Level of consciousness: The degree of arousal and awareness.
A manifestation of altered consciousness implies an underlying brain dysfunction.
Its onset may be
§ Sudden [Example following an acute head injury]
§ Gradually [Such as in hypoglycemia]
CAUSES OF ALTERED CONSCIOUSNESS
A range of situations can lead to altered consciousness.
These include:
§ Profound hypoxaemia
§ Hypercapnia
§ Cerebral hypoperfusion
§ Stroke
§ Convulsions
§ Hypoglycemia
§ Recent administration of sedatives
§ Drug overdose
§ Subarachnoid hemorrhage
§ Alcohol intoxication
GLASGOW COMA SCALE [GCS / EVM]
It 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
Ø 3 (Indicating deep unconsciousness)
Ø 15 (Indicating conscious)
GCS was initially used to assess level of consciousness after head injury, and the scale is now used by first aid, EMS, 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.
ELEMENTS OF GCS
The scale comprises 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).
BEST EYE RESPONSE (E)
There are 4 grades starting with the most severe:
1. No eye opening
2. Eye opening in response to pain. (Patient responds to pressure on the patient’s fingernail bed; if this does not elicit a response, supraorbital and sternal pressure or rub may be used.)
3. Eye opening to speech. (Not to be confused with an awaking of a sleeping person; such patients receive a score of 4, not 3.)
4. Eyes opening spontaneously
BEST VERBAL RESPONSE (V)
There are 5 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)
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.)
BEST MOTOR RESPONSE (M)
There are 6 grades starting with the most severe:
1. No motor response
2. Extension to pain (abduction of arm, internal rotation of shoulder, pronation of forearm, extension of wrist, decerebrate response)
3. Abnormal flexion to pain (adduction of arm, internal rotation of shoulder, pronation of forearm, flexion of wrist, decorticate response)
4. Flexion/Withdrawal to pain (flexion of elbow, supination of forearm, flexion of wrist when supra-orbital pressure applied ; pulls part of body away when nailbed pinched)
5. Localizes to pain. (Purposeful movements towards painful stimuli; e.g., hand crosses mid-line and gets above clavicle when supra-orbital pressure applied.)
6. Obeys commands. (The patient does simple things as asked.)
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:
Ø Severe, with GCS ≤ 8
Ø Moderate, GCS 9 - 12
Ø Minor, GCS ≥ 13
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).