![]() High metabolic demand with poor perfusion or hypoxia.Metabolism mismatch leads to brain 'suicide'.The primary mediators involved in secondary brain injury include oxygen free radicals, excitatory amino acids (ie glutamate) and nitric acid.This secondary brain injury has a significant effect on outcome and can lead to continued death of neurons and glial cells. After impact, a cascade of biomolecular events occurs causing continued and progressive brain pathology.See pathophysiology of brain trauma Head: trauma.Production of physiologically active products.Hemorrhage Intracranial hemorrhage (intraparenchymal, intraventricular, extradural or subdural).Impairment of cerebrovascular autoregulation.Impairment of vascular supply to normal tissue (ischemia).Metabolic alterations in neuronal or glial cells.This primary injury may initiate a number of secondary pathophysiological sequelae such as: Intracranial disease processes may result in mechanical disruption of intracranial tissues from direct trauma and the forces applied to the brain at impact (primary injury).Foramen magnum (can cause respiratory depression).Raised intracranial pressure usually leads to brain herniation Brain: tentorial hernation. The rigid cranium does not allow expansion of contents (blood, CSF and brain tissue), so brain edema causes an increase in intracranial pressure.This may be made worse by a decrease in cerebral perfusion pressure due to hypovolemic shock or an increase in cerebral blood flow in response to hypocapnia secondary to hypoventilation. The response of the brain to most types of insult is swelling or edema.In coup injuries, the brain is injured directly under the area of impact, while in contre-coup injuries, it is injured on the side opposite the impact. Contusions commonly occur in coup and contre-coup injuries.It represents a bruising of the brain surface without rupture of the pia-arachnoid and/or interruption of the brain architecture. Contusion is a common result of severe head injury, often associated with a concussion. ![]() The effects of concussion on the brain function may last for a variable amount of time.
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