Glasgow Coma Scale (GCS)

One of our best selling quick reference pocket cards, is the Glasgow Coma Scale Tool. Do you know what it’s for?

What is the Glasgow Coma Scale?

The Glasgow Coma Scale (GCS) is a system to “score” or measure how conscious you are. It works by giving numbered scores for how awake you are, your level of awareness and how you respond to basic instructions.

Experts at the University of Glasgow in Scotland developed the GCS in 1974. Despite “coma”being part of the name, the GCS is the most commonly and widely used scale for measuring no decreases in consciousness, including coma.

What is consciousness?

In the medical context, consciousness has three requirements. To be conscious, you have to be:

• Awake: This includes whether or not you have the ability to wake up because of voice or touch. That’s what makes a coma different from just being asleep.
• Alert: This is how responsive you are to people talking to you and if you’re able to understand what’s happening in your immediate surroundings.
• Oriented: This means you know who you are, where you’re at, what day it is and other details related to the here and now.

When is the Glasgow Coma Scale used?

Medical staff, such as nurses, can use the GCS as part of a neurological exam. It’s also useful for any situation where you might have a decrease in how conscious you are. That includes injury-related conditions like concussions and traumatic brain injuries.

The scale also can help with conditions that don’t involve injuries, such as low blood sugar (hypoglycemia), poisoning or after a seizure.

What does the Glasgow Coma Scale measure?

A neurological exam looks for any problems with the function of the two main parts of your nervous system. Those parts are your:

• Central nervous system: This consists of your brain, brainstem, optic nerves (these link your brain to the retinas at the back of your eyes) and spinal cord.
• Peripheral nervous system: This is all the nerves outside of your central nervous system.

The Glasgow Coma Scale has three categories that apply to a neurological exam. Most of them apply to your brain itself, but some can also involve your spinal cord and nerves throughout your body:

• Eye response: This relates to how awake and alert you are.
• Motor response: This part is about how well your brain can control muscle movement. It can also show if there are any issues with the connections between your brain and the rest of your body.
• Verbal response: This tests how well certain brain abilities work, including thinking, memory, attention span and awareness of your surroundings.

How does the Glasgow Coma Scale work?

To get your Glasgow Coma Scale score, medical staff take the scores from the three categories of the GCS and add them together. A healthcare provider will test each of the three categories in multiple ways. An example of this is testing your verbal response by asking you a few different questions, such as what day of the week or date it is or what city you're in currently.

One of the best uses of the GCS is to track changes in your level of consciousness. A nurse will often repeat a neurological exam at regular intervals to check for and document any changes in your GCS score.

The scoring guidelines for the categories are as follows:

Eye response

This is mainly about how awake you are. If you’re unconscious, it measures the level of unconsciousness by testing reflex responses to pressure. Pressure here means something like a pinch or a poke. It should be just enough to cause minor, momentary discomfort but not injury.

Eye response score
4
Score meaning
You can open your eyes and keep them open on your own.
3
Score meaning
You only open your eyes when someone tells you to do so. Your eyes stay closed otherwise.
2
Score meaning
Your eyes only open in response to feeling pressure.
1
Score meaning
Your eyes don’t open for any reason.

 

Verbal response

A nurse checks this by asking you questions that test your memory, thinking ability and your awareness of the world around you. Your provider can also use this to see if there are any brain or nerve problems affecting control of your face and mouth.

Verbal response score
5
Score meaning
You’re oriented. You can correctly answer questions about who you are, where you’re at, the day or year, etc.
4
Score meaning
You’re confused. You can answer questions, but your answers show you’re not fully aware of what’s happening.
3
Score meaning
You can talk and others can understand words you say, but your responses to questions don’t make sense.
2
Score meaning
You can’t talk and can only make sounds or noises.
1
Score meaning
You can't speak or make sounds.

 

Motor response

This part can reveal any issues with the connections between your nerves, spinal cord and brain. It also tests your brain’s ability to control muscle movement and how well you can understand and follow instructions.