Coma

Definitions

  • Coma: unresponsive, unrousable state
  • Stupor: unresponsive, rousable state
  • Confused: alert, but disorientated
  • Delirium: like confusion, but also agitated and restless

Glasgow Coma Scale

  • Eyes: 4
    • 4 spontaneous opening
    • 3 opening to command
    • 2 opening to pain
    • 1 not opening
  • Verbal: 5
    • 5 spontaneous, orientated,
    • 4 confused speech
    • 3 inappropriate words
    • 2 inappropriate sounds
    • 1 no sounds
  • Motor: 6
    • 6 obeys commands
    • 5 localises to pain
    • 4 flexor withdrawal response to pain
    • 3 abnormal flexor posturing (above the red nucleus, decorticate)
    • 2 abnormal extensor posturing (below the red nucleus, decerebrate)
    • 1 no movement

Pathogenesis

Consciousness depends on the following structures:

  • Pontomesencephalic reticular formation
  • Thalamus and hypothalamus
  • Diffuse cortical projections

Causes of coma

  • Coma without focal signs
    • Post-ictal
    • Anoxic
    • Metabolic
      • Hypoglycaemia
      • Hyponatraemia
      • Acidaemia
      • Uraemia
      • Liver failure
      • Myxoedema
      • Wernicke encephalopathy
    • Toxic
      • Opiates
      • Benzos
      • Tricyclics
      • Alcohol
      • Neuroleptics
    • Coma with focal signs
      • Vascular event
      • SOL compressing the brainstem
    • Coma with signs of meningism
      • SAH
      • Meningitis
      • Encephalitis

Initial assessment & Management

  • Resuscitation
  •  Examination
    • Document the level of consciousness
    • Define the cause of coma
      • Diffuse encephalopathy
      • Supratentorial lesion
      • Infratentorial lesion

Resuscitation

  • Airway & C-spine
  • Breathing – give O2
  • Circulation
  • Diabetes
    • 50ml 50% dextrose
    • If suspicious of Wernicke encephalopathy, consider thiamine as well
  • Drugs
    • Consider naloxone
  • Epilepsy
    • If seizures are ongoing, terminate IV 4mg lorazepam, buccal 10mg midazolam
  • Fever
    • Meningitis? Encephalitis?
  • GCS
  • Herniation: is there evidence of coning?
    • Check the pupils
    • Tone and reflexes in all 4 limbs
  • Investigate

Examination

  • Inspection of stigmata of cause
    • Head injury
    • Fever
    • Surgical scars/shunts
    • Ketotic/alcoholic breath
    • Bitten tongue
    • Needle track marks
    • Alert bracelets
    • Hepatomegaly
    • Diabetes prick marks
    • Purpuric rash
  • Inspection
    • Posturing
      • Decorticate: arms all flexed, legs all extended
      • Decerebrate: like decorticate, but elbows extended
    • Hemiparesis?e. is the patient lying asymmetrically?
    • Myoclonus?
  • GCS: note best response
    • Eyes
    • Verbal
    • Motor
  • Head and neck
    • If there is evidence of trauma, do not move the neck
    • Percuss for a cracked pot sound
    • Inspect ears and nose for CSF leak
    • Test for stiffness
    • Look for brudzinski’s and kernig’s signs
  • Eyes
    • Ptosis?
    • Facial weakness?
    • Pupils
      • Note the size
      • Test the reflexes
Symmetry? Size? Reactive? Diagnosis
Equal Pinpoint Opiates

Pontine lesion

Small Reactive Metabolic encephalopathy
Mid-size Unreactive Midbrain
Reactive Metabolic
Unequal Dilated Unreactive IIIn palsy
Small Reactive Horner’s
  • Fundoscopy
    • Papilloedema?
    • Subhyaloid haemorrhage?
  • Eye movements
    • Any deviation
      • Pontine wrong way eyes
      • Cortical right way eyes (massive MCA stroke)
    • Test movements normally
    • Then do doll’s head manoeuvre
  • Motor system
  • Order further investigations
    • Post-ictal
      • EEG
    • Infection
      • LP
      • Bloods & cultures
      • Abscess
    • Neoplasia
      • CT/MRI
    • Vascular
      • SAH
        • Noncontrast CT
      • Hypertensive encephalopathy
      • Haemorrhage
        • Intra-axial
          • Cerebellum
          • Pons
        • Extra-axial
          • EDH
          • SDH
        • Infarction
      • Trauma
      • Endocrine metabolic
        • Hypoglycaemia
        • Hyperglycaemia
        • Hypoxia
        • Acidosis
        • Thyrotoxicosis
        • Hypothyroidism
        • Thiamine deficiency
        • Hepatic failure
        • Renal failure
        • Hypercapnia
        • Addisonian crisis
      • Drugs
        • Alcohol
        • Barbiturates
        • Opioids
        • Benzos
        • tricyclics