Letter: Inverse Trends in Rates of Middle Meningeal Artery Embolization and Mortality in Subdural Hematoma in the United States.

Abstract

To the Editor: Subdural hematoma is one of the most diagnosed neurosurgical conditions in adults with an incidence rate reported to be 13.4 per 100 000 persons per year.1,2 Although mortality rates have decreased over the past several decades due to progressive advancements in diagnostics, novel treatment strategies are required to better manage patient outcomes.3 Middle meningeal artery (MMA) embolization is one such strategy that has recently emerged to reduce postoperative recurrence. This minimally invasive technique devascularizes the subdural membranes to prevent further bleeding and has proven viable and safe, especially among nonsurgical candidates.4 Here, we investigate the trends in the rates of middle meningeal artery embolization and mortality in patients with subdural hematoma. We queried the National Inpatient Sample database from 2016 to 2020 for patients with principal diagnosis of nontraumatic subdural hematoma (SDH) using the International Classification of Disease 10th Edition (ICD10) code I62. Cases at large urban teaching hospitals were selected. The yearly rate of inpatient mortality and MMA embolization was extracted. Trends in severity, as measured using variables suggestive of clinical severity (mechanical ventilation, hydrocephalus, treatment of hydrocephalus, coma, stupor, cranial nerve palsy, paralysis/paraparesis, and aphasia), were also explored. Multivariate regression analysis was performed to analyze the association between MMA embolization and mortality when controlling for age, socioeconomic status, race, and severity. All statistical analyses were performed using Statistical Product and Service Solutions (SPSS) Statistical Software, and significance was set to P < .05 (IBM Corp. Released 2020. IBM SPSS Statistics for Windows, version 28.0., IBM Corp). All data and ICD10 codes used in this study are available on reasonable request of the corresponding author. There were 173 165 patients with a principal diagnosis of SDH at large urban teaching hospitals from 2016 to 2020. We report an overall decrease in the mortality rate in 2020 (10.5%) as compared with 2016 (10.9%) (Figure 1). The mortality rate in 2016 and 2017 averaged 11.0%, whereas the mortality rate from 2018 to 2020 averaged 10.4%. On the other hand, severity trended upward throughout the years (Figure 2). The yearly rate of craniotomy and burr hole increased slightly from 1.18% to 1.46% and 8.36% to 9.12%, respectively. Notably, the rate of MMA embolization increased more than 10-fold from 2016 (0.2%) to 2020 (2.8%) (Figure 3). Most notable increase was post-2018, depicting its recent importance and success for managing subdural hematoma. Finally, when controlling for severity and demographics, MMA embolization was found to become protective against mortality in 2020, validating the trends stated above (Figure 4).Figure 1.: Yearly trends in mortality rate.Figure 2.: Yearly trends in severity.Figure 3.: Yearly trends in the rate of MMA embolization. MMA, middle meningeal artery.Figure 4.: Relationship between MMA embolization and mortality. MMA, middle meningeal artery.Surgical evacuation through craniotomy is one of the conventional treatments for chronic subdural hematoma. However, studies cite a 30-day mortality rate of 16.5% to 18% and high rates of adverse outcomes, including prolonged mechanical ventilation, return to the operating room, and prolonged length of stay, following craniotomy for subdural hematoma evacuation.3,5 Owing to a high rate of recurrence and perioperative complications associated with open surgery, MMA embolization is emerging to be not only an adjunct but also a stand-alone treatment option for chronic subdural hematoma.6,7 In a prospective study, Ban et al7 reported MMA embolization to be a superior option than conventional treatment options. In this same study, treatment failure for MMA embolization was reported to be only 1.4% as compared with 27.5% among patients who underwent surgical drainage. As we await the results of ongoing clinical trials, our analysis supports these findings and shows an overall inverse trend among the rate of MMA embolization and mortality throughout the United States, even when controlling for severity.