Chapter 15 – Neurological system assessment
Glasgow Coma Scale
The Glasgow Coma Scale (GCS) is a common neurological tool to assess level of consciousness and detect and track clinical changes in consciousness when clients have had a traumatic brain injury or any condition that causes an impairment in consciousness (Teasdale et al., 2014).
GCS is used in the context of head injuries, cerebral hemorrhage or lesions, stroke, and general trauma. It is commonly used in acute and emergency care, critical care, post-operative care, and in neurological settings. It is important to elicit a baseline and then monitor trends, particularly with an altered GCS or during the acute phase of a neurological condition.
Steps in the GCS assessment include:
- Assess for any factors that could influence your assessment (see Contextualizing Inclusivity textbox below).
- Observe behaviours as per Table 3 and apply verbal and physical stimuli as needed (e.g., if spontaneous behaviours are absent).
- Judge criteria with rating and score.
- Evaluate the score for each component (eye opening, verbal response, best motor response).
- Evaluate the total GCS score by adding up scores for the three components of the GCS
- If any components are “non-testable,” note this and do not provide a total score. For example, verbal responses may not be testable if a client has a breathing tube, and eye opening may not be testable if a client has periorbital edema that prevents eye opening.
See Video 2 on how to use the Glasgow Coma Scale with a demonstration.
Table 3: Components of the Glasgow Coma Scale. (copyright Teasdale, 2015, permission to use in this resource).
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Eye opening
Verbal response
Best motor response
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Clinical Tips: Physical Stimuli and Flexion Responses
If no response is elicited when using the GCS, you may need to apply physical stimuli (see Figure 5), which are usually applied in the following order to:
- Finger nail bed.
- Trapezius muscle.
- Supraorbital notch.
Figure 5: Physical stimulus.
Copyright Teasdale, 2015 (used with permission), https://www.glasgowcomascale.org/downloads/GCS-Assessment-Aid-English.pdf?v=3.
Contextualizing Inclusivity
Before using the GCS, assess for factors that could influence the validity of the tool.
For example, children under five may not be able to obey commands and answer questions. The GCS components provided in Table 3 are considered reliable for those over the age of 5 (Royal College of Physicians and Surgeons of Glasgow, n.d.). When working with children, it is best to check with your institution about whether they use a specific scale, e.g., the Paediatric Glasgow Coma Scale or other tools to evaluate level of consciousness.
Another issue is that a hearing impairment can influence a client’s ability to respond to verbal stimuli. You may need to employ alternative options such as gently touching the client’s arm to observe if their eyes are open, using sign language, or writing on a piece of paper.
Other factors could include or barriers that inhibit clients from speaking, such as a breathing tube. Many pathologies and conditions can affect the validity of the GCS such as the presence of hypoxemia, intellectual and neurological deficits, and movement disorders, pharmacological agents such as sedation, and use of alcohol, cannabis, or other substances that affect cognition.
Prioritizing Care
GCS scores can range from 3 (unresponsiveness in all three components of the GCS tool) to 15 (no deficits in responsiveness in all three components of the GCS tool) (National Institute for Health and Care Excellence [NICE], 2023). With acute traumatic brain injury, GCS scores are classified as:
- Severe injury: GCS 8 or less (suggestive of coma state).
- Moderate injury: GCS 9 to 12.
- Mild injury: GCS 13 to 15.
(NICE, 2023).
Anyone presenting in a community or emergency setting with decreased consciousness or a score of less than 15 should be assessed immediately. At first, clients with GCS scores below 15 should be monitored regularly. The frequency of GCS assessment varies significantly: it is contingent on timing since the injury/trauma as well as trends in improvement or deterioration. Until a stable pattern is observed, all changes should be reported to the physician/nurse practitioner. NICE (2023) recommends the following frequency of observation:
- Every 30 minutes until GCS is 15 or every 30 minutes if there is a decrease in the GCS.
- If GCS is 15: observe every 30 minutes for 2 hours, then hourly for 4 hours, then every 2 hours.
These frequencies may vary depending on the client’s situation, the acuity of symptoms, and the institution/unit.
NICE (2023). Head injury: Assessment and early management. https://www.nice.org.uk/guidance/ng232/resources/head-injury-assessment-and-early-management-pdf-66143892774085
Royal College of Physicians and Surgeons of Glasgow. (n.d.). The Glasgow structured approach to assessment of the Glasgow Coma Scale. https://www.glasgowcomascale.org/faq/
Teasdale, G., Maas, A., Lecky, F., Manley, G., Stocchetti, N., & Murray, G. (2024). The Glasgow Coma Scale at 40 years: Standing the test of time. The Lancet Neurology, 13(8), 844-854.
is when you (ie., the nurse) and the client do not speak the same language.
