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