Radiology

A comparison of clinical characteristics, radiographic findings, and outcomes of bihemispheric versus unihemispheric gunshot wounds to the head

a b s t r a c t

Introduction: Unihemispheric head gunshot wound (HGSW) are associated with improved survival; however, specific clinical and radiographic characteristics associated with survival have not been clearly defined. To further guide prognosis estimates and care discussions, this study aims to identify unihemispheric HGSWs injury patterns; comparing them to bihemispheric HGSWs characterizing factors associated with improved clinical outcomes and survival.

Methods: Patients presenting to our Level 1 trauma center from January 2013 through May 2019 with HGSW injury were reviewed. Patients were grouped into those with unihemispheric versus bihemispheric HGSWs and survivors versus non-survivors. Clinical variables and head computed tomography features were compared using comparative statistics.

Results: 62 HGSW patients met study criteria (unihemispheric = 33, bihemispheric = 29). Regardless of injury type, avoidance of injury to multiple lobes, temporal, parietal and basal ganglia brain regions and intracranial Vascular injury were also associated with survival (p < 0.05). Lower admission GCS score and lower motor GCS score was associated with reduced survival in unihemispheric HGSW injury (p < 0.05). Unihemispheric HGSW survivors demonstrated improved clinical outcomes, with reduced hospital length of stay (5 days vs. 47 days, p = 0.014) and Intensive care unit length of stay (3 days vs. 20 days, p = 0.021) and more favorable disposition location.

Conclusion: We found presenting clinical features and CT imaging patterns previously associated with improved survival in HGSW patients is similar in unihemispheric specific injuries. Importantly, a more favorable admission GCS score may portend survivability in unihemsipheric HGSW. Furthermore, unihemispheric HGSW survivors may have improved clinical outcomes, length of stay and disposition location.

(C) 2022

  1. Introduction

Abbreviations: AIS, Abbreviated Injury Score; AMA, Against medical advice; APR, Abnormal pupillary response to light; CT, Computed tomography; DBP, Diastolic blood pressure; ED, Emergency department; EDH, epidural hematoma; GCS, Glasgow Coma Scale; HGSW, Head gunshot wound; HR, Heart rate; ICP, Intracranial pressure; ICU, Intensive care unit; INR, International Normalized Ratio; IQR, Interquartile range; IVH, Intraventricular hemorrhage; ISS, Injury severity score; LOS, Length of stay; NSGY, Neurosurgery; PTT, Partial thromboplastin time; SAH, Subarachnoid hemorrhage; SBP, Systolic blood pressure; SDH, subdural hematoma; TBI, Traumatic brain injury.

* Corresponding author at: UCSF-East Bay Department of Surgery, 1411 E 31st St QIC 22134, Oakland, CA 94602, United States of America.

E-mail address: [email protected] (G. Beattie).

Patients sustaining head gunshot wounds (HGSWs) make up the largest proportion of deaths from traumatic brain injury in the United States. An estimated 20,000 people each year suffer from HGSWs [1] and <10% survive [2]. Among HGSW survivors, these often devastating injuries carry with them a considerable socioEconomic burden, with only 3% [1] ultimately achieving a favorable quality of life (eligible for acute rehabilitation or home discharge).

Guidelines for management of penetrating brain injury based on consensus of the International Brain Injury Association, the Brain Injury Association, USA, members of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons were published 2001 [3], however, these guidelines were not restricted to gunshot

https://doi.org/10.1016/j.ajem.2022.07.043

0735-6757/(C) 2022

injury and were based on expert opinion and military reports which dif- fer from civilian HGSW injury. While optimal management of civilian HGSW remains undefined, studies have begun to examine the prognos- tic factors and predictors of outcome in these injuries [2,4,5].

In HGSW injury, direct and secondary tissue damage from impact and bullet trajectory have a significant influence on patient outcome. In- jury types are often categorized into unihemispheric (unilateral), affect- ing only one hemisphere, and bihemispheric (bilateral), crossing midline and affecting both brain hemispheres. While unihemispheric HGSW injuries are postulated to have better overall survival [2,4-6], specific injury patterns and clinical characteristics within this subgroup associated with improved prognosis have not been identified. A better understanding of unihemispheric HGSW injury patterns combined with clinical presentation may help determine patients that could ben- efit from early aggressive surgical management. This study aims is to define unihemispheric HGSWs injury patterns and compare them to bihemispheric patterns to characterize clinical and radiographic factors associated with improved clinical outcomes and survival.

  1. Methods

After institutional review board approval, consecutive patients pre- senting to our Level 1 trauma center from January 2013 through May 2019 with HGSW were reviewed. HGSW was identified by query of the trauma registry and verified by medical record review. Included were all trauma patients, age >= 16 years, with confirmed HGSW. Patients were excluded if they sustained isolated facial or extracranial gunshot wounds, or if they died prior to obtaining head computed tomography imaging.

Patients were grouped into those with unihemispheric versus bihemispheric HGSWs and survivors versus non-survivors. A uni- hemispheric injury was defined as bullet trajectory affecting only one brain hemisphere, and a bihemispheric injury was defined as bullet tra-

to define statistical significance. Statistical analysis was performed using IBM SPSS Statistics for Windows, version 25.0. Armonk, NY: IBM Corp software.

  1. Results

During the study period, 105 patients presented with gunshot wounds to the head. Patients that died in the trauma bay prior to Head CT imaging (n = 26) and those identified with extra-cranial HGSW (n = 17) were excluded from further study. Of the remaining 62 HGSW patients, 33 (53%) suffered a unihemispheric intra-cranial injury and 29 (47%) a bihemispheric intra-cranial injury. There was no prehos- pital anticoagulation use in any of the HGSW patients (Anticoagulation use was unknown in n = 1 unihemispheric and n = 2 bihemispheric HGSW patients).

    1. Comparison of survivors versus non-survivors

Of the 62 HGSW patients with Intracranial injury, uni- or bihemis- pheric, 44% (n = 27) survived, the remaining 56% (n = 35) died as a direct result of their HGSW. HGSW survivors were similar in age and gender compared to non-survivors. Markers of injury severity were lower in survivors compared to non-survivors, this included ISS, head AIS, and presenting GCS (Table 1). Overall, the majority of patients in the study group had an isolated head injury, 89% in survivors and 83% in non-survivors. Survivors of HGSW were more likely to undergo a neurosurgical intervention than non-survivors (48% vs. 11%, p = 0.0018). On initial physical exam, survivors were less likely to have an APR (33% vs. 91%, p = 0.0001). Presenting laboratory studies

Table 1

Demographics and Clinical Characteristics of HGSW Survivors versus Non-survivors.

jectory crossing midline and affecting both brain hemispheres. Patient demographics, clinical and radiographic data points, and outcomes were

Survivors

N = 27

Non-survivors

N = 35

P-value

compared between groups.

Demographic and clinical characteristics analyzed included sex, age, presenting vitals and laboratory studies, prehospital anticoagulation use, abnormal pupillary response to light (APR), injury severity score (ISS), abbreviated head injury scores (head AIS), presenting and dis- charge Glasgow Coma Scale (GCS), presence of an isolated head injury, neurosurgical interventions performed, intensive care unit (ICU) and hospital length of stay , mortality, and discharge disposition.

Characterization of HGSW injury patterns was based on initial head CT imaging. Head CT imaging was independently reviewed by two staff neurosurgeons using a standardized data collection sheet. The following data points were collected on all study patients: HGSW laterality, trajec- tory, evidence of retained bullet, number of and which lobes injured, presence of epidural, subdural, subarachnoid, intraventricular hemor- rhage, trajectory hematoma, patency of basal cisterns, Midline shift, and vascular injury (arterial and/or venous). The data points were then combined for each patient. The number of lobes involved and de- gree of midline shift (in millimeters) were averaged between reviewers, allowing for a difference in lobe involvement by one and midline shift by 3 mm. The 3-mm cut-off was determined based on the typical slice thickness of our institution’s head CT imaging. Any discrepancy be- tween individual neurosurgeon reviews was re-reviewed by the study neurosurgeons and a final decision agreed upon.

Unless otherwise specified, normally distributed continuous

data values are reported as mean +- standard deviation and non- parametric data as medians with interquartile ranges [IQR]. Categorical data are reported as proportions. Clinical characteristics and outcome differences were analyzed using paired t-test and the Mann-Whitney U test, as applicable for continuous data. Similarly, for analyzing differ- ences between categorical variables chi-squared analysis and Fisher’s exact test were used as appropriate. An alpha value of <0.05 was used

Sex, male %(n) 74 (20) 86 (30) 0.34

Age, median [IQR] 25 [21-32] 25 [19-34] 0.84

Presenting Vitals, median [IQR]:

SBP

139 [115-150]

118 [96-147]

0.037

DBP

80 [68-89]

70 [40-86]

0.047

HR

75 [58-88]

98 [77-128]

0.002

Presenting Labs, median [IQR]:

INR

1.1 [1.0-1.1]

1.4 [1.2-2.0]

<0.0001

PTT

25.4 [24.6-26.7]

38.6 [28.6-73.9]

0.0006

Platelets

248 [213-293]

184 [148-274]

0.013

Sodium, mEq/L

140 [139-142]

140 [137-142]

0.55

APR, %(n)

33 (9)

91 (32)

0.0001

ICP medication, %(n)

26 (7)

29 (10)

1.0

ED GCS, median [IQR]

3 [3-15]

3 [3-3]

<0.001

ED Motor GCS, median [IQR]

1 [1-6]

1 [1-1]

<0.001

Discharge GCS, median [IQR]

15 [15-15]

Discharge Motor GCS, median

6 [6-6]

[IQR]

Head AIS, median [IQR] 4.0 [3.0-4.0] 5.0 [5.0-5.0] <0.001

16 [11-21]

25 [25-30]

<0.0001

89 (24)

83 (29)

0.72

48 (13)

11 (4)

0.0018

7 [4-24]

3 [2-5]

<0.0001

6 [3-17]

3 [2-5]

0.057

37 (10)

22 (6)

ISS, median [IQR] Isolated Head, %(n) NSGY Intervention, %(n) Total LOS, median [IQR] ICU LOS, median [IQR] Disposition, % (n):

Home Transfer

Rehab 33 (9) –

OTHER/AMA 7 (2) –

Significant data presented in bolded font. HGSW = Head gunshot wound. IQR = Interquartile range. SBP = Systolic blood pressure, mmHg. DBP = Diastolic blood pressure, mmHg. HR = Heart rate, beats per minute. INR = International normalized ratio. PTT = Partial thromboplastin time, seconds. APR = Abnor- mal pupillary response to light. ICP = Intracranial pressure. ED = Emergency department. GCS = Glasgow Coma Scale. AIS = Abbreviated injury score. ISS = Injury Severity Score. NSGY = Neurosurgery. LOS = Length of stay, days. ICU = Intensive care unit. AMA = Against medical advice.

demonstrated survivors to have less clinical indices of coagulopathy than non-survivors with lower International normalized ratio (1.1 [1.0-1.1] vs. 1.6 [1.2-2.0], p = 0.0007), partial thromboplastin

Table 3

Demographics and Clinical Characteristics Unihemispheric HGSW Survivors versus Non- Survivors.

time (PTT) (25.6 s [24.6-26.7] vs. 42.2 s [28.6-73.9], p = 0.0006) and

higher platelet level (248 [213-293] vs. 184 [148-274], p = 0.013).

Survivors

N = 23

Non-Survivors

N = 10

p-value

Head CT imaging characteristics demonstrated the majority of survivors to have unihemispheric injury (85%) with remaining bihemispheric injury (15%) (p = 0.001). On average, HGSW survivors had a lower number of brain lobes injured (2.0 vs. 3.1, p = 0.0003). Also, an associated vascular injury or intraventricular hemorrhage was less often present in survivors (Table 2).

    1. Analysis of patients with unihemispheric injuries

Sex, male %(n) 70 (16) 100 (10) 0.07

Age, median [IQR] 26 [21-32] 29 [21-39] 0.36

Presenting Vitals, median [IQR]:

SBP

139 [115-148]

110 [51-147]

0.14

DBP

80 [68-88]

62 [28-86]

0.18

HR

75 [57-88]

86 [54-130]

0.25

resenting Labs, median [IQR]:

INR 1.1 [1.0-1.1] 1.3 [1.0-1.4] 0.011

PTT

25.4 [24.8-28.5]

30 [28.5-57.5]

0.020

Platelets

247 [213-293]

218 [154-285]

0.33

Sodium, mEq/L

140 [139-142]

138 [136-140]

0.034

P

non-survivors had lower markers of injury severity compared to non- survivors: head AIS (3.0 [3.0-4.0] vs. 5.0 [5.0-5.0], p < 0.001), ISS (14

Of the patients who were found to have unihemispheric injuries,

APR, %(n)

30 (7)

100 (10)

0.0003

70% (n = 23) survived. Overall, unihemispheric HGSW survivors versus

ICP medication, %(n)

26(6)

30 (3)

1.0

[10-21] vs. 26 [25-35], p < 0,001) and presenting GCS (14 [3-15] vs. 3 [3-3], p = 0.015) (Table 3). On initial physical exam, survivors were less likely to have an APR to light (30% vs. 100%, p = 0.0003). Presenting laboratory studies demonstrated unihemispheric HGSW survivors to have lower INR (1.1 [1.0-1.1] vs. 1.3 [1.0-1.4], p = 0.011) and PTT

(25.4 s [24.8-28.5] vs. 30s [28.5-57.5], p = 0.02) (Table 3). No signifi-

cant differences in head CT imaging characteristics were demonstrated between unihemispheric HGSW survivors and non-survivors. (Supple- mentary Table S1). Neurosurgical intervention did not differ between groups, 43% in survivors versus 30% in non-survivors (p = 0.70).

    1. Analysis of patients with bihemispheric injuries

Only 14% of bihemispheric HGSW patients survived (n = 4). Bihemispheric HGSW survivors versus non-survivors had a lower head AIS (4.0 [4.0-4.8] vs. 5.0 [5.0-5.0], p < 0.001) and trend towards lower ISS (18 [16-30] vs. 25 [25-30], p = 0.056). Presenting GCS was consistent with severe TBI in both groups (6 [3-12] vs. 3 [3-3], p = 0.11)

ED GCS, median [IQR]

14 [3-15]

3 [3-3]

0.015

ED Motor GCS, median [IQR]

6 [1-6]

1 [1-1]

0.013

Discharge GCS, median [IQR]

15 [15-15]

Discharge Motor GCS, median [IQR]

6 [6-6]

Head AIS, median [IQR]

3.0 [3.0-4.0]

5.0 [5.0-5.0]

<0.001

ISS, median [IQR]

14 [10-21]

26 [25-35]

<0.001

Isolated Head, %(n)

91 (21)

80 (8)

0.57

NSGY Intervention, %(n)

43 (10)

30 (3)

0.70

Total LOS, median [IQR]

5 [4-17]

3 [2-6]

0.012

ICU LOS, median [IQR]

3 [2-11]

4 [3-7]

0.90

Disposition, % (n):

Home

43 (10)

Transfer

26 (6)

Rehab

26 (6)

OTHER/AMA

4 (1)

Significant data presented in bolded font. HGSW = Head gunshot wound. IQR = Interquartile range. SBP = Systolic blood pressure, mmHg. DBP = Diastolic blood pressure, mmHg. HR = Heart rate, beats per minute. INR = International normalized ratio. PTT = Partial thromboplastin time, seconds. APR = Abnor- mal pupillary response to light. ICP = Intracranial pressure. ED = Emergency department. GCS = Glasgow Coma Scale. AIS = Abbreviated injury score. ISS = Injury Severity Score. NSGY = Neurosurgery. LOS = Length of stay, days. ICU = Intensive care unit. AMA = Against medical advice.

Table 2

Head Computed tomography imaging Characteristics HGSW Survivors versus Non- survivors?.

Survivors N = 27 Non-survivors N = 35 P-value

(Supplementary Table S2). On initial physical exam, APR was significantly associated with reduced survival in bihemispheric HGSW (50% survivors vs. 92% non-survivors, p = 0.042). Also, presenting laboratory studies demonstrated bihemispheric HGSW survivors to also have lower INR (1.10 [1.03-1.10] vs. 1.40 [1.18-2.05], p = 0.020) and PTT (25.2 s

[22.8-26.3] vs. 42.2 s [28.5-77.4], p = 0.024) (Supplementary Table S2). No significant differences in head CT imaging characteristics were dem- onstrated between bihemispheric HGSW survivors and non-survivors (Supplementary Table S3). Despite, similar radiographic findings, bihemispheric survivors more frequently underwent neurosurgical inter- vention compared to non-survivors, 75% versus 4% (p = 0.004).

Bihemispheric

15 (4)

71 (25)

0.001

Unihemispheric

85 (23)

29 (10)

Trajectory

Anteroposterior

56 (15)

46 (16)

0.61

Lateral

44 (12)

63 (22)

0.20

Retained Bullet

74 (20)

86 (30)

0.34

# Lobes, mean (SD)

2.0 (0.91)

3.1 (1.16)

0.0003

Frontal

56 (15)

71 (25)

0.28

Temporal

41 (11)

69 (24)

0.040

Parietal

37 (10)

69 (24)

0.02

Occipital

19 (5)

20 (7)

1.0

Posterior Fossa

11 (3)

6 (2)

0.65

Basal Ganglia

11 (3)

57 (20)

0.0002

Trajectory Hematoma

26 (7)

43 (15)

0.19

EDH

4 (1)

3 (1)

1.0

    1. Comparison of all survivors

When comparing survivors of unihemispheric (n = 23 patients) versus bihemispheric (n = 4 patients) HGSW, demographic, clinical

SDH

56 (15)

80 (28)

0.053

presentation, and lab values were similar (Table 4). As expected, radio-

SAH

78 (21)

91 (32)

0.16

graphic findings were different. All bihemispheric patients sustained a

IVH

11 (3)

40 (14)

0.020

lateral trajectory injury versus 35% of unihemispheric patients (70% vs.

100%, p = 0.028)(Supplementary Table S4).

Midline shift:

>5 mm

15 (4)

34 (12)

0.14

>10 mm

7 (2)

11 (4)

0.69

Patent Basal Cisterns

74 (20)

29 (10)

0.0007

arterial injury

15 (4)

34 (12)

0.14

Venous Injury

15 (4)

40 (14)

0.047

Vascular Injury

30 (8)

69 (24)

0.004

Significant data presented in bolded font. HGSW = Head gunshot wound. EDH = Epidural hematoma. SDH = Subdural hematoma. SAH = Subarachnoid hemorrhage. IVH = Intraventricular hemorrhage.

* Data presented as % (n) unless otherwise noted.

    1. Outcomes

When comparing unihemispheric to bihemispheric HGSW out- comes, mortality was considerably lower for unihemispheric, 30% ver- sus 86% (p < 0.0001). Survivors of unihemispheric HGSW had shorter hospital length of stay (5 days [4-17] vs. 47 days [17-77], p = 0.014) and intensive care unit length of stay (3 days [2-11] vs. 20 days

Table 4

Demographics and Clinical Characteristics HGSW Survivors Unihemispheric versus Bihemispheric.

HGSW survivors regardless of radiographic injury pattern. When looked at separately, lower admission GCS score and lower motor GCS score was associated with reduced survival in unihemispheric HGSW injury,

Unihemispheric

N = 23

Sex, male %(n)

70 (16)

100 (4)

0.55

Age, median [IQR]

Presenting Vitals, median [IQR]:

26 [21-32]

23 [20-36]

0.86

SBP

139 [115-148]

151 [122-165]

0.23

DBP

80 [68-88]

87 [74-99]

0.32

HR

75 [57-88]

74 [61-95]

0.68

Presenting Labs, median [IQR]:

INR

1.1 [1.0-1.1]

1.1 [1.0-1.1]

0.92

PTT

25.4 [24.8-28.5]

25.2 [22.8-26.3]

0.36

Platelets

247 [213-293]

253 [211-327]

0.72

Sodium, mEq/L

140 [139-142]

140 [136-140]

0.34

APR, %(n)

32 (7)

50 (2)

0.59

ICP medication, %(n)

26 (6)

25 (1)

1.0

ED GCS, median [IQR]

14 [3-15]

3 [3-12]

0.40

ED Motor GCS, median [IQR]

6 [1-6]

1 [1-5]

0.33

Discharge GCS, median [IQR]

15 [15-15]

15 [6-15]

0.31

Discharge Motor GCS, median

[IQR]

6 [6-6]

6 [2-6]

0.31

Head AIS, median [IQR]

3.0 [3.0-4.0]

4.0 [4.0-5.0]

0.16

ISS, median [IQR]

14 [10-21]

18 [16-30]

0.16

Isolated Head, %(n)

91 (21)

75 (3)

0.40

NSGY Intervention, %(n)

44 (10)

75 (3)

0.33

Total LOS, median [IQR]

5 [4-17]

47 [17-77]

0.014

ICU LOS, median [IQR]

Disposition, % (n):

3 [2-11]

20 [12-31]

0.021

Home

48 (11)

0 (0)

0.041

Transfer

26 (6)

0 (0)

Rehab

26 (6)

100 (4)

OTHER/AMA

0

0

Significant data presented in bolded font.

Bihemispheric

N = 4

p-value

but not bihemispheric injury. Prior research supports increased mortal- ity with lower initial GCS in civilian HGSW injury [2,4,5,7,8]. We suspect the difference in our findings for unihemispheric versus bihemispheric HGSW injury may be related to the severity of brain injury encountered between unihemispheric and bihemispheric gunshot injuries. In prior studies, unihemispheric and bihemispheric injuries were not examined separately. It may be that admission GCS is a more sensitive marker for improved survival in unihemispheric injury. Unihemispheric injury is proposed to be a favorable prognostic factor of survival [2,5]. If the se- verity of brain injury is more variable in unihemispheric injury then ad- mission GCS scoring may highlight those with more favorable unihemispheric HGSW injuries whereas bihemispheric injury may overwhelming present with poor admission GCS not as predictive of survivability.

Abnormal pupillary response is often associated with mortality fol- lowing a severe head injury; however, reliance on this clinic finding for overall outcome is controversial. This study supports abnormal pap- illary response as a predictor of mortality in patients who sustained HGSW regardless of radiographic findings. While bilateral fixed and di- lated pupils can indicate brainstem injury and dysfunction or severe dif- fuse cerebral edema, in cases of penetrating injury with bullet or bony fragments near the oculomotor nerve, it is important to consider direct structural damage to the Pupillary light reflex pathway [2,4,5,7,8].

Overall, we found that specific radiographic features of brain injury were associated with improved survival in HGSW patients. In particular, survivors had a lower number of brain lobes injured and less often had involvement of the temporal and parietal regions. Additionally, mortal-

HGSW = Head gunshot wound. IQR = Interquartile range. SBP = Systolic blood pressure, mmHg. DBP = Diastolic blood pressure, mmHg. HR = Heart rate, beats per minute. INR = International normalized ratio. PTT = Partial thromboplastin time, seconds. APR = Abnor- mal pupillary response to light. ICP = Intracranial pressure. ED = Emergency department. GCS = Glasgow Coma Scale. AIS = Abbreviated injury score. ISS = Injury Severity Score. NSGY = Neurosurgery. LOS = Length of stay, days. ICU = Intensive care unit. AMA = Against medical advice.

[12-31], p = 0.018) than bihemispheric injuries. Disposition of unihemispheric survivors and bihemispheric survivors also differed; 48% of unihemispheric survivors were Discharge home, 26% transferred to another acute care facility, and 26% discharged to a rehabilitation facility. In comparison, 100% of bihemispheric HGSW survivors were discharged to a rehabilitation facility (p = 0.041) (Table 4).

  1. Discussion

While the majority of intracranial gunshot wounds are fatal, some HGSW patients have favorable clinical outcomes [1,2] Unihemispheric HGSWs have been attributed to higher survival rates [2,4-6]; however, injury patterns and clinical features associated with improved outcomes in unihemispheric HGSW patients has not been analyzed in detail. This study describes unihemispheric HGSWs injury patterns in comparison to bihemispheric patterns in order to better understand clinical and ra- diographic factors associated with improved clinical outcomes and sur- vival. We found that overall HGSW survivors had specific clinical features and injury patterns associated with survival, regardless of uni- versus bihemispheric injury; yet, unihemispheric HGSW patients had a higher survival rate and superior clinical outcomes, length of stay parameters and disposition location, compared to bihemispheric patients.

These findings suggest presenting clinical features may be used to identify patients with potential for improved survival independent of unihemispheric versus bihemispheric brain involvement.

Expectantly, lower markers of injury severity, in particular higher GCS, ISS, and head AIS, scores on presentation were noted for all

ity was more than quadrupled with basal ganglia injury. Increased mor- tality with multi-lobar injury [4,7] and violation of midbrain structures in bihemispheric HGSW [6] has been described.

Likewise, HGSW survival was associated with absence of intraven- tricular hemorrhage and intracranial vascular injury on initial head CT imaging. Patent basal cisterns were also associated with survival. Lack of these findings on imaging may denote less hemorrhage and therefore reduced intracranial pressure and herniation, mechanisms that result from severe injury to the brain [6,9]. Identification of these injuries pat- terns on presentation can provide more immediate insight into progno- sis and help guide family and goals of care discussion.

Unihemispheric injuries are reported to have higher survival rates in comparison to bihemispheric [4,5,7,10]. This study also demonstrated this with a 70% survival rate in unihemispheric HGSW patients com- pared to a 14% survival rate in bihemispheric HGSW patients. Notably, we found that unihemispheric HGSW survivors had better outcome pa- rameters than bihemispheric HGSW survivors despite similar head AIS and injury severity scores. Unihemispheric survivors had decreased intensive care unit and total hospital length of stay. Additionally, unihemispheric survivors were more frequently discharged home while all bihemispheric survivors required subsequent rehabilitation. Our findings suggest improved survival and clinical outcomes with unihemispheric HGSW injury. We propose that aggressive medical and neurosurgical management in unihemispheric HGSW injury is indi- cated as it may provide the opportunity for heightened recovery.

This study has several limitations. First, as a retrospective study, it re- lies on previously collected data not specifically intended to address the aim of our study. Second, our findings are based on a single institution chart review that may limit generalizability. Moreover, the limited sample size, particularly when comparing survivors of HGSW, (unihemispheric HGSW = 33, survivors = 23; bihemispheric HGSW =29, survivors =

4) may have prevented us from detecting differences in outcomes between groups. Additionally, we found an association between neuro- surgical intervention and survivability in bihemispheric, but not in unihemispheric HGSWs. We suspect this is related to selection bias; how- ever, inference is limited due to sample size. Finally, our study is unable to

clearly assess functional outcomes. While we can infer improved clinical outcomes based on length of stay and disposition location, this does not necessarily imply improved functional status. However, even taking this into consideration, our study begins to describe injury patterns and clini- cal outcomes in unihemispheric injury providing new insight into these types of HGSW injuries.

  1. Conclusion

Little is known regarding clinical features associated with improved outcomes in unihemispheric HGSW injury. This study suggests that the majority of presenting clinical features and CT imaging patterns previ- ously associated with improved survival in HGSW patients remain rele- vant in unihemispheric specific injuries. Furthermore, admission GCS score may be more prognostic marker of survivability in unihemispheric HGSW injuries. Importantly, when compared to bihemispheric survivors, survivors of unihemispheric HGSW injury appear to have improved clinical outcomes, length of stay and disposition location, sug- gesting aggressive management is needed in these patients to optimize recovery.

Disclosures of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Presentations

None.

CRediT authorship contribution statement

Genna Beattie: Writing – review & editing, Writing – original draft, Methodology, Investigation, Formal analysis, Conceptualization. Caitlin

M. Cohan: Writing – review & editing, Writing – original draft, Method- ology, Formal analysis, Conceptualization. Emma A. Smith: Writing – review & editing, Writing – original draft, Conceptualization. Sun I. Lee: Writing – review & editing, Writing – original draft, Project

administration, Methodology, Formal analysis, Conceptualization. Margaret Riordan: Writing – review & editing, Writing – original draft, Supervision, Project administration, Methodology, Investigation, Formal analysis, Conceptualization.

Declaration of Competing Interest

None.

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi. org/10.1016/j.ajem.2022.07.043.

References

  1. Bizhan A, Mossop C, Aarabi JA. Surgical management of civilian gunshot wounds to the head. Handb Clin Neurol. 2015;127:181-93.
  2. Aarabi B, Tofighi B, Kufera JA, Hadley J, Ahn ES, Cooper C, et al. Predictors of outcome in civilian gunshot wounds to the head. J Neurosurg. 2014;120(5):1138-46.
  3. Part 1: Guidelines for the management of penetrating brain injury Introduction and methodology. J Trauma. 2001;51:S3-6.
  4. Maragkos GA, Papavassiliou E, Stippler M, Filippidis AS. Civilian Gunshot Wounds to the Head: Prognostic Factors Affecting Mortality: Meta-Analysis of 1774 Patients. J Neurotrauma. 2018;35(22):2605-14.
  5. Gressot LV, Chamoun RB, Patel AJ, Valadka AB, Suki D, Robertson CS, et al. Predictors of outcome in civilians with gunshot wounds to the head upon presentation. J Neurosurg. 2014;121(3):645-52.
  6. Turco L, Cornell DL, Phillips B. Penetrating bihemispheric traumatic brain injury: a collective review of gunshot wounds to the head. World Neurosurg. 2017;104: 653-9.
  7. Martins RS, Siqueira MG, Santos MTS, Zanon-Collange N, Moraes OJS. Prognostic fac- tors and treatment of penetrating gunshot wounds to the head. Surg Neurol. 2003; 60(2):98-104.
  8. Mikati AG, Flahive J, Khan MW, Vedantam A, Gopinath S, Nordness MF, et al. Multi- center validation of the Survival After Acute Civilian Penetrating Brain Injuries (SPIN) score. Neurosurgery. 2019;85(5):E872-E9.
  9. Shoung H, Sichez J, Pertuiset B. The early prognosis of craniocerebral gunshot wounds in civilian practice as an aid to the choice of treatment. Acta Neurochir. 1985;74:27-30.
  10. Izci Y, Kayali H, Daneyemez M, Koksel T. Comparison of clinical outcomes between anteroposterior and lateral penetrating craniocerebral gunshot wounds. Emerg Med J. 2005;22(6):409-10.

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