Evaluating an unresponsive patient in a meaningful and consistent way can be challenging. Some coma scoring tools are complex, while others don’t promote comprehensive assessment of the patient’s level of consciousness.
The Glasgow Coma Scale (GCS)—the most widely used tool—falls into the second category. It doesn’t allow for cranial nerve examination or help determine if the patient is “locked in” (aware but unable to respond except by blinking or tracking). Also, it can give a misleading picture of the cognitive status of an intubated patient.
The GCS has three components—eye opening, verbal response, and motor response. The examiner scores each component individually, then totals the three scores to obtain the overall score (which, in many cases, is the only score documented). The lowest possible score for any component is 1, indicating complete lack of response. The highest possible score varies; for eye opening, it’s 4; for verbal response, 5; for motor response, 6. Significantly, intubated patients always score 1 on verbal response—even if they’re able to communicate their needs.
The GCS has undergone numerous challenges, all of them unsuccessful. Some alternative scales lack the simplicity of the GCS, while others require a full neurologic assessment, which is impractical for a quick assessment of coma depth.
Moving beyond Glasgow
At our facility, practitioners identified the need for an easily used coma scale that was more comprehensive than the GCS and promoted clear communication among caregivers. To meet these criteria, neuro-intensivist Dr. Eelco Wijdicks devised the FOUR (Full Outline of UnResponsiveness) Score scale.
Easy to learn and use, the FOUR Score provides a standard tool for clearly communicating the patient’s level of responsiveness. It has four components—eye response, motor response, brainstem reflexes, and respiration. (To remember them, we use the acronym EMBR.) The examiner rates each component on a 0-to-4 scale, with 0 signifying complete lack of response and 4 indicating a normal or expected response. Each component is scored individually—for example, E4, M3, B4, or R1; the four components are not totaled.
- To test eye response, the examiner evaluates the patient’s eye opening and tracking. Assessment of tracking may reveal “locked-in” syndrome, which may otherwise go undetected for more than a week.
- To test motor response, the examiner asks the patient to make a fist or to give a “thumbs up,” victory, or peace sign. A patient who’s able to perform these actions can translate cognitive understanding of a command into a motor response. (Motor response tests are superior to the traditional hand squeeze, which is easily confused with a simple grasp reflex.)
- To test brainstem reflexes, the examiner checks the patient’s pupillary response, corneal response, and cough reflex. (To reduce the risk of corneal damage, a drop of saline solution is instilled into the eye.) Brainstem reflex testing (not included in the GCS) may promote earlier recognition of progression to brain death, possibly helping to avert disaster. When such progression can’t be prevented, early recognition can help the family prepare for the patient’s imminent death and begin to consider possible organ donation.
Testing respiration with the FOUR Score
Many critically ill neurologic patients require intubation during the acute phase of injury or disease—and using the GSC in an intubated patient is difficult. But with the FOUR Score, the respiration component takes into account whether the patient is intubated. Intubated patients may receive a score of either 0 or 1, depending on whether they’re breathing at or above the preset ventilator rate.
To get a better idea of the FOUR Score’s advantage with intubated patients, imagine that your intubated patient opens her eyes when you walk into the room and follows you around the room with her eyes. Although she can’t move her left side, she can give the “thumbs up” sign and the peace sign and can make a fist when you ask her to. She can also communicate by writing. Her pupils are equal and reactive to light, and her corneal reflexes are brisk bilaterally. Her respiratory rate is 12; the preset ventilator rate is 8. So you’d give her a FOUR Score of E4, M4, B4, R1.
On the other hand, if you used the GCS to assess her, you’d give her a total score of 11 (E4, V1, M6)—and you’d have a cloudier impression of her cognitive status because the GCS requires you to give all intubated patients a “1” for verbal response.
Validating the FOUR Score
To validate the Four Score, our Neuroscience ICU conducted a 120-patient study. Neuro-intensivists, experienced neurology nurses, and neurology residents independently scored patients on both the FOUR Score and GCS; data were analyzed to demonstrate inter-rater reliability.
Results showed that in many cases, the FOUR Score proved superior to the GCS in determining level of unresponsiveness, identifying “locked-in” syndrome, and predicting in-hospital mortality. In the study, 34 patients scored a 3 (the lowest possible score) on the GCS; using the FOUR Score to evaluate these patients yielded a broader distribution of scores, which provided more detail about coma depth.
Additional studies are under way to investigate the validity of the FOUR Score in settings other than a neuroscience ICU and with physicians and nurses less experienced in conducting neurologic exams and using coma rating scales.
FOUR Score’s future
At Mayo, we use the FOUR Score and the GCS in conjunction with cranial nerve, motor, and sensory exams to assess and communicate a patient’s neurologic function. (We can’t use the FOUR Score exclusively because the GCS is incorporated into other tools, such as the APACHE Score and the Trauma Injury Severity Score). The FOUR Score has been presented at various forums and has garnered much interest. Dr. Wijdicks has received over 300 outside requests for copies of the scale and permission to use it. We’re certain it surpasses the GCS in promoting a comprehensive neurologic examination.
Laureys S, Piret S, LeDoux D. Quantifying consciousness. Lancet. 2006;4:789-790.
Teasdale G, Jennet B. Assessment of coma and impaired consciousness. A practical scale. Lancet. 1974;2:81-84.
Wijdicks E, Bamlet W, Maramattom B, Manno E, McClelland R. Validation of a new coma scale: the FOUR Score. Ann Neurol. 2005; 58:585-593.
Dorothy Gusa, MS, RN, CNRN, is a Nursing Education Specialist in the Neuroscience ICU at the Mayo Clinic in Rochester, Minn. Anne Miers, MSN, RN, APRN-BC, CNRN, is a Clinical Nurse Specialist in the Neuroscience ICU at Mayo. Dale Pfrimmer, BSN, RN, is a Nurse Administrator in Critical Care at Mayo. Eelco Wijdicks, MD, is Professor of Neurology and Chair of the Division of Critical Care Neurology at Mayo.