[2Y2T2S] [PT10111] [3.1] Traumatic Brain Injury

Major cause of disability and death that is the leading cause of death in <25 y/o

Traumatic Brain Injury (TBI)

What are the two (2) major causes of traumatic brain injury (TBI)?

1. MVA (motor vehicle accident)

2. Falls in elderly

Up to how many percent of cases can violence cause closed head injury?

7-10%

Traumatic brain injury can occur in all ages but peaks among?

Young adults

Violent shaking or jarring of the brain and resultant transient functional impairment

Concussion

Defined by transient appearance of neurologic signs and symptoms following either:

1. Direct or indirect rapid movement in the brain —> extreme rotational/translational brain acceleration

2. Deceleration injury

   • Sudden change in the momentum of the head

Mild TBI

What are the two (2) core features of concussion?

1. Immediately after trauma

2. Largely reversible

CONCUSSION

True or False: Loss of consciousness at impact is required for diagnosis

False: Loss of consciousness at impact is not required for diagnosis

CONCUSSION

True or False: There is no evidence of structural brain injury (using conventional neuroimaging) in concussion.

True

However, there is physiological injury to the brain

What is the most commonly used procedure to check for structural brain injury in concussion?

Non-Contrast CT Scan (NCCT)

What is the mechanism of injury in concussion? (2)

Mechanisms of Injury — Concussion

1. Linear acceleration

2. Rotational acceleration

Both intracranial brain deformation forces can cause a stretch that damages the brain.

What causes the transient functional disruption of the ARAS in a concussion?

Rotational forces to the upper brainstem

What is the initial clinical manifestation of a concussion?

Brief period of disorientation, staggering or amnesia

Patient will also appear normal

What are the clinical manifestations of a concussion later on after having its initial presentation? (5)

1. Immediate loss of consciousness

2. Suppression of supporting reflexes

3. Transient respiratory arrest

4. Brief bradycardia

5. Fall in BP following a momentary rise

CONCUSSION — CLINICAL MANIFESTATIONS

What are other possible clinical manifestations of amnesia (aside from initial response and its progression later on)? (3)

1. Concussive convulsions

2. Retrograde amnesia

3. Anterograde amnesia

CONCUSSION — CLINICAL MANIFESTATIONS

May occur immediately after LOC and confer an increased risk of later seizures

Concussive convulsions

CONCUSSION — ATHLETES

True or False: Athletes who have had a concussion are more likely to have another concussion in the same playing season than others.

True

CONCUSSION — ATHLETES

What happens to athletes after a concussion?

Decline in reaction time and other neuropsychologic tests

CONCUSSION — ATHLETES

After a concussion, how long will an athlete take to recover their reaction time and other neuropsychologic tests back to baseline?

Several days or weeks

CONCUSSION — ATHLETES

The number of recollected concussions is ____________ to the degree of impairment on neuropsychological tests.

The number of recollected concussions is proportional to the degree of impairment on neuropsychological tests.

CONCUSSION — ATHLETES

Because of concussion among athletes, there is an increased risk of: (2)

Increased risk of:

1. Dementia

2. Other neurodegenerative disorders

CONCUSSION — DIAGNOSIS AND TREATMENT

Based on clinical suspicion

• Neurological symptoms without significant _____ __________ ________

Based on clinical suspicion

• Neurological symptoms without significant focal neurologic findings

CONCUSSION — DIAGNOSIS AND TREATMENT

True or False: There is no rigorously studies or FDA approved medical or physical therapies that are clearly proven to hasten recovery.

True

CONCUSSION — OUTCOME

How many persons with single uncomplicated concussions can fully recover within two weeks?

80-90%

CONCUSSION — OUTCOME

What concussion has a more prolonged recovery with decreasing threshold to injury?

Recurrent concussions

CONCUSSION — OUTCOME

Concussions can likely express as: (3)

1. Migraine headaches

2. Mood disorders

3. BPPV

CONCUSSION — OUTCOME

What concussion has increased risk of developing major neuropsychiatric disorders associated with aging?

Examples:

• Depression

• Dementia

• PD

• ALS

• Erratic psychosocial behavior

Recurrent concussions

What type of skull fracture is letter C?

Linear Fracture

What type of skull fracture is letter B?

Depressed fracture

Where is linear fracture most commonly occurring?

Temporoparietal region

One or more bony fragments are displaced inward —> compressing the underlying brain

Depressed fracture

How many percent of depressed fractures are open and prone to infection and CSF leakage?

85%

Skull fracture that shows multiple, shattered bony fragments

Comminuted

Skull fracture presenting a lacerated scalp over the fracture

Open or compound

What types of skull fractures require surgical management? (2)

For:

• Debridement

• Elevation of bone fragments

• Repair of dural lacerations

1. Depressed fracture

2. Comminuted fracture

What skull fracture may be missed by a skull x-ray?

Basal skull fractures

Basal skull fracture is best identified by what imaging procedure?

NCCT bone window

What are the possible symptoms if there is a fracture along the petrous portion of the temporal bone?

1. Hemotympanum or tympanic perforation

2. Hearing loss

3. CSF otorrhea

4. PFP

5. Battle sign

What are the possible symptoms if there is a fracture along the sphenoid, frontal, or ethmoid bones?

1. Anosmia

2. Bilateral periorbital ecchymosis

3. CSF rhinorrhea

Initial axonal stretch causes temporary ondulation and cytoskeletal misalignment

• Associated with mechanical injury to the Na channels, causing massive Na influx

Diffuse axonal injury

DIFFUSE AXONAL INJURY

What causes massive Ca influx in Diffuse Axonal Injury?

Depolarization of the axonal openings for voltage gated Ca channels

DIFFUSE AXONAL INJURY

Along with activation of various metabolic pathways and cytoskeletal changes, what protease is also activated which degrades microtubule proteins?

Calpain

DIFFUSE AXONAL INJURY

What region/s is axon shearing injury most severe?

Regions that are anatomically predisposed to maximal stress from rotational forces

DIFFUSE AXONAL INJURY

Macroscopic tears occur in midline structures. What are these specific structures? (5)

1. Dorsolateral midbrain and pons

2. Posterior corpus callosum

3. Parasagittal white matter

4. Periventricular regions

5. Internal capsule

DIFFUSE AXONAL INJURY

Diffuse microscopic damage occurs as manifested by:

Axonal retraction bulbs throughout the white matter of the cerebrum

DIFFUSE AXONAL INJURY

Diffuse microscopic damage occurs as manifested by axonal retraction bulbs throughout the white matter of the cerebrum following… (3)

1. Microporation of membranes

2. Leakage of ion channels

3. Stearing conformational changes of proteins

DIFFUSE AXONAL INJURY

How many hours will a traumatic coma last?

> 6 hours

DIFFUSE AXONAL INJURY

What causes traumatic coma?

Multiple small lesions in the white matter tracts

DIFFUSE AXONAL INJURY

True or False: Localized micro- and macroscopic axonal shearing injury. There is also localized degeneration of white matter.

True or False: Widespread micro- and macroscopic axonal shearing injury. There is also diffuse degeneration of white matter.

DIFFUSE AXONAL INJURY

How long does it take with mild diffuse axonal injury?

6-24 hours

DIFFUSE AXONAL INJURY

How long does it take with moderate/severe diffuse axonal injury?

>24 hours

DIFFUSE AXONAL INJURY

What parts of the brain are injured with a moderate/severe diffuse axonal injury? (associated symptoms can also be included)

1. Brainstem injury

2. Hypothalamic injury

Associated Symptoms

1. Autonomic dysfunction

2. Brainstem signs and extensor posturing

Single most important cause of persistent disability after traumatic brain damage

Diffuse Axonal Injury

Mild Concussion — Loss of Consciousness (duration)

None

Mild Concussion — Decerebrate posturing (occurrence)

None

Mild Concussion — Posttraumatic amnesia (duration)

mins

Mild Concussion — Memory deficit (severity)

None

Mild Concussion — Motor deficit (severity)

none

OUTCOME AT THREE MONTHS

Mild Concussion — Good recovery outcome (%)

100%

OUTCOME AT THREE MONTHS

Mild Concussion — Death (%)

0%

Cerebral Contusion — Loss of consciousness (onset)

Immediate

Cerebral Contusion — Duration of LOC (duration)

<6 hours

Cerebral Contusion — Decerebrate posturing (occurrence)

None

Cerebral Contusion — Posttraumatic amnesia (duration)

Mins to hours

Cerebral Contusion — Memory deficit (severity)

Mild

Cerebral Contusion — Motor deficit (severity)

None

OUTCOME AT THREE MONTHS

Cerebral Contusion — Good recovery outcome (%)

95%

OUTCOME AT THREE MONTHS

Cerebral Contusion — Death (%)

0%

Mild DAI — Loss of consciousness (onset)

Immediate

Mild DAI — Duration of LOC (duration)

6-24 hours

Mild DAI — Decerebrate posturing (occurrence)

Rare

Mild DAI — Posttraumatic amnesia (duration)

Hours

Mild DAI — Memory deficit (severity)

Mild to moderate

Mild DAI — Motor deficits (severity)

None

OUTCOME AT THREE MONTHS

Mild DAI — Good recovery outcome (%)

63%

OUTCOME AT THREE MONTHS

Mild DAI — Death (%)

15%

Moderate DAI — Loss of consciousness (onset)

Immediate

Moderate DAI — Duration of LOC (duration)

>24 hours

Moderate DAI — Decerebrate posturing (occurrence)

Occasionally

Moderate DAI — Posttraumatic amnesia (duration)

Days

Moderate DAI — Memory deficit (severity)

Mild to moderate

Moderate DAI — Motor deficits (severity)

Mild

OUTCOME AT THREE MONTHS

Moderate DAI — Good recovery outcome (%)

38%

OUTCOME AT THREE MONTHS

Moderate DAI — Death (%)

24%

Severe DAI — Loss of consciousness (onset)

Immediate

Severe DAI — Duration of LOC (duration)

Days to weeks

Severe DAI — Decerebrate posturing (occurrence)

Present

Severe DAI — Posttraumatic amnesia (duration)

Weeks

Severe DAI — Memory deficit (severity)

Severe

Severe DAI — Motor deficits (severity)

Severe

OUTCOME AT THREE MONTHS

Severe DAI — Good recovery outcome (%)

15%

OUTCOME AT THREE MONTHS

Severe DAI — Death (%)

51%

CEREBRAL SWELLING

True or False: It can manifest as diffuse or focal.

True

CEREBRAL SWELLING

What are the four (4) mechanisms of cerebral swelling?

1. Mass

2. Cerebral edema

3. Increased cerebral blood volume d/t abnormal vasodilation

4. Delayed inflammatory response or dysfunction of cerebral vasomotor regulatory centers in the brainstem

CEREBRAL SWELLING

What happens when there is increased cerebral blood volume d/t abnormal vasodilation?

Hyperperfusion, increased vascular permeability causing plasma leakage and vasogenic edema

CEREBRAL SWELLING

What happens when there is delayed inflammatory response or dysfunction of cerebral vasomotor regulatory in the brainstem? (3)

1. During the first 24 hours

   • Cerebral hypoperfusion

2. 1-3 days after severe head injury

   • Hyperemia

3. 4-7 days after severe head injury

   • Arterial vasospasm

CEREBRAL SWELLING

Does the magnitude of swelling always correlate with the severity of injury?

No.

The magnitude of swelling does not always correlate with the severity of injury

Focal parenchymal hemorrhages that result from “scraping” and “bruising” of the brain as it moves across the inner surface of the skull

Cerebral contusions

What are the most common sites of cerebral contusions? (2)

1. Inferior frontal lobe

2. Temporal lobe

Why are the inferior frontal and temporal lobes commonly subjected to cerebral contusions?

D/t irregular protuberances at skull base