Module 2D - Stroke Flashcards
2 causes of ischaemic strokes
thrombotic or embolic
Types of haemorrhagic stroke + aetiology
- Extradural –> bleeding between skull and dura mater
- Subdural –> bleeding between dura mater and arachnoid mater
- Intracerebral –> bleeding into brain tissue
- Subarachnoid –> bleeding in the subarachnoid space
Oxford classification of stroke (Bamford classification)
Risk factors for a stroke
- Main –> smoking, AF, hx of previous stroke or TIA
- Other –> hypertension, hypercholesterolemia, obesity, family hx, vasculitis, combined oral-contraceptive pill
(stroke is associated with co-morbidities such as cardiovascular disease and vascular disease –> share the same risk factors)
Definition of stroke, TIA, crescendo TIAs
- Stroke = a clinical syndrome characterised by rapidly developing clinical symptoms and/or signs of focal neurological deficit lasting more than 24hrs and thought to be of vascular origin
- TIA = neurological signs/symptoms that are consistent with a stroke that resolve within 24hrs
- Crescendo TIAs = two or more TIAs within a week and indicate a high risk of stroke
Common symptoms of a stroke
- One-sided muscle weakness (hemiparesis)
- Dysphasia (speech disturbance)
- Aphasia (expressive/receptive/global)
- One-half visual field defects (hemianopia) - often lose one-half of visual field in each eye which results in neglect on one side of the body
- Sensory loss
- Ataxia and vertigo
Stroke findings on examination (tone, power, sensation, reflexes, coordination, visual fields, facial nerve)
- Tone –> low/normal early in stroke, but increases with time (clasp knife spasticity/reflex)
- Power –> reduced power on affected side, pronator drift
- Sensation – > can be reduced (affects limbs rather than dermatomes), pt may have signs of neglect on affected side (tactile agnosia/astereognosis = inability to recognise objects by touch alone)
- Reflexes –> should be normal in a stroke patient
- Coordination –> can be affected
- Visual fields –> usually have hemianopia
- Facial nerve (7th cranial nerve) –> usually facial droop (spares eyebrows, complete paralysis is Bell’s Palsy)
Does stroke always affect the contralateral side of the body?
Not always –> if cerebellum affected then ipsilateral presentation
Is stroke an UMN or LMN?
UMN
Label the cerebral arteries.
- Which arteries supply anterior brain
- Which arteries supply posterior brain
- Blood is delivered to brain through 4 main arteries, two internal carotid arteries (anterior supply), and two vertebral arteries (posterior supply to the brain)
- Anterior supplied by internal carotid arteries which form the ACA and MCA
- Anterior connects with Posterior via posterior communicating artery
- Posterior supplied by vertebral arteries which combine to form the Basilar artery
(The brain also has a venous drainage system which drain into the venous sinuses)
Which arteries form the Circle of Willis?
- What is function of Circle of Willis?
- Formed by basilar artery, internal carotid artery, and middle cerebral artery
- Safeguards the oxygen supply from interruption by arterial blockage
- For example, if there is stenosis in one artery then other source arteries to the Circle of Willis can provide an alternative blood flow (collateral circulation)
The limbic system is made up of the hippocampus and amygdala, what are their functions?
Limbic system is involved in behavioural and emotional responses (survival, fight or flight)
- Hippocampus –> memory centre, spatial orientation, neurogenesis occurs here (key brain structure for learning new things)
- Amygdala –> central role in emotional responses (pleasure, pain, fear, anxiety, anger), attaches emotional content to memories
Functions of frontal lobe, parietal lobe, temporal lobe, and occipital lobe
- Frontal lobe –> higher executive function (emotions, planning, reasoning, problem-solving), primary motor cortex (responsible for voluntary movement)
- Parietal lobe –> sensory info (touch, temp., pressure, pain), two-point discrimination can be used to assess
- Temporal lobe –> sensory info (hearing, recognising language, forming memories), primary auditory cortex (can understand what we hear), making sense of complex visual info (faces and scenes), hippocampus (memory, learning, emotions)
- Occipital lobe –> Primary visual cortex (major visual processing centre in the brain)
MCA infarct:
- locations affected?
- symptoms associated
- Locations affected –> frontal, parietal, and temporal lobes
Symptoms:
- hemiparesis –> arm worse than leg
- Sensory loss
- Facial weakness –> facial droop/dysarthria
- Dysphasia –> expressive, receptive, global
- Hemianopia –> without macula sparing
Broca’s aphasia vs Wernicke’s aphasia
- Broca’s –> expressive dysphasia (pt can understand what is said but cannot express with words, difficult to speak)
- Wernicke’s –> receptive dysphasia (pt doesn’t understand what is being said, but can still talk normally, but it doesn’t make any sense)
If a right-hand dominant patient has Broca’s or Wernicke’s aphasia then which side is the stroke?
- Left MCA
- Broca’s and Wernicke’s area are found in the dominant cerebral hemisphere
- left side for right-handed
- right side for left-handed
ACA infarct:
- locations affected?
- symptoms associated
- Locations affected –> frontal and parietal lobes
Symptoms:
- hemiparesis –> leg worse than arm
- Apathy –> lack of interest, enthusiasm, or concern
- incontinence
- Disinhibition –> lack of restraint in social scenarios (affects motor, emotional, cognitive, instinctual, and perceptual behaviours)
- Mutism
Lacunar stroke:
- locations affected?
- symptoms associated
Locations affected –> Lenticulostriate arteries (small penetrating arteries that supply deep structures
(susceptible to injury secondary to uncontrolled hypertension)
Symptoms:
- Pure motor –> hemiparesis or hemiplegia, dysrthria, dysphagia
- Pure sensory –> numbness/tingling/pain on one side of body
- Sensorimotor –> hemiparesis or hemiplegia with contralateral sensory impairment
What are the watershed zones?
- Symptoms for each
Watershed zones are prone to infarction as they receive blood supply from two arteries
PCA infarct:
- locations affected?
- symptoms associated
Locations affected –> mainly occipital, parts of temporal
Symptoms:
- Hemianopia –> with macular sparing
- Amnesia
- Sensory loss (thalamus)
- Thalamic pain
Where does basilar artery supply and if basilar artery is affected in a stroke, what is the serious condition that can result? + what structure is damaged to cause this
- Supplies lower midbrain, pons, and medulla (and occipital lobe)
- Infarction causes locked-in syndrome –> individual has full consciousness but is paralysed
- due to damage to corticospinal tracts (quadriplegia)
- Respiratory muscles also paralysed so individual has to be ventilated –> resp. failure and coma/death can be result
Grey and white matter
- Grey matter –> neuronal cell bodies (business end)
- White matter –> myelinated axons (wiring)
Note: stroke doesn’t differentiate between grey and white matter – can affect both
Acute stroke management
- Non-contrast CT is mainstay investigation
- Thrombectomy –> Can be done together with IV thrombolysis if within 4.5hrs onset –> CT perfusion or CT angiography used to assess salvageable brain tissue
Contraindications for thrombolysis
- pt on DOAC or Warfarin (check INR)
- Hx of surgery, Hx of bleeding (external/internal)
- Uncontrolled hypertension –> BP > 180/120mmHg
