ABSTRACT
Traumatic brain injury can be considered as the combination of primary injury sustained on impact, and hence not medically modifiable, and secondary injury developing in the following hours and days. Understanding the importance of intracranial pressure and related parameters is key to minimising secondary injury and improving outcomes. The brain depends on continuous perfusion for oxygen and glucose delivery, and hence survival. Normal cerebral blood flow is about 55 mL/min for every 100 g of brain tissue. Ischaemia results when this rate drops below 20 mL/min, and even lower levels will result in infarction unless promptly corrected. Concussion is defined as the alteration of consciousness as a result of closed head injury but is generally used to describe mild head injury without imaging abnormalities: loss of consciousness at the time of injury is not a prerequisite.
