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
Define Subarachnoid Haemorrhage. Give symptoms.
Bleeding between the pia and the arachnoid membranes
- Most likely to occur spontaneously (e.g. ruptured aneurysm or
AVM) - but can also be the result of a physical injury (traumatic
subarachnoid haemorrhage).
Symptoms include:
* Sudden severe headache
* Nausea
* Stroke-like symptoms
* Loss of consciousness
* Convulsions
Can be diagnosed by CT and/or lumbar puncture – the subarachnoid
space contains CSF
In an x-ray blood can be seen mostly around the brainstem
Subarachnoid Haemorrhage Treatment
Treatment
* Nimodipine
– Calcium channel blocker
– Used to prevent vasoconstriction
– Vasoconstriction can result in further damage to the brain due to
cerebral ischemia.
* Anticonvulsants & antiemetics
* Surgery may be used to repair the blood vessel, particularly if an
aneurysm of AVM is identified as the cause
What are aneurysms
- Weakness in the wall of a blood vessel results in a bulge
- Smoking and high blood pressure are risk factors, + genetic risk
- Often asymptomatic unless they rupture
- Ruptured aneurysm is fatal in approx. 50% of cases
- Survivors may have long term deficits
- Ruptured aneurysm may be repaired with endovascular coiling
Symptoms of aneurysms
Often asymptomatic, but depending on location may cause neurological symptoms such as:
– Double vision, pain, balance issues, short-term memory issues
Symptoms of ruptured aneurysm:
* “Thunderclap headache”
* Nausea/vomiting
* Stiff neck, aversion to bright lights
* Seizures, loss of consciousness
Aneurysm Treatments
Often nothing – most aneurysms won’t rupture
* Risk of rupture vs risk of surgery will be assessed
* Surgery – same for ruptured or unruptured
Surgeries:
– Coiling: a catheter is used to reach the aneurysm. Platinum coils
are used to fill the aneurysm, stopping blood from entering.
– Clipping: a clip is placed around the neck of the aneurysm,
stopping blood from entering
What is a Arteriovenous Malformations? (AVMs)
- Arteriovenous malformations can occur anywhere in the body
- Abnormal connection between arteries & veins
- Often asymptomatic, but can rupture
What is a Intracerebral haemorrhage?
What are its risk factors?
How would you identify in an X-ray
- aka intraparenchymal haemorrhage
- Similar presentation to ischemic stroke
Risk factors include
* Hypertension
* Alcohol intake
* Low cholesterol (contrast to ischemic stroke risk)
* Genetic risk
* Anticoagulants
* Drug use (e.g. cocaine)
In an X-ray: deeper brain structures are affected (light areas in the middle of the brain)
What are the 3 types of oxygen deprivation?
Hypoxia, Anoxia, and Ischemia
What is Hypoxia and anoxia
- Hypoxia – restricted supply of oxygen
- Anoxia – absence of oxygen
Brain cells die after just a four minutes without sufficient oxygen.
Extent of damage, likelihood of recovery & symptoms depend on
various factors: duration of hypoxia/anoxia & which brain regions were affected.
Causes of Hypoxia and anoxia
Causes: Anything that prevents effective ventilation or circulation, including:
* Ischaemic stroke
* Cardiac arrest, respiratory arrest/lung injury
* Haemorrhagic/hypovolemic shock
* Suffocation/strangulation/choking
* Smoke inhalation
* Near drowning
* Drug overdose
* Anaphylaxis
* Severe asthma
Treatment of Hypoxia and anoxia
Priority= restore ventilation, heartbeat, and blood pressure – prevent ongoing injury
Treatment of any associated injuries e.g. heart/lung/neck
Most improvement in brain function comes in the first few months
Rehabilitation team would include occupational therapists,
physiotherapists, speech/language therapists
As with other brain injuries, younger age generally have better prognosis
What is a stroke?
- Haemorrhagic strokes
- Ischemic strokes
- Transient ischemic attack (TIA)
Ischemia is disruption of blood supply.
Note this is different (but with some overlap) from anoxia/hypoxia,
which are disrupted oxygen supply.
What is a Ischemic Stroke?
State Risk factors & Symptoms
The majority of strokes are ischemic (approx. 85%)
- A blood clot blocks blood flow within the brain
- The clots often form as a result of atherosclerosis Atherosclerosis
- Atrial fibrillation also increases risk Atrial fibrillation - NHS
- Risk increases with age – arteries become narrower and stiffer
Risk factors:
* Smoking
* Alcohol
* Hypertension
* Obesity
* Diabetes
* High cholesterol
Specifics and severity depend on brain regions affected. General
advice: BE FAST (Balance, Eyes, Face, Arm, Speech, Time)
> ROSIER carried out on clinical assessment (Recognition of Stroke in Emergency Room)
CT scan will likely be performed
Ischemic Stroke Symptoms
Thrombolysis drugs
* Altepase
Thrombectomy
* Surgical removal of the clot
Aspirin/long-term antithrombotic therapy
* Only once haemorrhagic stroke ruled out
What is a Transient Ischemic Attack (TIA)
- Blood supply temporarily blocked, usually by a blood clot
- Symptoms are the same as ischemic stroke, but will be temporary
- Resolve in minutes/hours with little or no lasting effects
- Indicates risk of future strokes
- Prevention of future attacks: Lifestyle advice, anti-
platelet/anticoagulants, blood pressure and cholesterol control.
How is memory impaired after a brain injury?
- Post-traumatic amnesia (PTA) can occur after a TBI.
- PTA can occur regardless of whether the patient lost consciousness,
but is more common following a period of unconsciousness. - The main symptom of PTA is: loss of memory (particularly of recent
events), confusion, disorientation & uncharacteristic behaviours.
PTA can last a few minutes to several weeks, with longer duration indicating a more severe brain injury.
Difference between Retrograde amnesia & Anterograde amnesia?
Following a brain injury patient may suffer ongoing memory problems.
Retrograde amnesia: loss of memories from before the injury
Anterograde amnesia: difficulties forming new memories since the
injury
- Both can range in severity. Both retrograde & anterograde can cause significant problems for patients, anterograde amnesia
has been reported by patients to be a bigger problem as it is an
ongoing issue.
Brain regions involved in memory
Several brain regions are involved in memory
Damage to any one of them may impact upon memory to some
degree.
- Hippocampus has an important role in memory formation,
particularly consolidating short term memory into long term
memory. Damaged hippocampus can result in anterograde
amnesia.
What are explicit, implicit memories & short-term working memory?
explicit memories – which are about events that happened to you (episodic), as well as general facts and information (semantic) – there are three important areas of the brain: the hippocampus, the neocortex and the amygdala.
Implicit memories, such as motor memories, rely on the basal ganglia and cerebellum.
Short-term working memory relies most heavily on the prefrontal cortex.
https://qbi.uq.edu.au/brain-basics/memory/where-are-memories-stored
Loss of consciousness
blow to the head can result in being knocked out - the person
becomes unconscious.
Swelling, bruising, and movement of the brain within the skull result in a disruption to the normal function of the brain (similar to TBI).
This may present with:
– very minor symptoms (perhaps a bit of a headache)
– the person may remain conscious but become dizzy, disorientated
& nauseous
– loss of consciousness
In most cases loss of consciousness= temporary, lasting secs to mins.
* Acquired brain injuries (traumatic or non-traumatic) can result in
longer term impairments of consciousness.
* Note that short term impairments of consciousness can also be
caused by internal factors - this is syncope (fainting).
* Can be caused by factors such as low blood pressure, which can
result in insufficient blood flow to the brain and therefore a
disruption of normal brain function.
Coma
- No sign of being awake or aware
- Duration is variable
– Generally longer duration -> worse prognosis - Waking from a coma is a gradual process
- In some patients they may wake from the coma but remain in a
vegetative state, or a minimally conscious state, for a period of time.
This may be temporary in some cases but can also be long term.
Glasgow Coma Scale (GCS)
- Used to assess degree of consciousness
- NICE guidelines indicate a patient who has suffered a head injury
should not be discharged unless they score 15 on the GCS - Three criteria:
– Eye opening
– Verbal response
– Motor response - Scores 3-15 (<8 = coma)
Induced Coma
- A coma may be induced to reduce the energy demands of the brain
- Aim is to protect the damaged areas as they attempt to heal (i.e.
swelling to reduce, bruising to heal), and to reduce intracranial
pressure to minimise further damage - Coma can be induced and regulated using drugs such as
barbiturates.
Vegetative state
- Periods of wakefulness but no signs of awareness
- Basic reflexes, but no meaningful responses (such as responding to
voices) - Can occur when there has been damage to the higher centres of the
brain, but the brain stem has remained intact and functional and so
the patient is still able to regulate their breathing and heart rate - > 4 weeks = continuing (or persistent) vegetative state
- > 6-12 months, then the patient may be considered a permanent
vegetative state.
Minimally conscious state
- Patient does show signs of awareness, but this may be limited
and/or inconsistent - May be able to respond to voices, questions, or other stimuli with a
simple response e.g. moving a finger or moving/blinking their eyes. - Better prognosis for minimally conscious state than it is for
vegetative state
– Minimally conscious state is not usually considered permanent
until it has continued for several years.
Locked in syndrome
- Patient is conscious but is unable to move or speak
- They are entirely paralysed other than eye movement
- Caused by damage to the pons, which is part of the brain stem
What exactly is the Glasgow Coma Scale?
Eye Opening Response
* Spontaneous–open with blinking at baseline 4 points
* To verbal stimuli, command, speech 3 points
* To pain only (not applied to face) 2 points
* No response 1 point
Verbal Response
* Oriented 5 points
* Confused conversation, but able to answer questions 4 points
* Inappropriate words 3 points
* Incomprehensible speech 2 points
* No response 1 point
Motor Response
* Obeys commands for movement 6 points
* Purposeful movement to painful stimulus 5 points
* Withdraws in response to pain 4 points
* Flexion in response to pain (decorticate posturing) 3 points
* Extension response in response to pain (decerebrate posturing) 2 points
* No response 1 point
