EMS Recap: The Glasgow Coma Scale

Emergency medical responders need to immediately assess anyone experiencing an acute brain injury for brain dysfunction and level of consciousness. Medical improvements and advances in resuscitation have resulted in more patients surviving with severe head injuries, thus increasing the need for intensive neurosurgical care and rehabilitation to limit disabilities. Having prehospital practitioners assess brain function and detect complications early helps hospital practitioners provide effective treatment.¹

The Glasgow Coma Scale was originally developed to assess and document the severity of brain dysfunction, with descriptions that medical professionals at all levels of training could understand, even if English was not their primary language. ¹ The categories assessed when evaluating a patient are eye opening, motor response and verbal response (see Table 1).¹

Head injury studies in the 1970s started using computers for collection and analysis. Early computer programs could not evaluate descriptions; therefore, data had to be converted to number values for input and analysis. The descriptions used on the original Glasgow Coma Scale were given number values for processing. Consequently, the Glasgow Coma Score published in 1974 had 14 descriptions, 3 to 17 levels, and scores from a low of 3 to a high of 14.¹ The original Scale did not distinguish between flexion-withdrawal and decorticate flexion.² Abnormal flexion was added a year later, raising the score for a fully conscious and alert patient from 14 to 15.³

Today, physicians use the Glasgow Coma Score to assess patient survivability. Patients with scores between 13 and 15 are considered mildly impaired and will often fully recover. Patients with scores between 9 and 12 are categorized as moderately disabled. A majority of patients will have experienced a loss of consciousness of more than 30 minutes with scores between 9 and 12, and will often have physical and cognitive impairments that may resolve with rehabilitative therapy. Patients with GCS scores of 3 to 8 are often comatose, unconscious with no purposeful movements, have no interaction with their environment, or have no localized response to pain.⁴ Approximately 50% of patients with a score of 8 will be unconscious or in a coma, and almost all patients with a score of 7 or less will be unconscious or in a coma.¹ A patient with a GCS of 3 is either dead or in a vegetative state with possible sleep-wake cycles.⁴ Additional modifications to the Glasgow Coma Scale include response levels for small children.³

The initial assessment is considered a prime opportunity to score a patient and determine optimum care and transport to the most appropriate medical facility.¹ Another time to assess a patient using the Glasgow Coma Scale is after resuscitation and stabilization, with the understanding that intubation and sedation can make this difficult or impossible. The Glasgow Coma Score given by pre-hospital providers is a good predictive baseline for physicians to compare to the score given a patient upon arrival with traumatic brain injuries. Changes in the field score upon arrival are excellent predictors of patient outcome.⁵

Remember, the numbers assigned to the Glasgow Coma Scale were originally used to enter research data for computer analysis. Today, the Glasgow Coma Scale is widely used by emergency medical personnel to assess trauma and medical patients and make treatment and transport decisions.

References

1. Jennett B. Development of Glasgow coma and outcome scales. Nepal Journal of Neuroscience 2(1):24-28, 2005.

2. JAMA 2004.

3. Brain and Spinal Cord, 2011. Glasgow coma scale.

4. Traumatic Brain Injury, 2011. Symptoms of traumatic brain injury. Glasgow coma scale.

5. Davis DP, et al. The predictive value of field versus arrival Glasgow coma scale score and TRISS calculations in moderate-to-severe traumatic brain injury. The Journal of Trauma, Injury, Infection and Critical Care 2006.

Robert E. Sippel, Major, USAF (Ret.) MS, MAEd, NREMT-P, LP, is an assistant professor/clinical coordinator in the Emergency Health Sciences Department at the University of Texas Health Science Center, San Antonio, TX.