Head Injury Flashcards
An increase in intracranial pressure can cause brain herniation. What is a brain herniation?
displacement of the brain tissue under the falx cerebri or through the tentorial notch of the tentorium cerebelli
Intracranial pressure is normally kept within what range?
0-15 mmHg
Describe the Monro-Kellie Hypothesis regarding intracranial pressure?
Volumes within each of the three intracranial compartments (blood, brain tissue and CSF) can vary slightly without causing marked changes in intracranial pressure as small increases in the volume of one component are compensated for a by a decrease in volume in one or both of the other two components.
What is the cerebral perfusion pressure?
The difference between the mean atrial blood pressure and the intracranial pressure which gives the pressure which is perfusing the brain
Within what range does the cerebral perfusion pressure normally lie?
70-100mmHg
What is the difference between hypoxia and ischaemia?
Hypoxia is a deprivation of oxygen with maintained blood flow
ischaemia is a deprivation of oxygen (and glucose) with impaired blood flow and also insufficient removal of metabolic wastes
Hypoxia is fairly well tolerated by the brain especially in cases of chronic hypoxia. T/F?
True
Cerebral ischaemia can be focal as occurs in conditions such as…?
Stroke
Cerebral ischaemia can be global as occurs in conditions such as…?
Cardiac arrest
What is the term for the areas of the brain which sit between the overlapping territories supplies by different cerebral arteries which are extremely vulnerable to focal ischaemia?
Watershed areas
The metabolic depletion of energy associated with ischaemia can result in inappropriate release of excitatory amino acid neurotransmitters. What are the consequences of this?
In prolonged ischaemia, depletion of ATP leads to release of glutamate which initiates cell damage by allowing excessive influx of calcium ions which causes the release of intracellular enzymes that cause protein breakdown, free radical formation, lipid per oxidation, mitochondrial injury, nuclear breakdown and cell death
What type of oedema occurs in conditions which impair the function of the blood-brain barrier and allow transfer fo water and proteins from the vascular to interstitial space?
Vasogenic oedema
White matter is more affected by vasogenic oedema than grey mater. t/f?
True
What are the possible consequences of vasogenic oedema in the brain?
Displacement of a cerebral hemisphere, disturbances in consciousness, severe inter cranial hypertension
Ishcaemia of the brain is associated with what type of oedema?
Cytotoxic
What is meant by a primary brain injury?
The immediate response to the initial injury
Give an example of a focal lesion which may occur as a primary brain injury?
Contusion and haemorrhage
Give and example of a diffuse lesion which may occur as a primary brain injury?
concussion
diffuse axonal injuries
What is meant by secondary brain injury?
This involves complicated processes resulting from the initial injury which include brain swelling and infection
What is the most common cause of secondary brain injury?
Ischaemia
Contusions in the brain can cause secondary mass effects from oedema. What effects might these be?
Increased ICP and possible herniation syndromes
In an epidural haematoma, radii expansion of the haematoma compresses the brain. Why does this occur?
Because bleeding is arterial in origin
An epidural haemotoma develops between the inner side of the skull and the dura. How do these injuries usually occur?
Fracture of the skull
Acute subdural haematomas have a high mortality rate. T/F?
True
Chronic subdural haematomas develops weeks after the injury, so much later that the person may not remember having the injury. T/F?
True
What vessels are usually torn in a subdural haematoma?
The small bridging veins which connect veins on the surface of the cortex to dural sinuses.
In which lobes of the brain are traumatic intracereberal haematomas most common?
Frontal and temporal lobes
What is a cerebral concussion?
A transient neurogenic dysfunction caused by mechanical force to the brain
Recovery from concussion usually takes place within 24 hours but mild symptoms may persist for months. What symptoms are these?
Headache
irritability
insomnia
poor concentration and memory
What is diffuse axonal injury caused by?
Shearing of fragile axons by acceleration-deceleration forces at the time of trauma
Acute management of a head injury should involve resuscitation and ABCDEs. What are the ABCDEs?
A - check airway, clear debris, insert oropharyngeal airway of endotracheal tube if necessary
B-breathing - give oxygen if necessary
C - circulation - check pulse and bp
D - disability - assess general and neurological status
E - environment - hypothermia
G - glucose check for hypoglycaemia
What symptoms would you want to ask for when trying to get a detailed description of a head injury?
Loss of consciousness amnesia / lucid period seizures confusion deterioration of mental status vomiting headache
Describe the Glasgow coma scale?
Score out of 15, used to assess level of consciousness in patients
3 components: best eye responses (possible four points), best verbal response (possible 5 points), best motor response (possible 6 points)