Coma
Definition:
A state of complete unarousable unresponsiveness regardless of the stimulus, typically
lasting for 2–4 weeks.
A comatose state is characterized by closed eyes and decreased/absent reflex responses and
motor activity, but preserved circulatory function and breathing drive. (absent respiratory
drive seen in brain death)
Aetiology:
1. Structural causes:
a. Head injury: extradural/subdural haematoma
b. Vascular: intracerebral/subarachnoid haemorrhage
c. Cerebral tumour
2. Cerebral infection: meningitis, encephalitis, abscess, cerebral malaria
3. Drugs: morphine, narcotic overdose, benzodiazepine, barbiturates
4. Toxins: CO gas toxification, lead, alcohol
5. Metabolic:
a. Cardiopulmonary arrest (hypoxia, hypercapnia)
b. Diabetic emergencies (DKA, Hyperglycaemic hyperosmolar state, hypoglycaemia)
c. Endocrine: myxoedema coma, thyroid storm, Addisonian crisis
d. Hypothermia/hyperthermia
e. Hyponatraemia/hypernatremia
f. Hypocalcaemia/hypercalcaemia
g. Thiamine (vitamin B1) deficiency (Wernicke’s encephalopathy)
h. Hepatic encephalopathy
i. Uraemia encephalopathy
6. Epilepsy: postictal state
7. Psychogenic coma
Structural causes vs metabolic causes:
Subject Structural cause Metabolic cause
State of consciousness Stationary, progressive Mild, intermittent
Respiration - Rapid & deep
Fundus Papilledema -
Muscle tone Asymmetrical Symmetrical
Approach to coma
1. Airway, breathing and circulation management and body temperature
a. Give O2 supply to maintain oxygen saturation >95%
b. Intubate patient if airway cannot be maintained (increased work of breathing,
pooling of secretions, irregular ineffective respiratory drive)
c. Correct hypotension by putting patient in Trendelenburg position and give
crystalloids; if no response give inotropes
d. Correct extreme hypertension (BP >220/>120 mmHg) by giving IV labetalol
e. Correct hypothermia with warming blanket
f. Correct hyperthermia with cooling blankets, icepacks
2. Take blood for investigation:
a. FBC
b. Fingerstick blood glucose
c. BUSE, serum creatinine: look for serum Ca & phosphate, serum Na
d. Liver function test (AST/ALT): evaluate for hepatic encephalopathy
e. ABG
f. Toxic screening (acetaminophen, salicylates, opioids)
3. Administer:
a. 50 mL IV 50% dextrose (for hypoglycaemia or when glucose level not obtained)
b. Thiamine
i. Given if patient looks malnourished or alcohol intoxication
ii. It is given before dextrose administration to avoid worsening alcohol
intoxication (Wernicke-Korsakoff syndrome)
c. Naloxone: given if narcotic overdose (opioid toxication) suspected
d. Flumazenil: given if benzodiazepine overdose suspected
4. Obtain detailed history and physical examination
5. History
a. Obtain from accompanying family, relatives, friends
b. Find out medical history: whether patient has DM, thyroid disease, adrenal disorder,
use of corticosteroid, history of injury, recent fever (infection), psychiatric disease
(suicidal overdose)
c. Review all patient’s medication
6. Physical examination
a. Vital signs
i. Hypertension: hypertensive encephalopathy, increased ICP
ii. Hypotension: alcohol/barbiturate intoxication, MI, Addisonian crisis, sepsis
iii. Fever: cerebral infections, thyrotoxicosis, sepsis
iv. Bradycardia: beta-blocker/calcium channel blocker overdose, increased ICP
v. Tachycardia: hypovolaemia, sepsis
vi. Cheyne-Stokes respiration (brainstem not enough O2): stroke, heart failure,
diencephalic herniation
vii. Kussmaul’s breathing: DKA
b. Inspection
i. Cherry red lips: CO gas poisoning
ii. Bitten tongue: convulsive seizure
iii. Needle tracks: IV drugs user (drug abuse)
iv. Jaundice, spider angiomata, palmar erythema: liver disease
v. Goitre: hypo/hyperthyroidism
vi. Sign of injury (skull fractures)
c. Assessment of Glasgow coma scale score.
d. Brainstem function assessment:
i. Pupillary reflexes
ii. Corneal reflexes
iii. Vestibulo-ocular reflexes
e. Eyes: fundoscopic for papilledema (increased ICP), retinal haemorrhage
(subarachnoid haemorrhage)
f. Tongue and mouth
i. Breath:
Alcohol (alcohol intoxication)
Fruity smell (DKA)
Fishy smell (Uraemic encephalopathy)
Musty smell (Hepatic encephalopathy)
ii. Gag reflex
g. Neck and meningism
i. Neck stiffness (tonsillar herniation, meningitis)
ii. Kernig’s sign, Brudzinski sign
h. Motor exam (power is not able to obtain from comatose patient)
i. Posture
Decorticate: indicate lesion above the midbrain
Decerebrate: indicate lesion at the midbrain (tonsillar herniation)
Progression from decorticate to decerebrate often indicate
uncal/tonsillar herniation
ii. Involuntary movement
Twitching of eye lids (seizures)
Flapping tremors (renal/liver failure, indicate CO2 retention)
Myoclonus: quick, involuntary muscle jerk (anoxic encephalopathy)
Shivering (sepsis, hyperthermia)
7. If there is sign of increased ICP from PE:
a. Urgent measure to reduce ICP
i. IV mannitol
ii. Head elevation 30 degree
iii. Mechanical hyperventilation
b. Urgent CT scan to find out cause of increased ICP (intracerebral haemorrhage,
cerebral abscess, hydrocephalus, ischaemic stroke)
8. If there is focal neurological deficits and external evidence trauma from PE:
a. Urgent CT scan to look for intracranial haemorrhage
9. If there is sign of meningism:
a. Start empirical antibiotic immediately
b. Urgent CT brain, then LP if there is no contraindications
10. If there are no significant findings from PE do further investigation:
a. Thyroid function test for hypo/hyperthyroidism
b. Serum cortisol Addisonian crisis
c. Blood and urine culture suspect for sepsis
d. Blood Film for Malaria Parasite (BFMP)
e. Urine ketone for DKA
f. Chest X-ray
g. ECG: look for causes of cardiac arrest (e.g., ventricular tachycardia)
h. EEG for non-convulsive epilepticus
11. General care for comatose patient
a. Hydration and nutrition – IV fluids and NG feedings
b. Joint mobility – Maintained with passive exercise
c. Corneal abrasion – prevent by taping eyelids and applying methylcellulose drops (1
drop every 4 hourly)
d. Prevention of stress-induced gastric ulcer – protein pump inhibitor
e. Prevention of DVT – Heparin or LMWH, pneumatic compression device
f. Urinary catheterization
Glasgow coma scale assessment:
1. Eye movement
Criterion Score
Spontaneously opens eyes 4
Eye opening to sound 3
Eye opening to pain (pain can be induced with finger prick/trapezius 2
pressure/supraorbital pressure)
No response 1
2. Verbal response
Criterion Score
Orientated (able to answer question correctly) 5
Confused (able to answer but answers are not correct) 4
Inappropriate words (respond with random words unrelated to 3
question)
Incomprehensible sounds (making noise instead of speaking words) 2
No response 1
3. Motor response
Criterion Score
Obeys command 6
Localises to pain (patient make attempts to reach toward site where 5
pain is applied)
Withdraws to pain (patient tries to pull away from painful stimulus) 4
Decorticate: Flexion of arm and wrist, adducted arm, leg extension 3
(abnormal flexion to pain)
Decerebrate: Head extended, arms and legs extended, patient 2
appear rigid with teeth clenched
No response to pain 1
4. Score of 3 components are added together to become a GSC score. The highest possible
score is 15 (fully conscious) and the lowest possible score is 3 (coma or dead).
Brainstem function assessment
1. Pupillary reflexes: Done by shining light onto pupil and see the response of pupil
a. Pinpoint (small, 2mm), unreactive pupils: opioid overdose, pontine lesion
b. Mid-sized, fixed pupils (4-6mm): midbrain injury
c. Unilateral, dilated (>8mm), unreactive pupil: uncal herniation with 3 rd nerve
compression, diencephalic herniation
d. Bilateral (>8mm), dilated, unreactive pupil: brain death, deep coma of any cause
2. Corneal reflexes: Done by gentle touching cornea with cotton
a. Normal: both eyes blink
b. Absent reflex (eyes blink): brainstem injury
3. Vestibulo-ocular reflexes
a. Doll’s eye maneuver
i. Technique: Head is turned abruptly form one side to another and observe
the movement of eyes
ii. If eyes move in opposite direction: normal
iii. If eyes move in similar direction: brainstem injury, deep coma
b. Caloric test
i. Technique: External auditory canal is irrigated with ice water and observe
eye movement
ii. Normal: eyes deviate to irrigated ear
iii. Brainstem injury: absence of eye response
