A young man is brought to the emergency depament with head injury following a motor vehicle accident. The patient is unconscious. BEST prognostic factor for head injury is:

In severe head injury, the clinical features of eye opening, motor responses of the limbs, and verbal output have been found to be generally predictive of outcome. These three responses are assessed by the Glasgow Coma Scale; a score between 3 and 15 is assigned. Over 85% of patients with aggregate scores of Ref: Ropper A.H. (2012). Chapter 378. Concussion and Other Head Injuries. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.