10- Raised Intracranial Pressure

Question 1

What is the normal intracranial pressure range in adults?

Answer 1

5-15mmHg. Generally >20mmHg is considered raised

Question 2

What does the Monro-Kellie doctrine say?

Answer 2

‘Any increase in one of the intracranial constituents must be compensated by a decrease in the volume of one of the others’

Question 3

In the age of an intracranial mass such as a brain tumour what are the first components to be pushed out of the intracranial space?

Answer 3

CSF and venous blood as they are at the lowest pressure

Question 4

How do you calculate the cerebral perfusion pressure?

Answer 4

Mean arterial pressure (MAP) - intracranial pressure (ICP)

Question 5

What is a normal CCP value?

Answer 5

> 70mmHg

Question 6

How will an increase in MAP affect CPP and how does the brain compensate for this change?

Answer 6

Increase in MAP increases CPP which causes vasoconstriction to maintain cerebral blood flow

Question 7

Explain the Cushing’s reflex?

Answer 7

Rise in ICP will lead to hypertension to increase MAP to maintain CPP, this is detected by baroreceptors stimulating bradycardia. Finally irregular breathing is seen as there is compression of the respiratory centres in brain stem

Question 8

what are the three features of the Cushing’s reflex?

Answer 8

Hypertension, bradycardia and irregular breathing

Question 9

How can hydrocephalus be caused?

Answer 9

Congenitally: obstructive, over production, reduced absorption
Acquired: meningitis, trauma, tumour compressing drainage

Question 10

What are some clinical signs of hydrocephalus?

Answer 10

Bulging head, head circumference increasing quicker than expected, sun setting eyes

Question 11

What are three cardinal symptoms of increased intracranial pressure?

Answer 11

Headache, vomiting, visual disturbance