Traumatic Brain Injury

Question 1

what are the different types of brain injury?

Answer 1

non-missile (car crash or fall= rapid acceleration or deceleration of the head) vs missile (gun-shot), focal (small area) vs diffuse (larger area- axonal, oedema), primary (at the time of the injury) vs secondary (things that happen hour or day after the injury and what we are trying to minimise with our treatment), progressive neurological deterioration (normally due to repetitive brain injuries eg in boxing)

Question 2

what does ischaemia in the brain cause?

Answer 2

brain swelling which causes a rise in ICP which causes reduced CPP (MAP-ICP) and the reduced CPP can result in ischaemic damage and further swelling, ischaemic damage to the brain is not uniform as some areas are more susceptible (wedge infarcts)

Question 3

what is brain herniation caused by?

Answer 3

differential pressures in intracranial compartments may result in herniation of brain

Question 4

what is coning?

Answer 4

transtentorial herniation caudally - transformanial herniation of the brainstem and cerebellar tonsils through the foramen magnum which causes ischaemia and loss of brainstem function and death

Question 5

what are the biochemical changes in a brain injury?

Answer 5

a head injury triggers a cascade of biochemical changes- some have a protective effect and some contribute to cell injury

Question 6

what happens to amino acids in brain injury?

Answer 6

widespread neuronal depolarisation causing massive release of excitatory amino aids including glutamate which contribute to release of free radicals

Question 7

what happens to glutamate in brain injury?

Answer 7

widely distributed in the brain and acts of many receptors, over stimulation causes a massive calcium influx into neurones

Question 8

what happens to calcium in brain injury?

Answer 8

calcium influx have a neurotoxic effect and activate phospholipidases which break down cell membranes causing cerebral oedema

Question 9

what happens to nitrous oxide in a brain injury?

Answer 9

in the 1st hours after a head injury nitrous oxide is produces by neurones and endothelial cells which has vasodilator and neurotoxic effects

Question 10

what is a scalp injury?

Answer 10

can indicate a potential underlying skull/parenchymal injury and may indicate type of object which caused injury

Question 11

what does a scalp laceration cause?

Answer 11

extensive haemorrhage and route for infection

Question 12

what does a skull fracture cause?

Answer 12

not always significant clinically but indicate reasonable force and increased risk of intracranial haemorrhage, can cause depressed fracture= significant force over a small area and can require elevation, diastolic fracture= follow suture lines and is more common in children, compound fracture= fracture and overlying skin break causing risk of infection

Question 13

what does bruising of the head cause?

Answer 13

periorbital= orbital roof fractures, mastoid bruising= battle sign- blood tracking from a fracture of the petrous temporal bone

Question 14

what are brain contusions?

Answer 14

tears of pill membrane are often associated with underlying contusions (bruising to cortex and white matter), contusions can be coup and contra-coup due to continues movement of the brain with the cranial cavity- particularly following rapid deceleration

Question 15

what is an extradural haematoma?

Answer 15

typically egg/lens shaped haematomas that accumulate over a few hours and is caused by the dura being stripped from the skull

Question 16

why and who does an extradural haematoma occur in?

Answer 16

results from direct impact and is uncommon at the extremes of age- 10% of HI patients, often associated with fractures of the squamous temporal bone and tear in the underlying MMA, accommodated quite well and then ICP rises too high for accommodation

Question 17

what is a subdural haematoma?

Answer 17

caused from shearing/tearing of the riding veins in the outermost meningeal layer- between dura and arachnoid mater and on a CT scan will appear as a cresent shape as they are not limited by cranial sutures and may cause a degree of midline shift away from the haematoma

Question 18

who does a subdural normally present in?

Answer 18

more common in the elderly and alcoholics as they have more atrophy in their brains making vessels more likely to rupture

Question 19

who does a subdural normally present in?

Answer 19

more common in the elderly and alcoholics as they have more atrophy in their brains so more space for brain to move within the skull cavity making vessels more likely to rupture

Question 20

what is a subarachnoid haemorrhage?

Answer 20

bleeding in the subarachnoid space where the CSF is located and is usually the result of a ruptured cerebral aneurysm

Question 21

how does a SAH present?

Answer 21

thunderclap headache- sudden onset occipital headache that occurs during strenuous activity (described like being hit really hard in the back of the head), neck stiffness, photophobia, neurological symptoms

Question 22

what are the risk factors for SAH?

Answer 22

hypertension, smoking, alcohol,

Question 23

what are the risk factors for SAH?

Answer 23

hypertension, smoking, alcohol, black patients, female, age 45-70, cocaine

Question 24

what investigations are usually done for suspected SAH?

Answer 24

immediate CT head is first line (may be normal), bloods will show hyper attenuation in the subarachnoid space

Question 25

what investigations would then be done if CT normal?

Answer 25

lumbar puncture to collect sample of CSF for signs of SAH= red cell count will be raised and xanthochromia which is yellow colour to CSF caused by bilirubin

Question 26

how is a SAH managed?

Answer 26

managed by specialist neurosurgical unit, surgical intervention may be used to treat aneurysms= coiling (endovascular) or clipping (surgical), nimodipine= CCBs to prevent vasospasm which is a common complication, anti-epileptic medications to treat seizures

Question 27

what is a diffuse axonal injury?

Answer 27

widespread axonal damage within the brain which results from many possible insults= trauma/sheering (rapid acceleration/deceleration), hypoxia, ischaemia, hypoglycemia, common following RTAs or falling from height or assault and typically unconsciousness

Question 28

what is axonal damage?

Answer 28

swollen transected fibres throughout white matter eg corpus callosum etc