Head Injury - Causes and symptoms

The most common causes of head injuries are traffic accidents, sports injuries, falls, workplace accidents, assaults, and bullet wounds. The head may be damaged both from direct physical injury to the brain and from secondary factors. Secondary factors include lack of oxygen, swelling of the brain, and loss of blood flow to the brain. Both closed and penetrating head injuries can cause tearing of nerve tissue and widespread bleeding or a blood clot in the brain. Swelling may cause the brain to push against the skull, blocking the flow of blood and oxygen to the brain.

Trauma (sudden shock) to the head can cause a concussion (pronounced kun-KUH-shen). A concussion often causes loss of consciousness without visible damage to the skull. In addition to loss of consciousness, initial symptoms of brain injury include:

  • Memory loss and confusion
  • Vomiting
  • Dizziness
  • Partial paralysis or numbness
  • Shock
  • Anxiety

After a head injury, a person may experience a period when his or her brain does not function normally. The person may become confused, have partial memory loss, and lose the ability to learn normally. Other people experience amnesia (memory loss) that may last for a few weeks, months, or even years. As the patient recovers from the head injury, memory normally returns slowly.

A less common aftereffect of head injury is epilepsy (see epilepsy entry). Epilepsy is a seizure disorder characterized by shaking and loss of control over one's muscles. Epilepsy occurs as a result of 2 to 5 percent of all head injuries.

Closed Head Injury

Closed head injury is any head injury in which the skull is not broken open. A common cause of closed head injury is a direct blow to the head. Sudden starts and stops in a motor vehicle may also cause a closed head injury. In such cases, the brain is suddenly thrown with great force against the skull, causing damage to the brain.

Penetrating Head Injury

Penetrating head injuries occur when some object passes through the skull into the brain. The object itself may cause damage to the brain. A bullet wound to the head is an example. Pieces of the skull can also be pushed into the brain by the object. These pieces can damage the brain. An open wound to the brain may also lead to an infection that can cause further brain damage.

Skull Fracture

A skull fracture is an event in which one or more of the bones that make up the skull are broken. Skull fractures are serious accidents and require immediate medical attention. Some skull fractures are visible. Blood and bone fragments may be obvious. In some cases, however, there are no visible signs of a skull fracture. In such cases, other symptoms may indicate the possibility of a skull fracture. These include:

  • Blood or clear fluid leaking from the nose or ear
  • Pupils in the eyes having unequal sizes
  • Bruises or discoloration around the eyes or behind the ears
  • Swelling or a dent on any part of the head

Intracranial Hemorrhage

Bleeding inside the skull may accompany a head injury and may cause additional damage to the brain. A blood clot may also form between the brain and the skull. A blood clot is a mass of partly solidified blood that forms in the body. The clot can press against the brain and interrupt the flow of blood and oxygen through the brain. A reduced flow of oxygen prevents the brain from functioning normally.

The discovery of X rays in the late 1890s changed the course of medicine. X rays gave doctors a way of seeing into a patient's body. Hard materials, like bone and teeth, show up clearly in an X-ray photograph.

But X-ray photographs have some serious disadvantages. They provide only a two-dimensional ("flat") view. They may not show cuts, breaks, lumps, and other disorders behind a bone or some other object. The problem is similar to trying to find out what the back of a person's head is like by looking at a photograph of his or her face.

In the 1960s, scientists found another way to use X rays that solved this problem. The technique is known as axial tomography. In axial tomography, X-ray photographs are taken of thin slices of an object. The X-ray camera is aimed at one part of the body, and a photograph taken. Then the camera is moved just slightly, and another photograph is taken. This process is repeated over and over again. Eventually, the researchers has a whole set of photographs of a part of the patient's body.

The problem is that it takes a long time to examine all these photographs and to see how they fit together. The obvious solution to that problem is to let a computer do the work. Today, the X-ray photographs can be fed into a computer, which assembles them into a three-dimensional photograph called a computerized axial tomography (CAT) scan or a computed tomography (CT) scan. The final product provides a much more detailed image of the body part being studied.

Bleeding can also occur deep within the brain. Wherever it occurs, bleeding in the brain is a very serious condition. It can lead to unconsciousness and death. The symptoms of bleeding within the brain include:

  • Nausea and vomiting
  • Headache
  • Loss of consciousness
  • Pupils in the eyes having unequal sizes
  • Listlessness

Postconcussion Syndrome

Mild head injuries usually produce symptoms such as headache, confusion, dizziness, and blurred vision. In some cases, these symptoms may last for a few days or weeks. Up to 60 percent of patients who sustain a head injury experience these symptoms for an even longer period of time. The symptoms can last as long as six months or a year after the injury. This condition is known as postconcussion syndrome.

Postconcussion syndrome is often difficult to diagnose. The symptoms include:

  • Headache
  • Dizziness
  • Mental confusion
  • Behavior changes
  • Memory loss
  • Loss of ability to think clearly
  • Depression
  • Sudden changes in mood

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