Acute ischaemic stroke

Question 1

What is the classification system for strokes?

Answer 1

Bamford classification:

Total anterior circulation syndrome (TACS) - occlusion of MCA
Symptoms:
1) Unilateral motor or sensory deficit affecting 2 of face, arm or leg
2) dysphasia (difficulty with production and understanding of language) or dyspraxia (difficulty with motor tasks)
3) homonymous hemianopia (visual field loss on the same side of both eyes)

Partial anterior circulation syndrome (PACS) - occlusion of MCA or branch of ACA
Symptoms:
2/3 of the components of TACS

Lacunar syndrome (LACS) - occlusion of small deep penetrating artery causing subcortical stroke in pons or internal capsule
Symptoms:
1) Pure motor or sensory deficit affecting at least 2 of face, arm or leg
2) ataxic hemiparesis -

Posterior Circulation syndrome (POCS) - brainstem, cerebellum, occipital lobe

Symptoms:
1) isolated homonymous hemianopia
2) cranial nerve palsy
3) Loss of consciousness

Question 2

What imaging should be obtained if stroke is suspected?

Answer 2

Non contrast CT - designed to rule out haemorrhage, may not always show ischaemia

Later investigations to identify causes in younger people include:

-carotid doppler (looking for occlusion of carotid supply to the brain/ ICA stenosis (plaque build up on vessel wall reducing blood flow)
-TTE - if more than one territory involved, murmur present or abnormal ECG- to r/o cardiac embolus - AF, or IE or valvular pathology
MRI-more detailed information

Question 3

Describe the vascular system of the brain

Answer 3

Common carotid goes to internal carotid, which joins circle of willis and branches directly into Middle cerebral artery (MCA) which is a large vessel. Smaller vessels forming the circle of willis are the anterior cerebral artery (ACA) and the posterior cerebral artery(PCA) which joins the basilar artery ( which branches off from the vertebral arteries)

Question 4

Clinical features of strokes according to territory

Answer 4

MCA - blood supply to lower primary motor cortex - head, neck and arm, sensory cortex, brocas & wernickes areas

Weakness to contralateral face and arm, sensory deficit, aphasia, hemianopia (loss of sight in half the visual field)

ACA - blood supply to upper primary motor cortex & frontal lobe

Weakness of contralateral leg, personality and behaviour change

PCA - blood supply to occipital lobe & thalamus

Visual change, sensory deficits, whole body more global symptoms

Vertebrobasilar system - cerebellar
Dizziness, impaired balance, pupil & eye movement abnormalities
Changes to voice or swallowing
Decreased consciousness

Cerebral vein and sinuses - decreased consciousness, headache, vomiting

Question 5

Which is the most common area for ischaemic strokes to occur?

Answer 5

MCA - large vessel directly branching from ICA
(M1 - proximal segment)

Question 6

What are the treatment aims for a patient with acute ischaemic stroke?

Answer 6

1) To restore cerebral blood flow - anticoagulation
2) prevent secondary brain injury - neuroprotection

Question 7

Management of ischaemic stroke

Answer 7

1) Investigate
-imaging to rule out haemorrhage
-Bloods- don’t forget glucose - hypoglycaemia =stroke mimic, clotting, FBC - plts
-ECG
-TTE +/- bubble contrast echo

2) Neuroprotect
- BM 4-10
-Sats >94%
-Avoid fever
- BP parameters unclear - hypertension is a compensatory mechanism to maintain CPP when raised ICP and disordered autoregulation are present
If thrombolysing, aim BP <185/110, otherwise treat in the presence of hypertensive emergency (SBP<220)

3) Anticoagulate
-Thrombolysis (alteplase - breaks down fibrin within fibrin mesh) if:
- within 4.5hrs of symptoms & ongoing neuro deficits
- no previous ICH
- no uncontrolled hypertension
-no evidence of head trauma within 3months
- no thrombocytopenia or coagulopathy
-not on oral anticoagulants within last 48hrs
-no major surgery within past 2 weeks
-no seizure
- no recent MI
- no recent GI haemorrhage
-no hyper/hypoglycaemia

-Aspirin 300mg

4) Decompressive craniectomy should be considered for malignant MCA syndrome ( cerebral oedema in the context of large territory infact leading to transtentorial herniation

5) potential for thrombectomy - may want perfusion scan to evaluate salvageable penumbra

Question 8

Risk factors for ischaemic stroke

Answer 8

Smoking
DM
Hypertension
Hyperlipidaemia
Obesity

Question 9

Causes of ischaemic stroke

Answer 9

Thrombus - Large vessel plaque ruptures causing platelet aggregation and thrombus formation
Embolus - cardiac secondary to AF, mechanical valve, IE
Global hypoperfusion - cardiac arrest, severe hypoxia, cerebral intervention

Vasculitis - autoimmune or infectious (tb, syphillis, vzv) - inflammation injures endothelial cells which increases risk of clot formation

Dissection - vertebral or carotids - trauma, iatrogenic (eg thrombectomy), endothelial lining is broken, allowing blood to track in and form vessel lumen obstruction

Question 10

Complications of acute ischaemic stroke

Answer 10

• haemorrhagic transformation - stop alteplase if still going, check fibrinogen - may need reversal of alteplase ???
  -cerebral oedema/ increased ICP - particulary with large hemispheric infarct (large territory MCA) = cytotoxic oedema as cells rupture and spill out cell contents
• seizures - usually cortical infarct
  -aspiration pneumonia