The most frequent non-neurological diseases that cause disturbances of consciousness, and their therapy

1. Big picture

Most patients with an altered level of consciousness do not have a primary brain lesion — they have a systemic (non-neurological) disturbance that secondarily depresses the reticular activating system and cortex. These causes are crucial because many are rapidly reversible if recognized.

The exam wants you to list the systemic causes by category and give the immediate therapy for each, especially the ones that kill or reverse within minutes.

Core exam idea: In any unconscious patient, check and treat the reversible metabolic causes first — glucose, oxygen, and (where appropriate) thiamine and naloxone — before assuming a structural brain lesion.