Glasgow Coma Scale - Past Present Future

Glasgow Coma Scale
Past, Present, Future
KKH Morning Teaching - March 2013
Tan Hon Liang

Past: Background
 1940s
 WWII: Medical Research Council, UK issued glossary of terms
used in cases of head injury.
 16 terms included coma, semi-coma, stupor, confusion,
obtundation.
 Tedious and not unified.

Past: Background
 Advent of Critical Care (1947 Polio outbreak)
 Improved survival with resuscitation.
 Intensivists wanted to know how to predict who was worth
treating (or continuing to treat), and to assess the relative value
of alternative management
 Need for uniform language to communicate patient status and
for research

Past: Background
 In 1974
 (Sir) Graham Teasdale (1940 - )
 RCS President 2003-2006
 Knighted 2006
 Bryan Jennett (1926-2008)
 Other fame: “Economy Class Syndrome”
 Computerized database
 Neurosurgeons in Glasgow

Lancet. 1974 Jul 13;2 (7872):81-4.
Assessment of coma
and impaired consciousness.
A practical scale.
Citation count: 7417

Past: Background
 Original 14 point scale intended to objectively determine the
severity of brain dysfunction and coma six hours after the
occurrence of head trauma.
 Why 6 hours?
 Subsequent revised in 1976 with the addition of a sixth point
in the motor response subscale for “withdrawal from painful
stimulus”

Past: Background
 Accepted classification:
 13-15 (mild HI)
 9-12 (moderate HI)
 < 8 (severe HI)

Past: Background
 World wide adoption contributed in no small part by nurses.
 Easy to chart.

Past: Background
 Numerical, easy to analyze.
 Since 1974, > 4000 articles published.
 Added into other scores: APACHE, SAPS, TRISS, CRAMS,
ASCOT.
 Used to prognosticate.
 Used to recommend treatment: WFNS for SAH, ATLS for
intubation.
 Advocates and detractors.

Past: Background
 How about kids?

Past: Background
 Different total score proposed:
 9 (at six months),
 11 (at 1 year),
 13-14 (at 5 years)
 Paediatric Glasgow Coma Scale
 For adjust for milestones which have not been reached.

Past: Background
 EYE OPENING
 Spontaneous (4) : indicative of activity of brainstem arousal
mechanisms but not necessarily of attentiveness.
 To speech (3) : tested by any verbal approach (spoken or
shouted).
 To pain (2) : tested by a stimulus in the limbs (supraorbital
pressure may cause grimacing and eye closure).
 None (1) : no response to speech or pain.

Past: Background
 EYE OPENING Limitations:
 Vegetative States: Eyes may spontaneously open. “Lights on, but
nobody at home”.
 Noxious stimulus: grimace and eye closure. Then how?
 Eye injury.
 Drugs: muscle relaxants, sedation.

Past: Background
 BEST VERBAL RESPONSE
 Oriented (5): awareness of the self and the environment (who /
where / when).
 Confused (4): responses to questions with presence of
disorientation and confusion.
 Inappropriate words (3): speech in a random way, no
conversational exchange.
 Incomprehensible sounds(2): moaning, groaning.
 None (1): no response.

Past: Background
 BEST VERBAL RESPONSE Limitations:
 Facial injury.
 Focal neurological injury:
 Broca’s aphasia
 Wernicke’s aphasia
 Conductive aphasia
 Language.
 Intubation, tracheostomy.
 Drugs: muscle relaxants, sedation.

Past: Background
 BEST MOTOR RESPONSE
 Obeying commands (6)
 Localizing (5): movement of limb as to attempt to remove the
stimulus, the arm crosses midline.
 Normal flexor response (4): rapid withdrawal and abduction of
shoulder.
 Abnormal flexor response(3): adduction of upper extremities, flexion
of arms, wrists and fingers, extension and internal rotation of lower
extremities, plantar flexion of feet, and assumption of a hemiplegic or
decorticate posture.
 Extensor posturing (2): adduction and hyperpronation of upper
extremities, extension of legs, plantar flexion of feet, progress to
opisthotonus (decerebration).
 None (1)

Past: Background
 BEST MOTOR RESPONSE Limitations
 M4-6: Must rule out grasp reflex or postural adjustment.
Peripheral stimuli may elicit a spinal reflex response, while
pressure on the sternum or the supraorbital ridge may cause
injury.
 M3: implies that the lesion is located in the internal capsule or
cerebral hemispheres
 M2: score of 2 describes a midbrain to upper pontine damage
 M1: must rule out an inadequate stimulus, spinal transection,
limb injury/pain.

Past: Background
 Despite all that limitation, GCS continues to be widely
adapted.
 Used to:
 assess coma, monitor changes in coma,
 as indicator of severity of illness
 Triage patients with head injury in EMD/to ICU
 aid in clinical decisions, such as intubation

Present: True or False
1. Glasgow Coma Scale is an accurate neurological assessment
tool.
2. GCS predicts outcome.
3. GCS < 9: I should intubate the patient.
 If I don’t, the patient will aspirate/die.
 Other than trauma, I can use GCS for
 Poisoning,
 Stroke,
 Sepsis.

1. Glasgow Coma Scale is an
accurate neurological assessment
tool?
 Effects of resuscitation
 Benzodiazepine, induction drugs, muscle relaxants, intubation,
eye trauma, ear injury.
 GCS 3 performs better than GCS 4
 Less than 4% of patients die without opening eyes. Arousal
does not mean awareness.
 Hence does not accurate reflect extent of neurological
dysfunction.

GCS has observer bias.
- Observations may not be standardized.
- Errors up to 2 points.

2. Glasgow Coma Scale can
predict outcome?
 A number of studies show correlation.
 But a number also show no correlation.

predict outcome?
 Bruechler et al (1998) contacted 73 Level I trauma centers
and questioned them about GCS scoring in case of
intubation.
 26% of the trauma centers gave 1 point for verbal component,
 23% 3 points,
 16% assigned a “T” for verbal component.
 Other studies mention the pseudoscoring technique
 replacing missing values with an average value of the testable
score (Meredith et al., 1998)
 or assigning a score of 5 if patients seem able to talk, of 3 if there
is questionable ability to talk and of 1 if patients are generally
unresponsive (Rutledge et al., 1996).

As a result, a lot of research cannot be reliably intepreted.
Or trusted.

predict outcome?
 The GCS is an ordinal scale.
 The difference between unit values is not consistent and
compares only better with worse
 Yet, minimal differences of GCS scores are important in terms of
prognosis.
 The scale incorporates a numerical skew towards motor
response, because there are only 4 points for eye response,
versus 5 for verbal and 6 for motor responses.
 Summing the three sub- scales assumes an equal weighting for
each one, thus leading to loss of information since the same
score can be made up in various ways

predict outcome?
 GCS: collection of 120 mathematical combinations
 eighteen possible permutations exist for total GCS score of 9
 seventeen for scores 8 and 10
 fourteen for scores 7 and 11
 ten for scores 6 and 12
 Therefore, not all GCS 9 are equal.
 How can one prognosticate outcome if not all that seems are
equal?

3. GCS and Intubation
 GCS < 9 = Intubate

Clinical Case 1
 You are the Anaesthetic On Call.
 You are called to the Emergency Department to assist in the
airway management of a 14 year old female, A.

Clinical Case 1
 You are informed that this child was found by her parents
drowsy at home in bed with 2 empty can of beer and 1 empty
750 ml bottle of wine.
 You assess the patient…

Clinical Case 1
 Eyes do not open to stimulus.
 Speech is incoherent and slurred.
 There is flexion of her upper limbs to stimulus.

Clinical Case 1
 What do you do next?
 Do you intubate this patient?

Clinical Case 2
 You are the Anaesthetic On Call.
 You are called to the Emergency Department to assist in the
airway management of a 14 year old female, B.

Clinical Case 2
 You are informed that this child was found by her parents
drowsy at home in bed.
 She is known to have epilepsy.
 You assess the patient…

Clinical Case 2
 Eyes do not open to stimulus.
 Speech is incoherent and slurred.
 There is flexion of her upper limbs to stimulus.

Clinical Case 2
 What do you do next?
 Do you intubate this patient?

Advocates
 On the basis of recommendations from
 the American College of Surgeons Committee on Trauma,
 the European Society of Intensive Care Medicine and
 the Eastern Association for the Surgery of Trauma,
 GCS <9 is used as the level at which intubation is considered
mandatory.

One paper that ruled them all….

Advocates
 Rationale:
 Hypoxemia is bad for the injured brain.
 Tracheal intubation is the surest way of delivering oxygen.
 Therefore, intubation is mandatory.
 (How about just providing oxygen with jaw thrust??)
 Additional benefit of preventing aspiration.
 (Chances are it would already have occurred)

3. GCS < 9 does not mandate
intubation
 Not all GCS < 9 are equal.
 GCS scoring wise, we seen that.
 Not to be extrapolated to all forms of depressed neurology.
 Trauma is different from poisoning, stroke, sepsis.
 Not all GCS < 9 lose gag/cough reflex.
 Not all who loses gag/cough reflex aspirates.

Association with respiratory insufficiency but no association
between a particular GCS and impaired pharyngeal control!
GCS < 9 does not mandate intubation

Considerable proportion of patients with low GCS had
gag/cough.
Many patients with GCS>8 had impaired airway reflexes.

All GCS < 9 non trauma EMD patients included:
557 patients. 129 tubed for cardiac arrest, resp failure, severe stroke.
428 not tubed: 364 (85%) regained consciousness,
64 remained unconscious – 12 of these needed to be tubed

Drug or alcohol intoxication: 73 patients
12 GCS <9 but none required intubation or
aspirated.
1 patient intubated: GCS 12 on presentation!

Clinical Cases
 Case 1: intoxicated A
 Tube?
 Case 2: post ictal B
 Tube?

The Future?
 GCS
 Past has been glorious.
 Present is murky.
 Future is uncertain.

My Conclusion
 GCS:
 It’s for Head Injury. Be careful extrapolating beyond what it is
meant to do.
 After 6 hours.
 For communication
 For standardized classification/research.
 Useful for trending, but beware observer error. Drop in 2 points
probably good trigger for reassessment.
 No magic number for intubation
 <9 doesn’t always mean tube, while >/= 9 does means it is safe.

Glasgow Coma Scale - Past Present Future

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