Abstract

Background: Chronic subdural hematoma (CSDH) recurrence remains a challenge, with risk factors still debated.

Methods: A retrospective review of 185 CSDH cases surgically treated at Hospital Juárez de México (2014–2019) was conducted. Recurrence was defined as clinical deterioration with radiological re-expansion. Demographic, clinical, imaging and perioperative variables were analyzed statistically (P

Results: The cohort included 145 males (78.4%) median age of 55 years. Head trauma was present in 75.7%. Hematomas were mostly chronic (69.2%), with 49.18% showing heterogeneous density. The surgical approaches used were single burr-hole (4.3%), double burr-hole (10.8%), and craniotomy (84.9%). Recurrence occurred in 16 cases (8.4%), primarily within a week. The significant risk factors for recurrence included thrombocytopenia (P = 0.001) and prolonged partial thromboplastin time (>38.6 s, P = 0.005). Craniotomy had lower recurrence (7%) than burr-holes (P = 0.053).

Conclusion: Thrombocytopenia and coagulopathy increase recurrence risk in CSDH. Craniotomy may reduce recurrence compared to burr-hole techniques. Further studies are needed to optimize surgical management.

Keywords: Chronic subdural hematoma, Computed tomography, Partial thromboplastin time, Platelet count, Prothrombin time

INTRODUCTION

Chronic subdural hematoma (CSDH) is a collection of blood products in the subdural space (between the dura mater and the arachnoid).[ 2 , 6 ] Clinically, it tends to present in an insidious and progressive form [ Figure 1 ].[ 4 ] It is thought to be secondary to the rupture of bridging veins in atrophic brains or the rupture of vessels resulting in the new formation of chronic subdural hygromas.[ 6 , 11 , 12 ] It has a high incidence of 58/100,000 in the senile population,[ 24 ] a morbidity rate of 0–25%, and a mortality rate of 0–32%.[ 2 , 4 ] Some risk factors, such as advanced age, use of anticoagulants or antiplatelet agents, and cerebral atrophy, among others, promote its appearance.[ 1 , 21 , 28 ]

Figure 1:

A patient with rapid clinical deterioration in the context of chronic subdural hematoma; (a) edge of skin flap, (b) edge of craniotomy, (c) edge of durotomy, (d) parietal layer of chronic subdural hematoma, (e) visceral layer of chronic subdural hematoma (through this the space can be observed subarachnoid and cerebral cortex), and (f) deteriorating subdural hematoma.

The clinical expression ranges from asymptomatic manifestations such as headache, seizures, visual disturbances, language disorders, incontinence, dysarthria, nausea and vomiting, weakness, ataxia, altered mental status, and coma.[ 9 , 22 , 28 ]

The diagnostic study of choice is computed tomography (CT) without contrast.[ 14 ] The density of the hematoma on CT is determined by the time interval between the bleeding episode and the imaging study.[ 18 ] It reflects the age of the hematoma, which allows them to be classified as acute (hyperdense, [ Figure 2a ]), subacute (isodense, [ Figure 2b ]), and chronic (hypodense, [ Figure 2c ]). In the case of presenting multiple densities (mixed), it is considered secondary to several bleeding events [ Figures 3 and 4 ]. In addition, in the chronic stage, we will observe the presence of a capsule with newly formed vessels likely to show enhancement with contrast.[ 20 ]

Figure 2:

(a) Computed tomography (CT) scan of right frontoparietal acute subdural hematoma, (b) CT scan of left hemispheric subacute subdural hematoma, note lateral to the dark line, isodense to the gray matter, and (c) CT scan of right frontoparietal chronic subdural hematoma.

Figure 3:

Computed tomography scan of left hemispheric mixed subdural hematoma, the hyperdense image is observed adjacent to the cerebral cortex; lateral to it, we find a hypodense collection; additionally, we observe membranes that go from the hyperdense portion to the dural edge. We did not observe a hematocrit effect [ Figure 4] since the hyperdense collection is encapsulated.

Figure 4:

Computed tomography scan showing bilateral subdural hematomas. The blue circle highlights the transition zone between densities within the right-sided hematoma, showing posterior hyperdensity and anterior hypodensity. This pattern is consistent with a chronic-on-acute subdural hematoma, indicating different stages of bleeding and a mixed-age collection.

The therapeutic options are observation,[ 17 , 19 , 23 , 26 ] pharmacological,[ 3 , 8 , 25 , 26 ] or surgical treatment.[ 4 , 16 , 20 ]

Recurrence is a serious complication characterized by a clinical event that reflects deterioration or lack of improvement in neurological function, which is correlated with radiological findings [ Figure 5 ].[ 20 ] It should not be confused with post-surgical collections that do not have clinical manifestations, as this entity does not require any intervention and is highly frequent.[ 13 ] Therefore, we must always consider the patient’s neurological state to determine if a residual collection is a true recurrence. Recurrence rates vary between centers, ranging from 0% to 76% [ Table 1 ].[ 27 ]

Table 1:

Recurrence rate of SDH in different series

Figure 5:

Computed tomography scan of postoperative acute subdural hematoma in a patient with clinically manifest symptoms (recurrence). Note the suggestive postoperative data; (a) craniotomy site, (b) subcutaneous emphysema, (c) pneumocephalus, (d) associated hyperdense hematoma, and (e) postoperative residual fluid (collection adjacent to the occipital cortex).

This work seeks to illustrate the recurrence in the surgical practice of residents in training at our center and identify potentially modifiable risk factors.

MATERIALS AND METHODS

Of the 288 patients registered in the neurosurgery department of Hospital Juárez de México between January 2014 and January 2019 with a diagnosis of CSDH, 185 files were considered. In this study, we followed the standard classification of subdural hematomas based on their time of evolution and imaging characteristics. Acute subdural hematomas are defined as those <72 h old, presenting as hyperdense collections on CT scans. The subacute phase begins between 3 and 7 days after the initial event, often showing an isodense appearance. CSDHs develop over weeks and are typically hypodense in imaging studies.

We dismissed 103 files because they were either incomplete or absent. Recurrence was defined as clinical deterioration associated with hematoma re-expansion observed on imaging. In cases where no clinical changes were present, radiological criteria alone were sufficient to define recurrence if at least one of the following was met: midline shift ≥5 mm or hematoma volume ≥10 mm.

Descriptive statistical analyses were performed for continuous and categorical variables. Continuous variables are presented as mean ± standard deviation (SD) or median with interquartile range (IQR), depending on their distribution. Specifically, the following values were obtained for the main quantitative variables:

Age (years): mean = 55.0, SD = 0, median = 55.0, IQR = 0.0, blood pressure (BP) at admission (mmHg) ≥140/90: systolic BP (mean = 138.32, SD = 0.47, median = 138.0, IQR = 1.0), postoperative BP (mmHg) ≥140/90: systolic BP (mean = 138.32, SD = 0.47, median = 138.0, IQR = 1.0), platelet count (PLT) (×10³/μL): mean = 134.38, SD = 1.65, median = 134.38, IQR = 0.0, prothrombin time (PT, sec): mean = 11.75, SD = 0.43, median = 12.0, IQR = 0.0, partial thromboplastin time (PTT, sec): mean = 35.9, SD = 2.4, and median = 35.5, IQR = 2.0, categorical variables are presented as absolute (n) and relative frequencies (%). The selection of cutoff values for continuous variables (e.g., age ≥60 years, PLT <130,000/μL, PT >11.5 s, and PTT >38.6 s) was based on previously published studies that have used these parameters in CSDH research.[ 4 , 5 ] We acknowledge that these predefined thresholds may not be the most sensitive or specific for our particular patient cohort. A receiver operating characteristic (ROC) curve analysis was not conducted to determine optimal cutoff points. This limitation will be further discussed in the manuscript, and future studies with a larger sample size should consider an ROC-based approach to optimize cut-off selection.

For the comparison of recurrence rates among different subgroups, we used the Chi-square test or Fisher’s exact test, as appropriate. Continuous variables were analyzed using the Mann–Whitney U-test for non-normally distributed data and the Student’s t-test for normally distributed data. P < 0.05 was considered statistically significant. Statistical analyses were performed using (statistical software, e.g., Statistical Package for the Social Sciences version X.0 [IBM Corp., Armonk, NY, USA]).

Patients who were consumers of oral anticoagulants and antiplatelet drugs underwent a protocol of substituting their drug for enoxaparin 5 days before the intervention. Enoxaparin was suspended 24 h before and restarted 12– 24 h after the procedure. All patients were discharged on the drug that they were taking during admission. In our study, no patients undergoing active antiplatelet or anticoagulation therapy in acute or rapid deterioration scenarios were included for surgical intervention. This exclusion was intentional, as the presence of such pharmacological factors could significantly alter the natural course of the disease and influence the primary outcomes under investigation.

The procedure performed on each patient was selected by the surgeon responsible for the case based on the following characteristics: presence of acute hematoma, presence of hematoma membranes, hematoma segmentation, multiple hematoma densities, midline shift, Glasgow coma scale score at admission, and the neurosurgeon’s experience.

Various systemic, local, and procedure-related factors that increased the recurrence rate in the analyzed studies were considered [ Table 2 ].

Table 2:

Risk variables for CSDH recurrence.

Although we did not systematically classify CSDHs based on their traumatic or non-traumatic origin, most patients (82%) did not report any prior history of head trauma or identifiable impact that could be directly linked to hematoma formation.

Although this study primarily investigates risk factors for CSDH recurrence, we included some acute and subacute cases to evaluate additional variables that may contribute to recurrence. This approach allows for a broader assessment of factors beyond hematoma chronicity, particularly those related to surgical decision-making, the operative technique performed by trainees, and perioperative management.

RESULTS

Of the 185 studied patients, 145 (78.4%) were male. Their ages ranged from 19 to 91 years, with 78% of patients above 60 years old. Head trauma was present in 140 (75.7%) patients. We found a history of systemic arterial hypertension in 64 (34.6%) patients, which, in this study, was considered ≥140/90 mmHg. At admission, 50 (27%) patients had BP readings ≥140/90 mmHg, and 59 patients (31.89%) had the same readings within 24 h after surgery. The hematoma appeared on the right side in 68 (36.8%), on the left in 82 (44.3%), and bilaterally in 35 (18.9%) patients. According to the appearance in simple head CT, the hematoma’s chronicity presented the following distribution: acute (hyperdense) in 6 (3.2%), subacute (isodense) in 51 (27.6%), and chronic (hypodense) in 128 (69.2%) patients. Among subacute and chronic hematomas, 91 (49.18%) cases were documented as heterogeneous (mixed). We identified 7 (3.8%) patients under anticoagulation and 21 (11.4%) consuming antiplatelets at admission. During complete blood count and coagulation studies, 23 (12.4%) patients had a PLT <130,000/microliter, 139 (75.1%) showed a preoperative PT >11.5 s, and 33 (17.8%) had a PTT >38.7 s. A single burr-hole was performed in 8 (4.3%) patients and a double burr-hole in 20 (10.8%). The rest of the patients underwent a craniotomy (84.9%).

The characteristics of the patients are shown in Table 3 .

Table 3:

Characteristics of the patients.

Of the 185 intervened patients, 16 (8.4%) experienced recurrence, with one on the 1^st day, six between days 1 and 2, four between days 3 and 4, three between days 5 and 7, one on the 8^th day, and one on the 30^th day. Among the recurrent patients, 11 (68.8%) were above 60 years old. Subdural drainage was used for over 48 h in all patients except those with acute subdural hematoma diagnoses. No pharmacological treatment was used before, during, or after surgery, aiming for recurrence reduction.

There was no significant difference in recurrence between males (9.7%) and females (5%) with a P = 0.354. Patients with known systemic hypertension had double the recurrence rate compared to those without it, 12.5% and 6.6%, respectively (P = 0.175). There was no significant difference between those who arrived with BP readings >140/90 mmHg and those with <140/90, 8 and 8.8%, respectively (P = 0.849).

Of all the patients studied with CSDH, only 5.17% presented a postoperative hypertensive event (readings above 140/90 mmHg in the postoperative phase) associated with recurrence, proving not to be a determinant risk factor (P = 0.238). Regarding the location of the hematoma, those with a bilateral component recurred 17.14% of the time, as opposed to 7.35% (right) and 6.09% (left) when they were unilateral (P = 0.205).

According to the CT densities, we observed that hypodense (chronic) hematomas had a greater recurrence rate (9.37%) than isodense (subacute) and hyperdense (acute) hematomas, which had rates of 7.84% and 0%, respectively (P = 0.552).

When dealing with heterogeneous hematomas, we observed a recurrence rate of 10.98% compared to 6.38% for homogeneous hematomas (P = 0.498).

The group that consumed oral anticoagulants had a higher recurrence rate (14.28%) than the group that did not (8.42%) (P = 0.589). Patients on antiplatelet therapy had a lower recurrence rate than those who did not, with rates of 4.76% and 9.14%, respectively (P = 0.501).

The group of patients considered to have thrombocytopenia (according to local laboratory parameters: <130,000 × µL) had a recurrence rate of 26.08%. In contrast, the group of patients with higher readings showed a recurrence rate of 6.17% (P = 0.001). No patient entered the operating room with values lower than 80,000 × μL (five had lower values and received transfusions until their values reached >80,000 × μL).

The group of patients with PT >11.6 s had a recurrence rate of 9.35% compared to those with lower readings (P = 0.554). The group of patients with PTT >38.6 s showed a recurrence rate of 21.21%, which was significantly different than that of patients with shorter time (5.92%) (P = 0.005).

Regarding the variety of surgical techniques, the single burr-hole technique had a recurrence rate of 25%, the double burr-hole technique had a recurrence rate of 15%, and craniotomy had a recurrence rate of 7%, almost reaching statistical significance (P = 0.053). In this study, we rarely used the single burr-hole technique (4.3%).

DISCUSSION

CSDH is a common type of intracranial hemorrhage that primarily affects elderly individuals. Several risk factors have been associated with the development and recurrence of CSDH.

Concerning the risk factors associated with CSDH recurrence, we observed some demographic similarities with those described in the literature, such as advanced age and gender.[ 4 , 7 ] An interesting and somewhat counterintuitive finding in our study was the lower recurrence rate observed in patients with prior antiplatelet therapy (4.76%) compared to those without it (9.14%). Notably, none of the patients under antiplatelet therapy presented with acute neurological deterioration requiring emergent surgical management. Instead, these patients underwent preoperative evaluation and individualized adjustment of their antiplatelet regimen, which might have contributed to a more controlled perioperative course. This finding suggests that recurrence may not be solely influenced by antiplatelet therapy but rather by a combination of factors such as the surgical approach, patient-specific susceptibilities, and other underlying mechanisms. Further research is warranted to elucidate the potential protective or confounding factors in this population. The relationship between age and recurrence is thought to be due to a decrease in cerebral volume and an increase in tension and fragility of the bridging veins.[ 7 ] Moreover, the higher recurrence and incidence seen in males could be related to two specific reasons: (1) males tend to have a higher incidence of traumatic brain injury history, and (2) the high levels of estrogen in females tend to show a protective effect helping in vascular repair and angiogenesis. While estrogen has been proposed to exert neuroprotective and vasoprotective effects, potentially reducing the risk of CSDH recurrence through its influence on vascular integrity, inflammation, and coagulation, we acknowledge that these benefits may be less relevant in a postmenopausal cohort, where circulating estrogen levels are significantly diminished. This limitation is important to consider when interpreting our findings, as the presumed protective effect of estrogen in our study population may not be as pronounced as in premenopausal women.

Nevertheless, it remains a point of interest whether residual estrogenic activity, prior lifetime exposure, or hormone replacement therapy could play a role in modifying recurrence risk even in postmenopausal women. Further studies focusing on the hormonal milieu in elderly female patients with CSDH would be required to elucidate the precise impact of estrogen depletion on recurrence rates.[ 9 ]

Our service’s overall recurrence rate was 8.64%, which falls within the range presented in the world literature.[ 27 ] Table 2 summarizes the variables considered risks.

In our study, we found that hypodense hematomas in CT showed a higher recurrence rate (9.37%), which differs from other cohorts found in the literature that demonstrated a higher incidence in isodense and single-layer hematomas.[ 9 ]

Although our series demonstrated a higher recurrence rate with the double burr-hole technique (15%) compared to craniotomy (7%), multiple international studies have identified the double burr-hole procedure as the most effective technique for CSDH drainage.[ 10 ] Effectiveness in this context is defined by achieving complete evacuation of the hematoma rather than recurrence rates alone.[ 16 ] However, our findings suggest that recurrence might be influenced by other patient-specific or perioperative factors that warrant further investigation.

Based on the data obtained through inferential statistics, we can identify some risk factors that, although they did not show statistical significance if modified, could hypothetically reduce the risk of recurrences, such as the surgical technique (the limited sample size could represent a significant bias when interpreting the results) and the use of anticoagulants. Moreover, our cohort found that a PLT <130,000 and PTT >38.6 showed statistical significance as risk factors for recurrence. Hence, we strongly recommend that more careful measures be taken with this group of patients. Specifically, patients on antiplatelet therapy (e.g., aspirin and clopidogrel) or anticoagulation therapy (e.g., warfarin and direct oral anticoagulants) require distinct preoperative management strategies, such as platelet transfusion or administration of procoagulant agents (e.g., prothrombin complex concentrates or Vitamin K antagonists). These interventions, aimed at reversing the anticoagulant effects, could confound our assessment of hematoma recurrence and the impact of surgical technique. Given our study’s focus on evaluating recurrence rates under standard perioperative conditions, we opted to exclude this subgroup to maintain homogeneity in our patient population and avoid potential confounding variables.

Other readily available measures that could impact the reduction of recurrence, morbidity, and mortality include the use of drainage and preoperative administration of drugs such as steroids.[ 14 , 23 ] Moreover. However, we could not reach statistical significance; the use of two burr-hole surgical procedures appears to be the most effective option. Taking into consideration the higher surgical risk with a craniotomy. In our study, alcohol consumption was considered a contributing factor to coagulation abnormalities, particularly in relation to platelet adhesion, PLT, and the availability of coagulation factors. However, we did not specifically quantify the number of patients with chronic alcohol use who developed thrombocytopenia directly attributable to their alcohol consumption. Given the complexity of this topic and its multifactorial nature, we have chosen to explore this association in a separate study to provide a more thorough analysis of its impact on CSDH pathophysiology and recurrence.

In addition, acute alcohol intoxication has been reported in the literature as a potential risk factor for CSDH recurrence due to its transient effects on platelet function and coagulation pathways. However, in our current study, we did not systematically evaluate acute alcohol intoxication as a distinct risk factor. We acknowledge that this variable may have influenced our findings and recognize the importance of addressing it in future research to further clarify its role in the risk of recurrence.

At present, there are studies focused on assessing the scope of endovascular therapy to facilitate the reabsorption of the collection through the embolization of the middle meningeal artery.[ 4 ]

CONCLUSION

This study shows a statistically significant association between recurrence and the patient’s and the hematoma’s characteristics. For this reason, this paper will support the conduction of prospective studies that solidly support any recommendation to reduce the recurrence rate.

As far as we are concerned, our patients’ prognoses can improve if we modify some of the risks identified here, especially the PLT and PTT. Although no statistical significance was reached, we recommend the double burr-hole technique for the surgical management of this neurological entity.

Ethical approval:

The Institutional Review Board of Hospital Juárez de México approved this study (Approval Number: HJM 0667/19-R; Date: July 28, 2020) in compliance with all ethical guidelines for human research.

Declaration of patient consent:

The authors certify that they have obtained all appropriate patient consent.

Financial support and sponsorship:

Nil.

Conflicts of interest:

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

Acknowledgment:

We thank everyone involved in the process of this research project.

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