Traumatic Brain Injuries (TBIs; also referred to as acquired brain injuries or head injuries) occur when people's brains are injured due to physical trauma. At the time of this writing (2008), TBIs have appeared in the news with some frequency, as increasing numbers of soldiers (particularly those who have served or are serving in Iraq and Afghanistan) are being diagnosed with this condition. Traumatic brain injuries are not limited to soldiers, but also commonly occur in the general population as a consequence of various physical traumas such as car accidents and physical beatings. According to the Centers for Disease Control, approximately 1.5 million people in the U.S. sustain a TBI each year. It is unclear exactly how many soldiers have been affected by TBIs, but one large scale study by the Rand Corporation suggests that as many as 320,000 men and women have sustained this type of injury.
Two types of Traumatic Brain Injury may occur. A closed head injury occurs when the brain is damaged inside an intact skull, for instance, when the brain is bounced against the inside of the skull. In contrast, an open head injury is diagnosed when an object pierces the scalp and skull and enters the brain, destroying the brain tissue in its wake. Closed head injuries may occur as a consequence of blunt trauma or exposure to a shock wave (e.g. when a person is near an explosion).
Open head injuries may occur as a consequence of being shot at, impaled, stabbed or being located in the path of shrapnel or debris scattered by an explosion. It is possible for both types of TBI to co-occur simultaneously, such as brain injuries that are sustained in a modern combat situation where soldiers are attacked with improvised explosive devices (IEDs) which generate shrapnel, shock or pressure waves, a strong electromagnetic pulse, and an intense blast of light, heat, and sound upon detonation. Pressure waves and possibly the other components of these explosions may cause closed head injuries.
Several types of brain damage are associated with a TBI. The traumatized brain may become bruised and as a consequence, swell and/or bleed inside the skull. Brain tissue may also physically tear. Neuronal axons (long cell extensions that connect one neuron to another, making inter-neuron communication possible) are particularly vulnerable to being severed and destroyed.
Medical professionals classify Traumatic Brain Injuries into two broad categories: mild and moderate/severe. A person's symptoms and the residual degree of impairment that persists in the wake of a TBI depends on the severity and location of the injury that each person sustains, as well as his or her age and general health at the time of injury. Symptoms may appear immediately after the injury, or they may not show up for days or weeks afterward.
Mild traumatic brain injuries (sometimes referred to as concussions) are the most common form of TBIs. Somewhere between 10 to 20% of all American troops sent to Iraq have experienced this type of injury. People with a mild TBI may lose consciousness for a few seconds or minutes, or they may remain fully conscious during and after the event. Loss of consciousness may occur in the immediate aftermath of a mild TBI, but by definition, does not last longer than 30 minutes.
Other, longer-lasting symptoms associated with mild TBI may include:
- blurred vision
- ringing in the ears
- an unpleasant taste in the mouth
- altered sleep