The Glasgow Coma Scale (GCS) is a 15-point scoring system that measures a person’s level of consciousness by testing three things: whether they open their eyes, whether they can speak, and how they move. The total score ranges from 3 (completely unresponsive) to 15 (fully alert and oriented). Each component is assessed separately, then added together for the total.
The Three Components
The GCS breaks consciousness into three observable responses: eye opening (scored 1 to 4), verbal response (scored 1 to 5), and motor response (scored 1 to 6). You assess each one independently, always recording the best response the person demonstrates. The assessment follows a structured sequence: start by observing, then use voice, then use physical stimulation if needed. Only escalate to the next level of stimulus when the previous one produces no response.
How to Score Eye Opening
Eye opening tells you about the person’s arousal, which is the most basic layer of consciousness. Score it on a scale of 1 to 4:
- 4, Spontaneous: The person’s eyes are already open before you do anything. They may be looking around or tracking movement.
- 3, To sound: The eyes open only after you speak to them or make a loud noise. Try a normal voice first, then a louder command if needed.
- 2, To pressure: The eyes open only when you apply physical stimulation, such as pressing firmly on the fingernail bed or pinching the trapezius muscle at the shoulder.
- 1, None: The eyes do not open at all, even with physical stimulation.
If the person’s eyes are swollen shut from injury or surgery, you cannot score this component. Rather than guessing or assigning a 1, record the eye component as “not testable” (NT). This distinction matters because a swollen eye is not the same as a brain that cannot trigger eye opening.
How to Score Verbal Response
The verbal component measures whether the person can process language and produce meaningful speech. Score it from 1 to 5:
- 5, Oriented: The person can tell you who they are, where they are, and the date or time. They carry on a normal conversation.
- 4, Confused: They speak in full sentences and respond to questions, but their answers are wrong or muddled. They might say they’re at home when they’re in a hospital.
- 3, Inappropriate words: They produce recognizable words, but not in a conversational way. They might shout random words or curse without context.
- 2, Incomprehensible sounds: They make noises like moaning or groaning, but nothing that qualifies as an actual word.
- 1, None: No sounds at all, even with physical stimulation.
If the person has a breathing tube in place (intubation), verbal response is physically impossible. Record it as NT rather than scoring a 1. The same applies to anyone with a tracheostomy or severe facial trauma that prevents speech. In these cases, you can still assess and report the eye and motor scores individually.
How to Score Motor Response
Motor response is the most informative of the three components and carries the most weight in predicting outcomes. It is scored from 1 to 6:
- 6, Obeys commands: Ask the person to perform two distinct actions, like “hold up two fingers” and “touch your nose.” If they do both correctly, score a 6. Using two commands rules out coincidental movement.
- 5, Localizing: When you apply a physical stimulus, the person reaches toward the source of the pain and attempts to remove it. For example, if you press on their fingernail, their other hand comes across to push yours away.
- 4, Normal flexion (withdrawal): The person pulls the limb away from the stimulus in a normal bending motion, like quickly pulling a hand off a hot stove. The movement is rapid but not purposeful.
- 3, Abnormal flexion: The arms bend inward toward the body, wrists curl, and fingers clench. This stereotyped posture indicates damage to brain structures above the brainstem. It looks distinctly different from normal withdrawal because the whole arm and wrist flex in a rigid, slow pattern.
- 2, Extension: The arms straighten out, rotate inward, and the wrists extend. This posture signals deeper brain damage, involving the brainstem itself.
- 1, None: No movement at all in response to any stimulus.
The critical distinction to practice is the difference between scores of 3, 4, and 5. Normal withdrawal (4) is a quick pull-away. Abnormal flexion (3) is a slow, stereotyped curling of the arms and wrists. Localizing (5) involves purposeful movement toward the stimulus. When in doubt, watch whether the person’s hand crosses the midline of their body to reach the source of pain, which is a reliable sign of localizing.
Applying Physical Stimulation Correctly
When the person does not respond to voice, you need to apply a physical stimulus to test their response. The recommended techniques are peripheral pressure (pressing a pen or pencil against the side of a fingernail bed) and central pressure (pinching the trapezius muscle between your thumb and two fingers). Pressing on the trapezius is generally preferred for testing motor response in the upper body because it allows you to observe the arm’s response pattern clearly.
Sternal rubs, where you grind your knuckles into the breastbone, are falling out of favor. They can leave bruising and are harder to standardize. Fingernail bed pressure works well for testing limb withdrawal but may not trigger a localizing response since the person would need to use the same hand being stimulated. Using at least two sites gives you a more complete picture.
Always test both sides of the body. Record the best response from either side. If the right arm localizes (5) but the left arm shows abnormal flexion (3), the motor score is 5. The individual component scores still carry important information, though, so note side-to-side differences when they exist.
Calculating and Recording the Score
Add the three component scores together: E + V + M = total GCS. A fully conscious, oriented person scores E4 + V5 + M6 = 15. A completely unresponsive person scores E1 + V1 + M1 = 3. The minimum is 3, not 0, because each component bottoms out at 1.
Always record the individual component scores alongside the total. Writing “GCS 9” alone is far less useful than writing “E2 V3 M4” because two patients can have the same total score with very different clinical pictures. A person scoring E3 V5 M1 has a dramatically different problem than someone scoring E1 V2 M6, even though both add up to 9. The motor score, in particular, carries the strongest predictive value for outcomes after brain injury.
If any component cannot be tested, do not substitute a 1 and do not calculate a total score. Instead, report the testable components individually. For example, a patient who is intubated and has swollen eyes but localizes to pain would be recorded as “ENT VNT M5.”
What the Scores Mean
In the context of traumatic brain injury, total GCS scores are grouped into three severity categories:
- 13 to 15: Mild injury
- 9 to 12: Moderate injury
- 3 to 8: Severe injury
A score of 8 or below is a common threshold for considering that a patient cannot protect their own airway. A GCS of 15 means the person is fully alert, oriented, and moving normally, but it does not rule out brain injury entirely. Someone with a concussion can score 15 and still have significant symptoms.
Trending the score over time is often more valuable than any single measurement. A drop of 2 or more points from one assessment to the next is a significant change that signals worsening brain function. Conversely, a rising score after injury suggests recovery. This is why repeated, consistent assessments by the same method matter so much.
Common Factors That Affect Accuracy
Several situations can make GCS assessment unreliable if you are not aware of them. Sedation and pain medications suppress all three components, so a low score in a medicated patient may reflect the drugs rather than brain damage. Alcohol intoxication can mimic a depressed consciousness level. Ideally, you would note these factors alongside the score rather than adjusting the numbers.
Spinal cord injuries can eliminate motor responses in the limbs even when the brain is functioning normally. Hearing impairment or a language barrier can make a person appear disoriented when they simply cannot understand the questions. Pre-existing conditions like dementia or aphasia from a prior stroke will lower the verbal score at baseline. In all of these cases, documenting the confounding factor is just as important as documenting the score itself, because the number alone can be misleading.