OBJECTIVEVenous thromboembolism (VTE) after spinal surgery is a major cause of morbidity, but chemoprophylactic anticoagulation can prevent it. However, there is variability in the timing and use of chemoprophylactic anticoagulation after spine surgery, particularly given surgeons’ concerns for spinal epidural hematomas. The goal of this study was to provide insight into the safety, efficacy, and timing of anticoagulation therapy after spinal surgery.METHODSThe authors retrospectively examined records from 6869 consecutive spinal surgeries performed in their departments at Northwestern University. Data on patient demographics, surgery, hospital course, timing of chemoprophylaxis, and complications, including deep venous thrombosis (DVT), pulmonary embolism (PE), and spinal epidural hematomas requiring evacuation, were collected. Data from the patients who received chemoprophylaxis (n = 1904) were compared with those of patients who did not (n = 4965). The timing of chemoprophylaxis, the rate of VTEs, and the incidence of spinal epidural hematomas were analyzed.RESULTSThe chemoprophylaxis group had more risk factors, including greater age (59.70 vs 51.86 years, respectively; p < 0.001), longer surgery (278.59 vs 145.66 minutes, respectively; p < 0.001), higher estimated blood loss (995 vs 448 ml, respectively; p < 0.001), more comorbid diagnoses (2.69 vs 1.89, respectively; p < 0.001), history of VTE (5.8% vs 2.1%, respectively; p < 0.001), and a higher number were undergoing fusion surgery (46.1% vs 24.7%, respectively; p < 0.001). The prevalence of VTE was higher in the chemoprophylaxis group (3.62% vs 2.03%, respectively; p < 0.001). The median time to VTE occurrence was shorter in the nonchemoprophylaxis group (3.6 vs 6.8 days, respectively; p = 0.0003, log-rank test; hazard ratio 0.685 [0.505–0.926]), and the peak prevalence of VTE occurred in the first 3 postoperative days in the nonchemoprophylaxis group. The average time of initiation of chemoprophylaxis was 1.46 days after surgery. The rates of epidural hematoma were 0.20% (n = 4) in the chemoprophylaxis group and 0.18% (n = 9) in the nonchemoprophylaxis group (p = 0.622).CONCLUSIONSThe risks of spinal epidural hematoma among patients who receive chemoprophylaxis and those who do not are low and equivalent. Administering anticoagulation therapy from 1 day before to 3 days after surgery is safe for patients at high risk for VTE.

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OBJECTIVEVenous thromboembolic events (VTEs), including both deep venous thrombosis (DVT) and pulmonary embolism, are a major cause of morbidity and mortality after spine surgery. Prophylactic anticoagulation, or chemoprophylaxis, can prevent VTE. However, the timing of VTEs after spine surgery and the effect of chemoprophylaxis on VTE timing remain underinvestigated.METHODSThe records of 6869 consecutive spine surgeries were retrospectively examined. Data on patient demographics, surgical variables, hospital course, and timing of VTEs were collected. Patients who received chemoprophylaxis were compared with those who did not. Appropriate regression models were used to examine selection for chemoprophylaxis and the timing of VTEs.RESULTSAge (OR 1.037, 95% CI 1.023–1.051; p < 0.001), longer surgery (OR 1.003, 95% CI 1.002–1.004; p < 0.001), history of DVT (OR 1.697, 95% CI 1.038–2.776; p = 0.035), and fusion surgery (OR 1.917, 95% CI 1.356–2.709; p < 0.001) predicted selection for chemoprophylaxis. Chemoprophylaxis patients experienced more VTEs (3.62% vs 2.03% of patients, respectively; p < 0.001), and also required longer hospital stays (5.0 days vs 1.0 days; HR 0.5107; p < 0.0001) and had a greater time to the occurrence of VTE (median 6.8 days vs 3.6 days; HR 0.6847; p = 0.0003). The cumulative incidence of VTEs correlated with the postoperative day in both groups (Spearman r = 0.9746, 95% CI 0.9457–0.9883, and p < 0.0001 for the chemoprophylaxis group; Spearman r = 0.9061, 95% CI 0.8065–0.9557, and p < 0.0001 for the nonchemoprophylaxis group), and the cumulative incidence of VTEs was higher in the nonchemoprophylaxis group throughout the 30-day postoperative period. Cumulative VTE incidence and postoperative day were linearly correlated in the first 2 postoperative weeks (R = 0.9396 and p < 0.0001 for the chemoprophylaxis group; R = 0.8190 and p = 0.0003 for the nonchemoprophylaxis group) and the remainder of the 30-day postoperative period (R = 0.9535 and p < 0.0001 for the chemoprophylaxis group; R = 0.6562 and p = 0.0058 for the nonchemoprophylaxis group), but the linear relationships differ between these 2 postoperative periods (p < 0.0001 for both groups).CONCLUSIONSAnticoagulation reduces the cumulative incidence of VTE after spine surgery. The cumulative incidence of VTEs rises linearly in the first 2 postoperative weeks and then plateaus. Surgeons should consider early initiation of chemoprophylaxis for patients undergoing spine surgery.

The ventral tegmental area (VTA) and the rostromedial tegmental nucleus (RMTg) each contribute to opiate reward and each receive inputs from the laterodorsal tegmental and pedunculopontine tegmental nuclei, the two principle brainstem cholinergic cell groups. We compared the contributions of VTA or RMTg muscarinic cholinergic receptors to locomotion induced by morphine infusions into the same sites. VTA co-infusion of atropine completely blocked VTA morphine-induced locomotion providing additional support for the important role of VTA muscarinic cholinergic receptors in the stimulant effects of opiates. By contrast, RMTg co-infusion of atropine increased RMTg morphine-induced locomotion. Furthermore, RMTg co-infusion of the M3-selective antagonist 4-DAMP, but not the M4-selective antagonist Tropicamide, strongly increased RMTg morphine-induced locomotion. RMTg infusions of 4-DAMP, but not of Tropicamide, by themselves strongly increased drug-free locomotion. Muscarinic cholinergic receptors in the RMTg thus also contribute to the stimulant effects of morphine, but in a way opposite to those in VTA. We suggest that the net effect of endogenous cholinergic input to the RMTg on drug-free and on RMTg morphine-induced locomotion is inhibitory.

OBJECTIVEVenous thromboembolic events (VTEs) are a common cause of morbidity and mortality after spine surgery. Patients admitted to the intensive care unit (ICU) following spine surgery exhibit high-risk clinical characteristics.METHODSThe authors retrospectively analyzed 1269 ICU patients who had undergone spine surgery between January 1, 2009, and May 31, 2015. Relevant demographic, procedural, and outcome variables were collected.RESULTSPatients admitted to the ICU postoperatively had a postoperative VTE rate of 10.2%, compared to 2.5% among all spine surgery patients during the study period. ICU patients had a higher comorbid disease burden (odds ratio [OR] 1.45, p < 0.001), and were more likely to have a history of a bleeding disorder (2.60% vs 0.46%, OR 2.85, p = 0.028), receive a transfusion (OR 4.81, p < 0.001), have a fracture repaired (OR 4.30, p < 0.001), have an estimated blood loss > 500 ml (OR 1.95, p = 0.009), have an osteotomy (OR 20.47, p = 0.006), or have a corpectomy (OR 3.48, p = 0.007) than patients not admitted to the ICU. There was a significant difference in time to VTE between patients undergoing osteotomy and patients undergoing scoliosis corrections without osteotomy (p = 0.0431), patients with fractures (p = 0.0113), and patients undergoing fusions for indications other than scoliosis or fracture (p = 0.0056). Patients who developed a deep vein thrombosis (DVT) during their ICU stay were more likely to have received a prophylactic inferior vena cava filter placement (OR 8.98, p < 0.001), have undergone an interbody fusion procedure (OR 2.38, p = 0.037), have a history of DVT (OR 3.25, p < 0.001), and have shorter surgery times (OR 0.30, p = 0.002). Patients who developed a pulmonary embolism (PE) during the ICU stay were more likely to have a history of PE (OR 12.68 p = 0.015), history of DVT (OR 5.11, p = 0.042), fracture diagnosis (OR 7.02, p = 0.040), and diagnosis of scoliosis (OR 7.78, p = 0.024). Patients with higher BMIs (OR 0.85, p = 0.036) and those who received anticoagulation treatment (OR 0.16, p = 0.031) were less likely to develop a PE during their ICU stay.CONCLUSIONSPatients admitted to the ICU following spine surgery have a higher rate of VTE than non-ICU patients. Time to VTE varied by pathology. Factors independently associated with VTE in the ICU are distinct from factors otherwise associated with VTE. Some factors are independently associated with VTE throughout the 30-day postoperative period, while others are associated with VTE specifically during the initial ICU stay or after leaving the ICU.

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Summary of Background Data. The impact of not achieving ideal realignment in the global alignment and proportion (GAP) score in adult spinal deformity (ASD) correction on clinical outcomes is understudied at present. Objective. To identify the clinical impact of failing to achieve GAP proportionality in ASD surgery. Study Design. Retrospective cohort. Methods. Operative ASD patients with fusion to S1/pelvis and with pre-(BL) and 2-year (2Y) data were included. Patients were assessed for matching their 6-week (6W) age-adjusted alignment goals.1 Patients were stratified by age-adjusted match at 6W postoperatively (Matched) and 6W GAP proportionality (proportioned: GAP-P; moderately disproportioned: GAP-MD; severely disproportioned: GAP-SD). Groups were assessed for differences in demographics, surgical factors, radiographic parameters, and complications occurring by 2Y. Multivariable logistic regression was used to assess independent effects of not achieving GAP proportionality on postoperative outcomes for Matched and Unmatched patients. Results. Included: One hundred twenty three ASD patients. At baseline, 39.8% were GAP-SD, and 12.2% GAP-SD at 6W. Of 123 patients, 51.2% (n =63) had more than or equal to one match at 6W. GAP-SD rates did not differ by being Matched or Unmatched (P = 0.945). GAP-SD/Unmatched patients had higher rates of reoperation, implant failure, and PJF by 2Y postop (all P <0.05). Regressions controlling for age at BL, levels fused, and CCI, revealed 6W GAP-SD/Unmatched patients had higher odds of reoperation (OR: 54 [3.2–899.9]; P =0.005), implant failure (OR: 6.9 [1.1–46.1]; P =0.045), and PJF (OR: 30.1 [1.4–662.6]; P =0.031). Compared to GAP-P or GAP-MD patients, GAP-SD/ Matched patients did not have higher rates of reoperation, implant failure, or junctional failure (all P >0.05). The regression results for both Matched and Unmatched cohorts were consistent when proportionality was substituted by the continuous GAP score. Conclusion. In ASD patients who meet age-adjusted realignment goals, GAP proportionality does not significantly alter complication rates. However, GAP proportionality remains an important consideration in patients with sub-optimal age- adjusted alignment. In these cases, severe global disproportion is associated with higher rates of reoperation, implant failure, rod fracture, and junctional failure.