Glasgow Coma Scale

The Glasgow Coma Scale or GCS is a neurological scale that aims to give a reliable, objective way of recording the conscious state of a person for initial as well as subsequent assessment. A patient is assessed against the criteria of the scale, and the resulting points give a patient score between 3 (indicating deep unconsciousness) and either 14 (original scale) or 15 (the more widely used modified or revised scale).

GCS was initially used to assess level of consciousness after head injury, and the scale is now used by first aid, EMS, nurses and doctors as being applicable to all acute medical and trauma patients. In hospitals it is also used in monitoring chronic patients in intensive care.

The scale was published in 1974 by Graham Teasdale and Bryan J. Jennett, professors of neurosurgery at the University of Glasgow's Institute of Neurological Sciences at the city's Southern General Hospital.

GCS is used as part of several ICU scoring systems, including APACHE II, SAPS II, and SOFA, to assess the status of the central nervous system, as it was designed for. The initial indication for use of the GCS was serial assessments of patients with traumatic brain injury^[1] and coma for at least 6 hours in the neurosurgical ICU setting, though it is commonly used throughout hospital departments. A similar scale, the Rancho Los Amigos Scale is used to assess the recovery of traumatic brain injury patients.

Elements of the scale

Note that a motor response in any limb is acceptable.^[2] The scale is composed of three tests: eye, verbal and motor responses. The three values separately as well as their sum are considered. The lowest possible GCS (the sum) is 3 (deep coma or death), while the highest is 15 (fully awake person).

Eye response (E)

There are four grades starting with the most severe:

1. No eye opening
2. Eye opening in response to pain stimulus. (a peripheral pain stimulus, such as squeezing the lunula area of the patient's fingernail is more effective than a central stimulus such as a trapezius squeeze, due to a grimacing effect).^[3]
3. Eye opening to speech. (Not to be confused with the awakening of a sleeping person; such patients receive a score of 4, not 3.)
4. Eyes opening spontaneously

Verbal response (V)

There are five grades starting with the most severe:

1. No verbal response
2. Incomprehensible sounds. (Moaning but no words.)
3. Inappropriate words. (Random or exclamatory articulated speech, but no conversational exchange. Speaks words but no sentences.)
4. Confused. (The patient responds to questions coherently but there is some disorientation and confusion.)
5. Oriented. (Patient responds coherently and appropriately to questions such as the patient’s name and age, where they are and why, the year, month, etc.)

Motor response (M)

There are six grades:

1. No motor response
2. Decerebrate posturing accentuated by pain (extensor response: adduction of arm, internal rotation of shoulder, pronation of forearm and extension at elbow, flexion of wrist and fingers, leg extension, plantarflexion of foot)
3. Decorticate posturing accentuated by pain (flexor response: internal rotation of shoulder, flexion of forearm and wrist with clenched fist, leg extension, plantarflexion of foot)
4. Withdrawal from pain (Absence of abnormal posturing; unable to lift hand past chin with supra-orbital pain but does pull away when nailbed is pinched)
5. Localizes to pain (Purposeful movements towards painful stimuli; e.g., brings hand up beyond chin when supra-orbital pressure applied.)
6. Obeys commands (The patient does simple things as asked.)

Interpretation

Individual elements as well as the sum of the score are important. Hence, the score is expressed in the form "GCS 9 = E2 V4 M3 at 07:35".

Generally, brain injury is classified as:

• Severe, with GCS < 8–9
• Moderate, GCS 8 or 9–12 (controversial)^[4]
• Minor, GCS ≥ 13.

Generally when a patient is in a decline of their GCS score, the nurse or medical staff should assess the cranial nerves and determine which of the twelve have been affected.

Tracheal intubation and severe facial/eye swelling or damage make it impossible to test the verbal and eye responses. In these circumstances, the score is given as 1 with a modifier attached e.g. "E1c" where "c" = closed, or "V1t" where t = tube. A composite might be "GCS 5tc". This would mean, for example, eyes closed because of swelling = 1, intubated = 1, leaving a motor score of 3 for "abnormal flexion". Often the 1 is left out, so the scale reads Ec or Vt.

The GCS has limited applicability to children, especially below the age of 36 months (where the verbal performance of even a healthy child would be expected to be poor). Consequently the Pediatric Glasgow Coma Scale, a separate yet closely related scale, was developed for assessing younger children.

Revisions

• Glasgow Coma Scale: While the 15-point scale is the predominant one in use, this is in fact a modification and is more correctly referred to as the Modified Glasgow Coma Scale. The original scale was a 14-point scale, omitting the category of "abnormal flexion". Some centres still use this older scale, but most (including the Glasgow unit where the original work was done) have adopted the modified one.
• The Rappaport Coma/Near Coma Scale made other changes.
• Meredith W., Rutledge R, Fakhry SM, EMery S, Kromhout-Schiro S have proposed calculating the verbal score based on the measurable eye and motor responses.
• The most widespread revision has been the Simplified Motor and Verbal Scales which shorten the respective sections of the GCS without loss of accuracy.^[5]

Controversy

The GCS has come under pressure from some researchers who take issue with the scale's poor inter-rater reliability and lack of prognostic utility.^[6] Although there is no agreed-upon alternative, newer scores such as the Simplified motor scale and FOUR score have also been developed as improvements to the GCS.^[7] Although the inter-rater reliability of these newer scores has been slightly higher than that of the GCS, they have not gained consensus as replacements.^[8]

See also

• AVPU scale
• Blantyre Coma Scale
• Early warning score
• Paediatric Glasgow Coma Scale
• Rancho Los Amigos Scale
• Revised Trauma Score
• Triage

References

• Teasdale G, Jennett B (1974). "Assessment of coma and impaired consciousness: A practical scale".  
• Teasdale G, Murray G, Parker L, Jennett B (1979). "Adding up the Glasgow Coma Score". Acta Neurochir Suppl (Wien) 28 (1): 13–6.  
• Meredith W, Rutledge R, Fakhry SM, Emery S, Kromhout-Schiro S. (1998). "The conundrum of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores". J Trauma 44 (5): 839–44; discussion 844–5.  

External links

• Website to calculate the Glasgow Coma Scale
• Glasgow Coma Scale Calculator
• Glasgow Coma Scale at the US National Library of Medicine Medical Subject Headings (MeSH)
• An Android app to calculate GCS / PGCS
• Dr. Graham Teasdale speaks with The Lancet - podcast, August 2014
• Glasgow Coma Scale at 40
• Simplified Motor Score