Combining pedicle screw stimulation with spinal navigation, a protocol to maximize the safety of neural elements and minimize radiation exposure in thoracolumbar spine instrumentation.

PURPOSE: The O-arm-based navigation increases the accuracy of pedicle screw positioning and offers the possibility of performing a 3D scan before wound closure. However, repeating the 3D scan exposes the patient to additional radiation. We combined O-arm navigation with pedicle screw (PS) stimulation followed by a 3D scan to evaluate their accuracy and aimed for the creation of a protocol that maximizes the safety and minimizes radiation. METHODS: Patients had pedicle screws insertion using O-arm spinal navigation, then had PS triggered electromyography (EMG), and finally a 3D scan to evaluate the accuracy of screw position. RESULTS: 447 screws were inserted in 71 patients. In 10 patients, 11 screws needed repositioning. Comparing results of PS triggered EMG responses to the 3D scan, we found: (a) negative stimulation response with negative 3D scan findings, corresponding to 432 acceptable screw position (96.6 %) in 58 patients (81.7 %). In these cases, the redo 3D scan could be avoided. (b) Positive stimulation response with positive 3D scan findings, corresponding to 7 unacceptable screw position (1.5 %) in 6 patients (8.4 %). In these cases, PS stimulation detected malpositioned screws that would be missed without a redo 3D scan. CONCLUSION: We propose a protocol of routinely performing PS stimulation after screw insertion using spinal navigation. In case of positive stimulation, a 3D scan must be performed to rule out a probable screw mal position (6 patients 8.4 %). However, in case of negative stimulation, redo 3D scan can be avoided in 81.7 % of patients.

Deep venous thrombosis in spine surgery patients: incidence and hematoma formation.

Deep venous thrombosis (DVT) is a significant health care problem; a variety of factors place spinal surgery patients at high risk for DVT. Our aim is to define the incidence of DVT occurrence in spite of prophylactic measures (mechanical and chemoprophylaxis), and the development of spinal epidural hematoma as a complication of chemoprophylaxis. In a single-center prospective study, 158 patients who underwent spinal surgical procedures were evaluated by clinical evaluation and lower limb Doppler ultrasonography imaging. Only one patient (0.6%) developed DVT; this patient was treated successfully without thrombus progression, with full recanalization. Three patients (1.8%) developed spinal epidural hematoma, but only one required surgical evacuation, and none sustained neurologic deficit. Careful evaluation for DVT risk on an individual basis and good prophylaxis helps to minimize the risk of DVT. The neurosurgeon is thus left to weigh the risks of postoperative hematoma formation against the benefits of protecting against DVT.