Several complications can occur immediately or soon after a traumatic brain injury. Severe injuries increase the risk of a greater number and more-severe complications.
Moderate to severe traumatic brain injury can result in prolonged or permanent changes in a person's state of consciousness, awareness or responsiveness. Different states of consciousness include:
- Coma. A person in a coma is unconscious, unaware of anything and unable to respond to any stimulus. This results from widespread damage to all parts of the brain. After a few days to a few weeks, a person may emerge from a coma or enter a vegetative state.
Vegetative state. Widespread damage to the brain can result in a vegetative state. Although the person is unaware of surroundings, he or she may open his or her eyes, make sounds, respond to reflexes, or move.
It's possible that a vegetative state can become permanent, but often individuals progress to a minimally conscious state.
- Minimally conscious state. A minimally conscious state is a condition of severely altered consciousness but with some signs of self-awareness or awareness of one's environment. It is sometimes a transitional state from a coma or vegetative condition to greater recovery.
- Brain death. When there is no measurable activity in the brain and the brainstem, this is called brain death. In a person who has been declared brain dead, removal of breathing devices will result in cessation of breathing and eventual heart failure. Brain death is considered irreversible.
- Seizures. Some people with traumatic brain injury will develop seizures. The seizures may occur only in the early stages, or years after the injury. Recurrent seizures are called post-traumatic epilepsy.
- Fluid buildup in the brain (hydrocephalus). Cerebrospinal fluid may build up in the spaces in the brain (cerebral ventricles) of some people who have had traumatic brain injuries, causing increased pressure and swelling in the brain.
- Infections. Skull fractures or penetrating wounds can tear the layers of protective tissues (meninges) that surround the brain. This can enable bacteria to enter the brain and cause infections. An infection of the meninges (meningitis) could spread to the rest of the nervous system if not treated.
- Blood vessel damage. Several small or large blood vessels in the brain may be damaged in a traumatic brain injury. This damage could lead to a stroke, blood clots or other problems.
- Headaches. Frequent headaches are very common after a traumatic brain injury. They may begin within a week after the injury and could persist as long as several months.
- Vertigo. Many people experience vertigo, a condition characterized by dizziness, after a traumatic brain injury.
Sometimes, any or several of these symptoms might linger for a few weeks to a few months after a traumatic brain injury. This is currently referred to as persistent post-concussive symptoms. When a combination of these symptoms last for an extended period of time, this is generally referred to as post-concussion syndrome.
Traumatic brain injuries at the base of the skull can cause nerve damage to the nerves that emerge directly from the brain (cranial nerves). Cranial nerve damage may result in:
- Paralysis of facial muscles or losing sensation in the face
- Loss of or altered sense of smell
- Loss of or altered sense of taste
- Loss of vision or double vision
- Swallowing problems
- Ringing in the ear
- Hearing loss
Many people who have had a significant brain injury will experience changes in their thinking (cognitive) skills. It may be more difficult to focus and take longer to process your thoughts. Traumatic brain injury can result in problems with many skills, including:
- Attention or concentration
Executive functioning problems
- Beginning or completing tasks
Language and communications problems are common following traumatic brain injuries. These problems can cause frustration, conflict and misunderstanding for people with a traumatic brain injury, as well as family members, friends and care providers.
Communication problems may include:
- Difficulty understanding speech or writing
- Difficulty speaking or writing
- Inability to organize thoughts and ideas
- Trouble following and participating in conversations
- Trouble with turn taking or topic selection in conversations
- Problems with changes in tone, pitch or emphasis to express emotions, attitudes or subtle differences in meaning
- Difficulty understanding nonverbal signals
- Trouble reading cues from listeners
- Trouble starting or stopping conversations
- Inability to use the muscles needed to form words (dysarthria)
People who've experienced brain injury often experience changes in behaviors. These may include:
- Difficulty with self-control
- Lack of awareness of abilities
- Risky behavior
- Difficulty in social situations
- Verbal or physical outbursts
Emotional changes may include:
- Mood swings
- Lack of empathy for others
Problems involving senses may include:
- Persistent ringing in the ears
- Difficulty recognizing objects
- Impaired hand-eye coordination
- Blind spots or double vision
- A bitter taste, a bad smell or difficulty smelling
- Skin tingling, pain or itching
- Trouble with balance or dizziness
Degenerative brain diseases
Research suggests that repeated or severe traumatic brain injuries might increase the risk of degenerative brain diseases. But, this risk can't be predicted for an individual — and researchers are still investigating if, why and how traumatic brain injuries might be related to degenerative brain diseases.
A degenerative brain disorder can cause gradual loss of brain functions, including:
- Alzheimer's disease, which primarily causes the progressive loss of memory and other thinking skills
- Parkinson's disease, a progressive condition that causes movement problems, such as tremors, rigidity and slow movements
- Dementia pugilistica — most often associated with repetitive blows to the head in career boxing — which causes symptoms of dementia and movement problems