Hypoxic-ischemic brain injury can occur due to many causes and at any age in life. It can cause acute seizures at the time of the injury, as well as epilepsy as a longer-term complication.
The clinical presentation of hypoxic-ischemic injury depends on the extent of hypoxia-ischemia, location of the injury within the brain, age, the underlying cause, and associated factors such as raised intracranial pressure from cerebral oedema. Acute seizures typically occur, and are maximal, in the first 24 hours after the injury. Acute management centers both on management of seizures, and also management of the hypoxic-ischemic injury. If epilepsy occurs as a post-injury complication, there is typically a latent period, and then re-emergence of seizures months later. Cognitive and neurological impairments may occur as a consequence of the hypoxic-ischemic injury.
Hypoxic-ischemic brain injury may occur prenatally, with injury to posterior periventricular regions being common due to vascular watershed territory distribution in the fetal brain. Infants may present with spastic diplegia, which may only be diagnosed as development progresses and impaired motor function is recognized. Focal seizures with dyscognitive features are seen in these patients, relating to the area of brain injury in posterior occipito-parietal regions. Epilepsy associated with periventricular leukomalacia is not common, but seizures can be frequent and medically refractory in patients who have greater motor disability.