Chapter 4: Central Nervous System

Consciousness

The skull protects the brain. It is a thick bony box, the base of which is very thin and highly vulnerable to damage when the subject for example falls from a height or receives a blow to the head. This blow is usually transmitted through the head, through the brain, the brain is bounced off the base of the skull, which shatters and bleeds. The most critical injury is a skull fracture with a bleed inside the skull. If the bleed is arterial which as you may recall is under high pressure, this will result in blood flooding into the skull. There is no spare room within the skull to accommodate this situation and this results in the brain being compressed. This results in confusion, coma and death from convulsions or respiratory arrest.

In this situation one would anticipate the subject becoming increasingly confused that is

1. Does not know the correct time
2. Cannot recognised their surroundings
3. Cannot identify to whom they are speaking e.g. confuses dairyman with doctor.

This is technically known as confusion and is a significant deficit in brain function. It is the first sign in decline in such an injury and it is important that this is sought for in managing head injuries. If the situation progresses the subject will progressively go into a coma viz. they will not respond to voice or painful stimuli, they will not talk and they will not move. In this situation if the injury is amenable to surgical intervention this should be done so immediately. The simplest way of assessing the conscious level in a subject is the AVPU.

A - Alert
V - Responds to Voice
P - Responds to pain
U - Unresponsive - the most critical situation of all

A more elaborate system exists known as the Glasgow Coma Scale.