis (unfractionated or low molecular weight heparin) according to surgeon preference.

Results The overall incidence of post-operative deep vein thrombosis (DVT) was 3.4%. The incidence in those receiving pharmacological prophylaxis was 1.2% versus 6.3% in those who received mechanical prophylaxis alone (p< 0.05). Just under half of the post-operative DVTs (1.4%) occurred after hospital discharge with none of these patients receiving heparin. There were two cases of pulmonary embolism (0.7%), both occurring during hospitalization, and there were no deaths. There was no difference in blood loss or transfusion rates between patients receiving or not receiving pharmacological prophylaxis and there were no serious complications related to blood loss. There was a surprisingly high incidence of abnormalities detected on pre-operative scanning, with DVT occurring in 3.0% and superficial thrombophlebitis in 24.8%.

Discussion The incidence of DVT in patients after spinal surgery was 3.4% and was significantly lower (1.2 %) in patients who received pharmacological prophylaxis. Given that the rates of bleeding-related complications were not different between the two groups, we conclude that it is both efficacious and safe to use pharmacological prophylaxis in combination with mechanical prophylaxis routinely in patients undergoing spinal surgery. A 27.8% incidence of pre-operative venous abnormalities may reflect pre-operative immobility due to pain in this group of patients, and justifies the use of ultrasound scanning as an important pre-operative screening tool. In addition, the high incidence of late-onset DVT justifies the need for follow-up scanning several weeks after discharge. This study is the amongst the largest of its type to date, however a larger, randomized and controlled trial is now necessary to confirm these results and allow the formulation of unambiguous guidelines for spinal surgery and VTE prophylaxis.