Complications, outcomes, and management strategies of non-missile penetrating head injuries (2024)

General

Consecutive adult patients (age ≥ 18 years) with NMPHI who presented to Tygerberg Academic Hospital, Cape Town, South Africa, in the period from August 1, 2011, through July 31, 2018, were enrolled in an institutional review board–approved protocol (University of Stellenbosch Health Research Ethics Committee approval). Inclusion criteria consisted of a history of NMPHI confirmed on CT imaging.

Clinical Evaluation

Patients underwent detailed neurological examination on admission, immediately before and after surgery (if performed), during hospitalization, at discharge, and at distant follow-up. Time from injury to assessment and serial Glasgow Coma Scale (GCS) and Glasgow Outcome Scale (GOS) scores were recorded.^25,26 After discharge, the distant follow-up occurred at secondary hospitals, and patients were referred back to Tygerberg Academic Hospital for any complications, including all infectious and vascular complications.

General

All patients with NMPHI received care via a defined management protocol (Fig. 1). A single dose of cefazolin (2 g intravenously) was given for prophylaxis at admission, unless contraindicated. Noncontrast CT (0.6- to 1-mm slice thickness) was performed for all patients at the initial assessment. Laboratory evaluation on admission, during hospitalization, and after discharge was defined by clinical need.

Patients at High Risk for Vascular Injury

Those patients at risk for vascular injury—defined by deep subarachnoid hemorrhage (dSAH), intracranial depth of weapon penetration > 40 mm, tract near major vascular structures, intracerebral hematoma (ICH) larger than the weapon tract, or transorbital weapon entrance—underwent CTA if the weapon had already been removed or DSA under general anesthesia if the weapon was retained. Retained weapons in patients at high risk for weapon-associated vascular injury were removed using the “knockout” technique or craniotomy (see Surgical Technique). DSA was performed immediately after weapon removal. A post–weapon removal CT scan was performed to exclude intracranial hemorrhage. If a vascular lesion was present, it was treated using endovascular or open techniques.

Patients at Low Risk for Vascular Injury

Patients with a GCS score < 15 and at low risk for vascular injury with the weapon in situ underwent DSA under general anesthesia. The retained weapon was removed via the knockout technique or craniotomy (see Surgical Technique), and DSA was performed immediately after weapon removal. Post–weapon removal CT was performed to exclude intracranial hemorrhage. If a vascular lesion was present, it was treated using endovascular or open techniques. Patients with a GCS score of 15, a low risk for vascular injury, and the weapon in situ underwent weapon removal via the knockout technique under local anesthesia. Post–weapon removal CT and CTA were performed to exclude intracranial hemorrhage and vascular lesion. Finally, patients at low risk for vascular injury without a retained weapon underwent clinical management after wound debridement and closure. These patients underwent CTA if the weapon tract depth was ≥ 10 mm or any risk factors for vascular injury were present.

Knockout Removal

The mallet strikes are made parallel to the weapon tract to remove the weapon in-line to the tract. Alternatively, the vise grip can be attached in-line and an orthopedic slap hammer used to remove it. The wound is closed in layers after weapon removal.

Craniotomy

If it is not possible to attach a vise grip to the weapon, the weapon cannot be removed without significant manipulation, or there is an associated intraparenchymal mass lesion that requires removal, a craniotomy is performed. The craniotomy is made circumferentially around the retained weapon and designed to be large enough to accommodate removal of a mass lesion, if present. To eliminate any additional tissue injury, the weapon is removed en bloc with careful attention to remove the weapon in-line with the tract. The dura mater is closed in a water-tight manner, and the scalp is closed in layers.

TABLE 1.

Patient and clinical characteristics in 192 NMPHIs

TABLE 2.

Vascular injury among 192 patients with NMPHIs

Vascular

Vascular complications occurred in 37 patients (19%), all high-risk vascular patients (Table 1). The most common complications included aneurysms (17 patients [46%]) and vessel cutoffs (12 [32%]; Table 2). Eight patients, 22% of those with vascular complications, died from vascular-associated complications. Univariate analysis revealed dSAH, a stab wound across vascular territories, transorbital penetration, ICH larger than the tract, and a stab depth > 40 mm as significantly associated with vascular injury (Table 3). Multiple logistic regression revealed that dSAH and a tract crossing a vascular territory are significantly associated with vascular injury. No low-risk vascular patients had vascular complications.

Infectious

Infection occurred in 27 patients (14%; Table 1) and included abscess in 11 (41% of infectious cases), meningitis in 8 (30%), empyema in 4 (15%), wound infection in 2 (7%), abscess/empyema in 1 (4%), and ventriculitis in 1 (4%). The mean time from stab to referral for patients with infection was 4.1 ± 6.2 days (median 2.7 days, range 0.1–30 days). No patients died as a result of infectious complications. Univariate analysis revealed that time to referral (> 24 hours) and the lack of prophylactic antibiotics administration were significantly associated with an increased rate of infectious complications (Table 4). Multinomial regression revealed that the time from stab to referral, the lack of prophylactic antibiotics, and a weapon in situ were significantly associated with infectious complications.

TABLE 5.

Factors affecting outcomes after NMPHI

Management Algorithm

To effectively and consistently manage NMPHI, a systematic protocol for patients at Tygerberg Academic Hospital was developed. This protocol was designed to provide accurate and rapid assessment of time-sensitive neurosurgical issues in patients with NMPHI. Specifically, it was developed to identify intracranial mass lesions and the potential for vascular injury at the time of initial evaluation (Fig. 1). The effectiveness of this diagnostic and treatment paradigm was underscored by its utility in rapidly identifying critical primary injury–associated mass lesions and directing patients at high risk for vascular injury immediately into specific vascular imaging protocols. Alternatively, among the 36 patients with a low risk for vascular complications, no vascular lesions were found in the 8 who underwent imaging (i.e., 22% of the low-risk patients were imaged).

While prior studies have described weapon removal principally via craniotomy,^{5–7,14–16} we employed a knockout technique in all cases (79% of weapon removal cases; Video 1) except in those in which the weapon could not be removed without significant out-of-tract manipulation (e.g., weapon with barb lodged below inner table of calvaria) or a mass lesion that required surgical removal at the time of weapon retrieval. Movement of the blade is exaggerated at the tip and has the potential to cause injury to deep vessels and sensitive structures. This is seen after an assailant manipulates the blade to remove it (Fig. 3), and the removal technique should aim to avoid this. Further, we used the knockout technique in awake patients (GCS score 15) under local anesthesia, as this provided direct clinical assessment after removal and permitted immediate imaging and/or tract exploration if necessary. The thin profile of a knife (and other weapons) permits healing of the dura without direct closure and explains the lack of cerebrospinal fluid leakage encountered.

Primary Injury

Consistent with other forms of traumatic brain injury,¹⁷ NMPHI overwhelmingly occurred in young male patients (96% of cases; mean age at injury 26 years). Moreover, this injury was the result of interpersonal violence in all cases in this study. Consistent with a frontal attack by a right-handed assailant, 70% of wounds were left-sided and in the frontotemporal region. As in previous studies,^5,7–9 the most common weapon used in NMPHI in South Africa was a knife. Consistent with vascular damage at the primary injury, 55% of patients had ICH and 36% had SAH (including 29% with dSAH) on admission CT. Most patients (82%) presented without the weapon in situ, with the attacker having removed the weapon for repeated and/or later use. Surgical evacuation of a mass lesion was required in 29% of the patients because of the primary injury. The most frequent indication for surgery immediately after the primary injury was mass effect due to intracranial hemorrhage, including ICH (71% of surgical cases) and subdural hematoma (13%).

Vascular Complications

Vascular injuries were the most common secondary complication of NMPHI^{9,10,13,18,19} and occurred in 19% of patients. Specifically, pseudoaneurysms (46%) and vessel cutoff (32%) represented the most common secondary vascular complications (Table 2).^13,20 Left untreated, these lesions can lead to significant morbidity and death.^7,13,21–23 Twenty-two percent of patients with secondary vascular injuries died, underscoring the critical impact and need for effective management of these lesions. The presence of dSAH, a tract crossing a vascular territory, an ICH larger than the tract, and a stab depth > 40 mm were associated with vascular injury (Table 3), and these findings support immediate further diagnostic investigation (i.e., CTA and/or DSA).

As in prior studies,^7,9 transorbital stab wounds were associated with a higher risk of vascular injury (50% of injuries). Assessment of the intracranial weapon trajectory is critical in defining the risk of vascular injury after transorbital stab wounds. Wound tracts directed superiorly through the orbital roof frequently do not cross a major vascular territory. Alternatively, weapon tracts directed down and/or medially through the orbit can transect the internal carotid or middle cerebral artery. Consistent with this anatomical feature, a transorbital medio-inferior trajectory and dSAH were associated with major vascular injury (Table 3). CT evidence of these features support immediate further diagnostic investigation (i.e., CTA and/or DSA).

Infectious Complications

As in prior reports (15%–20% rate of infection),^8,9,24 infection was a common secondary complication in NMPHI (14% of patients; Table 1). Consistent with direct weapon inoculation and an open wound, the most common infectious complications were brain abscesses (41%) and meningitis (30%). Infection was managed with appropriate antibiotics and surgery when needed. The mean time from stab to referral for patients developing infection was 4 days. Twenty-two patients (81%) with infectious complications presented within 6 days of injury. No patients died of related complications. Risk of infection was associated with a prolonged time to referral (over 24 hours), lack of antibiotic prophylaxis, and weapon in situ. (Note that the nature of the multinomial regression model that took subgroups [including death] into account led to the difference in significance regarding a weapon in situ.) Patients presenting 24 hours after injury (25%) without effective primary wound care and prophylactic antibiotics had significantly higher rates of infection (26% vs 8%). Inconsistent prophylactic antibiotic administration was attributable to differences in referring center policies regarding antibiotic prophylaxis.

Contrary to authors of previous publications,^6,7 we did not find an increased rate of infectious complications after transection of a mucosal surface after NMPHI. This may be the result of the use of prophylactic antibiotics in the majority of our patients, whereas prior series have not used routine prophylaxis. Further, while differing outcomes associated with retained weapons have been reported in the literature, patients with retained weapons had a higher incidence of infection in the current series. Twenty-two (81%) infectious processes were clinically evident within 6 days of injury, underscoring the importance of early clinical surveillance and a reduced likelihood of infection beyond 1 week. While a single dose of prophylactic antibiotics within 24 hours of injury significantly reduced infectious complications, further study will be necessary to determine if additional antibiotic dosing can provide additional protection in certain circ*mstances.

Outcomes

Consistent with other traumatic brain injury studies,^8,25 we found an association (linear relationship) between admission GCS score and GOS score on discharge. Patients who presented with a low GCS score tended to have poorer functional outcomes than those presenting with a good GCS score. Higher mortality rates due to primary injury were found in patients with direct trauma to eloquent regions, including the basal ganglia, motor area, and brainstem. Patients who did not have primary injury to eloquent areas or major vessels had a good prognosis. These features of NMPHI are in contrast to high-velocity missile injuries, in which the kinetic and coagulative forces create significant primary injury away from the tract.¹ These properties of NMPHI and the current study findings underscore the importance of the successful management of secondary complications to avoid exacerbation of the impact of the direct injury, which is principally limited to (and not beyond) the wound tract.