The Glascow Coma Scale is a tool used to describe the level of consciousness of a person following a head injury. It relies upon an examiner, EMS personnel, emergency room physician, nurse, neurologist or other trained professional to assess the patient’s response to three stimuli: Eye response, motor response and verbal response. The scores from each of these categories total a sum between 3 and 15, with 15 representing the highest level of consciousness.
Although it has become a useful tool for triage in pre hospital patients and for assessing patients with ongoing issues, the scale only measures the response of a patient at a snapshot in time. Thus, if a first responder arrives to an accident scene 30 minutes after a trauma, the GCS taken at that time provides no information as to the patient’s level of consciousness immediately after the accident.
Moreover, the GCS has been shown to have limitations due to the interrater reliability of the score takers. Studies have shown a variation in score assessment for the same patient depending upon the training and skill level of the healthcare provider who is assessing the patient. For instance, in one study, experienced nurses were more consistent with GCS scoring than less experienced nurses and nursing students. These studies suggest that accuracy and reliability of scoring is dependent on tester experience with the GCS score.
Another potential issue with the GCS is the collection of valid scores. For example, the verbal response can be hindered by the presence of hearing loss, psychiatric disorders, dementia, developmentaldelay or injuries to the mouth or throat. Language barriers can also present a challenge to the accurate collection and scoring of data in all categories. The motor response is also vunerable to complicating factors such as spinal cord injury or peripheral nerve injury.
Finally, medical literature widely reports that the GCS is a poor predictor of functional outcome in neurologically impaired patients post-traumatic injury. In other words, patients with scores of 15 at the time of testing do not all recover from their traumatic brain injury in terms of the functional outcome. Thus, the GCS was not designed for and should not be used as a predictor of patient outcomes post-traumatic injury.