TBI is the cause of one third to one half of all trauma deaths, and the leading cause of disability in people under 40, severely disabling 15 to 20 per 100,000 population per year (Fleminger,  Ponsford, 2005).  Injuries, including TBI, are projected to account for 20% of the worldwide burden of death and disability by 2020 (Finfer, Cohen, 2001). Reliable assessment of prognostic factors in patients with TBI may guide the treatment strategy and allocation of resources (Alkhoury, Courtney, 2011).  Currently, the Glasgow Coma Scale (GCS) is used as a surrogate marker to score the severity of TBI. GCS has been implemented as a stratification tool in several outcome and prediction models (Duncan, Thakore, 2009). Various risk factors associated with poor outcome have been explored in the past, ranging from pupil size and reactivity and GCS scores and age (Schreiber, et al. 2002). Furthermore, improved outcome results when secondary or delayed neurological insults after trauma -resulting in reduced cerebral perfusion to the injured brain -are prevented or respond to treatment . This is reflected in the progressive and significant reduction in severe TBI mortality from 50% to 35% to 25% and lower over the last 30 years, even when adjusted for injury severity, sex, age and other admission prognostic criteria such as GCS & pupillary reaction .This resulted in reduced mortality and improved outcomes from TBI (Hesdorffer, et al. 2002 ).