Coma

Obtundation: blunting of arousal ("sleepy").
Stuporous: rousable with painful stimulus.
Coma: unrousable

Causes

History

Circumstances? Unwell? PMH? Drugs/toxins?

Examination

General examination: skin—needle tracks, snout rash; breath—ketones
Vital signs
Head injury? (look through hair, in ears, nose)

CNS exam

Meningism
Eyes: movements, pupils, fundi, corneal reflex
Breathing
Gag reflex
Tendon jerks

Eye movements

Gaze deviation, dysconjugate gaze, skew, roving, ocular bobbing
Doll's eye reflex, calorics

Investigations

Full screen: FBC U&E LFT toxins (EtOH, paracetamol, aspirin).
Brain imaging:
LP
Others as indicated

Differentials

No focal signs, no meningism

Metabolic, diffuse anoxia/ischaemia, drug, toxin.

No focal signs, meningism

Meningitis, encephalitis, subarachnoid haemorrhage

focal signs, meningism

stroke, tumour.