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
When the brain herniates under the tentorium cerebella?
Subtentorial
When the brain herniates through the foramen magnum it is known as?
Tonsillar herniation.
What tool do you use to assess someones consciousness?
The Glasgow coma score.
What parameters does the Glasgow coma score assess?
Eyes opening- spontaneously, to command, to pain or none
Verbal response- orientated, confused, inappropriate words, incomprehensible sounds, none
Best motor response- Obeys command, localises pain (this doesn’t just mean putting your arms up when pain is inflicted, it means putting them up and actively pushing the pain away), flexes to pain, abnormal flexion, extension, none.
What is the definition of a coma?
Do not open eyes. Do not obey commands. Do not speak.
What GCS score would a mild head injury have?
GCS of about 13-15
What is likely to kill patients with head injury?
Hypoxia
Hypotension
Raised ICP
When should you do a CT scan in head injury patients?
Patients with skull fractures
GCS of less than 15
Focal neurological signs
Taking anticoagulants.
From outside to in, describe the layers of the head and what bleeds in that area would be called?
Scalp Dura- extra dural (outside the dura) -subdural (between dura and arachnoid) Arachnoid- subarachnoid Pia Brain- intracerebral contusion Intracerebral haemorrhage Ventricle-intraventricular haemorrhage.
How would ICU manage a head injury (think ABCDE plus more)?
Sedation- reduces cerebral metabolic activity, reduces cerebral blood flow and ICP.
Ventilation- po2-13-15, pco2- 4-4.5
Blood pressure- manipulate to maintain CPP>60
Glucose- maintain norm
Temp- maintain norm.
How else (other than manipulating blood pressure) can you reduce ICP?
Manitol- diuretic and stops oedema build up. Improve circulation and prevent ischaemia also.Hypertonic saline does the latter too.
Drain CSF- ventricles are hard to access in head injury however.
What is a decompressive craniectomy?
Take part of the skull off to allow the brain to swell.
What are some late effects of head injury?
Epilepsy
CSF leak into nose/mouth.
Cognitive problems- post concussion syndrome (headache, poor concentration, poor memory, lethargy).
