Analysis of detailed clinical characteristics of spinal subdural hematoma following lumbar decompression surgery

Only a few reports have described symptomatic patients with postoperative spinal subdural hematoma (SSH) for which further surgery may have been required. No report has focused on the detailed clinical characteristics of postoperative SSH, including asymptomatic cases, in a case series. The reasons for this may be that SSH is an implicitly recognized rare entity, and there is no established consensus regarding the significance of performing postoperative magnetic resonance imaging (MRI) for all cases and the time at which to perform it. In this case-controlled retrospective analysis, we attempted to identify a detailed clinical presentation of SSH after open lumbar decompression surgery using MRI taken uniformly at 14 days before hospital discharge. We retrospectively studied 196 patients who underwent routine MRI following open lumbar spinous process-splitting decompression surgery between 2012 and 2016. We assessed the frequency, clinical presentation, and radiological findings of SSH that developed postoperatively. Furthermore, we used a multivariate analysis to identify factors that were postulated to increase the risk of SSH postoperatively. None of the patients developed serious neurologic deficits, such as paresis or bladder and bowel dysfunction that required emergency evacuation. However, our results showed that postoperative SSHs, including asymptomatic SSHs, developed considerably frequently (43/182 patients, 23.6%). Furthermore, of the 43 patients with SSH, three presented with new postoperative neurologic findings that were strongly suspected to be associated with SSH. Multivariate analysis identified that preoperative hypertension (adjusted odds ratio [aOR]: 2.501, P = 0.018), anticoagulant therapy (aOR: 2.716, P = 0.021), and multilevel procedures (aOR: 2.327, P = 0.034) were significant risk factors of postoperative SSH. Spine surgeons should be aware that postoperative SSH is not rare and is a potential cause of recurrent pain or neurologic deterioration perioperatively.