Head injury: from the Glasgow Coma Scale to quo vadis.

Background Work in the 1940s and 1950s revealed that the brainstem was key to consciousness. The experimental definition of the reticular activating system by Moruzzi and Magoun28 in 1949 was followed by various confirmatory clinical studies.15,38 Studies conducted during World War II and later demonstrated that rotational head injury was more effective than translational acceleration/deceleration in inducing loss of consciousness.30 From such beginnings came the hallmark studies of diffuse axonal injury44 and of the concussive neurometabolic cascade.8,19 In contrast, there was no simple clinical method for assessing the depth of coma and the severity of a head injury. Words such as comatose, drowsy, obtunded, stuporose, semistuporose, and others pervaded the literature. The publication of the Glasgow Coma Scale (GCS) in 1974 by Teasdale and Jennett45 has transformed clinical management by providing three simple tests—eye opening, verbal response, and best motor response—that can be readily understood and performed by all levels of professional staff from the roadside onwards and facilitates communication. In addition, the GCS has provided a platform for randomized, controlled trials (RCTs) and audits. Together with computed tomographic (CT) scanning, early resuscitation, and prevention of avoidable factors and secondary insults, the GCS has led to major improvements in outcome for patients after acute brain injury of various aetiologies. The publication of the Glasgow Outcome Scale (GOS) in 1975 by Jennett and Bond18 completed the two essential clinical tools required for RCTs in brain injury. Dr Tom Langfitt from Philadelphia immediately understood the importance of these two tools and, in an exemplary display of transatlantic cooperation, was key to the early and widespread international adoption of the GCS and GOS.21 Subsequently, the GCS has been modified for paediatric use. Alternative scales have been suggested in Japan and Europe (for example, the Scandinavian Reaction Level Scale) and comparisons have been made, but the GCS continues to be the most commonly used. Recently the FOUR score has been published from the Mayo Clinic, which adds to the GCS eye movement to command, a hand-position task, and four tests of brainstem reflexes (pupil, cornea, cough, and respiratory pattern).47 The inclusion of eye movements to command will hopefully reduce the risk of missing the diagnosis of locked-in syndrome, but the other assessments may require more expertise than the GCS and, hence, restrict the widespread adoption of the “Four Score.” Inevitably, the ordinal nature of the GCS has not always been understood, leading to discussion, for example, about a mean GCS of 4.5. With the advent of early intubation and ventilation, it is not always possible to accurately know what the initial GCS was after injury. Hence, the GCS has lost some of its prognostic power.2 Fortunately, knowledge of the CT scan abnormalities, intracranial pressure, and state of autoregulation are helping to provide powerful prognostic information.14