In moderate to severe injuries, the swelling may cause pressure on a lower part of the brain called the brainstem, which controls consciousness or wakefulness. Many individuals who suffer these types of injuries are in an unconscious state called a coma. A person in a coma may be completely unresponsive to any type of stimulation such as loud noises, pain, or smells. Others may move, make noise, or respond to pain but be unaware of their surroundings. These people are unable to communicate.
Some people recover from a coma, becoming alert and able to communicate.
In conscious individuals, cognitive impairments often include having problems concentrating for varying periods of time, having trouble organizing thoughts, and becoming easily confused or forgetful. Some individuals will experience difficulty learning new information. Still others will be unable to interpret the actions of others and therefore have great problems in social situations. For these individuals, what they say or what they do is often inappropriate for the situation. Many will experience difficulty solving problems, making decisions, and planning.