Your patient will usually exhibit subtle neurological changes that indicate changes in brain function.
Level of consciousness is the most important indicator in a conscious person.
In an unconscious person, pupillary response is the most important indicator. The level of consciousness deteriorates before any other neurological changes are noted. These deteriorations are subtle and must be monitored carefully. Because the terms used to describe levels of consciousness mean different things to different people, describing the activity required to elicit a response is best. The best motor response is recorded.