Pressure Neutralization in Surgical Management of Chronic Subdural Hematoma: An Enhancing Patient Safety Technique

Abstract

Background Chronic subdural hematoma (CSDH) is a common neurosurgical condition, often presenting with progressive neurological deficits. Surgical evacuation via burr hole craniotomy is a standard treatment. This study evaluates the pressure neutralization technique for gradual decompression using wide bore cannula before dural opening.

Materials and Methods This retrospective study included 81 patients with CSDH and previous history of head trauma who underwent gradual decompression using wide bore cannula before dural opening. Preoperative, intraoperative, and postoperative parameters were evaluated.

Results The mean patient age was 67 ± 8.7 years, with a male predominance (69.1%). The most common presenting symptoms were hemiparesis (70.4%) and headache (29.6%). Hematoma was predominantly left-sided (61.7%) with a mean thickness of 2.46 ± 0.5 cm. Midline shift exceeded 10 mm in 63.0% of cases preoperatively. Postoperatively, Glasgow Coma Scale improved to 14.84 ± 0.37, with clinical improvement in 77.8% of patients showing resolution of weakness. Midline shift resolved at 76.5%, and residual hematoma was minimal in 16%. The average hospital stay was 4.2 ± 1.3 days, and only one patient (1.2%) underwent postoperative wound infection.

Conclusion Gradual decompression using wide bore cannula before dural opening is highly effective in managing CSDH, leading to significant clinical and radiological improvement with minimal complications. Radiological findings, particularly hematoma thickness and midline shift, are reliable indicators of surgical efficacy and patient recovery.

Keywords

chronic subdural hematoma - burr hole craniotomy - midline shift - hematoma evacuation - neurosurgery

Introduction

Chronic subdural hematoma (CSDH) is a prevalent neurosurgical condition characterized by the accumulation of blood between the dura mater and the arachnoid membrane. It typically develops due to minor head trauma leading to the rupture of bridging veins, often exacerbated by conditions such as brain atrophy, anticoagulant use, or coagulopathies.[1] The condition primarily affects older adults, with an increasing incidence attributed to aging populations and the widespread use of antithrombotic medications.[2] Clinical presentations of CSDH vary widely, ranging from subtle cognitive changes and headache to more severe manifestations such as motor deficits and altered consciousness, necessitating prompt recognition and treatment.[3]

The management of CSDH, while generally effective through surgical drainage techniques such as burr hole evacuation, poses unique challenges due to the condition's recurrent nature and the potential for significant complications.[4] Factors like advanced age, comorbidities, and anticoagulant therapy increase the complexity of surgical intervention. Additionally, the variability in hematoma consistency and the patient's intracranial pressure dynamics further complicate the procedure, demanding a meticulous and cautious surgical approach.[5]

Complications associated with the surgical management of CSDH are significant, with acute intracranial hemorrhage (ICH) being among the most severe. This includes intracerebral hemorrhage (ICH) and brainstem hemorrhage, which can result from abrupt shifts in intracranial pressure during rapid evacuation or decompression.[6] Such complications often arise due to the rupture of fragile cortical vessels or sudden brain reexpansion, leading to catastrophic outcomes. These risks underscore the need for optimized surgical strategies to prevent harm while effectively relieving the hematoma.[7]

Rapid decompression, in particular, has been implicated as a key factor in triggering ICH. The sudden release of intracranial pressure can create a vacuum effect, exacerbating vessel vulnerability.[8] This has led to the exploration of alternative approaches, including gradual decompression techniques, to mitigate these risks. Recognizing the importance of controlled intracranial pressure modulation is critical in enhancing patient safety and improving surgical outcomes.

To address these challenges, our study evaluates the effectiveness and safety of a pressure neutralization technique involving gradual decompression using a wide-bore cannula (16G or 18G) before dural opening. This approach aims to minimize the risk of complications such as acute ICH by allowing for controlled evacuation, ultimately enhancing postoperative recovery.

Materials and Methods

Study Design and Setting

This was a retrospective observational study conducted on patients diagnosed with CSDH at Menoufia University Hospital, Shibin Elkom, Egypt, between January 2021 and January 2024. Ethical approval was obtained from the institutional ethics committee (8 -2024 NEUS 16–2) and informed consent was obtained from all participants before enrollment.

Inclusion and Exclusion Criteria

Patients were included if they were diagnosed with CSDH and had a history of head trauma based on clinical presentation and radiological evidence documented by computed tomography (CT) of the brain and underwent surgical evacuation via one or two burr hole craniotomy and if pressure neutralization technique was used intraoperatively. Patients with severe coagulopathies interfering with surgery, classic opening of the dura without the technique, or those lost to follow-up were excluded.

Preoperative Evaluation

All patients underwent detailed clinical and neurological assessments upon admission. Presenting symptoms, including headache, hemiparesis, and convulsions, were documented. Preoperative Glasgow Coma Scale (GCS) scores were recorded. Noncontrast CT of the brain was performed to confirm the diagnosis and assess hematoma thickness, laterality, and midline shift ([Fig. 1]).

Fig. 1 Preoperative computed tomography (CT) showing left frontoparietal chronic subdural hematoma with midline shift.

Surgical Technique

After obtaining patient consent and completing preoperative preparation and anesthesia consultation, the surgical intervention was conducted under sterile conditions and general anesthesia. Depending on the size of the hematoma and the surgeon's discretion, the procedure involved one or two burr hole craniotomies. The preparation began with careful creation of burr holes, ensuring secure hemostasis of the skin and subcutaneous tissue using bipolar cauterization, bone hemostasis with bone wax, and dural hemostasis through cauterization. Before opening the dura, a wide-bore cannula (16G or 18G) was inserted into the subdural space to a depth less than the hematoma's thickness, as measured preoperatively on CT imaging. If two burr holes were utilized for hematoma evacuation, cannulas were inserted simultaneously at both sites. The hematoma was allowed to drain gradually through the cannulas prior to classic dural opening. This approach facilitated gradual pressure neutralization. The amount of evacuated hematoma and the time required for the technique were recorded. Following this, the dura was opened conventionally to allow complete evacuation of the residual hematoma using irrigation as per standard practice. The dura was left open, subgaleal drains were typically placed, and meticulous hemostasis was achieved. The procedure concluded with wound closure and smooth recovery from anesthesia ([Figs. 2] and [3]).

Fig. 2 Intraoperative picture showing prepared burr holes before pressure neutralization technique start.

Fig. 3 Intraoperative picture showing cannula inserted and gradual evacuation through it.

Postoperative Management

Postoperative CT scans were performed within 24 hours to assess the extent of hematoma evacuation, midline shift improvement, and residual hematoma ([Fig. 4]). Patients were monitored for neurological improvement and complications, including infection, rebleeding, or seizures. Postoperative GCS scores were recorded before discharge.

Fig. 4 Postoperative computed tomography (CT) after two burr craniotomy with use of pressure neutralization technique showing complete evacuation of hematoma and no midline shift.

Data Collection and Analysis

Demographic data (age, sex), clinical features (presenting symptoms, GCS scores), hematoma characteristics (thickness, side, and midline shift), operative details (burr hole number, operative time, amount evacuated), and postoperative outcomes (clinical improvement, hospital stay, residual hematoma, complications) were systematically recorded.

Statistical Analysis

Data were analyzed using SPSS version 28.0 for Windows. Continuous variables, such as age, hematoma thickness, operative time, and amount evacuated, were expressed as mean ± standard deviation, median, and range. Categorical data, such as presenting symptoms and postoperative complications, were presented as frequencies and percentages.

Results

Demographic and Clinical Characteristics

A total of 81 patients with CSDH were included in the study. The mean age of the patients was 67 ± 8.767 years, with a median age of 68 years and a range of 45 to 78 years. The majority of patients were male (56, 69.1%), and 25 patients (30.9%) were female. Among the comorbidities, 24 patients (29.6%) had diabetes mellitus, while 57 patients (70.4%) were nondiabetic. Hypertension was observed in 56 patients (69.1%), with the remaining 25 patients (30.9%) being nonhypertensive. The preoperative GCS scores ranged from 11 to 15, with a mean of 14 ± 1.314. [Table 1] demonstrates the demographic data of included cases.

Table 1 Demographic and clinical characteristics of patients

		N	%
Age
• Mean ± SD • Median • Range		67 ± 8.7 68 45–78
Sex	Male	56	69.1
	Female	25	30.9
DM	Yes	24	29.6
	No	57	70.4
HTN	Yes	56	69.1
	No	25	30.9
GCS
• Mean ± SD • Median • Range		14 ± 1.3 14 11–15

Abbreviations: DM, diabetes mellitus; GCS, Glasgow Coma Scale; HTN, hypertension; SD, standard deviation.

Clinical Data Related to Subdural Hemorrhage

The predominant presenting symptom was hemiparesis (57 patients, 70.4%), followed by headache (24 patients, 29.6%). Convulsions were observed in 13 patients (16.0%). The subdural hematoma (SDH) was more commonly located on the left side (50 patients, 61.7%) compared with the right side (31 patients, 38.3%). The mean hematoma thickness was 2.46 ± 0.5 cm, with a median of 2 cm and a range of 2 to 3 cm. Midline shift measurements showed that 51 patients (63.0%) had a shift greater than 10 mm, 18 patients (22.2%) had a shift between 5 and 10 mm, and 12 patients (14.8%) had a shift of less than 5 mm. Clinical Data is demonstrated in [Table 2].

Table 2 Clinical data related to subdural hemorrhage of the operated patients

		N	%
Presenting symptoms	Headache	24	29.6
	Hemiparesis	57	70.4
Convulsion	Yes	13	16.0
	No	68	84.0
Hematoma side	Right	31	38.3
	Left	50	61.7
Hematoma thickness (cm)	Mean ± SD Median Range	2.46 ± 0.5 2 2–3
Midline shift	Between 5 and 10 mL	18	22.2
	Less than 5 mm	12	14.8
	More than 10 mm	51	63.0

Abbreviation: SD, standard deviation.

Operative Data

Most patients (75, 92.6%) underwent a two-burr hole craniotomy, while a single burr hole was used in 6 patients (7.4%). The mean technique duration was 6.64 ± 1.56 minutes, with a median of 7 minutes and a range of 4 to 9 minutes. The mean amount of hematoma during cannula evacuation was 61.17 ± 11.1 mL, with a median of 60 mL and a range of 40 to 80 mL. Operative data are shown in [Table 3].

Table 3 Operative data of the patients

		N	%
Burr hole number	One bur hole	6	7.4
	Two bur holes	75	92.6
Technique time (min)		Mean ± SD Median Range	6.64 ± 1.5 7 4–9
Amount evacuated (mL)		Mean ± SD Median Range	61.17 ± 11.1 60 40–80

Abbreviation: SD, standard deviation.

Postoperative Assessment and Complications

The mean postoperative GCS score improved to 14.84 ± 0.37, with a median of 15. Clinical improvement was reported as improved hemiparesis in 63 patients (77.8%) and resolution of headache in 18 patients (22.2%). The average hospital stay was 4.2 ± 1.3 days, with a median of 4 days and a range of 2 to 6 days. Postoperative imaging revealed no midline shift in 62 patients (76.5%), while 19 patients (23.5%) showed a midline shift of less than 5 mm. Residual hematoma was absent in 68 patients (84.0%) and was mild in 13 patients (16.0%). Only one case underwent postoperative wound infection (N = 1, 1.2%). Notably, no other postoperative complications, including rebleeding, were observed in this cohort. [Table 4] delineates the postoperative assessment and complications.

Table 4 Postoperative assessment and complication of the operated patients

		N	%
Post-GCS		14.84 ± 0.37 15 14 - 15
Clinical improvement	Headache improved	18	22.2
	Improved weakness	63	77.8
Hospital stay (d)		4 0.2 ± 1.3 4 2–6
Midline shift improvement	No midline shift	62	76.5
	Less than 5 mm	19	23.5
Residual	No	68	84.0
	Mild	13	16.0
Postoperative wound infection	Yes	1	1.2

Abbreviation: GCS, Glasgow Coma Scale.

Discussion

SDH evacuation via burr hole craniectomy is a common procedure for patients with CSDHs. Gradual decompression techniques, such as the use of wide-bore cannulas, are being explored to minimize the risk of complications associated with rapid evacuation. Our study aims to assess the effectiveness and safety of a pressure neutralization technique, specifically gradual decompression using a wide-bore cannula (G16 or G18), prior to dural opening, in the surgical management of CSDH.

In our study, we observed that the majority of patients showed improvement in neurological status, with 77.8% experiencing weakness improvement and 22.2% showing improvement in headaches. Postoperatively, most patients (76.5%) had no significant midline shift and 84% had no residual hematoma. Our technique of gradual decompression resulted in no postoperative complications, suggesting a favorable outcome for slow and controlled evacuation. These findings are consistent with prior studies advocating for gradual evacuation techniques to minimize risks like brainstem hemorrhage and ICH, in contrast to rapid decompression approaches that may lead to neurological deterioration.

The technique employed had a mean operative time of 6.64 minutes, which is comparable to other reports in the literature. Rusconi et al highlighted that careful and gentle evacuation, avoiding excessive rotation of the head and maintaining a controlled drainage technique, are key to minimizing complications.[9] This aligns with our practice of gradual decompression, which likely contributed to relatively short operative times. Our technique, involving gradual decompression, requires careful management but appears to reduce the need for prolonged surgical intervention, aligning with findings that emphasize the importance of a controlled approach.

The mean amount of hematoma evacuated collected through cannulas before surgical dural opening was 61.17 mL, a value consistent with findings from other studies examining CSDH surgery. In a study by Kim et al, the authors emphasized the importance of slow drainage in preventing ICH, which is a potential complication when large volumes of hematoma are evacuated too quickly.[10] Our approach, which avoids rapid drainage, may be partly responsible for minimizing the risk of ICH, as we favor more gradual evacuation.

Postoperatively, patients showed a mean GCS of 14.84, indicating excellent neurological recovery. This is consistent with findings from Sundstrøm et al, which suggested that slow evacuation procedures could lead to better neurological outcomes.[11] The gradual decompression technique in our cohort seems to have contributed to preserving cerebral perfusion and minimizing the risk of brain injury, resulting in favorable GCS scores. In contrast, a study by Hsieh et al reported that rapid decompression can lead to deterioration in GCS scores due to the risk of postoperative ICH and other complications.[12]

In our study, we observed that 77.8% of patients experienced improvement in weakness, while 22.2% had improvement in headaches. These findings indicate a positive clinical response to gradual decompression, suggesting that a controlled and slow evacuation technique can improve neurological recovery. This aligns with the findings in Rusconi et al, which emphasized the benefits of gradual and controlled evacuation for improving recovery outcomes and minimizing secondary complications.[9] In contrast, the study by Pavlov found that rapid decompression is associated with a higher risk of neurological deterioration, which could negatively impact recovery, particularly in terms of improvement in weakness.[13] This suggests that our approach of gradual decompression may reduce the risk of such deterioration.

Our study also found that the mean hospital stay was 4.2 days, which is consistent with reported literature. A study by Sundstrøm et al highlighted that larger hematomas and significant midline shifts typically lead to longer hospital stays.[11] However, in our study, 76.5% of patients showed no midline shift postoperatively, and 23.5% had a shift of less than 5 mm, indicating that gradual decompression may better control midline shifts compared with more rapid techniques. These results align with the study by Rusconi et al, which reported that slow drainage techniques were associated with better midline shift outcomes.[9] Our findings suggest that gradual decompression can reduce the occurrence of significant midline shifts and their associated complications.

The rate of residual hematoma in our cohort was low, with 84% of patients showing no residual hematoma, and 16% presenting with mild residuals. This is consistent with the recommendations in a study by Rusconi et al, which advised against excessive evacuation as it may increase the risk of complications, such as brainstem hemorrhage.[9] In our study, 100% of patients had no postoperative complications, highlighting the success of the gradual decompression technique. These outcomes contrast with the findings in Kim et al and Hsieh et al, where rapid decompression was linked to a higher risk of complications like ICH and brainstem hemorrhage.[10] [12] Our approach, characterized by slow and controlled evacuation, appears to reduce the likelihood of these complications, leading to a safer postoperative course.

One of the key strengths of our study is the use of a gradual decompression technique, which has shown promising results in terms of clinical improvement, low complication rates, and controlled midline shifts. Additionally, our cohort had a relatively short hospital stay, reflecting the effectiveness of the gradual evacuation method. However, a limitation of the study is its small sample size and single-center design, which may limit the generalizability of the findings. Moreover, the study did not assess long-term outcomes, such as recurrence of hematoma or neurological status over time, which would provide more comprehensive insight into the benefits of gradual decompression.

Conclusion

Our study highlights the effectiveness of gradual decompression using wide-bore cannulas in the management of CSDHs. This approach was associated with favorable clinical outcomes, including significant improvement in neurological status, low complication rates, and minimal midline shift. The absence of complications such as ICH or brainstem hemorrhage supports the safety of gradual evacuation. Moreover, the technique is rapid and accessible with very minimal cost.

Conflict of Interest

None declared.

Study Design

This retrospective study included 81 patients with CSDH and previous history of head trauma who underwent gradual decompression using wide-bore cannula before dural opening. Preoperative, intraoperative, and postoperative parameters were evaluated.

Note

This study was performed in the Department of Neurosurgery, Faculty of Medicine, Menoufia University Hospital, Egypt.

Authors' Contributions

All authors made a significant contribution to the work reported, whether that was in the conception, study design, execution, acquisition, analysis, and interpretation of data. All authors took part in drafting, revising, and final approval of the article. This article has been read and approved by all authors and all agreed to be accountable for all aspects of the work.

Ethical Approval

This study was approved by the clinical research committee of the Faculty of Medicine, Menoufia University, Shibin Elkom, Egypt, and it followed the tenets of the Declaration of Helsinki.

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Publication History

Article published online:
21 April 2025