MCB 170: Traumatic Brain Injuries

Why is the brain an important organ? What is it responsible for?

• vital functions

• learning and memory

• reproductive activities

• emotions and motivations

• circadian rhythms and sleep

How many neurons are in the brain? How many synapses?

86 billion neurons and each neuron is made up of 200,000 synapses

How many glial cells are in the brain?

85 billion

Why is the brain a demanding organ?

• contributes to 2% of body weight

• needs 15-20% of blood supply

• needs 20% of daily energy

What is a traumatic brain injury (TBI)?

induced structural damage and/or physiological disruptions of brain function as a result of a physical external force

True or False: In a TBI, the insult is not of degenerative or congenital nature.

true

How can TBIs happen?

• closed brain injury

• penetrating brain injury

What is a closed brain injury?

there is not a break in the skull

What is a penetrating brain injury?

there is a break in the skull

What are some physical symptoms of a TBI?

• loss of consciousness

• headache

• nausea

• sleeping disorders

• blurred vision

What are some mental symptoms of a TBI?

• memory problems

• speaking disorders

• depression

How many deaths per year do TBIs cause?

more than 60,000

How many hospitalizations per year do TBIs cause?

more than 370,000

How many emergency department visits do TBI's cause?

more than 2,000,000

True or False: TBI is the leading cause of death in young and healthy people.

true

What are the three classifications of TBI?

• mild (concussion)

• moderate

• severe

What are the characteristics of a mild TBI (concussion)?

• normal brain imaging

• 0-30 minutes of loss of consciousness

• less than 24 hours of an altered mental state

• less than 1 day of post-trauma amnesia

• 13-15 score on the Glasgow Coma Scale

What are the characteristics of a moderate TBI?

• normal or abnormal brain imaging

• 30 minutes-24 hours of loss of consciousness

• more than 24 hours of an altered mental state

• 1-7 days of post-trauma amnesia

• 9-12 score on the Glasgow Coma Scale

What are the characteristics of a severe TBI?

• normal or abnormal brain imaging

• more than 24 hours of loss of consciousness

• more than 24 hours of an altered mental state

• more than 7 days of post-trauma amnesia

• a score of 9 or less on the Glasgow Coma Scale

What is the Glasgow Coma Scale?

a measurement of a patient’s level of consciousness

What 3 measurements does the GCS contain?

• eye opening response

• verbal response

• motor response

What is the minimum GCS score?

3

What is the maximum GCS score?

15

What is a coma?

a deep and prolonged state of unconsciousness

What is persistent vegetative state (PVS)?

a state of altered consciousness where the patient appears to be awake but does not have a meaningful response

What percentage of individuals who suffered a severe TBI can develop some independent living capabilities?

15%

What percentage of individuals who suffered a mild TBI have symptoms one year later?

10-15%

What is a mild TBI/concussion?

a temporary loss of neurological function without apparent structural damage

For a concussion to occur, what does the patient not need to be/have?

• unconscious

• directly hit to their head

• have amnesia

What is post-concussion syndrome (PCS)?

the constellation of symptoms that persist after mild TBI

What can the symptoms of PCS be?

• physical

• cognitive

• behavioral

• emotional

What are some common symptoms of PCS?

• headache

• dizziness

• anxiety

• insomnia

• problems with concentration and memory

True or False: Patients who suffer more than one TBI are at an increased risk for PCS.

true

What are the three biomechanical forces resulting in a TBI?

• linear (translational) acceleration

• rotational (angular) acceleration

• impact deceleration

What is a coup injury?

the damage occurs directly under the site of impact

What is a counter-coup injury?

the damage occurs on the side opposite from the impact

What is a primary injury?

results from mechanical injury at the time of trauma

What are two primary injuries?

• diffuse axonal injury (DAI)

• hematomas/hemorrhages

What is a secondary injury?

caused by the physiological responses to the initial injury and include a series of neuro-electro-chemical cascade events

What are three secondary injuries?

• excitotoxicity

• ischemia

• inflammation

What is a cerebral hemorrhage?

uncontrolled bleeding inside the brain

What is a cerebral hematoma?

a blood clot in the brain

What is a cerebral contusion?

a bruise of the brain’s surface that extends down through the cortex

True or False: The pressure-volume relationship within the cranium approximates an exponential curve.

true

What is cerebral ischemia?

a condition in which there isn’t enough blood flow to the brain to meet metabolic demand

What is cerebral hypoxia?

a condition in which there is a decrease of oxygen supply to the brain

What is brain herniation?

a pressure gradient originating from the lesion site that causes displacement of brain tissue

What is a diffuse axonal injury (DAI)

the shearing/tearing of axons that lead to disconnection or malfunction of neurons’ interconnections

What does DAI induce in regards to the AB peptide?

extensive axonal pathology with retraction bulb and varicosities

Where does amyloid precursor proteins (APP) accumulate?

injured neurons

What does sequential APP proteolysis generate?

the neurotoxic amyloid B (AB) peptide

What is the crucial step in the development of Alzheimer’s disease?

APP proteolysis generates the AB peptide

What does DAI induce in regards to the tau protein?

accumulation and spread of phosphorylated tau protein

What is sprouting?

restoration of damaged neural circuits by growing new dendrites, axons, and synapses

What does the generation of new neurons depend on?

neuronal replacement depends on the maintenance of a neural stem cell

What is functional compensation?

uninjured areas of the brain take over the functions lost or reroute information around the injured area

What does the success of brain injury rehabilitation depend on?

• nature and severity of the brain injury

• type and degree of any resulting impairments and disabilities

• overall health of the patients

• family support