PENETRATING BRAIN INJURIES

A.

Penetrating injuries can be subcategorized into gunshot wounds and lower velocity injuries; the prognosis between the two is very different.

• Gunshot wounds to the brain carry a high mortality rate. As the bullet traverses the brain tissue, it causes a cylinder of tissue destruction extending perpendicular from the bullet tract to a distance of as much as 10 times the diameter of the bullet.
• General management of gunshot wounds to the brain follows the same principles of cerebral resuscitation as other brain injuries. The incidence of elevated ICP is high.
• Superficial debridement of the entrance and exit wounds is generally recommended, although it is usually not necessary to retrieve all deep-seated bullet and bone fragments.
• Broad-spectrum intravenous antibiotics and prophylactic anticonvulsant therapy are recommended.
• Prognosis depends largely on the trajectory of the bullet through the brain. If the bullet traverses deep brain structures (e.g., the basal ganglia or brainstem), traverses the posterior fossa, or has a transcranial trajectory, the mortality rate is high. If the bullet avoids these structures, the outcome can be more optimistic.
• Patients with an initial GCS score of 3 to 4 will have a high mortality rate (>80%). Conversely, 80% of patients who are able to follow commands on admission to the hospital (GCS >8) will have mild or no disability.

B.

Lower velocity missile wounds. The most important factor determining outcome from lower velocity missile wounds (e.g., stab or arrow wounds) to the head is the location of brain injury. If the missile damages the motor cortex, for example, contralateral motor weakness should be confined to the area of cortex that was damaged.

• The missile may be tamponading a major intracranial arterial injury, so it is best to remove protruding knives or other objects only in the operating room and only when the surgeon is prepared to deal with the consequences of major arterial bleeding.
• A 7- to 14-day course of broad-spectrum antibiotics and prophylactic anti-convulsants (7 days) is indicated.

C.

Following a penetrating head injury—including high- or low-velocity missile or nonmissile injury (e.g., stab wound)—it is important to perform an angiogram to exclude a traumatic aneurysm.