Strokes Flashcards
What is a ‘Stroke’ and how can they be classified?
A stroke is a neural dysfunction that results from a disruption of blood supply to the brain, characterised by a developing disturbance of cerebral functions lasting over 24 hours.
Classification:
Occlusive - caused by an atheroma or thomboembolism (or more rarely trauma infection or tumours). They result in an ischaemic infarction and account for 70% of strokes
Haemorrhagic - caused by an intracerebral haemorrhage. Primary haemorrhages accounts for 15% of strokes and subarachnoid haemorrhages account for 5%.
In what locations can infarctions occur and what are the characteristic signs of this type of infarct?
Cerebral hemisphere infarcts 50%)
Contralateral hemiplegia, contralateral sensory loss, homonymous henianopia and dysphasia
Brainstem infarcts (25%) Quadriplegia, disturbances of gaze and vision and locked in syndrome
Lacunar infarcts (25%) - small infarcts around the basal ganglia, internal capsule, thalamus and pons Pure motor, pure sensory or mixed motor/sensory symptoms may occur. Cognition and consciousness is intact
Which cerebral arteries are commonly implicated in strokes, and which parts of the brain do they supply?
Anterior cerebral artery
Supplies the frontal lobe, medial surface of each hemisphere back to the parietal-occipital border and the corpus callosum.
Middle cerebral artery
Supplies two thirds of the brains lateral area including frontal, parietal and temporal lobes, corpus callosum, internal capsule and thalamus.
Posterior cerebral artery
Supplies the midbrain, choroid plexus of the lateral ventricle, posterior end of the corpus callosum, cortex of the occipital and temporal lobes, thalamus, subthalamic nucleus and optic radiation.
What symptoms arise from anterior cerebral artery occlusion
Paralysis and sensory loss of contralateral foot/leg
Motor aphasia if supplementary region is affected
Dysarthia
What symptoms arise from middle cerebral artery occlusion
Paralysis and sensory loss of face and arm
If it affects the internal capsule it can affect eye movements
If on the dominant side can cause Broca’s and Wernicke’s aphasia.
If on the non-domiannt side can result in neglect syndrome.
What symptoms arise from posterior cerebral artery occlusion
Contralateral loss of pain and temperature sensation,
Ballism
Memory defects
Contralateral hemianopia with macula sparing
Difficulty in facial recognition
Where does the posterior inferior cerebellar artery supply and if occluded, which important brain regions are damaged?
The PICA supplies the cerebellum, choroid plexus of the fourth ventricle and the medulla.
Known as Wallenberg Syndrome:
Occlusion damages the dorsolateral medulla of the brainstem which involves the nucleus ambiguous, the spinothalamic tract, trigeminal nucleus and tract, vestibular nuceli and cerebella connection.
What symptoms arise from posterior inferior cerebellar artery occlusion?
Contralateral loss of pain and temperature from the body (resulting from damage to the lateral spinothalamic tract)
Ipsilateral loss of pain and temperature sensation from the face (resulting from damage to the trigeminal nucleus and tract)
Ipsilateral loss of taste (resulting from damage to the solitary tract and nucleus)
Ipsilateral lack of limb co-ordiation (resulting from damage to cerebellar connections)
Difficulty with swallowing (resulting from damage to nucleus ambiguous)
What are the current treatment and recovery methods for strokes?
Prevention of blood clot formation by anticoagulants such as aspirin and warfarin
Brain scans to locate clot and allow surgical removal of atherosclerotic deposit and introduction of anti-thrombotic agents such as tissue plasminogen activator
Optogenic neuronal stimulation has shown potential hope.
What is optogenic neuronal stimulation and how is it showing hope in future stroke treatment?
Neurones in layer V of the motor cortex which are bioengineered to express a bacterial channel rhodopsin (allowing them to be selectively depolarised by implanted optical fibres).
Ipsilegional primary motor cortex stimulation showed enhanced cerebral blood flow, neurotrophin expression and growth associated proteins (in mice)
