- Rhythmic variations in ICP described first described by Lundberg in the 1960’s
- Clinically less useful in modern practice, with an emphasis on earlier recognition and treatment of raised ICP meaning A waves rarely seen:
Type
A-wave
B-wave
C-wave
Description
- Slow plateau waves for 5-15 minutes
- Pressures of 50-100 mmHg
- Small oscillations over 30-120 seconds (freq. 0.5-2 / min)
- Pressures up to 50 mmHg in amplitude
- Low amplitude oscillations over 10-20 seconds (freq. 4-8 / min)
- Pressures up to 20 mmHg in amplitude
Example
Implication
- Always associated with intracranial pathology - represent critical hypoperfusion and early brain herniation
- Thought to be due to reflex vasodilatation in response to decreased cerebral perfusion leading to a vicious circle of increased intracranial volume and pressure
- Usually a sign of evolving cerebral injury
- Thought to be due to vasomotor centre instability when CPP is unstable
- Present in healthy individuals and are of little clinical importance
- Thought to occur because of interaction between cardiac and respiratory cycles