Risk factors for extra-axial hemorrhage during invasive monitoring using subdural electrodes

Introduction Despite the increasing use of stereoelectroencephalography, subdural electrode (SDE) implantation remains valuable to identify the epileptogenic network. Extra-axial hemorrhage, including subdural and epidural, is one of the most frequent complications of SDE implantation. This study aimed to identify risk factors associated with extra-axial hemorrhage post–SDE implantation in patients with focal drug-resistant epilepsy. Methods We retrospectively reviewed consecutive patients who underwent SDE implantation via craniotomy at Hiroshima University Hospital between 2008 and 2022. Multivariate logistic regression analysis was performed to identify risk factors for postoperative extra-axial hemorrhage. Results A total of 64 patients were included in the analysis; 13 of them had extra-axial hemorrhage after SDE implantation, and two required hematoma evacuation. The hematoma thickness increased over time in 7 of 11 patients who did not undergo surgical intervention. Univariate analysis revealed that extra-axial hemorrhage was associated with the number of electrodes (p = 0.0138), the number of leads (p = 0.0320) and selection of an artificial dura substitute (p = 0.0087). In multivariate analysis, the use of an absorbable artificial dura substitute for duraplasty (OR = 7.69, 95% CI: 2.39–24.72, p = 0.0006) was independent risk factors for post-implantation extra-axial hemorrhage. Conclusion The use of an absorbable artificial dura substitute for duraplasty is associated with the occurrence of extra-axial hemorrhage after SDE implantation. The risk of this complication can be minimized through careful selection of dura substitute materials. Close observation is essential during SDE implantation because an extra-axial hematoma may develop over time.