There are many different types of brain injury, depending upon the severity of the force upon the head, as well as which portion of the brain is affected. To simplify, brain injuries can be classified as traumatic or acquired, with additional types under each heading. All brain injuries are described as either mild, moderate, or severe. Traumatic Brain Injury Traumatic brain injury is a result of an external force to the brain that results in a change to cognitive, physical, or emotional functioning. The impairments can be temporary or permanent. Types of traumatic brain injury include: * Diffuse axonal injury. Shaking or strong rotation of the head causes brain structures to tear. Nerve tissue is disturbed throughout the brain. * Concussion. Caused by a physical force to the head that causes blood vessels to stretch and cranial nerves to be damaged. * Contusion. A result of a direct impact to the head, which causes bleeding on the brain. * Coup-contrecoup injury. The force to the brain is large enough to cause contusion at the side of impact, as well as the site opposite impact. * Penetration injury. The impact causes a foreign object to penetrate the skull. Acquired Brain Injury An acquired brain injury is an injury to the brain that is not hereditary, congenital, degenerative, or the result of birth trauma. Acquired brain injury generally affects cells throughout the entire brain. Types of acquired brain injury include: • Axnoxic brain injury. This occurs when the brain doesn't receive oxygen.

• Hypoxic brain injury. This occurs when the brain receives some, but not enough, oxygen.