Dysfunction of the central nervous system (CNS) can present as either a reduction in consciousness or with a focal neurological deficit.

Focal neurological deficit can be due to injury, infarction, haemorrhage, mass effect or infection affecting one part of the cerebral cortex (e.g. cerebral abscess). A specific region of the body is affected, resulting in a weak leg, arm or one side of the face.

A reduced level of consciousness can be assessed with either:

Agitation or confusion can be non-specific signs secondary to cerebral irritation, of which there are a number of causes.

More information may have to be obtained from any witnesses or relatives to establish the cause for a reduced level of consciousness e.g. speed of onset, incontinence of urine, history of diabetes, alcohol/drug use or history of trauma.