Coma is rarely a permanent state, and those surviving the causative insult either recover or enter a minimally aware or vegetative state. The vegetative state is caused by widespread damage to both hemispheres with preservation of brainstem function and most commonly follows traumatic or hypoxic-ischaemic cerebral injury. The vegetative state may be partially or totally reversible or may progress to a persistent or permanent vegetative state or death. A number of conditions may mimic coma and need to be excluded when evaluating the apparently unresponsive patient. The syndrome is caused by lesions of the ventral pons that disrupt the corticospinal, corticobulbar and corticopontine tracts. In most cases, the cause of coma is associated with an obvious medical cause. The level of consciousness should be assessed by the ability of the patient to respond to external stimuli in three regards: by speech, eye opening, and motor movements.