Glasgow Coma Scale
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The Glasgow Coma Scale (GCS, or sometimes Glasgow Coma Score) is a scale for measuring the conscious level of a patient quantitatively. It aims to provide a reliable, reproducible and objective indication of impairment of consciousness, for use both in initial assessment and continuing observation of both trauma and medical patients. The scale was originally introduced to aid in assessing the conscious level after head injury, and has since been generalised for use in all neurological observation. It is used in calculating disease severity scores such as the APACHE II, SAPS II and SOFA.
The original score permitted a maximum of 14; this was modified to include abnormal flexion, giving a maximum score of 15. This score, technically the modified Glasgow Coma Scale, is now the generally accepted form.
Calculating the GCS
The scale comprises three parts:
- Eye opening
- Best verbal response
- Best motor response
- The score should be made after rousing the patient (if asleep), and the best response noted in each category.
- The three parts of the score should be recorded each time the GCS is measured, such as "GCS 8/15 (M4 V2 E2)", so that if a change occurs in the score it can be ascertained exactly where this change occurred.
- The patient's premorbid condition should be taken into account. For example, if a patient is known to be aphasic, the two other components of the score can be recorded, i.e. "GCS 8/10 (M5 E3 VN/A).
- This part records the best eye opening response to stimuli, and is scored from 1 to 4:
- Eyes open spontaneously
- Eyes open to verbal stimulus
- Eyes open to painful stimulus
- No eye opening
Best verbal response
- This part records the best verbal response made by the patient to various stimuli, and is scored from 1 to 5:
- Oriented - patient responds appropriately to questions
- Confused - patient responds to questions but is disoriented or confused
- Inappropriate words
- Incomprehensible sounds
- No verbal response
Best motor response
- This part records the best motor response made by the patient to various stimuli, and is scored from 1 to 6:
- Obeys commands
- Localises to pain - purposeful movement to source of painful stimulus
- Flexion - withdrawal from painful stimulus
- Abnormal flexion to pain - decorticate response of arm adduction and internal rotation and flexion of wrist
- Extension to pain - decerebrate response of arm adduction and internal rotation with extension of wrist
- No motor response
This can be summarised in a table for quick reference:
|Score||Best motor response||Best verbal response||Eye opening|
|3||Abnormal flexion||Words||To speech|
The scale is used to classify head injury according to severity:
|Severe head injury||GCS ≤ 8*|
|Moderate head injury||GCS 9-12|
|Minor head injury||GCS 13-15|
* after initial resuscitation
A GCS of 8 or less is taken to be equivalent to coma, and can be used as a part of clinical assessment of the need to provide airway protection (i.e. endotracheal intubation) in unconscious patients of any cause.
The GCS is also used in patients requiring neurological observation. A drop in the GCS of 2 points or more, or a drop of one point persisting for more than 30 minutes should prompt review of head injured patients and consideration of brain imaging (i.e. CT scan).