Penetrating Head Trauma Treatment & Management

Patients with severe penetrating injuries should receive resuscitation according to the Advanced Trauma Life Support guidelines. Specific indications for endotracheal intubation include inability to maintain adequate ventilation, impending airway loss from neck or pharyngeal injury, poor airway protection associated with depressed level of consciousness, and/or the potential for neurological deterioration.

Virtually all individuals with an admission GCS of 8 or less meet these criteria. A systolic blood pressure of at least 90 mm Hg should be maintained. In a large series of patients with severe traumatic brain injury, a single episode in which systolic blood pressure fell below 90 mm Hg was associated with an 85% increase in morbidity. Isotonic saline (0.9% NaCl) is the most common preparation for volume resuscitation. In general, the acute loss of as much as 20% of total blood volume can be replaced with crystalloid solution, while loss of 30% or more requires replacement with blood.

The cervical spine is stabilized, and a careful examination for injuries to the neck, chest, abdomen, pelvis, and extremities is performed. A Foley catheter should be inserted, appropriate IV access secured, and volume replacement started.

In patients with anterior skull base fractures, nasogastric tubes always should be avoided because of the increased risk of intracranial tube insertions. An orogastric tube can be placed carefully under direct vision. During and after resuscitation, a history is taken, and physical and neurological examinations are performed.

The GCS score (see Indications section) should be noted at the scene, upon arrival to the emergency department, and after resuscitation. If pharmacologic paralytic agents were administered during resuscitation, these agents should be reversed in order to complete the neurological examination. Tetanus prophylaxis is administered. Routine laboratory tests, including CBC count, electrolytes, coagulation profile, type and cross, alcohol levels, and drug screen, are obtained. A sterile dressing is applied on the entrance/exit wounds, and, if hemodynamically stable, the patient is sent for diagnostic evaluation.

Patients are triaged based on their clinical condition and findings on CT scan/angiography. Patients without significant mass lesions on CT scan are triaged to the intensive care unit (ICU) for further management. An ICP monitor is placed in all patients with a GCS of 8 or less. Ventriculostomy is preferred because it is useful both for ICP monitoring and cerebrospinal fluid (CSF) drainage for control of ICP. Head elevation to 30° appears to facilitate venous drainage and reduce ICP.

Sedation may be useful in comatose patients for control of ICP. Reversible agents should always be used to facilitate hourly neurological evaluations. The authors prefer to use propofol, a lipophilic rapid-onset hypnotic with a short half-life that can be titrated to control ICP. In addition to monitoring the ICP, the authors are evaluating the usefulness of other invasive devices, such as jugular venous catheters and cerebral oximeters, to identify treatable causes of cerebral ischemia in patients with severe brain injury.

Mannitol administered as intravenous bolus as needed results in decreased ICP; reduces the viscosity of blood, improving cerebral blood flow; and it might serve as a free-radical scavenger. Serum osmolality should not be allowed to rise above 320 mOsm/kg in order to avoid systemic acidosis and renal failure. If the ICP cannot be controlled, barbiturate coma or a decompressive craniectomy may be indicated. Barbiturate therapy reduces ICP, cerebral metabolic rate of oxygen (CMRO₂), and cerebral blood flow. Barbiturate coma or a decompressive craniectomy should be used in conjunction with a Swan-Ganz catheter to ensure ideal cardiac output. Barbiturates are contraindicated if the patient is initially hypotensive.

Additional routine orders include seizure prophylaxis (phenytoin 15-18 mg/kg IV bolus followed by 200 mg IV q12h) and antibiotics. If seizures are not evident in the acute phase, anticonvulsants are discontinued in 1 week. The duration of use of antiepileptics remains somewhat controversial, but long-term use does not seem to be beneficial. Broad-spectrum antibiotics should be administered for at least a few days postoperatively. The duration of antibiotic therapy also remains controversial and often is based on the experience of the surgeon.

Because head injury is an independent risk factor for stress ulcers and gastritis, prophylaxis with histamine blockers and/or antacids should be implemented. The stress of head injury, which often is treated in conjunction with other traumatic injury, leads to increased energy consumption by the injured patient's body; thus, nutritional support is implemented in the first few days following admission. Enteral nutrition is employed if no contraindications exist; whereas, parenteral nutrition is reserved for patients with associated abdominal injuries at the authors' institution.

Despite the effectiveness of hyperventilation in rapidly reducing ICP in some patients, its use is not recommended because it can result in marked reductions of cerebral blood flow and may worsen long-term neurological outcome significantly. Also, note that the efficacy of hypothermia remains controversial, although some studies have shown an improvement in outcome with moderate hypothermia.

The following are significant reasons for surgery: (1) to remove masses such as epidural, subdural, or intracerebral hematomas; (2) to remove necrotic brain and prevent further swelling and ischemia; (3) to control an active hemorrhage; and (4) to remove necrotic tissue, metal, bone fragments, or other foreign bodies to prevent infections. The approach to surgery varies; some surgeons are conservative, while others are more aggressive.

A major reason to operate is the removal of hematomas; however, the minimum size of hematoma that requires surgical evacuation depends of multiple factors, including patient's age and clinical condition and the location of the hematoma. Hematomas and contusions in the temporal region or posterior fossa should be treated more aggressively because they tend to cause herniation more frequently than similar lesions elsewhere and more often are associated with vascular injury.

Bullets and fragments may contain metals that cause electrolysis, may predispose to fibroglial scarring with secondary epilepsy, or may migrate within the intracranial or intraspinal compartments. Because retained fragments have not been associated strongly with infection, most authors have suggested that they should be removed only if the fragments are accessible. Scalp tissue, clothes, and hair are frequently carried with bone into the brain, with the associated risk of infection. This is variable and depends on the velocity of the bullet and the size of the penetration. In most cases, removal of a deep-seated bullet is not necessary, however, some authors have advocated the used of computer-image guided procedures for the removal of missiles or bullet fragments.

The approach to surgery varies; some surgeons are conservative, while others are more aggressive. The surgical management of penetrating injuries, as with any other neurosurgical procedure, requires a careful preoperative planning.

• In preparation for surgery, the patient's head is shaved and thoroughly prepped with an antiseptic solution under routine sterile conditions.
• The patient's head is positioned at a higher level than the chest.
• The head draping should cover the entire available surface of the scalp to allow extension of the surgical incision beyond the actual confines of the wound or to allow possible scalp rotation procedures.
• The skin incision is planned so that the blood supply to the scalp is not compromised.
• Fresh frozen plasma and platelets should be administered (1) when an elevated prothrombin time (PT) or elevated activated partial thromboplastin time (aPTT) suggests a coagulopathy in a patient who requires evacuation of an intracranial hematoma or (2) if an intraoperative coagulopathy is suspected.

• Often a craniotomy or craniectomy with removal of accessible bone fragments and foreign bodies is performed.
• Gentle debridement of devitalized brain is performed using a combination of suction and irrigation.
• In gun shot wounds, the bullet is not removed unless it is easily accessible because the risk of brain injury from the retrieval of the bullet exceeds the benefit of its removal.
• In cases of stab wounds, the knife or penetrating object should not be removed until the dura is opened in the operating room and the procedure can be performed under direct vision.
• In all cases, the surgeon should be prepared to manage potential vascular injuries that may be encountered. The importance of a watertight dural closure cannot be overemphasized in order to prevent centripetal infection and CSF fistula.
• If a dural defect is present, pericranium or temporalis fascia may be needed for the dural repair. The use of artificial synthetic or biological dural substitutes should be avoided.
• Patients with penetrating head injury often require cranioplasty secondary to craniectomy and/or damage by the missile. Cranioplasty should be delayed for approximately 1 year, when the patient is medically stable and risk of infectious complications is low.

The same principles discussed under Medical therapy apply to the postoperative care of patients with penetrating head trauma. An ICP monitor or a ventricular drain usually is placed intraoperatively in patients with a GCS of 8 or less. This is placed to monitor and maintain an adequate cerebral perfusion pressure. If the patient is neurologically stable, a CT scan is obtained 24-72 hours postoperatively.

Patients' cases are followed up clinically with standard neurological checks, and their vital signs are assessed every hour. Routine laboratory tests are performed as needed.

The follow-up radiological studies to be obtained depend on the patient's neurological evolution but typically consist of serial CT examinations.

Patients who survive penetrating craniocerebral injuries are at risk of experiencing multiple complications, including persistent neurological deficits, infections, epilepsy, CSF leak, cranial nerve deficits, pseudoaneurysms, arteriovenous fistulas, and hydrocephalus.

Intracranial infections

These infections can complicate as many as 11% of penetrating craniocerebral injuries. Therefore, prevention and proper management of infectious complications can lead to improved outcome in these patients. Patients can develop meningitis, epidural abscess, subdural empyemas, or brain abscess.

• Posttraumatic meningitis usually is associated with skull fractures or CSF leak.
• Cranial epidural abscess is an uncommon infection that most often occurs secondary to osteomyelitis or because of foreign bodies. The purulent collection remains well localized due to the tight adherence of the dura to the overlying calvaria; however, cranial epidural abscess can cause meningitis and subdural empyema associated with significant morbidity and mortality.
• The most frequent source of subdural empyema is penetration through adjacent facial infections, such as paranasal sinusitis or mastoiditis.
• Brain abscess can occur after a long period of silent infection. Hida et al (1978) reported a case of delayed brain abscess following a penetrating gunshot injury, found 38 years after the insult.^[5] The treatment of epidural abscess, subdural empyema, and brain abscess consists of prompt surgical intervention followed by prolonged antibiotic therapy.

Epilepsy

Posttraumatic epilepsy is linked to psychosocial disability and is probably a contributing factor to premature death after penetrating head injury. The incidence of posttraumatic epilepsy varies widely, depending on the type and severity of the injury. In closed head injury, the incidence of posttraumatic epilepsy varies from 2.9-17% for moderate and severe head injury. In contrast, the incidence of epilepsy for military craniocerebral missile wounds is twice as high; most series report a 5- to 10-year incidence of seizures of 32-51%. Almost 50% of victims of penetrating head trauma enrolled in military series become epileptic.

The exact pathophysiology of posttraumatic epilepsy after closed or penetrating head injury is not known. Many confounding risk factors, such as retained metal fragments, the extent and site of injury, level of consciousness, residual focal deficit, and complications, have been studied to pinpoint the importance of each in efforts to clarify the pathophysiological mechanisms of posttraumatic epilepsy.

Cerebrospinal fluid leak

Head trauma is the most common cause of CSF leak. Meningitis occurs in approximately 20% of acute (within 1 wk) posttraumatic leaks and 57% of delayed posttraumatic leaks. The use of prophylactic antibiotics administration for CSF leak has been demonstrated to lead to serious infections, including drug-resistant meningitis.

Patients with posttraumatic CSF leak are initially treated conservatively with bed rest in a position that results in decrease or cessation of the fistulous drainage. If the drainage has not ceased within 24-48 hours, a lumbar drain is inserted and drained at a rate of 10 cc of CSF per hour for 5-7 days. A lumbar drain should not be inserted in patients with significant pneumocephalus. During CSF drainage, progressive diminution of the level of consciousness should alert the clinician to the possibility of pneumocephalus. If the CSF leak does not stop with the lumbar drainage, a surgical intervention to repair the fistulous tract may be indicated.

Vascular injuries may result from direct injury of the vessels by the penetrating object, blast effect at the time of trauma, or by skull fractures or bone fragments producing vascular occlusion. Direct vascular injuries sustained at the time of head injury initially may be clinically silent and may remain so for weeks, months, or years. In addition, delayed posttraumatic pseudoaneurysms can appear weeks to months after the injury.

Cranial nerve deficits

Patients who experience an injury to the temporal area and/or have a fracture of the temporal bone are especially at risk for carotid artery injury as well as injury to the facial nerve. Hence, in patients who experience penetrating brain injuries, maintaining a high index of suspicion and obtaining follow-up radiological studies, usually via cerebral angiography, is important.

Pseudoaneurysm

Pseudoaneurysms may result in a perturbation of the normal blood flow and can act as foci of thrombus formation, or they can rupture, causing a subarachnoid or intracerebral hematoma. They usually require surgical or endovascular treatment. The role of anticoagulation in the treatment of pseudoaneurysms remains controversial, but it may be beneficial in minimizing thrombus propagation and embolization.

Arteriovenous fistula

Arterial dissections occur when a laceration through the intima and sometimes the media permits entry of blood and separation of these inner and outer vascular layers, compromising the vessel lumen. They usually present with transient ischemic attacks or symptoms of stroke. Nonsurgical management of arterial dissections with chronic anticoagulation is usually effective.

Probably the best-recognized posttraumatic arteriovenous fistula is the posttraumatic carotid-cavernous sinus fistula. In general, these fistulae are associated with the blast injury rather than the intracranial penetration, they are usually high-flow fistulas, and they are clinically characterized by a clinical syndrome consisting of pulsating exophthalmos, chemosis, and bruit. Carotid-cavernous fistulae can be diagnosed by a cerebral angiography and are best treated by endovascular occlusion.

Many studies have attempted to associate various prognostic factors with outcome. The most important prognostic factor currently recognized is the GCS after cardiopulmonary resuscitation. Traditionally, the higher the GCS after resuscitation, the better the patient outcome. However, concern has developed that, because patients who present in coma are thought to have a dismal prognosis, less aggressive management is often used, contributing to the poorer outcome.

Studies over the last decade have examined the outcome of patients with a postresuscitation GCS of 3-5 who underwent aggressive medical and surgical management. Grahm et al (1990) found that no patient in a study of 100 patients with postresuscitation GCS of 3-5 had a satisfactory outcome (good/moderately disabled).^[6] They also found that no patients with a GCS of 6-8 and bihemispheric or multilobar dominant hemisphere injuries had a satisfactory outcome.

In a review of 190 patients, Levy et al (1994) found that only 2 patients with a GCS of 3-5 achieved a moderately disabled outcome.^[7] Further analysis showed that these patients had reactive pupils at admission and did not have bihemispheric/multilobar dominant hemispheric injuries. They concluded that surgical intervention is not beneficial in most patients with a GCS of 3-5 but may be beneficial for the rare patient with reactive pupils but without ominous findings on CT scan. Despite these studies, some controversy remains regarding surgery performed on patients with a GCS of less than 9 and especially regarding patients with a GCS of less than 5.

Other poor prognostic factors include age, suicide attempt, and through-and-through injuries. Patients who present with high ICP and/or hypotension also tend to have worse outcomes. CT scan findings associated with poor outcome include (1) bihemispheric injury, (2) intraventricular and/or subarachnoid hemorrhage, (3) mass effect and midline shift, (4) evidence of herniation, and/or (5) hematomas greater than 15 mL on CT scan.

Morbidity and mortality rates associated with penetrating brain injury remain unacceptably high. For patients presenting with a GCS of 3-5, mortality rates remain near 90%, and a satisfactory outcome as defined by the GCS only rarely occurs. Patients presenting with a GCS of 6-8 have a more variable outcome that may be related to differences in management and/or the smaller numbers of patients presenting in this category. Patients with a GCS greater than 9 have much lower mortality rates. Approximately one half of these patients make good recoveries, and 90% have satisfactory outcomes.

The results from one study found that insulin deficiency due to diabetes mellitus (DM) imparts an increased risk for mortality in patients with moderate-to-severe traumatic brain injury (TBI) compared with patients without DM (14.4% versus 8.2% ).^[8]

Many penetrating head injuries are incompatible with life, and people with these injuries often die almost immediately. Moderately injured patients more frequently are resuscitated and receive treatment. Upon presentation, beginning aggressive medical and surgical treatment is important in patients who may benefit from these interventions. Aggressive treatment of secondary mechanisms of injury must be initiated, and the patient must be monitored closely for possible complications.

Kaufman et al (1991) found that considerable variability exists among neurosurgeons currently as to what constitutes appropriate treatment of penetrating head injury.^[9] In particular, wide variations exist in the amount of surgical debridement performed, the use of ICP monitoring, and the use of various medical therapies. Duration of antiepileptics and antibiotics remains controversial, as does the use of hyperventilation, hypothermia, and steroids. Use of jugular bulb catheters and transcranial Doppler is institution-dependent.

Considerable research continues in the area of neurotrauma. Once secondary mechanisms of injury are better understood and treatment modalities are studied in prospective randomized clinical trials, less variation in management of penetrating head injury is likely to occur. The medical community as a whole will become more successful in the treatment of these patients.

Aggressive intensive care management in combination with surgical intervention, when appropriate, already has significantly reduced the mortality and morbidity associated with these injuries. Primary prevention of these injuries remains important. With the increasing numbers of firearms and firearm-related violence in our society, discussing the issues of violence with patients and offering appropriate intervention becomes the duty of all health care providers.