Lecture 5a. TBI Flashcards
What are causes of TBI?
- 0-4 years
- 4-11 years
- 12-18 years
- 0-4 years: dangers within the home environment, e.g. trying to climb on a closet.
- 4-11 years: primary cause shifts to the sports environment.
- 12-18 years: primary cause shifts to traffic (start to take part of traffic independently).
What are 4 primary consequences of a penetrating injury?
And 4 secondary consequences?
Primary:
- Focal cerebral damage, instead of diffuse brain damage (location)
- No loss of consciousness
- Increased risk of post-traumatic epilepsy
- Associated with selective cognitive deficits (location)
Secondary:
- Swelling, bleeding, increased intracranial pressure
- Increased risk of cerebral infections, because the brain barrier has been crossed (typical for a penetrating injury)
What are 4 primary consequences of a closed injury?
And 4 secondary consequences?
Primary:
- Cerebral contusion of the cortex
- Diffuse axonal injury (DAI): functions that are most sensitive for this are information processing and executive functioning (higher order functions), because these processes really depend on the connectivity of the brain
- Loss of consciousness
- Post-traumatic amnesia (PTA)
Secondary:
- Bleeding, swelling, intracranial pressure
- Cytotoxic cascades: many cells die during a TBI in which their membranes rupture, leading to a loss of all kinds of contents into the fluid surrounding other cells. This can lead to concentrations of for example excitatory neurotransmitters that are so high that they can become toxic to other cells, and they die as well
Which kind of swelling is really life threatening, and why?
Swelling of the brain stem: this is the only place where the brain is fixed to the rest of the body, so there is a lot of strain on this area. It is life threatening, because the brain stem regulates vital functions.
What type of force is more likely to induce DAI?
Rotational forces
Different types of bleeding:
- Epidural hematoma
- Subdural hematoma
- Intracerebral hematoma
- Oedema
- Epidural hematoma (around the brain): epidural means that the hematoma is between the dura mater and the skull. If blood enters this area, it collects like a lens-form (typical shape).
- Subdural hematoma (around the brain): hematoma located underneath the dura mater, so it’s not collecting as a lens shape, but in the same shape/contour as the brain has.
- Intracerebral hematoma: hematoma within the brain.
- Oedema: the signature of oedema is that it’s hard to see, but if tissue swells in the brain (and the brain is not elastic), this increases pressure in the brain on imaging this is signified by a loss of contrast between white and grey matter.
Intracranial pressure; there are different paths of action in which intracranial pressure can have a negative influence on brain integrity (2x)
- Anoxic pathway: it can start with oedema –> increases pressure in the brain –> therefore, the resistance (= ongevoelig) for blood flow entering the brain is higher –> this causes a suboptimal perfusion (= doorbloeding) of the brain –> can lead to anoxic damage (lack of oxygen) to neural tissue.
- Mechanical pathway: it can start with a hematoma (local effect) –> through the pressure of the hematoma, there is herniation of the neural tissue, called a ‘mass effect’ –> can lead to necrosis (cell death).
Why are children vulnerable to TBI?
- In physical terms (5x)
- In neurobiological terms (2x)
- In functional terms (1x)
Physical:
- They have a weak neck musculature, so they can’t stabilize their head, meaning that the acceleration/deceleration of the head is higher with the same impact.
- They have a relatively large head, so the impact of falling is higher.
- They have a relatively thin cranium, which increases the risk of penetrating injury.
- In young children (<12 months), the cranium plates have not closed fully.
- They are in development, which means they have myelinating axons, and axons that have not myelinated are more sensitive to impact.
Neurobiological:
- After TBI, children are at risk of extended white matter degeneration.
- Also, thickness of the cortex and cerebral volume reduces over time.
Functional:
- If there is an impact of TBI on neurocognitive functions, and these processes are less sufficient, this means that skill acquisition is also less sufficient. This means that you will learn slower than your peers, and will build up a gap over the years.
With which 3 parameters is the severity of TBI determined?
- Glasgow Coma Scale (GCS): you can observe a drop in the level of consciousness, running from 15 (fully conscious) to 3 (fully coma). There are 3 levels in which you can report responses –> responses of the eyes, of motor control, and a verbal response.
- Loss of consciousness duration (LOC): the time to which the GCS normalizes to 15.
- Post-traumatic amnesia (PTA): someone can be fully conscious, but not able to form new memories. This mostly recovers after the recovery of loss of consciousness. You can measure this by trying to extract things that a child should know. It’s mostly aimed at measuring anterograde amnesia (“can you remember these digits?”), but it can also be sometimes used to measure retrograde amnesia (“what’s the name of your father?”).
The Glasgow Coma Scale is difficult to measure, because … (4x)
- We know that the experience of the examiner influences the scoring.
- Children may have agitated behavior in the ambulance (due to panicking) and are therefore sedated –> this does then not reflect severity of the TBI.
- When children have a hard time to breath, they can be intubated to have mechanical assistance in breathing, and then the verbal reaction cannot be measured anymore.
- Also, there is an influence of alcohol on the level of your consciousness.
What are the characteristics, pros, cons of the following neuroimaging techniques used by TBI?
- Computed tomography (CT)
- Conventional MRI
- More advanced MRI scans
- Computed tomography (CT): most widely used, it’s always done to inform a clinician about the need for neurosurgical treatment, since it’s useful as an indicator for the need for neurosurgery. Also, it’s fast in acute settings and relatively cheap.
- Conventional MRI: relatively slow, expensive, but more sensitive for neuropathology than CT, however, that’s not really relevant for a neurosurgeon. Also, it’s predominantly qualitative examined, so it’s not objectively measured.
- More advanced MRI scans: for example, diffuse tensor imaging (DFI), also slow and relatively expensive, but more sensitive for neuropathology than CT and conventional MRI. Also, it’s predominantly quantitative examined, so with an objective measurement.
