Chronic subdural hematoma (cSDH) represents a prevalent concern in the field of neurosurgery, particularly among elderly individuals. Burr-hole craniostomy is the established treatment modality for cSDH. Controversies encompass various dimensions, including factors such as sex, age, medical history, the number and locations of burr holes, as well as the utilization of irrigation in management 19). This investigation specifically delves into the divergence between irrigation and non-irrigation approaches in the treatment of cSDH. The difference between our irrigated and non-irrigated procedures was primarily determined by the surgeon, with other variables such as subacute hematoma components, antiplatelet usage, and comorbidities remaining relatively consistent.
Several factors contribute to the increased incidence of chronic subdural hematoma (cSDH), including advanced age, male gender, and concurrent medical conditions such as hemodialysis or anticoagulant/antiplatelet therapies. However, conclusive evidence substantiating their role in recurrence rates remains lacking. Notably, our study excludes cases of bilateral cSDH, as Ishita et al. highlighted a correlation between bilateral cSDH and an increased recurrence risk 14).
Krupp et al. underscored the importance of patient age and admission condition in the context of chronic subdural hematoma (cSDH) recurrence, suggesting that advanced age and compromised neurological status increase the likelihood of recurrence10,17). However, in our study, there was no significant difference in recurrence rates with increasing age. Frantz et al. conducted a prospective randomized controlled trial to assess the impact of ACE inhibitors, specifically perindopril, on recurrence, but no significant effect was observed 16). In contrast, Neidert et al.'s retrospective case-control study revealed elevated hematoma volumes and increased recurrence frequency in patients treated with ACE inhibitors as an adjunct to surgery 15). Unfortunately, our study did not analyze the use of ACE inhibitors, but we did analyze patients with hypertension and found no association with an increased risk of recurrence or preventive effect. There are ongoing debates regarding the use of antiplatelet medications in relation to cSDH recurrence. Several previous studies have demonstrated no relationship between the use of drugs affecting hemostasis and recurrence3,4,8). Similarly, we found no significant difference in recurrence with or without antiplatelet use. Preoperative midline shift ≥ 10 mm, severe brain atrophy, post-operative severe pneumocephalus, and hematoma drainage volume ≥ 100 mL are independent radiographic risk factors for CSDH recurrence 1,18). For these factors, we couldn't find the same results as in previous reports, but we can estimate that immediate reduction of midline shift could possibly affect the recurrence rate. Moreover, there are many reports suggesting that post-op pneumocephalus and its volume are reliable factors for recurrence 12)
The role of irrigation remains unclear. Some studies have shown no significant differences in the recurrence rates with or without irrigation 13,21) Numerous investigations indicate comparable efficacy of irrigation and non-irrigation procedures for treating chronic SDH in terms of recurrence outcomes argued that the outcome with or without irrigation is the same in cSDH managed by a drainage system.7,24,26,27). Suzuki and associates reported a recurrence rate of 3.4% for the group without irrigation, and 3% for the group with irrigation. The difference did not reach significance.21) In the series by Matsumoto et al eight of 121 patients had no intraoperative irrigation. There were no significant differences in the recurrence rates.13) In Kuroki’s series, the recurrence rate was 3.6% without irrigation and 13.3% with irrigation.11) Our study corroborates this trend, demonstrating recurrence rates of 16.2% in the Irrigation Group (IG) and 2.3% in the Non-Irrigation Group (NIG). While subdural hematoma irrigation along with the modulation of chemokines within the hematoma may seemingly offer a potential means to reduce recurrence rates, a substantial body of literature suggests that extensive irrigation can engender pneumocephalus within the subdural space 6,22). This phenomenon can impede brain expansion, subsequently contributing to recurrent subdural hematoma formation. For summarizing evidences, we could hypothesize that irrigation of SDH while surgery can make pneumocephalus that can impede brain expansion. And those delayed brain expansion can make residual hematoma can format another chronic hematoma and recur. Evidently, non-irrigation emerges as a more effective treatment avenue than irrigation for reducing recurrence rates in cSDH in our study.
Furthermore, we couldn’t find significance in recurrence prediction of midline shift reduction, however, reduction rate of midline shift was significantly higher in NIG and that can may because of post operative pneumocephalus due to massive irrigation which seems to impede brain expansion after surgery.
While potential biases may be present, unforeseen complications were observed in the NIG. Overdrainage of cSDH may lead to microbleeding due to rapid pressure gradient changes, thereby increasing the risk of ICH 2). Since the NIG cannot carefully insert a drainage catheter while observing the brain's surface, there is a possibi4)lity of serious complications, such as catheter penetration of the cerebral cortex, leading to ICH and related issues. While we are not certain why these serious complications occurred, it's worth noting that both patients were taking antiplatelet agents, specifically cilostazol and3) clopidogrel, which may increase their risk of hemorrhage compared to others. Consequently, we advise surgeons to exercise caution when considering rapid drainage in cases of non-irrigated hematoma in order to mitigate the risk of ICH.
Limitations
Patients were randomly assigned to surgeons who utilized distinct surgical techniques. However, the uneven distribution of patients between the Irrigation Group (IG) and the Non-Irrigation Group (NIG) (44 vs. 37), coupled with the low recurrence rates, could potentially undermine the robustness of the findings. Categorizing the surgical methods into two broad groups, hematoma irrigation or non-irrigation, may obscure potential nuances stemming from variations in individual surgical practices, which could also impact surgical outcomes.
Despite these limitations, our study highlights significant differences between the two groups. However, given the small recurrence rate in relation to the total number of surgeries, and the fact that only one case in each group required revision surgery, statistical analysis couldn't be performed with precision. Therefore, further studies with larger cohorts are necessary to obtain more conclusive results.