Week 3- head injury Flashcards
Types of head injury
Open-penetrating- the dura mater is broken.
Closed- accelerating/decelerating force. Dura intact.
Describe primary and secondary brain injury?
Primary- from time of injury
Secondary- things that have occurred after the injury and are due to consequences of that injury.
What causes the cells to die during head injury (pathophysiology)?
Release of excitatory amino acids (glutamate, aspartate). Bind to the receptors causing excitation, releasing intracellular calcium, activation of phospholipase breakdown of the cell membrane and apoptosis.
What causes more cellular death after head injury?
Loss of the blood brain barrier allowing lymphocyte infiltration causing inflammation.
Loss of cerebral autoregulation of blood pressure
Loss of cerebral auto regulation of blood flow- metabolic decoupling
What equation denotes cerebral perfusion pressure?
CPP= MAP-ICP
MAP- mean arterial pressure
ICP- intracranial pressure
NOTE- cerebral perfusion pressure
Pressure of the blood being pushed up (MAP) minus the pressure of the head that opposes this (ICP)
What things can effect cerebral perfusion pressure?
Hypotension is the big one.
Other things that increase pressure in the head e.g. space occupying lesions.
What is the normal intracranial pressure for an adult?
9-11.
What happens to intracranial pressure in a head injury?
It increases due to inflammation and oedema causing the brain to swell.
After a head injury, what CPP are you aiming for?
> 60mmHg.
This would mean keeping the ICP <20 and the MAP about 80.
What physical findings may you see on examination of a patient with head injury?
Scalp lacerations and swelling.
Skull base fractures
Skull vault fractures.
What signs will a patient with an anterior skull base fracture show?
Panda eyes- two black eyes.
What signs will a patient with a posterior skull base fracture show?
Battle scar- bruise over mastoid area (behind ear).
What is a skull vault fracture and what types can you get?
Skull vault fracture is a fracture of the skull part that encases the brain.
Can be linear, depressed or compound.
When the brain herniates underneath the falx cerebri it is known as?
Subfalcine herniation