CNS Injuries & Damage Flashcards
Traumatic Brain Injury (Summary)
NICE: Traumatic brain injury is defined as a traumatically induced structural injury and/or physiological disruption of brain function as a result of an external force that is indicated by new or worsening of at least 1 of the following clinical signs, immediately after the event:
- Loss of/ decreased level of consciousness.
- Loss of memory for events immediately before or after the injury.
- Alteration in mental state at the time of the injury (confusion, disorientation or slowed thinking).
- Neurological deficits (weakness, loss of balance, change in vision, praxis, paresis, plegia, sensory loss or aphasia) that may or may not be transient.
- Intracranial lesion.
The severity can be highly variable, with some injuries treated in
outpatient care, while others may be a life threatening or life
changing injury with long term implications.
* Approx. 1.4 million patients per year (England & Wales) visit
hospital with a head injury
* One of the leading causes of death in people under the age of 40
Causes of TBI?
- Motor vehicle accidents
- Falls
- Sports
- Assaults
- Struck by an object – intentionally or not
- Gun shots
- Explosives
Causes of TBI
- Concussion
- Contusion (coup, contrecoup)
- Diffuse axonal injury
- Traumatic subarachnoid haemorrhage
- Hematoma
– Epidural hematoma
– Subdural hematoma - Penetrating head injuries
Injuries can be:
1. Focal – focused on a particular point
2. Diffuse – spread over a wide area
3. Open (penetrating)
4. Closed (non-penetrating)
What is concussion?
- Mild TBI – not generally visible through brain imaging
- Caused by external forces applied to the head – impact or inertial
- Many will not experience loss of consciousness
- In most cases symptoms last a few days to a couple of weeks– but symptoms can last several months
what is Second Impact Syndrome?
a second head injury which has more severe consequences as it occurs before full recovery from the first concussion
Chronic Traumatic Encephalopathy (CTE)
– Repeated head injuries/concussions result in long term &
progressive neurological deficits
– Encephalopathy is a broad term for altered brain function/structure
Define: Contusion (coup & contrecoup)
Contusion – ruptured blood vessels (bruising)
- Coup – site of impact
- Contrecoup – opposite side to the impact (French –
“counterblow”
The brain hits skull at point of impact, then rebounds and hits the
skull opposite point of impact
Diffuse Axonal Injury
- Severe acceleration/deceleration causes shearing forces – different parts of the brain move in different directions
- Causes damage to axons, particularly at junction of white and grey matter
- In more severe cases, corpus callosum and brain stem also affected
- Range of severity – very poor prognosis in severe cases
Shaken Baby Syndrome
Also known as abusive head trauma (AHT)
May present with a range of symptoms and severities:
* Irritability
* Vomiting
* Breathing difficulties
* Seizures
* Dilated pupils
* Unconsciousness
Subdural hematoma, retinal haemorrhage, and encephalopathy are
clearest signs
“One punch deaths”
A single punch can be fatal:
- The impact itself causes fatal damage to the brain e.g. ruptured
blood vessel - The punch causes the person to lose consciousness, so they’re likely to hit their head on a hard surface when they fall
In the falling example, the impact is comparable to being hit over
the head with a block of concrete.
Penetrating Brain Injuries
- Projectiles (e.g. bullets), knives, bone fragments (e.g. depressed skull fracture)
- Higher risk of infection, worse prognosis than closed TBI
- Prognosis depends on severity and location of damage
- Management is similar to closed TBI: management of intracranial haemorrhage & intracranial pressure
Intracranial Pressure
- Raised intracranial pressure (ICP) can result in secondary injuries
- ICP > 20mmHg is associated with increased mortality
- Treatments include
– Hyperosmotic agents e.g. Mannitol
– CSF drainage
– Induced hypothermia
– Barbiturates (e.g. sodium thiopental) – reduces metabolic rate
– Decompressive craniectomy
Causes of increased intracranial pressure
Intracranial:
1. Extra-axial mass lesion—Epidural or subdural hematoma
2. Intraparenchymal mass lesion—Intracerebral hemorrhage, contusion
3. Depressed skull fracture
4. Brain edema—Cytotoxic (intracellular) or vasogenic (extracellular)
5. Disturbed in CSF dynamics with or without ventricular enlargement
6. Hyperemia—Vasomotor paralysis or loss of autoregulation
7. Venous sinus thrombosis
8. Seizures
Extracranial:
1. Airway obstruction
2. Hypoventilation—Hypoxia, hypercarbia
3. Agitation
4. Pain
5. Hypertension
6. Cranial venous outflow obstruction
7. Head position or posture
8. Fever
9. Increased intrathoracic pressure including Valsalva maneuver
10. Increased intra-abdominal pressure (including compartment syndrome)
11. Liver failure
12. Altered sodium balance
13. Hypoosmolarity
Bleeding - Brain Injuries:
Haemorrhages and Hematomas
Hematoma is internal, whereas haemorrhage can be internal
or external
Haemorrhage is ongoing bleeding, hematoma is the often
clotted build up of blood, where the bleed itself may or may
not be ongoing.
Different types of Haemorrhages and Hematomas
Referred to by the location of the bleed:
* Epidural (aka extradural) – between skull and dura mater
* Subdural – between dura mater and arachnoid mater
* Subarachnoid – between arachnoid mater and pia mater
* Intracerebral (aka intraparenchymal) – within the brain itself
* Intraventricular – bleeding into the ventricular system within the
brain
Layers of the brain
- Subarachnoid space
- Arachnoid trabeculae
- Artery
- Perivascular space
- Cerebral cortex
- White matter
Subdural and Epidural Hematomas
Symptoms include:
* Worsening headache
* Confusion
* Nausea
* Problems with vision, movement, or speech
* Unusual behaviour (e.g. aggression, mood swings)
* Loss of consciousness
* Can present with loss of consciousness, lucid period, then rapid
deterioration
Subdural hematoma – usually acute, sometimes subacute/chronic
What is a Subdural Hematoma? what is its treatment?
In an X-ray it will show a build up of blood in the brain
Treatment:
* Acute subdural hematoma –
craniotomy
* Chronic subdural hematoma –
burr holes