TBI & Dementia

Question 1

_____ is the number one risk factor for development of dementia

Answer 1

Traumatic brain injury

(TBI = 5-15% of dementia, even one concussion increases risk)

Question 2

Define diffuse axonal injury

Answer 2

Widespread injury to axons secondary to traumatic brain injury

Question 3

Diffuse axonal injury is caused by a______

Answer 3

shearing of axons

Question 4

Diffuse axonal injury results in neuronal dysfunction by disruption of _____ (2).

Answer 4

• Axonal plasma membranes (dysreg. of ionflex)
• Cytoskeleton (defective axonal transport)

Question 5

Historical findings of diffuse axonal injury

Answer 5

Axonal swelling at sites of injury →Tearing of axons → bulbs or spheroids develop → proximal portion is retracted towards body → axonal retraction spheroids→ Wallerian degeneration: lost forever

Question 6

Diagnosis of diffuse axonal injury (2)

Answer 6

1. Immunostains for APP
2. Silver stains confirm diagnosis

Question 7

Answer 7

Diffuse axonal injury

(stain for APP- Brown precipitate)

Question 8

Answer 8

Routine H&E section from a patient w/ DAI.

(note: there are scattered axonal retraction spheroids/bulbs/balls. Black arrows are pointing at several good examples).

Question 9

Answer 9

Silver stains from a patient with DAI.

(scattered axonal retraction spheroids, which stain black on silver stains. Images to right: high power views also exhibiting axonal retraction spheroids (white arrows).

Question 10

A concussion is a _____ that results in sudden onset of ______.

Answer 10

• mild traumatic brain injury
• transient neurological dysfunction

(Common in: bycles or car accident, falls, sports injuries, exposure to explosion)

Question 11

Concussion: signs and symptoms

Answer 11

1. Headache
2. Loss of consciousness
3. Amnesia
4. Cognitive impairment: confusion, slowed rxn times
5. Behavioral changes
6. Sleep disturbance

Question 12

Concussion: pathogenesis

Answer 12

Diffuse axonal injury

Question 13

Symptoms of a concussion generally resolved within ___.

Answer 13

3 weeks

(if an athlete returns before they are fully recovered they could develop a secondary concussion)

Question 14

_______ (diagnostic) can visualize diffuse axonal injury.

Answer 14

Diffusion Tensor MRI

(regular CT & MRI will come back normal)

Question 15

Multiple concussions will increase the risk of developing (3)

Answer 15

1. Depression
2. Dementia
3. Parkinsonism

(chronic traumatic encephalopathy)

Question 16

What causes a cerebral contusion?

Answer 16

Blow To The Head resulting in abrupt acceleration / deceleration of the brain

(worse than concussion)

Question 17

Define coup versus counter-coup cerebral contusion

Answer 17

• Coup: contusion occurs at the point of impact
• Counter-coup: contusion occurs opposite the point of impact (180 degrees)

(it is possible to have both if the head as mobile)

Question 18

_______ (Coup/contre-coup) injuries occur when the head is stationary and stuck by an object (i.e. Hit by a baseball bat)

Answer 18

Coup

Question 19

______(Coup/contre-coup) injuries occur when the head is in motion and abruptly stops (i.e. falls of a ladder).

Answer 19

Contrecoup

Question 20

Cerebral contusion: Most common area(s) of the brain

Answer 20

1. Frontal
2. temporal

Question 21

Early histologic findings of a cerebral contusion

Answer 21

• Edema and Hemorrhage and cortex
• Neuronal injury in cortex buy 24 hours (Red neuron changes)
• Infiltrates of neutrophils than macrophages

Question 22

Later histologic findings of a cerebral contusion

Answer 22

• Gliosis with hemosiderin-laden macrophages
• Cavitary lesion (empty cystic cavity)

(image to the right: yello/brown is from the hemosiderin)

Question 23

Epidural hematomas are due to _____

Answer 23

• arterial bleeding
• Skull fracture → middle meningeal artery tear
• Blood collects between the skull and dura

Question 24

If an epidural hematoma is not repaired, what may result?

Answer 24

A transtentorial, uncal herniation may occur→ midbrain hemorrhage→ death

Question 25

“lucid interval”

Answer 25

After a blow to the head, a period of unimpaired consciousness for several hours while epidural blood accumulates under arterial pressure (20-50% of pts)

(Up to 1/3 of patients who develop an epidural hematoma do not lose consciousness at the time of the precipitating head injury)

Question 26

Subdural hematoma: causes

Answer 26

• Venous bleeding from torn bridging veins which course from the brain to the dural venous sinuses
• Blood collects between the dura and the arachnoid

Question 27

Subdural hematomas are bilateral in 15%–20% of cases, and these may impair ______.

Answer 27

cognitive function and lead to a mistaken diagnosis of dementia

Question 28

“Organization” of a subdural hematoma

Answer 28

Fibroblasts and blood vessels from the dura grow into the underlying hematoma (granulation tissue) → lay down collagen→ mature fibroconnective tissue→ retracts→no compression

(this can still bleed again from minor injury → transtentorial herniation → death)

Question 29

Patient population at a greater risk for a subdural hematoma from minor trauma

Answer 29

1. Elderly
2. Alcoholics
3. Dementics

(smaller atrophic brains)

Question 30

Traumatic subarachnoid hemorrhage

Answer 30

Traumatic rupture small vessels in subarachnoid space

Question 31

Potential complications of a traumatic subarachnoid hemorrhage (2)

Answer 31

1. Vasospasm→ ischemia (days later)
2. Hydrocephalus (communicating)

Question 32

Pathophysiology of communicating hydrocephalus post-traumatic subarachnoid hemorrhage

Answer 32

after subarachnoid hemorrhage heals→ fibrosis of the meninges can obliterate the arachnoid granulations→ interfering with resorption of CSF

Question 33

Traumatic intraparenchymal hemorrhage

Answer 33

Rupture of small vessels within the brain parenchyma

Question 34

Traumatic intraparenchymal hemorrhage: potential complication

Answer 34

herniation