P47. Acute postoperative epidural hematomas in minimally invasive lumbar fusions: A prospective comparative cohort study

Abstract

<h3>BACKGROUND CONTEXT</h3> The incidence of postoperative spinal epidural hematomas (SEH) in open lumbar decompression/fusions has been reported to be up to 89%. However, the incidence of asymptomatic SEH and the radiographic parameters predicting symptomatic SEH in minimally invasive transforaminal lumbar interbody fusions (MiTLIF) has not been established. <h3>PURPOSE</h3> To determine the incidence of asymptomatic epidural compression/SEH and the radiologic parameters which predict compression/SEH becoming symptomatic. <h3>STUDY DESIGN/SETTING</h3> Prospective comparative cohort study performed at a community hospital. <h3>PATIENT SAMPLE</h3> Forty-two consecutive patients undergoing MiTLIFs at a single institution from 2017-2018. Exclusions were >3 operative levels, revision spinal fusion, perioperative intake of Aspirin/Plavix/NSAID, abnormal clotting profile or hardware malpositioning. <h3>OUTCOME MEASURES</h3> Our primary outcome was the incidence of epidural compression/SEH and the associated radiographic parameters. <h3>METHODS</h3> The onset of pain and neurological deficits was evaluated daily. MRI was performed. <h3>RESULTS</h3> Thirty patients were enrolled in the asymptomatic group and 12 in the symptomatic group. Eight (26.67%) asymptomatic patients had postoperative thecal sac compression. Symptomatic patients had a significantly higher BMI compared to asymptomatic patients (34.6 ± 7.4 vs 28.2 ± 5.4, p=.010). Four of the asymptomatic patients had SEH (13.3%, 95%CI: 3.8–30.7). Comparing symptomatic vs asymptomatic compression, there were significant differences for the CR (0.57 ± 0.20 vs 1.08 ± 0.53, <b>Δ</b> 95%CI: -.84 - -.19, p<.001), the dural sac area at MC (0.62 ± 0.28 vs 1.3 ± 1.0, <b>Δ</b> 95%CI: -1.2 - -0.1, p=0.003). The CR of symptomatic SEH was not significantly different from asymptomatic SEH. (0.57 ± 0.20 vs 0.70 ± 0.15, <b>Δ</b> 95%CI: -0.37 - 0.09, p=.17). The length of MC of symptomatic SEH was significantly smaller when compared to asymptomatic SEH (2.3 ± 1.1 vs 5.3 ± 2.9, <b>Δ</b> 95%CI: -5.1 - -1.0, p=.030). <h3>CONCLUSIONS</h3> The incidence of early postoperative spinal epidural hematomas in asymptomatic patients following MiTLIF was lower than previously described for open lumbar surgeries. The CR can be used in evaluating the likelihood of a compression becoming symptomatic. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.