2a. Traumatic Brain Injury (TBI) Flashcards
What is TBI? (+definition)
And where is it characterized by? (2x)
Traumatic brain injury = damage to living brain tissue caused by an external mechanical force or motion, characterized by …
(1) a period of altered consciousness
(2) a clinical diverse picture with a broad spectrum of cognitive, emotional, and behavioral disorders
What is an open brain injury?
When an object fractures the skull, enters the brain, and injures the brain tissue
(far less more common than closed injuries and more often results in death)
What is a closed brain injury?
When the head accelerates and then rapidly decelerates or collides with an other object.
The brain tissue is damaged by the violent smashing, shaking, stretching, and twitching of the brain and additionally by physiological reactions following the injury
What is a primary injury?
Immediate damage that occurs at the time of impact
What is a secondary injury?
Damage caused by the effects of the physiological processes set in motion by the primary injury
What are 3 types of primary injuries?
And give explanations on these types.
- Bruising of brain parenchyma
- Laceration of nerve fibers
- Disruption of blood vessels
Explanation:
- When the external mechanical force is linear, it results in a contusion (=kneuzing)
- When the external force or motion is more rotational, it may result in tearing of the fibers
- Might be caused by both linear and rotational forces
What is accelaration?
The damage is the result of a moving object that hits the fixed head or the skull is moved by a forceful blow
What is deceleration?
The damage is the result of opposite movements, so the head is moving against a stationary object
What is a coup?
Disruption of the tissue at the point of impact
What is a contre-coup?
(Indirect) disruption of tissue located opposite to the site of impact
Mechanisms of primary injuries
What is Newton’s law of inertia?
And where does it result in?
Acceleration/deceleration process: the brain lags behind when the head is suddenly moved, so it continues to move at the original velocity against the bony ridges within the skull, causing bruises and micro-bleedings.
Where does it result in?
If the force is strong enough, both a coup and contre-coup lesion may result. It primarily results in contusions of the grey matter/parenchyma, frequently found in the orbitofrontal and temporal brain regions, since here is the base of the cranium very rough.
What is hyperextension?
Sudden backward acceleration of the skull causes the brain to move forward, striking the front of the skull.
What is hyperflexion?
The head recoils forward and suddenly stops, the brain shifts backward, striking the back of the skull.
Mechanisms of primary injuries
What is the result of rotating forces?
They cause diffuse axonal injury (DAI), due to the damage of axons by rotational forces
Mechanisms of primary injuries
What is the result of the disruption of blood vessels?
A rupture of a blood vessel may lead to heavy bleeding (primary injury) but it also causes swelling and intercranial pressure (secondary injuries).
Due to the disruption of a blood vessel, a hematomata will be present. What types of hematomata are there? (2x)
Explain the 2nd one (what do they mean & when do they occur?)
- Within the brain: intracerebral or intraparenchymal
- Cortical surface: subdural and epidural
What do they mean:
Epidural: forms between the skull and dura
Subdural: forms between dura and the membranes that cover the brain
When do they occur:
They regularly occur in the case of temporal fractures and damage in the ACM.
What is a ‘traumatic subarachnoid hemorrhage’ (TSAH)?
Subdural & epidural hematomata can result in a shift of brain matter which is life threatening if not recognized early on.
What are the main INTRACEREBRAL secondary processes? (5x)
And what is a main EXTRACEREBRAL secondary process?
Intracerebral
- Delayed axotomy
- Increased intracranial pressure
- Disturbed blood flow
- Coagulopathy
- Pyrexia
Extracerebral
1. Hypoxia
Intracerebral secondary processes
How does delayed axotomy occur?
It is the result of severe axonal injury. When an axon is damaged, many neurotransmitters are released, specifically glutamate > this causes an excess of calcium > this causes overexcitation of the already injured neuron
Intracerebral secondary processes
How does increased intracranial pressure occur?
This can occur due to massive edema (accumulation of fluid) or to the accumulation of blood caused by disrupted arteries
Intracerebral secondary processes
How does a disturbed blood flow occur/what does it mean?
This can occur due to laceration of an artery or swelling in the brain. A swelling in the brain hinders the blood flow and thus the supply of oxygen and nutrition to the cells (hypoxia).
Intracerebral secondary processes
What is coagulopathy?
The blood’s ability to coagulate (form clots) is impaired
Intracerebral secondary processes
What is pyrexia?
Having a temperature above the normal range (fever)
Extracerebral secondary processes
How does hypoxia occur/what does it mean? (when parts outside the brain are damaged)
When parts outside the brain are damaged (e.g. blood loss in leg) this may lead to failing of autoregulation such as shock or hypertension > then the brain receives insufficient oxygen (hypoxia) leading to brain ischemia
