Glasgow Coma Scale

[Maciek999]

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Glasgow: The Power Is in the Motor

Abstract & Commentary

Source: Healey C, et al. Improving the Glasgow Coma Scale score: Motor score alone is a better predictor. J Trauma 2003;54:671-680.

The Glasgow Coma Scale (GCS) has served as an assessment tool in head trauma, as a measure of physiologic derangement in outcome models, and often is used to rapidly assess neurologic status. Its value as a predictor of survival never has been prospectively validated. The authors used a large trauma data set (National Trauma Data Bank, N = 204,181), and compared the predictive power and calibration of the GCS to its component scores (motor, eye, verbal). The authors discovered that different combinations summing to a single GCS score often have very different mortalities. For example, the GCS score of 4 can represent any of three motor/verbal/eye combinations: 2/1/1 (survival 0.52), 1/2/1 (survival = 0.73), or 1/1/2 (survival = 0.81). In addition, the relationship between GCS score and survival is not linear, but decreases linearly from a GCS of 15 to 11, remains unchanged to a score of 7, and then decreases linearly again to a score of 3. The motor component of the GCS, by contrast, not only is related linearly to survival, but also preserves almost all the predictive power of the GCS. The authors conclude that the motor component of the GCS contains virtually all the information of the GCS itself, offers advantages over the other components (e.g., can be measured in intubated patients), and is much better behaved statistically than the GCS. They further state that the motor component of the GCS should replace the GCS in outcome prediction models.

Commentary by Richard J. Hamilton, MD, FAAEM, ABMT

The GCS is a score from 3 to 15, right? Wrong! It�s actually a collection of 120 different combinations of neurological abnormalities. A GCS of 13 could be someone who withdraws to pain, or speaks in incomprehensible words, or opens his or her eyes to painful stimuli, or is confused and only opens his or her eyes to speech. However, it�s hard to imagine that every single one of those patients has the same survival rate or severity of outcome. In fact, the 120 combinations end up being represented by a few scores with greater frequency than the others because of the specific pattern with which trauma patients deteriorate as measured by the scale. In this database of 204,181 patients, 80% of patients had a GCS of 15, 6% had a GCS of 14, 6% had a GCS of 3, and the rest of the scores were represented with a frequency of 1% or less.

Thus, most patients exhibit a score of 15, 14, or 3. Furthermore, this study demonstrates that survival is the same for GCS scores in the range of 7 to 11, although it does decrease linearly (as expected) for all other scores. Thus, it appears that GCS is a good tool only for predicting outcome when the score lies between 11 and 15 or between 3 and 7. The differences in the middle scores are meaningless.

Why is this? It turns out the strength of the correlation with survival is exclusively in the motor score. As the motor component goes from 6 to 1, survival decreases linearly. As the eye and verbal scores decrease, survival remains the same until the lowest possible score. The original authors of the GCS first intended it to be a three-score system, but later modified it to be a complete additive score. They never had a large number of patients to prospectively validate their findings. For example, when the score goes below 8 in a head trauma patient, we historically have taken that as a predictor of a bad outcome and instituted airway intervention. This probably makes little sense, because according to this large analysis, a score of 8 is no worse than a score of 7, 9, 10, or 11. One clearly can see the confounding issues (intoxication or behavioral abnormalities) in the verbal and eye components and why the motor scale makes clinical sense as well as statistical sense as a useful tool alone.

In conclusion, if you�re using the GCS, you had better pay more attention to the motor scale, or use the motor scale exclusively. Every time the patient drops a point on that scale, it means something important.

Dr. Hamilton, Associate Professor of Emergency Medicine, Program Director, Emergency Medicine, MCP Hahnemann University, Philadelphia, PA, is on the Editorial Board of Emergency Medicine Alert.

[Ridryder 911]

I believe Glasgow Coma Scale is one of the most mis-used ratings. As well, I find it to be used alone to be a poor predictor of anything, in conjunction with trauma scale and summary of TRISS, then yes.

Even a rotting corpse gets a 3 on the Glasgow. I liked the neuro eval that someone had posted earlier, a little bit more deatil and applicable.

Be safe,

R/r 911

[AZCEP]

I agree Rid. The FOUR point score was much more detailed, and made better clinical sense of what was happening. I don't remember reading any studies that indicated rates of morbidity/mortality from what the FOUR point score determined, but then I didn't really look either.

[AnthonyM83]

The authors discovered that different combinations summing to a single GCS score often have very different mortalities.

That's exactly why I never got why everyone felt this was so important. How does it change preparation of the ED when you give it in your radio report? Woudn't it be the actual components that really matter, rather than the total.

[EMS49393]

When I give a radio report, if the GCS is anything but 15 (unless a lower number is the baseline, as with a dementia patient for example) I give the components. They are going to certainly need to know if the patient you are bring in is posturing because that points to injury in certain areas of the brain. I consider the GCS a very important, underused and even misused tool. I've used it my entire career and unless the directive came down from God to stop using it, I'll probably use it the remainder of my career.

[Ridryder 911]

I will forewarn you as a ER nurse, the only thing I care about a Glasgow on a radio report is that it is < than 8... other than that, most of the Doc's or staff could care less....

R/r 911

[EMS49393]

I work hospital based EMS. I do things the way my hospital and my medical director want me to do them. My hospital is the regional trauma center, and I assure you that I know what is expected in my radio reports. Because you don't care really isn't my concern. I will not change the way I practice because some nurse doesn't care about a patient until they fall to a GCS of 8. Around here we care take any deterioration in patient condition seriously.

[Ghettomedic351]

I just happen to work in the same system as 49393 and they happen to be sticklers for detailed GCS. Although I work for a different service, the nurses and Doc's are very interactive with our delivery of care, they are also very critical of our competence in the field, I think we are just being held to a higher standard here than most places. I worked a busy metropolitan area for several years before coming here and in that area (Little Rock/MEMS) the hospitals seemed to care less other than throwing them a number on the GCS. I think it depends on the system in which you work. I will be curious to see how our highly trained Canadian friends use the GCS in day to day operations.

[Lithium]

EMS49393 ... Rid's post seems to have struck a chord with you.

I think what he was trying to imply is that when giving a radio report, only give what is absolutely necessary.

When you give your report, it goes like this: :XYZ, this 9999, we're enroute to your facility code 4 with a 82 y/o complaining of atypical, retrosternal chest pain which began aproximately 30 minutes ago while she was watching TV., She self administered 3 NTG prior to 9-1-1 initiation which afforded her no relief. Vitals are are as follow (insert vitals within normal range), we've given her an addition 2 NTG, 160 mg ASA and began 2 mg morphine. Our current ETA is 5 minutes, XYZ this 9999 out."

When they're listening all they really here is ... "XYZ, this is 9999, blah blah blah blah 82 y/o F blah blah blah CHEST PAIN, blah blah blah NO RELIEF blah blah blah ETA 5 minutes."

peace

[Lithium]

As far as GCS up here is concerned, I rarely report it in my radio report unless its of major concern. Even so, in my hand over I rarely report it unless there has been a change.

As far as documenting, on our forms it is broken down into each category and then the total number assessed.

peace