a b s t r a c t

Introduction: indications for hospitalization in patients with parafalcine or tentorial subdural hematomas (SDH) remain unclear. This study derived and validated a clinical decision rule to identify patients at low risk for com- plications such that hospitalization can be avoided.

Methods: A multicenter retrospective medical record review of adult patients with parafalcine or tentorial SDHs was completed. The primary outcome was significant injury, defined as injury that led to neurosurgery, discharge to another facility, or death. A multivariable logistic regression was performed to identify variables indepen- dently associated with the outcome in the derivation cohort. These variables were then validated on a separate cohort from a different institution abstracted without knowledge of the identified variables.

Results: In the derivation cohort, 134 patients with parafalcine/tentorial SDHs were identified. The mean age was 63 +- 19 years with 82 (61%) male. Seventy-one (53%) had Significant injuries. Variables independently associ- ated with significant injury included: age over 60, adjusted odds ratio (aOR) 3.46 (95% CI 1.24, 9.62), initial Glas- gow Coma Scale score below 15, aOR =7.92 (95% CI 2.78, 22.5), and additional Traumatic brain injuries (TBIs) on Computerized tomography , aOR =5.97 (95% CI 2.48, 14.4). These three variables had a sensitivity of 71/71 (100%, 95% CI 96, 100%) and specificity of 12/63 (19%, 95% CI 10, 31%). The validation cohort (n = 83) had a mean age of 62 +- 22 years with 50 (60%) male. The three variables had a sensitivity of 36/36 (100%, 95% CI 92, 100%) and specificity of 7/47 (15%, 95% CI 6.2, 28%). All 39 (100%, 95% CI 93, 100%) patients from both cohorts who un- derwent neurosurgery had additional TBI findings on their CT scan.

Conclusions: Patients with parafalcine/tentorial SDHs who are under 60 years with initial GCS scores of 15 and no addition TBIs on CT are at low risk and may not need hospitalization. Furthermore, patients with isolated parafalcine/tentorial SDHs are unlikely to undergo neurosurgery. Prospective, external validation with a larger sample size is now recommended.

Study type: Retrospective Cohort Study.

(C) 2023

1. Introduction

Approximately 1.4 million people in the United States suffer from Traumatic brain injury each year accounting for >50,000 deaths

* Corresponding author at: UPMC Hamot, 201 State Street, Erie, PA 16550, USA.

E-mail addresses: [email protected] (K.A. Juhasz), [email protected]

(E.R. Iszkula), [email protected] (G.R. English), [email protected] (C.Y. Estrada), [email protected] (D.E. Leshikar), [email protected]

(B.T. Pfeiffer), [email protected] (A.E. Wagle), [email protected] (J.F. Holmes).

annually [1]. Acute subdural hematomas (SDH) occurs in 12-29% of se- vere TBI and have mortality rates from 40 to 60% [2]. SDH is most often due to damage of bridging veins between the dura mater and arachnoid layers and are classified based on location, shape, and severity.

While medical literature tends to focus on convexity SDHs,

parafalcine and tentorial SDHs occur at the meningeal infoldings that encase the brain. The most prominent of these infoldings are the falx cerebri, falx cerebelli, and tentorium cerebelli, and it is in these areas that isolated parafalcine and tentorial SDHs may occur [3]. Parafalcine SDHs occur from disruption of bridging veins traversing the parieto-

https://doi.org/10.1016/j.ajem.2023.01.014

0735-6757/(C) 2023

occipital cortex to the superior sagittal sinus secondary to occipital trauma. Tentorial SDHs, however, result from injury to the bridging veins surrounding the temporo-occipital lobe.

Management of parafalcine and tentorial SDH remains controversial. As most research has focused on convexity SDHs, parafalcine and tentorial SDHs have remained largely unstudied. As such, traumatic dis- ease progression and evidence-based management for patients with parafalcine and tentorial SDHs likewise remain undefined. The purpose of this study is to determine the prevalence, risk factors, and outcomes in patients with parafalcine or tentorial SDHs after blunt head injury. Our specific objective is to identify a subset of patients with parafalcine or tentorial SDHs who can be observed and safely discharged from the Emergency Department (ED) without requiring hospital admission.

1. Methods
   1. Study design and setting

This is a multicenter retrospective cohort study of adult patients with parafalcine or tentorial SDHs. The first institution, University of Pittsburgh Medical Center (UPMC) Hamot, is a level 2 trauma center with approximately 2100 adult trauma admissions/year. The second in- stitution, University of California (UC) Davis, is a level 1 trauma center with approximately 3500 adult trauma admissions/year. The study was approved by both institutional IRBs. The STROBE and TRIPOD guidelines were used to ensure proper reporting of methods, results, and discussion.

• 1. Study population

A cohort of subjects with SDHs were identified from each center’s trauma registry by searching International Statistical Classification of Diseases and Related Health Problems, Ninth Edition (ICD9) codes 852.2-852.26 and 852.29 (“subdural hemorrhage following injury without mention of open intracranial wound” plus various modifiers re- garding presence, duration, and/or absence of loss of consciousness). From this database, patients with parafalcine or tentorial SDHs were identified. Patients were excluded if they did not have a parafalcine or tentorial SDH on initial cranial CT scan or if they had penetrating trauma.

• 1. Data variables and collection

Variables available from the trauma registry included patient demo- graphics (age, gender, race) mechanism of injury, initial Glasgow Coma Scale score, Abbreviated Injury Scale, Neurosurgery consultation, hospital admission and bed type (ward, intensive care unit), total hospi- tal length of stay, discharge disposition (home, skilled nursing facility, rehabilitation, morgue), and if the patient was transferred to the study facility.

Data not available from the trauma registry were manually ab- stracted. Data abstraction adhered to accepted guidelines for perform- ing retrospective medical record reviews [4]. Abstractors underwent specific training to properly identify those cases meeting study inclu- sion and exclusion criteria. Data abstracted included presence/absence of headache, loss of consciousness, vomiting, dizziness, confusion, re- peat cranial CT (timing of that CT), neurosurgical intervention, anticoag- ulation medications, and use of anti-seizure medications. A select number of cranial CT scans and medical records were independently re- viewed by two abstractors to evaluate inter-abstractor reliability and measured with the kappa statistic.

Isolated parafalcine or tentorial SDH was defined as a parafalcine or tentorial SDH present without other intracranial traumatic findings (other SDHs, epidural hematoma, subarachnoid hemorrhage, cerebral contusion, intraventricular hemorrhage, etc). Isolated head injury was considered present in those patients with abbreviated injury severity

(AIS 2015) scales <2 for all the following regions: face, thorax, abdo- men, extremities and external. [5]

• 1. Outcomes

The primary outcome of interest was any patient with a significant injury. Significant injury was defined as any parafalcine or tentorial SDH resulting in neurosurgical intervention, death, or discharge to a re- habilitation/skilled nursing facility. The secondary outcome was any neurosurgical intervention (subset of the primary outcome).

• 1. Statistical analysis

Data is described with simple descriptive statistics. Continuous data are provided with the mean +- one standard deviation when normally distributed or the median with the interquartile range when non- normally distributed. A multivariate logistic regression model was cre- ated to identify variables independently associated with the outcome of interest. Sample size was based on the number of variables entered in the regression model. We required 10 patients with the outcome of interest for every predictor variable entered in the regression model. We evaluated six predictor variables in the regression model, thus re- quired 60 patients with the outcome of interest. We anticipated 50% of the patients with parafalcine or subdural hematomas would have the outcome of interest. Therefore, approximately 120 patients were re- quired in the derivation phase. The decision rule was then validated on a separate cohort of patients from a separate institution. The validation cohort was abstracted prior to data analysis and thus abstractors were not aware of the variables that were identified in the decision rule. Per- formance of the decision rule in the validation phase was described with sensitivity and specificity. We anticipated the sensitivity of the decision rule to be 100% and required the lower bound of the 95% confidence in- terval for the sensitivity to be >90%. This required 30 patients with the outcome of interest (at least 60 total patients) in the validation sample.

1. Results

A total of 217 patients were enrolled including 134 in the derivation and 83 in the validation cohorts were enrolled. Demographics, mecha- nism of injury, initial GCS scores and injury findings are presented in Table 1. ED evaluation, neuroSurgical consultation/intervention, treat- ment with antiseizure medications, ED disposition and outcomes are presented in Table 2. Additional CT findings in those with multiple intra- cranial injuries are in Table 3. Inter-rater reliability of the abstraction ranged from moderate (kappa = 0.58 for vomiting) to perfect (kappa = 1.0 for neurosurgical intervention).

The primary outcome of interest was identified in 71 (53%, 95% CI 44, 62%) patients in the derivation cohort and 36 (43%, 95% CI 33, 55%) in the validation cohort. In the multivariate regression analysis, variables independently associated with a significant injury included: age >= 60 years, initial Glasgow Coma Scale score < 15, and additional TBIs on CT (Table 4). A three variable regression model with these three vari- ables had the following odds ratios: age over 60 years = 3.46 (95% CI 1.24, 9.62), GCS score <15 = 7.92 (95% CI 2.78, 22.5) and multiple inju- ries on cranial CT = 5.97 (2.48, 14.40). In the derivation set, these three high risk variables had a sensitivity = 71/71 (100%, 95% CI 96, 100%)

and specificity = 12/63 (19%, 95% CI 10, 31%). In the validation phase, the three high risk variables had a sensitivity for significant injury of 36/36 (100%, 95% CI 92, 100%) and specificity = 7/47 (15%, 95% CI 6.2,

28%). In examining the secondary outcome, all 39 (100%, 95% CI 93, 100%) patients who underwent neurosurgery had additional TBI find- ings on their cranial CT scan.

Demographics, mechanism of injury, initial GCS scores, ED evalua- tion, treatment and outcomes data categorized by patients with isolated versus multiple findings on cranial CT are presented in Tables 5 and 6. Patients with isolated injuries on CT were more likely to have an initial

Table 1

Patient characteristics in the derivation and validation cohorts.

	Derivation (n = 134)	% (95% CI)	Validation (n = 83)	% (95% CI)
Age +- SD (years)	63 +- 19		62 +- 22
Age > 60 years	87	65% (56, 73%)	49	59% (48, 70%)
Male Mechanism of injury	82	61% (52, 69%)	50	60% (49, 71%)
Fall	91	68% (59, 76%)	50	60% (49, 71%)
Motor vehicle/motorcycle	30	22% (16, 30%)	15	18% (10, 28%)
Assault	4	3% (1, 7%)	7	8% (3, 17%)
Bicycle	0	0% (0, 3%)	6	7% (3, 15%)
Auto versus Pedestrian	3	2% (0, 6%)	5	6% (2, 14%)
Other/unknown	6	4% (2, 9%)	0	0% (0, 4%)
Initial GCS score GCS = 15	83	62% (53, 70%)	38	46% (35, 57%)
GCS = 13-14	24	18% (12, 25%)	19	23% (14, 33%)
GCS = 8-12	4	3% (1, 7%)	9	11% (5, 20%)
GCS < 8	22	16% (11, 24%)	17	20% (12, 31%)
Transfer from non-trauma center	66	49% (41, 58%)	27	33% (23, 44%)
Isolated tentorial/parafalcine SDH	58	43% (35%, 52%)	24	29% (19, 40%)
Isolated head injury	76	57% (48, 65%)	36	43% (33, 55%)

CI = confidence interval, SD = standard deviation, GCS = Glasgow Coma Scale, SDH = subdural. Missing GCS score for one patient in the Derivation cohort.

GCS score of 15. None (0%, 95% CI 0, 4%) of the 82 patients with isolated parafalcine/tentorial SDHs underwent neurosurgical intervention. Pa- tients with isolated parafalcine/tentorial injuries were also less likely to be treated with antiseizure medications or hospitalized in the inten- sive care unit.

1. Discussion

Many of these patients were transferred from non-trauma centers to trauma centers.

Management strategies regarding TBIs vary across the United States and are a source of inefficient care [7]. At many centers, patients with TBIs are admitted for at least 24-h of observation and may be rescanned at 24 h or sooner if clinical deterioration occurs. Bed type (intensive care unit versus ward) is also variable. Some locations have adopted

In the current study, patients with parafalcine or tentorial SDHs often have additional findings on their cranial CT scan. Furthermore, these patients frequently undergo neurosurgery or have adverse out- comes from their intracranial injuries. A subset of patients with

Table 3

Additional CT findings in those with multiple injuries.

Derivation Sample (n = 69)

Validation Sample (n = 59)

parafalcine or tentorial SDHs, however, are at low risk for adverse out- comes and can be identified by three simple variables. Those patients who do not have any high-risk variables are at such low risk that they may not require hospitalization.

Although patients with Blunt head trauma are typically adolescent or young adults, prevalence of traumatic lesions on CT is higher in the elderly [6]. Consistent with that study, patients in this study were older. As this population was older, the most common mechanism of in- jury was unsurprisingly falls followed by motor vehicle/motorcycle in- jury. Most patients had GCS scores of 15 suggesting Minor head injury.

Hemispheric SDH 49 40

Epidural Hematoma 6 4

Extra-axial hematoma 10 1

Subarachnoid hemorrhage 39 23

Intraparenchymal hematoma 16 8

Cerebral Contusion 12 10

Intraventricular hemorrhage 7 4

Pneumocephalus 12 4

Mass effect/shift 14 25

Edema	9	7
Herniation	14	9

Table 2

Patient outcomes in the derivation and validation cohorts.

	Derivation (n = 134)	% (95% CI)	Validation (n = 83)	% (95% CI)
Repeat Cranial CT	126	94% (89, 97%)	77	93% (85, 97%)
Time (hours)	9.5 (6, 12)		6 (6, 9)
cranial MRI	11	8% (4, 14%)	16	19% (11, 29%)
Neurosurgery consultation	128	96% (91, 98%)	83	100% (96, 100%)
Neurosurgery intervention	18	13% (8, 20%)	21	25% (16, 36%)
Antiseizure medications	23	17% (11, 25%)	40	48% (37, 59%)
ED Disposition ICU	41	31% (23, 39%)	52	63% (51, 73%)
Ward	84	63% (54, 71%)	16	19% (11, 29%)
Operating Suite	9	7% (3, 12%)	14	17% (10, 27%)
Died in the ED	0	0% (0, 2%)	1	1% (0, 7%)
ICU length of stay (hours)	62 (23, 247)		30 (17, 96)
Hospital length of stay (hours)	89 (45, 162)		96 (48, 264)
Died	15	11% (6, 18%)	10	12% (6, 21%)
Discharged home	64	48% (39, 57%)	49	59% (47, 70%)
Transfer to other hospital	1	1% (0, 4%)	8	10% (4, 18%)
Discharged rehabilitation/SNF	54	40% (32, 49%)	16	19% (11, 29%)

CI = confidence interval, CT = computed tomography, MRI = magnetic resonance imaging, ED = Emergency Department, ICU = intensive care unit, SNF = skilled nursing facility. Time reported as median with interquartile range.

Table 4

Variable association with primary outcome (significant parafalcine/tentorial SDH).

	Univariate Analysis		Multivariate Analysis
	Odds Ratio	95% CI	Odds Ratio	95% CI
Age over 60 years	1.67	0.82, 3.40	3.46	1.24, 9.62
GCS score <15	7.07	3.12, 15.90	7.92	2.78, 22.5
Anticoagulation medication	1.38	0.68, 2.78	1.18	0.46, 3.03
Headache	0.42	0.20, 0.87	0.87	0.33, 2.26
Vomiting	1.19	0.29, 4.97	1.31	0.22, 7.90
Multiple injuries on Cranial CT	5.91	2.80, 12.50	5.97	2.48, 14.4

SDH = subdural hematoma CI = confidence interval, GCS = Glasgow Coma Scale, CT = computed tomography.

Table 5

patients outcomes by isolated parafalcine/tentorial SDHs or multiple traumatic brain injuries.

	Isolated Injuries (n = 82)	% (95% CI)	Multiple Injuries (n = 135)	% (95% CI)
Age +- SD (years)	64 +- 18		62 +- 21
Age > 60 years	56	68% (57, 78%)	80	59% (50, 68%)
Male	46	56% (45, 67%)	86	64% (55, 72%)
Mechanism of injury Fall	54	66% (55, 76%)	87	64% (56, 72%)
Motor vehicle/motorcycle	19	23% (15, 34%)	26	19% (13, 27%)
Assault	4	5% (1, 4%)	7	5% (2, 10%)
Bicycle	1	0% (0, 7%)	5	4% (1, 8%)
Auto versus Pedestrian	3	4% (1, 10%)	5	4% (1, 8%)
Other	1	0% (1, 7%)	5	4% (1, 8%)
Initial GCS score GCS = 15	63	63% (54, 71%)	58	43% (34, 52%)
GCS = 13-14	14	18% (12, 25%)	29	21% (15, 29%)
GCS = 8-12	2	3% (1, 7%)	11	8% (4, 14%)
GCS < 8	3	16% (11, 24%)	36	27% (19, 35%)
Transfer from non-trauma center	37	45% (34, 57%)	56	41% (33, 50%)
Isolated head injury	45	55% (43, 66%)	67	50% (41, 58%)

CI = confidence interval, SD = standard deviation, GCS = Glasgow Coma Scale. Missing GCS score for one patient in the isolated cohort.

guidelines to safely observe patients for 6 h, obtain a repeat cranial CT at 6 h, and then discharge from the ED with outpatient follow-up [8]. In most locations, trauma patients with isolated parafalcine or tentorial SDHs noted on CT head imaging regardless of other injuries are admit- ted to trauma centers for neurosurgical consultation and further man- agement. This includes a substantial number of patients who are transferred to a trauma center. This type of variability introduces ineffi- ciencies into the Trauma system. Providing Evidence-based guidelines for the management of patients with parafalcine or tentorial SDHs may improve trauma care.

Despite recent publications, little is known about the prevalence, injury progression, and outcomes in patients with isolated, blunt parafalcine and tentorial SDHs [3,9,10]. Reports suggest 9-13% of SDHs are parafalcine or tentorial [3,11]. As this type of intracranial hemorrhage is not common, treatment is often not evidence-based. In the current study, we attempted to determine factors associated with poor outcomes in this group to iden- tify those patients who require hospitalization. Conversely, those patients who are not at risk for bad outcomes may be safe for a period of observa- tion or even discharged from the ED. Those patients who do not require hospitalization may also not require transfer to a trauma center.

Table 6

Patients outcomes by isolated parafalcine/tentorial SDHs or multiple traumatic brain injuries.

	Isolated Injuries (n = 82)	% (95% CI)	Multiple Injuries (n = 135)	% (95% CI)
Repeat Cranial CT	75	91% (83, 96%)	128	95% (90, 98%)
Time (hours)	10 (6, 12)		6 (6, 12)
Cranial MRI	8	10% (4, 18%)	19	14% (9, 21%)
Neurosurgery consultation	78	95% (88, 99%)	131	97% (93, 99%)
Neurosurgery intervention	0	0% (0, 4%)	39	29% (21, 37%)
Antiseizure medications	5	6% (2, 14%)	58	43% (34, 52%)
ED Disposition ICU	23	28% (19, 39%)	70	52% (43, 61%)
Ward	55	67% (56, 77%)	46	34% (26, 43%)
Operating Suite	4	5% (1, 12%)	19	14% (9, 21%)
Died in the ED	0	0% (0, 4%)	1	1% (0, 4%)
ICU length of stay (hours)	24 (5, 27)		61 (24, 216)
Hospital length of stay (hours)	67.5 (35, 120)		104 (50, 256)
Died	2	2% (0, 9%)	25	19% (12, 26%)
Discharged home	57	70% (58, 79%)	56	41% (33, 50%)
Transfer to other hospital	2	2% (0, 9%)	7	5% (2, 10%)
Discharged rehabilitation/SNF	21	26% (17, 36%)	49	36% (28, 45%)

CI = confidence interval, CT = computed tomography, MRI = magnetic resonance imaging, ED = Emergency Department, ICU = intensive care unit, SNF = skilled nursing facility. Times reported as median with interquartile range.

While several clinical decision rules for cranial CT use in the ED exist (Nexus, Canadian CT Head, New Orleans) [12-14], there is a paucity of guidelines to assist clinicians in managing those with intracranial hem- orrhage found on CT. Extensive variability in ICU admissions in patients with minor intracranial hemorrhage has been demonstrated [15]. While studies such as the Brain Injury Guidelines were designed to reduce un- necessary ICU admission in a variety of TBI patients [7,16], ED disposi- tion in those with parafalcine/tentorial head bleed patients is limited by lack of evidence.

In this study, we demonstrate that isolated parafalcine and tentorial SDHs are unique injuries that require limited resource and are unlikely to benefit from ICU admission, intensive management, or repeat CT im- aging. We have derived a clinical decision rule that helps to determine which patients may require hospital admission and those that may be safely discharged from the ED. Those patients with parafalcine or tentorial SDHs who are over 60 years of age, have GCS scores <15 or have multiple injuries on cranial CT are at risk for poor outcomes and re- quire hospitalization. This suggests that patients <60 years old, with GCS scores of 15, and with isolated parafalcine/tentorial SDH do not need admission and may be candidates for ED observation and/or dis- charge. In addition, this low-risk group is highly unlikely to need neuro- surgical intervention.

Although use of anticoagulation medication was not a predictor of adverse outcomes, prior studies suggest adverse outcomes in this pop- ulation [17]. It is likely that those on anticoagulation have more signifi- cant intracranial injuries and frequently do not present with isolated parafalcine/tentorial SDHs. In the rare instances of an isolated parafalcine/tentorial bleed on anticoagulant medications, hospitaliza- tion and reversal of the coagulopathy is still likely warranted [18-21].

This study adds to the growing body of evidence that patients with mild TBI likely benefit little from ICU admission. While the majority of these patients with isolated parafalcine and tentorial bleeds were ad- mitted to the hospital, underwent repeat cranial CT scans and had neu- rosurgical consultation, these were generally unnecessary and a poor use of resources. Decreasing unnecessary admissions can help reduce costs to patients and institutions, free Hospital beds and personnel for other critically ill or injured patients and decrease patient load to an oth- erwise already burdened hospital system.

This study is subject to certain limitations. It is a retrospective med- ical record review and subject to the limitations of this design. We followed recommended methodologic guidelines to minimize any po- tential bias from this design. Although the study was derived in one sample and validated in a second sample, prospective validation is rec- ommended. A subsequent prospective study would allow further re- finement/derivation of a clinical decision rule for the management of patients with parafalcine and tentorial SDHs that may then be imple- mented and improve patient care. Despite using the same inclusion/ex- clusion criteria, differences existed in the demographics and care in the two samples. These differences, however, likely increase the generaliz- ability of the findings.

1. Conclusion

Patients with parafalcine/tentorial SDHs who have initial GCS score <15, are 60 years of age or older, and have other TBIs on their CT are at increased risk of complications and require hospitali- zation. Patients without these findings are at low risk and may not need hospitalization.

CRediT authorship contribution statement

Kristin A. Juhasz: Writing – original draft, Methodology, Investiga- tion, Formal analysis, Data curation, Conceptualization. Erik R. Iszkula: Writing – review & editing, Data curation. Gregory R. English: Writing – review & editing, Conceptualization. Daniel B. Desiderio: Writing – review & editing, Investigation, Data curation. Carmen Y. Estrada:

Writing – review & editing, Investigation, Data curation. David E. Leshikar: Writing – review & editing, Investigation, Data curation. Benjamin T. Pfeiffer: Writing – review & editing, Investigation, Data curation. Emily H. Roesel: Writing – review & editing, Investigation, Data curation. Ashley E. Wagle: Writing – review & editing, Investiga- tion, Data curation. James F. Holmes: Writing – original draft, Valida- tion, Methodology, Investigation, Formal analysis, Data curation, Conceptualization.

Declaration of Competing Interest

The authors declare no conflicts of interest or sources of funding.

Acknowledgements

Special thanks to Dr. James Holmes and ACEP’s EMBRS Course, Hamot Health Foundation, Dr. Gregory Beard, Dr. Christopher Cammarata, Mrs. Amanda Greenough, Dr. Dale Stevens, and Mr. Ryan Fancher for their assistance in the collaboration, development, data abstraction, and execution of this study. Thank you to Ms. Sarah Mattocks, Ms. Diane Voelker, Dr. Justine Schober, and Ms. Lynne Bianchi for their help and support.

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