Penetrating nonmissile stab wounds to the brain are relatively uncommon due to the
protective effect of the skull.[1] The majority of cases involve penetration through the orbit, temporal squama, or
large foramina or areas of thin bone within the skull base. Although these injuries
are rare, they were first described in the literature as early as 1806.[2] Penfield reexamined these injuries by studying pathological features of experimental
stab wounds using a cannula.[2]
[3] Pilcher in 1936 compiled a list of objects that had penetrated the brain, including
knives, pitchforks, crochet hooks, knitting needles, breech pins, umbrella bibs, crowbars,
and iron rods.[4] The current list of objects reported has expanded and now includes a toilet brush
handle,[5] arrows,[6] chopsticks,[7] flatware,[8] screwdrivers,[1] keys,[9] car antenna aerials,[10] and scissors.[11]
Due to the rarity of these events, there is not substantial literature on the management
and outcome of these patients. We report three cases of nonmissile penetrating brain
injuries at our institution and review the pertinent literature to highlight the proper
management of these cases with the goal to improve outcome and minimize short- and
long-term complications that may result from these injuries.
DESCRIPTION OF CASES
Case Report 1
HISTORY AND PRESENTATION
A 31-year-old man presented to our emergency room after a failed suicide attempt with
a transverse neck laceration, exposing the trachea and larynx, and retained intracranial
knife entering through the submental area into the cranium (Fig. [1A] and [1B]). On neurological examination, the patient's pupils were equal and reactive to light.
He had full strength and purposeful movements in all extremities. A noncontrast head
computed tomography (CT) scan showed intraventricular and subarachnoid hemorrhage
in the basal cisterns adjacent to the retained knife. There was no large hematoma.
A CT angiogram of his head and neck showed partial occlusion of the distal right A2.
He underwent digital subtraction angiography to better assess the intracranial vasculature
in relation to the knife's edge, and injury was again seen to the distal right A2
branch of the anterior cerebral artery (ACA) without evidence of further vascular
injury (Fig. [1D]).
Figure 1 (A) Preoperative photograph of a patient with retained intracranial knife, zone 2
neck laceration, and formal tracheostomy placement. (B) Unsubtracted lateral angiogram
during a selective right internal carotid artery (ICA) injection showing the trajectory
of the retained knife. (C) Intraoperative photomicrograph of anterior skull base with
retained knife located immediately anterior to optic apparatus. (D) 3-D reconstructed
angiography of right ICA injection showing relationship of the retained knife edge
to the adjacent vasculature.
OPERATION
The patient was taken to the operating room and underwent formal tracheostomy placement
followed by combined right pterional and interhemispheric craniotomies for knife extraction
(Fig. [1C]). Proximal vascular control was obtained through a transsylvian approach with exposure
of the A1/A2 complex. Subfrontal dissection followed with visualization of the knife
blade as it transgressed the floor of the anterior fossa. A simultaneous interhemispheric
approach was undertaken to dissect the distal ACA vessels off the knife's edge, protecting
them with cottonoids. A small laceration was noted in the right A2, prior to its bifurcation,
which was controlled with Surgicel (Johnson & Johnson, Somerville, NJ) and temporary
compression, salvaging the vessel. The knife was cautiously removed along the same
trajectory to minimize new injury. The anterior fossa floor was repaired with an onlay
dural substitute (Duragen, Integra, Plainsboro, NJ), a dural sealant (Tissel, Baxter,
Deerfield, IL), and a pedicled pericranial flap. Finally, a ventriculostomy was placed.
Our ear, nose, and throat team explored and repaired injuries to the larynx and oro-
and nasopharynx.
POSTOPERATIVE COURSE
The patient was managed in the intensive care unit (ICU) and required percutaneous
gastrostomy placement. He underwent a CT angiogram 2 weeks after his operation, which
showed a patent distal right A2 and a small area of encephalomalacia within the injury
bed. There was no evidence of distal ACA stroke or pseudoaneurysm. He was ultimately
weaned from the ventilator and cerebrospinal fluid (CSF) diversion. After extensive
psychiatric evaluation, he was discharged home. At 3-month follow-up, he was ambulatory,
had undergone tracheostomy and gastrostomy removal, and was cleared to return to work.
A follow-up CT angiography at that time did not demonstrate development of a pseudoaneurysm.
Case Report 2
HISTORY AND PRESENTATION
A 21-year-old woman presented to our emergency room (ER) in transfer, following a
love triangle dispute that resulted in a steak knife being inserted into the patient's
left eye (Fig. [2A] and [2B]). The patient was initially unresponsive with emesis and questionable seizure activity.
She was intubated and treated with antibiotics and mannitol. On neurological examination,
the patient's pupils were equal and reactive to light. She had minimal movement to
noxious stimuli. A skull X-ray showed the blade of the knife extending from the orbit
along the middle fossa floor posteromedially (Fig. [2B]). A noncontrast CT scan of the head did not show any significant hemorrhage and
confirmed the location of the retained knife extending into the left cavernous sinus
and perimesencephalic cistern (Fig. [2C]). Reconstructed CT angiography showed the knife blade adjacent to the petrous carotid
and posterior cerebral arteries with no large-vessel vascular occlusion (Fig. [2D]). A 3-D reconstructed digitally subtracted cerebral angiogram confirmed there were
no large-vessel abnormalities.
Figure 2 (A) Preoperative photograph of a patient with retained transorbital knife. (B) Preoperative
lateral X-ray showing the retained knife. (C) Noncontrast head computed tomography
(CT) showing the trajectory of the knife through the superior orbital fissure. The
knife ends within the perimesencephalic cistern. (D) 3-D reconstructed CT angiogram
shows the relationship of the knife edge to the left cavernous internal carotid artery
and perimesencephalic vasculature.
OPERATION
The patient was taken to the operating room and underwent a left cranio-orbito-zygomatic
approach for knife extraction with direct visualization of the adjacent neurovasculature.
Proximal vascular control was obtained through exposure of the cervical carotid. Additionally,
a lumbar drain was placed to maximize intraoperative brain relaxation. The proximal
knife blade was directly visualized transversing the superior orbital fissure extradurally
during initial exposure. Dissection proceeded through a transsylvian approach with
exposure and protection of the proximal vasculature with cottonoids. The distal knife
blade was clearly visualized exiting the cavernous sinus and lying lateral to the
brain stem within the perimesencephalic cistern, consistent with preoperative imaging.
The knife was removed along its initial trajectory under direct vision without significant
hemorrhage. Intraoperative Doppler confirmed filling along the vascular tree left
internal carotid artery (ICA), M1, and A1. At the time of closure, the brain appeared
edematous, requiring CSF diversion and posterior extension of the craniectomy. An
intraparenchymal intracranial pressure monitor was placed, and closure proceeded with
an onlay duraplasty substitute (Duragen, Integra, Plainsboro, NJ). Our ophthalmology
team explored the globe and closed the entry wound primarily, with the globe intact.
POSTOPERATIVE COURSE
The patient was managed postoperatively in the ICU and required tracheostomy and gastrostomy
placement. A follow-up CT scan showed minimal hemorrhage along the knife tract and
a hypodensity in the left midbrain felt to be related to initial injury. A 2-week
postoperative angiogram showed complete filling of the vascular tree without pseudoaneurysm
formation. She was discharged to a skilled nursing facility and at 1-year follow-up
has since undergone tracheostomy and gastrostomy removal as wells as a cranioplasty.
Her follow-up CT angiogram shows no abnormalities.
Case Report 3
HISTORY AND PRESENTATION
A 24-year-old right-handed man presented to Saint Louis University ER 1 day after
an altercation where he was stabbed with a corkscrew in the right temporal region.
There was no reported loss of consciousness immediately after the event, but he did
experience nausea, vomiting, right temporal region headache, and multiple syncopal
episodes over the following 19 hours. The patient initially presented to an outside
hospital, where a noncontrast head CT showed a right temporal skull fracture, intraparenchymal
and intraventricular hemorrhages, pneumocephalus, and midline shift (Fig. [3A]). The patient received broad-spectrum antibiotics and anticonvulsants and was transferred
to our institution. On neurological examination, he was confused, with intact speech
and no focal neurological deficits. There was a small puncture wound in the right
temporal region upon close examination. He was managed conservatively in the ICU.
A CT angiogram 2 days postinjury was negative (Fig. [3B]). On hospital day 21, an MRI with contrast demonstrated a traumatic pseudoaneurysm
in the distal middle cerebral artery (MCA) vasculature and enhancement in the right
frontal injury bed (Fig. [3C]).
Figure 3 (A) Initial noncontrast head computed tomography (CT) showing right frontal injury
bed and intraventricular hemorrhage. (B) Initial CT angiogram showing no evidence
of aneurysmal formation of the distal middle cerebral artery vessels at the cortical
entry site. (C) Contrasted axial T1-weighted magnetic resonance image showing a partially
thrombosed pseudoaneurysm at the cortical entry site of the right frontal injury bed.
(D) Intraoperative photomicrograph showing clip reconstruction of the pseudoaneurysm
at the right frontal entry site.
OPERATION
The patient was taken to the operating room for a stereotactic right frontal craniotomy
for aneurysm reconstruction and exploration of the injury bed. A right frontal craniotomy
was created and dissection proceeded to gain proximal vascular control of the right
frontal M2 branch of the MCA within the sylvian fissure. A thin-walled traumatic pseudoaneurysm
was identified on a distal frontal M4 branch at the site of cortical entry (Fig. [3D]). Circumferential dissection was undertaken, and the aneurysm was successfully reconstructed
with preservation of the parent vessel. The injury bed was explored and no evidence
of infection was seen. Cultures from the cavity were negative for organisms.
POSTOPERATIVE COURSE
The patient did well postoperatively, his neurological exam improved, and he was ultimately
discharged home. The patient was lost to follow-up.
DISCUSSION
Penetrating cerebral (craniocerebral or orbitocerebral) injuries can be divided between
missile and nonmissile injuries. The missile injuries are caused by shrapnel or bullets,
which carry a high incidence of morbidity and mortality[5]
[12] and are associated with shock waves, cavitations,[13] and additional concentric zones of injury related to blast effect.[14] The nonmissile (stabbing) injuries are, by comparison, relatively rare and usually
caused by objects such as knives, with an impact velocity of less than 100 m/s and
pathophysiology related to tissue laceration and maceration restricted to the wound
tract.[15] They are, therefore, more amenable to treatment and carry a better prognosis than
missile injuries.
The adult calvarium in most instances provides an effective barrier of protection
against stab wounds. However, there are specific areas of weakness, such as the orbit,
skull base foramina, anterior fossa floor, and temporal squama where the skull is
more penetrable.[1]
[11] The amount of force needed to penetrate the skull in the temporal region is estimated
to be 5 times greater than that of the skin, as compared with 11 times that of the
skin in the parietal region.[16]
Transorbital skull penetration follows two main pathways: either medially into the
superior orbital fissure through the cavernous sinus and toward the brain stem (as
seen in case 2) or superiorly through the thin orbital plate into the frontal lobe.
In one report, the orbital roof was observed as the entry point in 89% of cases and
could be explained by the tendency of the victims to extend their heads at the time
of the injury, exposing the orbital roof to the direction of the penetrating object.[13] A third, least common transorbital route includes the optic canal.[17]
Early recognition of these injuries is essential to ensure the best possible outcome.
This can sometimes be challenging in cases of nonretained objects where the entry
point may appear trivial or be hidden by hair (as seen in case 3). Additionally, the
patients may present with good initial Glasgow coma scale (GCS) presentation in many
cases, making it difficult to appreciate the extent of the injury, especially in children.[13]
[18]
[19] A high index of suspicion is needed in patients presenting with scalp injuries because
the actual amount of injury may be more extensive than what appear on the surface.
A meticulous examination of the scalp and thorough neurological and radiological assessment
are required to evaluate the extent of the damage.[18]
An initial head CT is the most effective tool for initial investigation of penetrating
injuries to the brain, but it fails to identify plastic, wood, or soil.[18] Given the high association of vascular abnormalities with such injuries, a CT angiogram
is recommended in all cases, although the presence of metallic artifacts from the
retained foreign body may limit visualization of intracranial contents.[20] Therefore, when a high index of suspicion for a vascular injury exists, an angiogram
should be performed. For the same reason, a second head CT should be considered after
removing the foreign body to look for missed brain contusion or hemorrhage obscured
by artifact in the original scan.
Situations in which cerebral angiography is indicated in the literature, given very
high likelihood of associated vascular injury, include: orbitofacial or pterional
entry point, presence of intracranial hematoma on CT, injuries with fragments crossing
two or more dural compartments, delayed or unexplained subarachnoid hemorrhage, or
delayed intraparenchymal hematoma.[20] The treatment goals are to treat and prevent both short- and long-term complications
associated with these injuries. In the short term, the objective is to remove the
foreign object, avoiding further neurological injury, hemorrhage, and possibly death.
Long-term management includes prevention and treatment of vascular abnormalities,
persistent CSF leakage, infection, and seizures.
The literature is inconsistent in respect to the safety of blindly removing retained
objects from the skull. Some authors suggest that blind removal of a retained blade
is acceptable,[21] others claim that the safety of blind removal is unknown due to the lack of evidence-based
studies,[5] and some authors suggest that blind removal is unacceptable.[22] In our experience, we feel blind removal is unacceptable, and removing the retained
blade prior to obtaining high-resolution imaging imposes undue risk on the patient,
including possibly death. We routinely use high-resolution CT scan, CT angiogram,
and formal four-vessel cerebral angiogram to assess both brain parenchyma injury as
well as potential vascular injury prior to surgical planning. As we reported in our
first and second cases, the high-resolution imaging protocol was critical to understanding
the relationship of the knife blades to intracranial vascular structures, allowing
us to successfully remove the retained blades without causing further injury and to
plan the necessary craniotomies to visualize the removal of the offending object around
the vascular structures at risk under direct vision with proximal control.
The most common vascular complications that can result from these injuries are usually
traumatic pseudoaneursym formation or carotid-cavernous fistula.[23] Traumatic aneurysms comprise less than 1% of intracranial aneurysms.[24]
[25] The most common aneurysm associated with penetrating brain injuries is actually
a false or pseudoaneurysm, rather than a true aneurysm. These lesions usually do not
have a neck, are irregularly shaped, and have delayed filling and emptying.[26] Kieck and de Villiers reviewed vascular lesions secondary to penetrating trauma
and found abnormalities in 26 of 74 patients, with the largest proportion of lesions
being aneurysm formation (42%).[27] Traumatic aneurysms may occur in a delayed fashion and carry a 50% mortality rate
if left untreated.[26]
[27]
[28]
[29] Not all these lesions are visible on initial angiography and therefore a second
angiogram should be performed 2 to 3 weeks later in all patients with penetrating
brain injuries. Our third case exemplifies this phenomenon. In Kieck and de Villiers'
series, 80% of the untreated aneurysms ruptured with subsequent death of the patient,
and 100% of the aneurysms that were treated had good outcomes.[27]
Pseudoaneurysms following transcranial or transorbital stab wounds have a tendency
to form in the peripheral vessels—sylvian candelabra and median hemispheric vessels—as
opposed to the circle of Willis. They are usually found along the course of the arteries
as opposed to vascular bifurcations. Haddad et al[30] found that these lesions range in size from 2 mm to 15 mm and are multiple in 20%
of the patients. Their natural history is more malignant than congenital aneurysms,
with greater propensity for intraoperative rupture. Surgical mortality of these lesions
varies from 15 to 20%.[31] Therefore, aggressive management of traumatic pseudoaneurysms associated with penetrating
brain injuries is warranted to prevent life-threatening hemorrhage and/or thromboembolic
phenomenon. Oftentimes, these aneurysms cannot be safely clipped, and therefore trapping
or occlusion of the parent vessel may be necessary. Preliminary results suggest that
placement of stent grafts through endovascular techniques associated with appropriate
antiplatelet therapy may be a safe and effective method to treat such traumatic ICA
pseudoaneurysms.[32] The main question still unanswered is the long-term efficacy of stenting in this
setting.
Infectious complications, such as brain abscesses and meningitis, are also associated
with penetrating brain injury, being found in 48 to 64% of cases[7]; however, in 20% of cases, microbiological culture remains sterile,[33] and this also happened to our case 3. Due to the incidence and potential severity
of this complication, it is essential to use broad-spectrum antibiotic prophylaxis
in these patients for at least 7 to 14 days.[23]
[34] Other factors associated with higher likelihood of infectious complications include
CSF leaks, air sinus wounds, transventricular injuries, or wounds crossing the midline.[19] Whenever an intracranial abscess occurs, presence of a retained foreign body should
be suspected and investigated.[13] About 30 to 50% of patients suffering penetrating brain injuries will develop seizures,
with up to 10% of them appearing early (first 7 days after trauma). Prophylactic antiseizure
drugs are recommended during the first week after injury to reduce the incidence of
early posttraumatic seizures.[19]
Stabbing injuries to the brain are more frequently seen as a cause of emergent neurosurgical
admissions in South Africa. The largest report in the literature regarding nonmissile
penetrating injury is from a neurosurgical group in South Africa where cranial stab
wounds are a frequent cause of emergent admission. In this study, the presenting GCS
score was identified as the most indicative prognostic factor of long-term outcome.[35] Other predictive factors included presence of intraventricular hemorrhage, intracranial
hemorrhage, and number of surgical procedures.[35] Additionally, there was a marked association between vascular abnormalities (41%
cases) and mortality (76.5% cases), especially when brain stem injury was involved.
Other reports confirmed the presenting GCS score as the strongest prognostic indicator
of outcome after penetrating brain injury.[16]
[19] Such injuries in the vast majority of the Western world remain uncommon among civilians
and are usually related to violence, accidents, or suicide attempts in association
with mental disorders.[19]
CONCLUSION
In our experience, the management of direct penetrating brain injuries requires high-resolution
imaging to assess the relationship of the surrounding vasculature to the foreign object.
Immediate surgical exploration, in our opinion, is essential when compared with blind
removal of the object. Skull base approaches are often required and can improve the
safety profile of foreign object removal. Craniotomies should be tailored to optimally
visualize the involved vascular and neural structures, provide access to proximal
vascular control, and offer a direct route to skull base reconstruction for prevention
of CSF leaks. Vascular studies must be obtained 2 to 3 weeks postinjury to evaluate
for delayed pseudoaneurysm formation.
