PBL 44 Flashcards
What are the two main types of stroke?
ischaemic & haemorrhagic
Give some causes of ischaemic strokes
Thrombosis
Embolism
Systemic hypoperfusion
Cerebral venous sinus thrombosis
Give some causes of haemorrhagic stroke
Cerebral haemorrhage
Subarachnoid haemorrhage
What is the right hemisphere involved in?
Creativity, imagination, recognition and emotion
What is the left hemisphere involved in?
Logic, number skills, language and analytical skills
Effects of stroke in the cerebellum
VANISH’D
- Dizziness
- Headache
- Nausea and vomiting
Effects of stroke in the brainstem
- Breathing and heart functions
- Body temperature control
- Balance and coordination
- Weakness or paralysis
- Chewing, swallowing, and speaking
- Vision
- Coma
- Death
Signs and symptoms of stroke
- Sudden weakness or paralysis on one side of the body
- Sudden loss of sensation or abnormal sensations on one side of the body
- Sudden difficulty speaking, including difficulty coming up with words and sometimes slurred speech
- Sudden confusion, with difficulty understanding speech
- Sudden dimness, blurring, or loss of vision, particularly in one eye
- Sudden dizziness or loss of balance and coordination, leading to falls
Difference between stroke and TIA
TIA symptoms usually disappear within minutes and rarely last more than 1 hour
Risk factors for stroke (modifiable and non-modifiable)
- Non-modifiable
1. Age: older
2. Gender: male
3. Race
4. FHx
5. Previous strokes - Modifiable
1. Hypertension
2. Diabetes
3. AF
4. Smoking
5. Hyperlipidaemia
6. Obesity
Treatments of ischaemic stroke
Antiplatelets - CLOPIDOGREL
Anticoagulants - DABIGATRAN (II), APIXABAN(Xa), WARFARIN
Hypertension drugs (Acei, ARB, CCblocker)
Thrombolysis = clot buster
Thromboectomy = widen a narrowed artery
Treatments of haemorrhagic stroke
Treatments that help blood clot = Vit K & transfusions of fresh frozen plasma or platelets
Hypertension drugs if needed
Surgery to remove large areas of accumulated blood or shunt to relieve increased ICP
Dysarthria vs dysphasia
Dysarthria is caused by UMN lesions of the cerebral hemispheres, or LMN lesions of the brainstem. Affects the bulbar muscles which are used in forming words, so it is a disorder of SPEECH
Dysphasia is a disorder of LANGUAGE. It is the impaired ability to understand or use the spoken word, caused by a lesion in the dominant hemisphere.
Causes of aphasia
Stroke
Severe head injury
Brain tumour
Progressive neurological conditions e.g. dementia
Give some means of primary stroke prevention
MANAGE THE RISK FACTORS WHEN THERE IS NO PREV. HISTORY
- Hypertension
- Smoking cessation
- Diabetes
- Dyslipidaemia
- AF
- Postmenopausal HRT
- Diet and exercise
- Weight
- Alcohol consumption
Explain secondary stroke prevention
WHEN IS PREV. STROKE HISTORY = ABCDE A - Antiplatelets and anticoagulants B - Blood pressure C - Cessation of smoking, cholesterol lowering medications and carotid revascularisation D - Diet E - Exercise
Mechanism of clopidogrel
ADP receptor inhibitor
ADP causes platelet aggregation
Anticoagulants vs antiplatelet function
Anticoagulants slow down clotting by reducing fibrin formation (DABIGATRAN, WARFARIN)
Antiplatelets prevent platelets clumping and prevent clots from forming and growing (CLOPIDOGREL/ASPIRIN)
How do anterior cerebral infarct symptoms compare to middle cerebral and posterior cerebral?
Anterior cerebral = contralateral limb weakness and contralateral sensory deficit where the LOWER LIMB IS MORE IMPACTED
Middle cerebral = contralateral limb weakness and contralateral sensory loss where the UPPER LIMB IS MORE IMPACTED
Posterior cerebral = contralateral problems with vision (homonymous hemianopsia) and also contralateral hemiparesis and sensory deficits
Clinical response to brain injury
- Altered conscious level
- Loss of consciousness
- Post traumatic amnesia - Symptoms
- Vomiting
- Pain
- Dizziness
Difference between primary and secondary brain injury?
Primary = occurs at the moment of trauma
Secondary = occurs immediately after and produces effects which last for a long time
Brain injury can be classified as focal or diffuse, what is the difference?
Focal = specific location: contusion or haemorrhage
Diffuse = over a widespread area: diffuse axonal injury, hypoxic brain injury, diffuse brain swelling
Symptoms of primary brain injury
Mechanoporation
Calcium influx
Oxygen free radical formation and lipid peroxidation
Axotomy
Cytokine-mediated inflammatory response
Symptoms of secondary brain injury
- Raised ICP
- Hypoxic brain injury
- Ischaemic brain injury
- Seizures
- Infection
- Hydrocephalus (>fluid in the brain)
- Cerebral oedema
- Excitatory amino acids (EAAs) - Can cause swelling, vacuolization and neuronal death
- Endogenous opioid peptides - Modulate the presynaptic release of EAA neurotransmitters
What is the normal ICP?
7-15mmHg
What is the Monro-Kellie hypothesis?
The pressure-volume relationship between ICP, CSF volume, blood, brain tissue and cerebral perfusion pressure
- It states that the cranial compartment is incompressible and the volume inside the cranium is a fixed volume. The principal buffers for increased volumes include CSF and to a lesser extend blood volume. These buffers respond to increases in volume of the remaining intracranial constituents
- There comes a point ‘Point of decompensation’ whereby the ability to compensate is LOST, so as the haematoma grows, the ICP will rise and exponentially, until herniation of the brain occurs.
- The contents of the skull are venous volume, arterial volume, the brain, and CSF. If we add another mass, such as a haematoma, which increases in size (increasing the ICP), there are compensatory mechanisms whereby CSF will leave the skull through systems and ventricles into the CSF spaces of the spine until the ICP is equalised
- The final pathway from which someone will die from an intracranial haematoma is herniation of the brainstem through the foramen magnum
Symptoms which suggest a rise in ICP?
- Headache
- Vomiting without nausea
- Ocular palsies
- Altered level of consciousness
- Back pain
- Papilloedema
The dorsal column medial lemniscus system is involved in which sensory functions? Where does it decussate and in which situations does it travel to the gracile fasciculus vs the cuneate fasciculus?
Fine touch, pressure, vibration, proprioception
Decussates in the medulla
Gracile = below T6 (inner) & Cuneate = above T6 (outer)
The spinocerebellar tracts are involved in which sensory functions? Where do they decussate and where do they synapse?
- Proprioception to cerebellum
- Ipsilateral - Posterior stay ipsilateral, anterior decussate twice (anterior white commisure, superior cerebellar peduncle)
- Synapse in clarke’s nucleus (posterior grey horn)
- Travel to cerebellum
The spinothalamic tracts are involved in which sensory functions? Where do they decussate and where do they synapse?
- Pain, temperature, crude touch
- Contralateral - Decussate in spinal cord (2-3 levels above entry)
- Synapse in posterior horn and thalamus
- Travel to primary sensory cortex
The UMN can be classified based on the region of synapse in the anterior horn, what are the two possibilities?
Ventromedial: posture, girdle, muscles
Dorsal lateral: distal movement, fine movement
What is the pyramidal UMN tract known as? It is involved in which motor functions? Where does it decussate and where do they synapse?
- It is the corticospinal tract
• Voluntary skilled motor activity
• Contralateral - 90% decussate in medulla (lateral), 10% decussate in spinal cord (anterior)
• Dorsal lateral
• Lateral controls distal movement, anterior controls proximal movement
What are the other extrapyramidal UMN tracts?
Vestibulospinal
Tectospinal
Reticulospinal
Rubrospinal
Explain the function, route and synapse of the vestibulospinal tract
- Balance, posture
- Ipsilateral
- Ventral medial
Explain the function, route and synapse of the tectospinal tract
- Orientation, flinching, navigational
- Contralateral
- Ventral medial
Explain the function, route and synapse of the reticulospinal tract
- Large movements of trunk and limbs
- Ipsilateral
- Ventral medial
Explain the function, route and synapse of the rubrospinal tract
- Distal arm and hand movement
- Contralateral
- Dorsal lateral