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3 - Pathology > Head Injury > Flashcards

Head Injury Flashcards

1
Q

Name the three categories trauma to the head may cause.

A

Skull fracture
Parenchymal brain injury
Traumatic vascular injury

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2
Q

List examples of parenchymal brain injury.

A

Concussion
Direct parenchymal injury: contusion, laceration
Diffuse axonal injury

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3
Q

List some examples of traumatic vascular injury.

A

Epidural (extradural haemorrhage)
Subdural haemorrhage
Subarachnoid, intraparenchymal (or intraventricular) haemorrhage

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4
Q

What is the presentation of concussion.

A

Immediate, but transient loss of consciousness with a short interval of amnesia
Some px may not lose consciousness, but appear dazed or confused

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5
Q

What chnages happen to the brain in concussion?

A

Caused by sudden deceleration of the head after blunt impact
No macroscopic or histological changes
Can be followed by brain compression by a developing haematoma = px put under observation

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6
Q

What is a contusion?

A

Bruise to the surface of the brain following a blunt impact to the head
Causes displacement and compression of brain tissue against the inner skull

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7
Q

Where do contusions occur?

A

In regions where cortical gyri impact rough or irregular bone surfaces

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8
Q

What other issues do contusions cause?

A

Petechial haemorrhage, oedema, tissue destruction

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9
Q

What are same side contusions called?

A

coup injury

A stationary blow to the head is more likely to produce a coup at the site of the blow

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10
Q

What are opposite side contusions called?

A

Contrecoup injury

A fall backward usually causes this on the inferior frontal lobes

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11
Q

What is the gross (macroscopic) morphology of a contusion?

A

Haemorrhage on brain surface or extending into underlying brain for a variable distance
Older lesions = depressed, yellow-brown plaques (plaque jaune)

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12
Q

What are the microscopic findings of a contusion?

A

Early: Haemorrhage, oedema, acute inflammation, extensive tissue loss in severe cases
Older lesions: gliosis (analogous to fibrosis in other tissues), macrophages containing hemosiderin (yellow, haemoglobin derived pigment)

*** if extensive tissue loss had occurred = cavity will result after resorption of necrotic material surrounded by gliosis

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13
Q

When does laceration of the brain occur?

A

With penetrating trauma (bullets or bone fragments from skull fracture) with tearing/disruption of brain tissue

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14
Q

What is diffuse axonal injury?

A

Damage to deep white matter structures of the brain (composed predominantly of myelinated axons)

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15
Q

What explains immediate and prolonged coma following severe head injury?

A

Extensive axonal damage (diffuse axonal injury) q

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16
Q

What are the macroscopic changes of diffuse axonal injury?

A

Edema
Petechial or splinter hemorrhages are present in the white matter = ruptured capillaries and small vessels
Axonal damage cannot be seen macroscopically

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17
Q

What is the microscopic damage of diffuse axonal injury?

A

Axonal swellings = retraction balls
These represent cellular proteins (organelles) that accumulate at the proximal stump of the severed axon
Axons distal to the injury degenerate

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18
Q

What does damage to a meningeal artery cause?

A

Epidural bleeding

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19
Q

What does rupture to a cerebral artery (aneurysm) cause?

A

Subdural haemorrhage

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20
Q

What does damage to a bridging vein cause?

A

Subdural bleeding

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21
Q

What does damage to a bridging vein cause?

A

Subdural bleeding

22
Q

What usually causes an epidural haematoma?

A

Tearing of a middle meningeal artery following a fracture of the temporal bone

23
Q

Why does the epidural haematoma rapidly expand?

A

The haemorrhage under arterial pressure dissects the dura from the skull

24
Q

Where does the haemorrhage of an epidural haematoma stop?

A

Stops at suture lines where dura/periosteum is adherent to skull bones

25
Q

How are epidural haematomas treated?

A

Evacuated acutely

26
Q

What does the CT scan of an epidural haematoma look like?

A

Biconvex (lens-shaped) mass
Midline shift and ipsilateral (same side) ventricular compression
Acute haemorrhage will appear hyperdense (bright white) - globin molecule is dense and absorbs X-ray beams
As it becomes older & the globin molecule breaks down, it will lose its hyperdense appearance

27
Q

Why are the bridging veins vulnerable to rupture?

A

Brain is slightly mobile, but the dural sinuses are fixed

Therefore traumatic displacement of the brain may rupture these veins

28
Q

Who is at greater risk of injury to bridging veins and why?

A

Elderly patients with cerebral atrophy - atrophy puts greater traction on the veins & so milder trauma may cause tearing of the veins

29
Q

Why may a subdural haematoma accumulate more slowly?

A

Bleeding is venous rather than arterial

30
Q

What are the symptoms of a subdural haematoma?

A

Symptoms vary depending on the extent of damage of the vessels
Slow oozing with vague neurological symptoms e.g. headache, confusion
Greater vascular injury = acute symptoms

31
Q

What does the CT scan of a subdural haematoma look like?

A

Sickle or crescent shaped, usually over the cerebral convexity
Bleeding can cross suture lines
Midline shift and ipsilateral ventricular compression

32
Q

Describe the macroscopic appearance of subdural haematoma.

A

Mass of freshly clotted blood on the surface of the brain = variable flattening of the brain
Over time the blood clot organizes with lysis of the red cells and ingrowth of fibrous tissue from the dura
Eventually forms a dense connective tissue membrane adherent to the dura

33
Q

What does the intercranial space contain?

A

Blood, brain, CSF

34
Q

What is the normal ICP?

A

10-15mmHg

35
Q

Why does head trauma (haemorrhage/oedema) cause the ICP to rise?

A

Skull is not distensible

36
Q

What other pressures are affected when ICP rises?

A

Cerebral perfusion pressure (CPP)
CPP = MAP - ICP
An increase in ICP will cause a decrease in CPP which if severe enough could lead to ischaemic injury

37
Q

What does increased ICP cause the brain to do?

A

Displacement of the brain/herniation of the brain because of the rigid dural folds (falx and tentorium)

38
Q

List the different types of herniation.

A

Subfalcine herniation
Transtentorial herniation
Tonsillar herniation

39
Q

What is a subfalcine herniation?

A

Displacement of the cingulate gyrus under the falx cerebri

40
Q

What happens as a result of a subfalcine herniation?

A

No specific clinical signs
Can result in occlusion of one or both of the anterior cerebral arteries leading to ischaemia in the territory of these vessels

41
Q

What causes a transtentorial herniation?

A

Herniation of the uncus of the medial temporal lobe downward through the tentorial notch
Results in pressure on and displacement of the rostral midbrain

42
Q

What is the most common herniation?

A

Transtentorial herniation

43
Q

Name the symptoms of a transtentorial herniation.

A
  • compression of the third cranial nerve
  • compression or one or both cerebral peduncles against tissue or the tentorial edge
  • haemorrhage into the midbrain or upper pons related to arterial stretching = Duret haemorrhages
44
Q

Name the three classical signs of a transtentorial herniation

A

1 - ipsilateral, dilated, unresponsive pupil “blown pupil”
2 - contralateral hemiparesis
3 - decreased level of consciousness or coma

45
Q

What is Kernohan’s phenomenon?

A

Midbrain may be pushed to the opposite side of the tentorial notch, compressing the opposite cerebral peduncle leading to ipsilateral hemiparesis (weakness on the same side of the compression)

46
Q

What is tonsillar/coning herniation?

A

Herniation of the inferior-medial aspects of the cerebellum down through the foramen magnum

47
Q

What are the clinical signs of tonsillar herniation?

A

Causes compression of the medulla which can disrupt cardiac and respiratory centres = cardiac/respiratory arrest and death

48
Q

Describe the time course of diffuse axonal injury?

A

Immediate coma because of immediate widespread transection of axons

49
Q

What is the timecourse of epidural hematoma?

A

Arterial bleeding!!

Progressively symptomatic over a period of hours

50
Q

Describe the timecourse of a subdural hematoma.

A

Venous bleeding!!

Over a period of days, but can be acute as well

51
Q

What symptoms usually present in a head injury case?

A

Increase in intracranial pressure (as a result from the expanding hematoma)

  • headache
  • confusion
  • nausea
  • vomiting
  • papilledema (swelling of optic disc, head of optic nerve)
  • signs and symptoms of brain herniation if present
52
Q

List longterm consequences of brain injury following trauma.

A

Post traumatic epilepsy
Post traumatic hydrocephalus
Chronic Traumatic Encephalopathy (CTE) - dementia following repeated head trauma
Psychiatric disorders

3 - Pathology (7 decks)

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