Brain injuries can be among the most traumatic and consequential of all injuries, and unfortunately, not all of the symptoms of a brain injury show up immediately. In some cases, it may be years before the full ramifications of a blow to the head become apparent.
Many times, traumatic brain injuries can lead to problems with movement, including tremors, ataxia (an inability to coordinate movements properly), and a lack of movement control or a limited range of movement. With a more traumatic injury, there is a risk of developing seizures years after. If the basal ganglia, a group of nuclei in the forebrain involved in movement impulses, has been damaged, Parkinson's disease has a risk of developing long after the initial injury. These symptoms appear as a group, and can include tremors, muscle rigidity or stiffness, slowed movements, an inability to move altogether, a stooped or hunched posture, and a shuffling walk. This disease has no cure as of yet, and becomes progressively worse over time, unlike some other long-term symptoms. Additionally, some people may experience a loss of, or changes to, their senses of vision, smell, or hearing.
In about 10 to 15 percent of people with a brain injury, the trauma can damage the pituitary gland, leading to a case of hypopituitarism. This in turn leads to disturbances stemming from a lack of hormone production, leading to symptoms as varied as diabetes, vision loss, enlargement of the hands or feet, anemia, a loss of sexual interest and function, weight loss, and hair loss.
There are many cognitive deficits that can occur for periods spanning years after an injury, including changes in personality, lack of proper judgment, and problems with planning or problem-solving, among other problems with abstract reasoning and thought. These often occur with other sets of symptoms that include depression, difficulty concentrating, dizziness, and headaches. Years after multiple brain concussions can lead to the development of dementia years later, as well as memory difficulties and Parkinsonian tremors.
Because of the emotional problems that can follow a brain injury, such as depression, mania, anger, and apathy, many psychiatric disorders can develop years after the initial injury has occurred. This variety of disorders includes schizophrenia, major depressive disorder, alcohol and substance abuse disorders, obsessive compulsive disorder, dysthymia, panic attacks, and phobias. Even without a clinical disorder, a person may still develop a lack of control over anger, impulsive behavior, a lack of initiative, and even an inability to control sexual urges. Sometimes, the consequences of these behavioral and emotional changes can be so severe as to create a risk of suicide; there is a two to three times' increase in the suicide rate.
A brain injury can often lead to post-concussive syndrome up to years after the event. Post-concussive syndrome is a medical condition that is characterized by headaches, dizziness, a sensitivity to bright lights and loud noises, blurred or double vision, and ringing in the ears, also known as tinnitus. Anxiety, irritability, depression, and other emotional symptoms may occur, including a total lack of emotion. People often have problems with memory and attention with this disorder, and these are among the longest-lasting and most persistent symptoms. There may be other cognitive difficulties as well, including a slowed reaction to external stimuli, problems with abstract thinking, and an inability to engage in problem-solving activities. Fatigue or difficulty sleeping may also result.
While many symptoms arise immediately after a brain injury, it is important to remember that some effects do not manifest until years after the injury has happened. If a person with a history begins to manifest groups of symptoms years later, a previous injury must not be ruled out as the cause.