Penetrating Head Injury

In the United States, cranial gunshot wounds (GSW) frequently cause morbidity and death in children and adolescents. More than two thirds of cranial gunshot wounds are fatal. Survivable injuries are most often functionally and cosmetically mutilating. Prevention is the only truly effective therapy for this problem.

GSWs are categorized by muzzle velocity. Low-velocity (<250 m/s) weapons, including most handguns, predominantly cause injury by direct trauma from projectile, bone and soft-tissue fragments. High-muzzle-velocity (>750 m/s) weapons, including most military weapons and hunting rifles, cause widespread parenchymal destruction resulting from shock waves and tissue cavitation. These injuries are often immediately fatal. Evaluation of GSW victims is similar to that for other head injured patients. Entrance and exit wounds should be shaved and carefully inspected. Anterior-to-posterior (AP) and lateral skull radiographs may help to identify missile fragments and prove useful for forensic purposes. The decision whether to treat a gunshot injury must be reached in consultation with the patient's family. Poor prognostic factors that may, in combination, mitigate against aggressive treatment include:

2. Trajectory across the midline.

3. Trajectory across the basal ganglia and/or diencephalon.

4. Trajectory across the ventricles.

5. Brainstem injury.

6. Extensive bihemispheric injury.

Patients with a survivable injury and for whom the family requests aggressive treatment should be resuscitated in the emergency room. Preoperative angiography should be obtained if the bullet trajectory is in close proximity to major intracranial vessels or if a large, focal, intracranial hematoma is present. Urgent operation is then indicated to debride entry and exit wounds, control bleeding and remove accessible bone and missile fragments. Exenteration and packing of air sinuses traversed by the

missile and watertight dural closure reduce the risk of CSF leak and intracranial infection. Comatose patients require intracranial pressure monitoring and aggressive ICP management. Any salvageable patient with a posterior fossa (i.e., cerebellar) injury should undergo urgent craniotomy for debridement and decompression. Such patients can deteriorate from a GCS of 15 to fatal brainstem compression in a matter of minutes due to fulminant cerebral edema.

Cranial GSW may be complicated by various other events such as seizures, intracerebral abscesses, pseudo-aneurysms, hydrocephalus and sudden ventricu-lar/aqueductal obstruction (rare). Prophylactic antibiotic and anticonvulsant medications are often employed. Early therapy, neuropsychology and rehabilitation consultation are necessary.

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