| Head injury is a trauma to the head, that may or | | | | trauma |
| may not include injury to the brain (see also brain | | | | Dementia pugilistica, or "punch-drunk syndrome", |
| injury). | | | | caused by repetitive head injuries, for example in |
| The incidence (number of new cases) of head injury | | | | boxing or other contact sports |
| is 300 per 100,000 per year (0.3% of the population), | | | | A severe injury may lead to a coma or death |
| with a mortality of 25 per 100,000 in North America | | | | Concussion |
| and 9 per 100,000 in Britain. Head trauma is a | | | | Mild concussions are not associated with any |
| common cause of childhood hospitalization. | | | | sequelae. However, a slightly greater injury can be |
| Causes | | | | associated with both anterograde and retrograde |
| Common causes of head injury are traffic accidents, | | | | amnesia (inability to remember events before or |
| home and occupational accidents, falls, and assaults. | | | | after the injury). The amount of time that the |
| Bicycle accidents are also a common cause of head | | | | amnesia is present correlates with the severity of |
| injury-related death and disability, especially among | | | | the injury. In some cases the patients may develop |
| children. [1] | | | | postconcussion syndrome, which can include memory |
| Types of head injury | | | | problems, dizziness, and depression. Cerebral |
| Head injuries include both injuries to the brain and | | | | concussion is the most common head injury seen in |
| those to other parts of the head, such as the scalp | | | | children. |
| and skull. | | | | Epidural hematoma |
| Head injuries may be closed or open. A closed | | | | Epidural hematoma (EDH) is a rapidly accumulating |
| (non-missile) head injury is one in which the skull is | | | | hematoma between the dura mater and the cranium. |
| not broken. A penetrating head injury occurs when | | | | These patients have a history of head trauma with |
| an object pierces the skull and breaches the dura | | | | loss of consciousness, then a lucid period, followed by |
| mater. Brain injuries may be diffuse, occurring over a | | | | loss of consciousness. Clinical onset occurs over |
| wide area, or focal, located in a small, specific area. | | | | minutes to hours. Many of these injuries are |
| A head injury may cause a skull fracture, which may | | | | associated with lacerations of the middle meningeal |
| or may not be associated with injury to the brain. | | | | artery. A "lenticular", or convex, lens-shaped |
| Some patients may have linear or depressed skull | | | | extracerebral hemorrhage will likely be visible on a CT |
| fractures. | | | | scan of the head. Although death is a potential |
| If intracranial hemorrhage, or bleeding within the brain | | | | complication, the prognosis is good when this injury is |
| occurs, a hematoma within the skull can put pressure | | | | recognized and treated. |
| on the brain. Types of intracranial hematoma include | | | | Subdural hematoma |
| subdural, subarachnoid, extradural, and | | | | Subdural hematoma occurs when there is tearing of |
| intraparenchymal hematoma. Craniotomy surgeries | | | | the bridging vein between the cerebral cortex and a |
| are used in these cases to lessen the pressure by | | | | draining venous sinus. At times they may be cause |
| draining off blood. | | | | by arterial lacerations on the brain surface. Patients |
| Brain injury can be at the site of impact, but can also | | | | may have a history of loss of consciousness but |
| be at the opposite side of the skull due to a | | | | they recover and do not relapse. Clinical onset occurs |
| contrecoup effect (the impact to the head can cause | | | | over hours. A crescent shaped hemorrhage |
| the brain to move within the skull, causing the brain | | | | compressing the brain will be noted on CT of the |
| to impact the interior of the skull opposite the | | | | head. Surgical evacuation is the treatment. |
| head-impact). | | | | Complications include uncal herniation, focal neurologic |
| If the impact causes the head to move, the injury | | | | deficits, and death. The prognosis is guarded. |
| may be worsened, because the brain may ricochet | | | | Cerebral contusion |
| inside the skull (causing additional impacts), or the | | | | Cerebral contusion is bruising of the brain tissue. The |
| brain may stay relatively still (due to inertia) but be | | | | majority of contusions occur in the frontal and |
| hit by the moving skull. | | | | temporal lobes. Complications may include cerebral |
| Specific problems after head injury can include: | | | | edema and transtentorial herniation. The goal of |
| Skull fracture | | | | treatment should be to treat the increased |
| Lacerations to the scalp and resulting hemorrhage of | | | | intracranial pressure. The prognosis is guarded. |
| the skin | | | | Diffuse axonal injury |
| Traumatic subdural hematoma, a bleeding below the | | | | Diffuse axonal injury, or DAI, usually occurs as the |
| dura mater which may develop slowly | | | | result of an acceleration or deceleration motion, not |
| Traumatic extradural, or epidural hematoma, bleeding | | | | necessarily an impact. Axons are stretched and |
| between the dura mater and the skull | | | | damaged when parts of the brain of differing density |
| Traumatic subarachnoid hemorrhage | | | | slide over one another. Prognoses vary widely |
| Cerebral contusion, a bruise of the brain | | | | depending on the extent of damage. |
| Concussion, a temporary loss of function due to | | | | |