Seizures & Brain Injury
In the United States, trauma is the leading cause of death in individuals under 45 years of age, and brain injury results in more trauma deaths than do injuries to any other region of the body.
Brain injury incidence is highest in children, young people and the elderly.
Most reports show that brain injury occurs twice as often in males as in females.
Motor vehicle crashes account for the major proportion of head and brain injuries and involve an overwhelmingly large number of young people.
Of all the people with brain injury seen in hospitals,
- about 50% have mild trauma
(amnesia or loss of consciousness for less than 30 minutes), - about 25% have moderate injuries
(loss of consciousness for up to 24 hours), and - about 25% have severe, life-threatening injuries
(intracranial mass lesions and/or unconsciousness for more than 24 hours).
Risk for epilepsy increases with increased severity of injury.
- For those with "mild" injury,
risk may be 50% greater than the general population through 5 years following the injury,
but returns to "normal" levels after 5 years.
- Those with "moderate" injury
may have a 6-fold increase in risk for epilepsy during the first year following the injury,
and up to a 3-fold increase for the next 9 years.
- Survivors of severe head injury
have up to a 100-fold increase for epilepsy during the first year after injury,
about a 15-fold increase during the next 9 years,
and a 4-fold increase thereafter.
- Among the military,
about 50% of survivors of penetrating head injuries will develop epilepsy.
- About 5% of persons with brain injury will experience 1 or more seizures at the time of the injury.
The exact frequency of disability — whether permanent or temporary, complete or partial — among those discharged from institutions is unknown.
- Almost all persons with a severe head injury develop some degree of disability.
- About 2 in 3 persons with moderate brain injury develop some degree of disability.
- At least 10% to 20% of individuals with head injuries who achieve a "good recovery" develop ongoing neuropsychological problems.
Primary injury refers to the mechanical trauma which occurs at the moment of impact. It may lead to irreversible cell damage from physical disruption of neurons or axons.
Secondary injury includes any physiological event which occurs within minutes, hours, or days after the initial injury and leads to further damage of nervous tissue.
Such secondary injuries may contribute to permanent neurological dysfunction.
- Hypotension (low blood pressure),
- hypoxia (inadequate oxygenation), and
- intracranial hypertension (elevated pressure inside the head)
are among the most serious and frequently seen secondary injuries after a head injury.
- Seizures often occur.
Early post-traumatic seizures, occurring in the first week after injury, are seen in approximately 25% of persons with traumatic intracranial haematomas (localized, usually clotted, collections of blood caused by a break in the wall of a blood vessel) and contusions (bruises).
The use of phenytoin (an anticonvulsant medication) during the first week after head injury reduces the risk of post-traumatic seizures by 70-75% during this period.
