PDF icon Download PDF
Open Access
CC BY-NC-ND 4.0 · Asian J Neurosurg 2025; 20(02): 211-218
DOI: 10.1055/s-0044-1801770
Review Article

The Clinical Presentation, Treatment Modalities, and Outcomes Associated with Interhemispheric Subdural Hematomas

Muhammad Kashif
1   Faculty of Medicine, Midwestern University, Glendale, Arizona, United States
,
Princess Afia Nkrumah-Boateng
2   Faculty of Medicine, University of Ghana Medical School, Korle Bu, Accra, Ghana
,
Elsayed Mohamed Hammad
3   Faculty of Medicine, Alexandria university, Alexandria, Egypt
,
Habiba Abdullahi
4   Faculty of Medicine, School of Medicine, Near East University, Cyprus
,
Wireko Andrew Awuah
5   Department of Research, Inter-Continental Omni-Research in Medicine Collaborative, Berlin, Germany
,
Mohammed Q. Alibraheemi 
6   Faculty of Medicine, Carol Davila University of Medicine, Bucharest, Romania
,
Hamza A. Abdul-Hafez
7   Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine
,
Alan Hernández-Hernández 
8   Department of Neurosurgery, National Institute of Neurology and Neurosurgery, Mexico City, Mexico
,
Fadi Al-Tarawni
9   Department of Neurosurgery, Hamburg-Eppendorf University Hospital, Hamburg, Germany
,
Mohsen Nabih Shama
10   Department of Emergency Medicine, King Abdullah Medical Center, Makkah, Saudi Arabia
,
Mohammed A. Azab 
11   Department of Neurosurgery, Cairo University Hospital, Cairo, Egypt
,
Oday Atallah 
12   Department of Neurosurgery, Evangelic Hospital Oldenburg, Carl Von Ossietzky University Oldenburg, Oldenburg, Germany
› Author Affiliations

Funding None.
› Further Information
Also available ateRef
 
 PDF Download Permissions and Reprints

Abstract

Interhemispheric subdural hematoma (ISH) poses significant challenges in neurosurgical practice owing to its deep localization within the cerebral hemispheres. Despite widespread adoption of advanced neurosurgical technologies, adverse patient outcomes hinder progress in enhancing overall prognosis. This review seeks to evaluate the etiology, clinical manifestations, treatment modalities, and outcomes associated with ISHs, thereby informing clinical decision-making and improving patient care. Databases such as PubMed, Scopus, and Google Scholar were systematically searched from 1964 to 2024. The search was limited to studies involving human subjects and published in English. Keywords such as “interhemispheric subdural hematoma” and “parafalcine subdural hematoma” were used in various combinations to identify relevant articles. Our search identified 167 individuals (87 females and 80 males) ranging in age from 6 weeks to 93 years. Trauma emerged as the leading risk factor, accounting for 86.8% of cases. Nausea and vomiting were the most frequent symptoms (14.7%), followed by headache (11.8%). Most patients (22.8%) had a Glasgow Coma Scale score of 13 to 16, indicating moderate severity. Radiological analysis showed that subdural hematomas were almost evenly distributed between hemispheres, with 51% located in the right hemisphere and 49% in the left. Quantitative analysis revealed that 65.1% of patients were managed conservatively, particularly those with minimal neurological impairment, while 34% underwent surgery, including burr hole drainage and craniotomy. Of the surgical cases, 18.4% experienced complications. Our findings reveal that the outcome of ISH management depends on several factors, the most important being the etiology and size of the hematoma, the clinical presentation and comorbidities of the patient, and the interval between presentation and treatment.


 

Keywords

parafalcine - interhemispheric - subdural hematoma - craniotomy

Introduction

Interhemispheric subdural hematoma (ISH) is a rare yet complex form of brain hemorrhage between the cerebral hemispheres.[1] [2] [3] [4] [5] Despite the condition being well-documented, it remains significantly understudied due to its low incidence rates. Since this type of hematoma is usually located deep in the brain and has the potential for severe neurological impairment; it presents substantial challenges in diagnosis and treatment.[6] [7] [8]

ISHs are primarily associated with occipital head trauma; however, they can also arise from tumors, aneurysms, and coagulopathies.[1] [3] [4] [6] [9] [10] Critical determinants of patient outcomes and prognosis include the Glasgow Coma Scale (GCS) score, pre-existing medical conditions, and age.[1] [5] [7] [11] [12] [13], Clinical presentation varies among patients, with the most common symptoms being headache, vomiting, nausea, seizures, and loss of consciousness.[1] [5] [7] [11] [12] [13] Radiological imaging, specifically computed tomography (MRI) and computed tomography (CT) scans, identifies and characterizes the hematoma, detailing its location and size, and any associated complications such as intraventricular or subarachnoid hemorrhages (SAHs).[1] [6] [10] [14] [15]

The degree of neurological deterioration is a key factor influencing treatment decisions; conservative management is typically advised for patients exhibiting minimal deficits, while surgical interventions, such as burr hole placement or craniotomy, are recommended for those with severe neurological impairment.[1] [2] [3] [9] [16] [17]

Despite gradual advances in neurosurgical modalities, patient outcomes remain relatively concerning with serious postoperative complications, prolonged hospital stays, and a moderately high mortality rate.[1] [2] [5] [7] [10] We need further studies to investigate the key risk factors and the best method for management, treatment, and to avoid the postoperative complication, to further understand this topic and advance the patient care by improving the clinical guidelines. Therefore, the findings of this review, after evaluating 63 studies focusing on etiology, clinical manifestations, treatment modalities, patient outcomes, and associated complications, will guide clinical practice and inform future research.


 

Materials and Methods

This systematic review and meta-analysis strictly followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Therefore, it was a primary objective to critically review the clinical presentation, treatment options, and results for ISHs, integrating available evidence from many sources.

Search Strategy

A thorough literature search was performed in the PubMed, Scopus, and Google Scholar databases spanning from 1964 to 2024. The inquiry was confined to research involving human participants and published in English. The mesh Keywords and terms including “interhemispheric subdural haematoma” and “parafalcine subdural haematoma” were employed in diverse combinations to locate pertinent articles. The inclusion criteria were rigorously confined to human studies published in English with full-text availability and were restricted to the primary studies about the same topic of interest and had the same PICO formula for our research question. The exclusion criteria encompassed non-English publications, articles lacking full-text access, as well as abstracts, letters to the editor, books, review papers, in vitro, animal or cell culture, and bench studies to enhance the validity and reliability of the research findings ([Fig. 1]).

Zoom
Fig. 1 Flow-diagram of the related articles.

 

Study Selection

This was followed by the screening of titles and abstracts by two independent reviewers who selected articles according to predefined eligibility. To confirm inclusion, a full-text review of potentially relevant studies was completed. Differences were resolved with consensus discussions with reviewers, or, if necessary, a third reviewer was consulted. This was a strictly PRISMA guideline-driven, transparently documented, rigorous, and reproducible selection process to confirm the high quality of the work.


 

Data Extraction

Two independent reviewers extracted key study variables, including study design, patient demographics, clinical characteristics, treatment modalities, and outcomes, using a highly structured and standardized extraction template via Excel sheet. The inconsistencies were iteratively resolved through reviewer discussions and third-reviewer arbitration. This process was as rigid as necessary to ensure that all of the critical data were captured consistently and accurately.


 

Data Analysis

These were synthesized into descriptive statistics to quantify patient demographics, clinical features, and treatment outcomes. It was analyzed for the prevalence and distribution of treatment approaches to discover patterns of clinical significance. Statistical methods were used to study the relationship between patient outcomes and treatment interventions that were applicable and to help provide a comprehensive understanding of the clinical management of ISH.


 

Quality Assessment

The quality of the included studies was assessed by two tools for the observational studies; the Newcastle–Ottawa Scale for cohort and case–control studies and the Joanna Briggs Institute Critical Assessment Checklist for case reports and case series. Studies were categorized as high, moderate, or poor quality according to their assessment scores, and no articles were eliminated following the examination to ensure the quality of the included papers.


 

 

Results

After a comprehensive screening process, a total of 63 studies were determined to meet the strict standards set during the preliminary searches. This work focuses on the analysis of patient-level data from a cohort of 167 individuals diagnosed with ISH for various underlying causes ([Table 1]).

Table 1

A summary of descriptive statistics of clinical characteristics of interhemispheric subdural hematoma analyzed for 167 patients from 63 studies reviewed in this study

Variable

Count

Category

Count

Continuous variable measurement

Percentage from total cases (167) (%)

Gender

167

Female

87

–

52.1

Male

80

47.9

Age (years)

167

–

–

Mean and SD: 55.2 (±22.1)

100

Range: 6 weeks to 93 years

Anticoagulation

167

Yes

13

–

7.8

No

154

92.2

Risk factors

131

Trauma

118

–

86.8

Tumor

4

2.9

Coagulopathies

2

1.5

Others

1

0.7

Unspecified

6

4.4

Symptoms

40

Hearing disturbances

0

–

0

Vertigo

1

0.6

Nausea/vomiting

20

12

Ataxia

3

1.8

Consciousness disturbances

16

9.6

Treatment

147

Conservative

71

–

65.1

Surgical

38

34.9

Burr holes

9

23.7 (from total surgery)

Craniotomy

29

76.3

(from total surgery)

Recovery

Yes

20

–

12

No

147

88

Follow-up (months)

146

–

–

Mean (5.7)

87 (21 cases died)

Median (6)

Demographics and Risk Factors

Across the case reports reviewed, the age of patients ranged from 6 weeks to 93 years. Male patients accounted for 47.9% (n = 80) of the total sample, while female patients accounted for 52.1% (n = 87). Approximately 7.8% (n =13) of patients were under anticoagulation therapy at the time of diagnosis. Among the risk factors evaluated, trauma (86.8%) was the prevalent cause, followed by aneurysm (3.7%), tumors (2.9%), and coagulopathies (1.5%).


 

Clinical Presentation

The most stated symptoms were nausea and vomiting (12% of the total cases) and consciousness disturbances (9.6%). Less frequent symptoms included ataxia (1.8%) and vertigo (0.6). Other symptoms reported included headache and dizziness, hemiparesis, lethargy, and seizures. Most patients had a GCS score ranging from 13 to 15 (22.8%), 9 to 12 (4.4%), and 3 to 8 (4.4%); the remaining were not specified. The GCS scores indicate that most cases were moderately severe.


 

Associated Radiological Features

Radiological findings showed subdural hematomas (SDHs) mostly located in the right hemisphere in 51% of the cases that indicated the site, with the remaining 49% in the left hemisphere. They also revealed SAH (17 cases), intracerebral hemorrhage (4 cases), intraventricular hemorrhage (2 cases), and fractures (1 case).


 

Treatment Methods

Notably, 65.1% of the patients were treated conservatively, particularly those who had minimal neurological impairment. Surgical interventions were carried out on 34.9% of the patients, with 23.7% of the surgical operations being burr holes and 76.3% of the surgical operations undergoing craniotomy. In addition, 18.4% of the patients who underwent surgery developed complications, and no recurrence was reported. Only two patients developed complications after conservative management, and recurrence was reported by only one patient.


 

Patient Outcomes

The patients recorded an average hospital stay of 29.8 days. The follow-up period after treatment ranged from 2 to 6 months. Death was recorded in 21 patients posttreatment or immediately after admission, with a higher risk for those admitted with GCS scores of less than 8. Recurrence was relatively low given that it was only recorded in one patient reported after being treated conservatively.


 

 

Discussion

ISH, also known as parafalcine hematoma, is a subtype of SDH.[18] [19] [20] [21] [22] Although it was reported to be rare, a recent study discovered that it is present in more than 35% of acute SDHs (ASDHs) requiring admission and in 19.4% of all admitted traumatic brain injury patients.[21] [23] [24] ISH is usually unilateral due to the tight adherence of subarachnoid trabeculations between the brain and the parasagittal dura mater ([Fig. 2]).

Zoom
Fig. 2 (A–C) Anatomical illustration of interhemispheric subdural hematomas.

The presence of an ISH together with a convexity SDH has recently been found to be strongly associated with underlying coagulopathies and/or anticoagulant use (94.7%, p < 0.005).[24] Our analysis revealed approximately 7.8% of the included patients were under anticoagulation at the time of ISH diagnosis. It has historically been associated with a high mortality rate (ranging between 24 and 27%).[7]

ISH accounts for about 6% of all traumatic SDHs and 0.8% of all hospitalized patients after head injury.[25] It is mostly reported to be seen in people over the age of 60, which is consistent with our findings of a mean age of 55.2 ± 22.1 years.[26] It is reported to be more prevalent in males, with a male-to-female ratio of 2:1.[21] [25] Intriguingly, our findings revealed a slightly lesser prevalence in males than females, with the former at 47.9% and the latter at 52.1%. This discordance is perhaps due to most of the reported literature analyses of ISH being of traumatic etiology, whilst our review included other etiologies such as meningiomas that are more commonly seen in females.[27]

Trauma is the most reported etiology in literature[17] [28] [29] [30] and 86.8% of our included cases had a traumatic etiology. It is mostly due to laceration of the parasagittal or parafalcine bridging veins from a medial force.[7] [17] [31] [32] It has rarely been reported to be due to a laceration of the anterior cerebral artery branch.[23] [33] Another unique etiology of traumatic ISH is the transformation of a posttraumatic convexity SDH into an ISH. Wu et al postulated this to be due to the high intracranial pressure measured intraoperatively. The course of the hematoma was an obvious reduction in the size of the convexity SDH, eventual resolution, and then the appearance of a novel ISH.[34] [35]

ISH has rarely been reported to be found in meningioma cases and only 10 cases have been reported to date. Hemorrhage in meningioma is rare and when it does occur, it mostly manifests as SAH,[36] [37] and less commonly as intracerebral and intratumoral.[12] In general, a rapid increase in meningioma size has been associated with an increased risk of hemorrhage.[11]

The meningioma subtypes with the highest risk of hemorrhage are angiomatous and fibroblastic meningiomas.[38] Eighty percent of these cases included female patients, whose mean age was 68 years old (range: 48–84 years). Usually, bleeding happens when the tumor was first discovered. The majority of symptoms during bleeding were headaches, which could be minor or severe.[12] [39] [40] [41] [42] [43] [44] Our findings revealed only 2.9% of ISH patients had an associated meningioma, with both angiomatous and fibroblastic meningiomas reported.[39] [45] [46] A few hypotheses have been described to explain how meningiomas cause ISH: (1) disruption of tumor vessels due to tumor growth; (2) disruption of bridging veins due to tumor growth; (3) direct invasion of tumor cells into blood vessels; (4) release of vasoactive substances by tumor cells; (5) disruption of bridging veins due to local venous hypertension caused by a secondary condition, such as Valsalva maneuver or cough; and (6) anticoagulant or antiplatelet medications, blood dyscrasias, or hypertension.[45] [47]

Two patients from our cohort presented with hemodialysis associated with ISH.[5] [20] Its diagnosis needs close neurological observation and high clinical suspicion, as the symptoms are like other complications of hemodialysis.[5] In such cases, the differentials of a hyperintense lesion around the region of the falx are sinus thrombosis and dural calcification, a documented complication of long-term dialysis.[20]

Another important differential of ISH without a trauma history or coagulopathy is a ruptured aneurysm.[48] We analyzed two patients with this etiology and its proposed mechanisms are: (1) successive small bleeding episodes cause adhesion of the aneurysm to the adjacent arachnoid membrane, and the final rupture occurs in the subdural space. (2) A hemorrhage under high pressure may lead to pia arachnoid rupture.[48] Other unique etiologies were ISH secondary to hemorrhagic disease of the newborn, corpus callosum agenesis, and post-birth injury associated with hydrocephalus.[14] [49]

The most reported symptom by far is headaches.[25] This is consistent with our findings and because it is often the sole presenting symptom, patients at risk of ISH, such as the elderly (>60 years) and patients on anticoagulants presenting with headaches, would benefit from radiological surveillance.[20] [25] The falx syndrome, a “contralateral hemiparesis with the leg more affected than the arm or contralateral leg monopoiesis, occasionally in conjunction with decreased mental status” is the classical presentation for ISH.[50] [51] It is important to note that immediate loss of consciousness is not often seen in ISH.[31] Although most of our reported GCS scores were high,[13] [14] [15] compared to convexity SDH, ISH has been reported to be associated with a lower GCS. It is thought to be due to the vulnerable cohort that develops this (older patients, patients with comorbidities). It could also be due to the associated bleeds that present with ISH, especially posttrauma.[21] [31] Our results revealed radiological evidence of a concurrent SAH, intracerebral hemorrhage, and intraventricular hemorrhage, in order of decreasing frequency. These accounted for the lower GCS scores, 9 to 12 (4.4%) and 3 to 8 (4.4%), found in our cases.

Thus, the best confirmation of an ISH is a MRI, as it has an advantage over CT due to the absence of beam-hardening and multiplanar imaging.[52] Therefore, it has been the consensus that even in the presence of an unrevealing CT finding, in the presence of falx syndrome, an MRI should always be done.[53] With larger ASDHs, concern about potential enlargement may prompt follow-up CT scanning roughly 4 to 6 hours after an initial scan.[54]

Conservative treatment has been the preferred management reported in the literature.[7] [21] [25] [28] [55] This is consistent with our findings of 65.1% of patients undergoing conservative management. Moreover, the evidence shows that conservative management is often the safest choice because of the proximity of these hematomas to critical structures and the risk of damage to them during surgery.[21] Our findings revealed that 34.9% of our cases had surgical management. Although there is a significant difference between this and our reported percentage of patients managed conservatively, we believe that the surgical management percentage is as high as it is because of the associated lesions in several of our cohorts (meningioma, aneurysms, and associated bleedings). Recent evidence has shown that sole ISHs are usually harmless and often resolve on their own.[21] There are no established guidelines on the protocol of follow-up imaging after diagnosing ISHs. Devulapalli et al designed a study that involved tentorial and falcine ASDHs. The average time between the initial and repeat examinations was 10.3 hours.[54] Servadei et al studied a population cohort of ASDH. Each patient underwent CT on admission within 3 hours from injury. Follow-up CT was performed within 12 to 24 hours after injury and in the following days.[56] Adequate research should be recruited to establish protocols to determine the follow-up imaging intervals in cases of ISHs.

Patients with ISH have better outcomes than patients with convexity SDH, with the latter requiring more intense surgical care and longer inpatient hospital stays, while the former is mostly managed conservatively with better outcomes.[30] Takeuchi and colleagues reported factors correlated with poor outcomes in patients with ISH: GCS score, hypovolemic shock, skull fracture, convexity or posterior fossa SDH, and associated SAH.[17] Similar prognostic factors have been reported to be associated with poor outcomes by Wang et al[57]; low GCS at presentation, the source of the hematoma, and greater thickness of hematoma.[55] These factors are in line with our findings of low GCS at presentation being associated with a poorer outcome.

Most of our conservatively managed cases had good outcomes in long-term follow-up, with complete resolution of symptoms and hematoma, which is similar to literature.[25] The surgical management of cases of tumor-related SDHs had good outcomes with complete recovery, except one that deteriorated despite aggressive management.[39]


 

Future Research

Clinical trials and longitudinal long-term research ought to be enlisted in order to assess clinical presentations, follow-up strategies, and appropriate management. There are no standardized recommendations for the proper care of patients with ISH due to the paucity of relevant literature. Animal studies are required to properly understand the pathophysiologic mechanism and causation of ISH.


 

Limitations

Despite the rigorous methodology employed in this review, certain limitations must be acknowledged. First, although the literature search spanned multiple databases, including PubMed, Scopus, and Google Scholar, relevant studies on the topic in other databases may have been inadvertently overlooked. Furthermore, the study's focus on English-language literature exclusively may have excluded valuable evidence from non-English publications, introducing potential language bias into the review. Lastly, due to the paucity of original studies and clinical trials, only data from case reports and case series were retrieved for this review, which may have resulted in the collection of data with small sample sizes. This may have limited the depth and breadth of our analyses.


 

Conclusion

In conclusion, our findings reveal that the outcome of ISH management depends on several factors. The most important factors are the etiology of the hematoma, the size of the hematoma, the clinical presentation and comorbidities of the patient, and the interval between presentation and treatment. We do not believe that the treatment modality choice is associated with outcome because although conservative management is commonly performed with good outcomes, surgical management, when indicated, has also been reported to have mostly good outcomes.[55]


 

 

Conflict of Interest

None declared.


Address for correspondence

Oday Atallah, MD, MBA
Department of Neurosurgery, Evangelic Hospital Oldenburg, Carl Von Ossietzky University Oldenburg
Steinweg 13, 26122 Oldenburg
Germany   

Publication History

Article published online:
10 January 2025

© 2025. Asian Congress of Neurological Surgeons. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

Thieme Medical and Scientific Publishers Pvt. Ltd.
A-12, 2nd Floor, Sector 2, Noida-201301 UP, India


  Permissions and Reprints
Zoom
Fig. 1 Flow-diagram of the related articles.
Zoom
Fig. 2 (A–C) Anatomical illustration of interhemispheric subdural hematomas.