Safety and Efficacy of Postoperative Anticoagulation for Deep Vein Thrombosis Prophylaxis in Vestibular Schwannoma Microsurgical Resection

Introduction: This institute experienced multiple devastating consequences of chemical anticoagulation-induced intracranial hemorrhages (ICH) after successful posterior fossa (PF) vestibular schwannoma (VS) resection surgeries, prompting the implementation of an anticoagulation protocol in May 2015: Stop Treating with Enoxaparin Postoperatively for Posterior fossa Surgery (STEPPS). The STEPPS Protocol calls for patients who have undergone PF craniotomies not to receive any chemical venous thromboembolism (VTE) chemical anticoagulation for 3 days postoperatively. All patients were to use mechanical anticoagulation while in bed and have lower extremity Doppler ultrasounds performed every other day to monitor for deep vein thromboses (DVT). Unfractionated heparin (UFH) could be used in a twice-daily dosage after 3 days and/or an inferior vena cava (IVC) filter could be placed. Enoxaparin would not be used prophylactically or therapeutically for 1 month postoperatively. This study sought to determine the efficacy of this protocol, and whether the reduction in enoxaparin use had a significant impact on reducing the incidence of ICH in this patient population.

Methods: Demographic, clinical, surgical, and postoperative treatment-related information on patients who underwent a VS microsurgical resection by a single neurosurgeon in one institution from 2011 through May 2019 was retrospectively recorded. The postoperative outcomes were followed with regard to the STEPPS protocol. A p-value of less than 0.05 was considered statistically significant.

Results: A total of 132 VS microsurgical resections were included in the analysis from 2011 through May 2019. Sixty-seven (50.8%) surgeries were performed before the STEPPS protocol was implemented from 2011 through April 2015. Of these, information regarding chemical anticoagulation use could be obtained for 33 patients. Twenty-nine (87.9%) of these patients received chemical anticoagulation (UFH or enoxaparin), including 63.6% (21/33) who received enoxaparin. Twenty (95.2%) of these patients received enoxaparin within 72 hours postoperatively, including three of the four patients who developed a postoperative, anticoagulation-related ICH. The incidence of postoperative anticoagulation-related ICH prior to the STEPPS protocol implementation is 5.97% (4/67) compared with 0% (0/65) after it's start (p = 0.0457). Of the four ICH patients, one succumbed to the complexities of his care within 2 years and one is bedridden at a functional Glasgow Outcome Scale of 2. Of the 65 (49.2%) operations performed after May 2015, 12 (18.5%) patients received prophylactic or therapeutic chemical anticoagulation, including only 4.6% (3/65) who received enoxaparin. The difference between the proportion of patients receiving enoxaparin before and after the STEPPS protocol was statistically significant (p < 0.0001). Three (4.6%) patients developed a DVT (two in lower extremities, one in upper extremity) and two (3.1%) patients developed a PE, at which point, they received UFH and one received an IVC filter. Both patients recovered well.

Conclusion: Chemical VTE prophylaxis can increase the susceptibility of PF neurosurgical patients to ICH. The STEPPS protocol results indicate that there is a statistical significance between the rates of ICH and enoxaparin use before and after implementation. Relying more strongly on mechanical prophylaxis and vigilant surveillance in the population of neurosurgical patients undergoing posterior fossa craniotomies can help prevent devastating ICHs from occurring.