Traumatic Brain Injury

Abstract

Traumatic brain injury is the leading cause of death among adults younger than 45 yr and in children .The majority of TBI is classified as mild, and around 8–10% is classified as moderate or severe. Patients with mild TBI have a good prognosis providing treatable complications are not missed . Overall mortality in this group is around 0.1 % and is associated with missed intra-cranial haemorrhage. . (Yates D,et al ,2007) Traumatic brain injury has been divided into two distinct periods: primary and secondary brain injury. The primary injury is the result of the initial , mechanical forces, resulting in shearing and compression of neuronal , glial , and vascular tissue . Axonal tissue is more susceptible to the injury than vascular tissue . Thus , focal injuries are usually superimposed upon more diffuse neuronal injury. The consequences of the initial injury include physical disruption of cell membranes , infrastructure , and disturbance of ionic homeostasis secondary to increased membrane permeability. This in turn may lead to astrocytic and neuronal swelling, hypoperfusion, and a cascade of neurotoxic events because of increased intracellular calcium . The secondary injury is described as the consequence of further physiological insults , such as ischaemia , re-perfusion