Stroke

Overview

A stroke is a sudden onset of brain dysfunction caused by an altered cerebrovascular blood supply. It is acute in onset and presents with focal neurological deficits (95% of the time). It is a clinical diagnosis, which requires imaging to confirm the diagnosis and.

Stroke and Transient Ischemic Attack (TIA) may present with similar symptoms. These symptoms depend on the artery where the lesion is located. The difference between a stroke and a TIA is that a TIA is temporary and resolves within minutes to hours. Stroke is present if neurological signs last for more than 24 hours. The management of ischemic and hemorrhagic stroke is different. However, the two cannot be distinguished based on symptoms. Hence, the best initial test is a non-contrast CT of the head to distinguish.

Up to 15% of patients with TIA will go on to have a stroke within 90 days. Most will have a stroke within 48 hours. 15 million people have a stroke every year. 80-90% are ischemic, while 10-20% are haemorrhagic.

Stroke affects 10 out of 1000 people per year at age 75. It is more common in men and uncommon before the age of 40. Most strokes occur in the morning since blood pressure spikes while waking are more likely to dislodge emboli.

Mortality of stroke is 20% in the first 2 months, then roughly 10% per year. < 40% of patients with stroke make a full recovery. Drowsiness at presentation carries a poor prognosis.

Definition of terms

Term	Definition
Transient ischaemic attack	Essentially a ‘minor stroke’. Presents with stroke like symptoms which completely resolve within 24 hours. Usually the result of micro-emboli (80%) but may be also be caused by mass lesions and massive postural hypotention.
Completed stroke	Clinical effects of stroke have reached their maximum (usually within 6 hours of onset)
Stroke in evolution	Describes the progress of stroke in the first 24 hours
Amaurosis fugax	Transient, sudden, painless loss of vision in one eye caused by temporary lack of blood flow to the retina
Transient global amnesia	Sudden, temporary episode of profound anterograde amnesia, often accompanied by mild retrograde amnesia with no other neurolgoical deficits

Presentation of stroke

Category	Presentation
Suggests hemorrhage (unreliable)	Meningism, severe headache, coma
Suggests ischaemia	Carotid bruit, atrial fibrillation, history of TIA, ischemic heart disease
Suggests cerebral infarction (50%)	Contralateral sensory loss, contralateral hemiplegia (flaccid then spastic), dysphasia, homonymous hemianopia, visuo-spatial defects
Suggests brainstem infarction (25%)	Quadriplegia, gaze, vision and balance disturbance, locked-in syndrome
Suggests lacunar infarction (25% – basal ganglia, internal capsule, thalamus, and pons)	Ataxic hemiparesis, pure motor loss, pure sensory loss, sensorimotor loss, dysarthria, involuntary movements (clusmy hand), impaired cognition and consciousness in thalamic stroke

• Risk factors for stroke
  • Hypertension (#1 risk factor, RR = 3 – 5)
  • Heart disease (RR = 2 – 4)
  • Atrial fibrillation (RR = 5 – 18)
  • Diabetes mellitus (RR = 1.5 – 3)
  • Smoking (RR = 1.5 – 3)
  • Alcohol use (RR = 1 – 4)
  • Older age
  • Family History of Stroke
  • Past History of Stroke
  • Dyslipidemia
  • Cerebral aneurysm
  • Obesity
• Signs and symptoms
  • Facial drooping
  • One-sided weakness of the arm or leg
  • Verbal deficit: slurring, dysarthria, aphasia, verbal agnosia
  • Altered level of consciousness
• Differential diagnosis
  • Head injury
  • Hypoglycaemia or Hyperglycaemia
  • Subdural hemorrhage
  • Focal-onset seizure with Todd’s paralysis
  • Intracranial neoplasm
  • Wernicke’s encephalopathy
  • Hepatic encephalopathy
  • Toxoplasmosis
  • Encephalitis
  • Cerebral abscess
  • Complicated migraine
• Investigations
  • Non-contrast CT: to distinguish ischemic from hemorrhagic stroke. It takes 6 hours for the CT scan to develop hypodensities. A hyperacute stroke can present with a normal head CT. Repeat in 3 days
    • Dense MCA sign is seen in MCA occlusion
    • Dense Basilar artery is seen in basilar artery occlusion
    • Haemorrhagic stroke presents with hyperdensity (corresponding to blood)
  • Brain MRI without contrast: Done after acute treatment. DWI sequence is gold standard (water cannot diffuse within infarcted tissue and shows hyperintensity). Checked against the ADC sequence.
  • Vacular imaging
    • CTA head with contrast: In emergency cases. Carries risk of contrast nephropathy and is susceptible to bone artefacts
    • MRA head with/without gadolinium: In non-emergency cases or patient that should not be repeatedly radiated. Gadolinium can be used in the workup for intracranial hemorrhage.
    • Carotid Doppler: for blockage
  • Blood Glucose: to exclude hypoglycemia, which can mimic stroke
  • Coagulation profile: for PT and INR. Hypercoagulable state
  • Electrocardiogram: for A-fib
  • Echocardiogram: for intraventricular or intraatrial thrombi, dilated cardiomyopathy and valvular heart disease
  • Lipid panel: for LDL
  • Complete blood count: for platelets
• Initial management (7 S’s)
  • Significant history and Systemic anticoagulation (stroke risk factors and last dose of anticoagulant)
  • Symptom onset time (time last normal for viable brain tissue)
  • Symptoms and deficits (for targeted neurological examination)
  • Systolic blood pressure (may need to be adjusted)
  • Sinus rhythm (A-fib may be present)
  • Stroke laboratory investigations (CBC, RBS, UEC, LFTs, coagulation panel)
  • Stroke scale (NIH stroke scale to screen for disabling deficits and localize lesions)
• Emergency Treatment
  • Secure Airway to prevent aspiration and hypoxia
  • Supplemental Oxygen if SpO2 < 94%
  • 2 Large bore IV access
  • Control Blood Pressure immediately if > 220 mmHg systolic
    • Generally aim for ≤ 185/110
    • Reduce MAP by 15% in the first 24 hours for acute ischemic stroke without fibrolysis
    • Reduce MAP by 15% over 1 hour for acute ischemic stroke with fibrolysis
    • Target 140 systolic within the first 24 hours in Haemorrhagic stroke
  • Maintain homeostasis
    • Treat hypoglycemia if < 4.4 mmol/L
    • Antipyretics (Acetaminophen) if Temperature is > 38 C
  • Nil per oral until the patient is screened for swallowing
  • High-dose aspirin once hemorrhagic stroke is excluded
  • Admit to the ICU or stroke unit

Ischaemic Stroke (78%)

Ischemic stroke is the most common cause of stroke (78%). Thrombosis or thrombectomy should be considered as soon as hemorrhagic stroke is ruled out.

Presentation of ischemic stroke (in order of increasing severity)

Cause	Presentation
Thrombotic small vessel disease (lacunar)	Milder symptoms, absence of cortical deficits (aphasia, neglect or field cut), <1.5 cm diameter lesion on MRI and subcortical lesions
Thrombotic large vessel disease	Preceding TIA, evidence of large vessel stenosis, vascular risk factors
Cardioembolic stroke	Maximal deficit at onset, severe deficits, large zone of infarct and infarction of multiple vascular territories
Hypercoagulability	Young patient, history of thromboembolism, late miscarriages, pro-thrombotic drugs, symptoms compatible with lupus or occult malignancy

• Causes of ischaemic stroke
  • Thrombotic large vessel disease
    • Atherosclerosis (intracranial or extracranial vessels)
  • Thrombotic small vessel disease (lacunar)
    • Lipohyalinosis
    • Microatheromas
    • Microembolism
  • Cardioembolic
    • Atrial fibrilation
    • Left atrial thrombus
    • Left ventricular thrombus
    • Valvular disease
    • Structural heart disease (dilated cardiomyopathy)
    • Paradoxical embolus through patent foramen ovale
    • Aortic arche plaque
    • Cardiac tumors
  • Rare causes
    • Arterial dissection
    • Sickle cell disease
    • Hypercoaguable state
    • Vasculitis
    • Vasospasm (SSRIs and Cocaine)
    • Venous sinus thrombosis
    • Genetics (CADASIL)
    • Complicated migraine
  • Cryptogenic or embolic strokes or undetermined source (ESUS)
• Treatment of ischemic stroke (restore flow)
  • Thombolysis with tPA (alteplase): onset within the past 3 hours or 4.5 hours in patients < 80 years without a history of stroke and not on anticoagulants. Best results are seen within 90 minutes.
  • Mechanical thrombectomy: onset more than 4.5 hours ago. Benefitial for large artery occlusion in the proximal anterior circulation
• Contraindications for tPA (currently blooding or likely to bleed)
  • Active bleeding
  • Recent stroke or serious head injury in last 3 months
  • BP > 185/110 despite treatment
  • Recent invasive surgical procedure in the last 2 weeks
  • Gastrointestinal or Genitourinary bleed in the past 21 days
  • Platelet < 100,000/mm3
  • INR > 1.7
  • Increased PTT if heparin was given in the preceding 48 hours
  • History of intracranial neoplasm
  • Coma or Stupor
  • Bleeding diathesis

Hemorrhagic Stroke (22%)

Hemorrhage accounts for ~ 20% of strokes. It is divided into intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH). Subarachnoid hemorrhage is covered in its own section. Hemorrhagic stroke is more severe than ischemic stroke since it creates mass effect faster than ischemic stroke (where edema peaks in 3 – 5 days). Aggressive blood pressure control is indicated often aiming for systolic BP of 120 – 140.

Includes intracerebral hemorrhage (ICH) or subarachnoid hemorrhage (SAH)

• Causes of intraerebral hemorrhage
  • Small vessel disease (basal ganglia, thalamus, pons, cerebellum)
    • Hypertension
  • Large vessel disease (lobar infarction)
    • Vascular malformations
    • Tumor
    • Voagulopathy
    • Vasculitis
    • Cerebral amyloid angiopathy
    • Septic emboli in endocarditis
    • Cocaine
  • Haemorrhagic transformation of ischaemic stroke
• Treatment of haemorrhagic stroke
  • Surgical evacuation
  • Aggressive blood pressure control
    • Reduce SBP to 130 – 150 mmHg (Nicardipine is commonly used)
  • Reverse anticoagulation
    • Administer FFP if the patient is on Warfarin
  • Monitor for Seizures (occurs in up to 28% of patients with hemorrhagic stroke)
  • Surgical clot evacuation: the clot has to be removed iron is toxic
    • Minimally invasive surgery with thrombolysis in intracerebral hemorrhage evacuation (MISTIE)
    • Endoport-mediated evacuation (ENRICH)

Prevention of Stroke

• Primary prevention
  • Control risk factors (hypertension, diabetes, hyperlipidaemia and cardiac disease)
  • Smoking cessation
  • Exercise (increases HDL and glucose tolerance)
  • Anticoagulation in atrial fibrilation and prosthetic valves
• Secondary prevention
  • Control risk factors as in primary prevention
    • BP goal of < 130/80
    • High-dose statin to stabilize plaques
    • Blood glucose control
    • Smoking cessation
  • Daily antiplatelets after stroke
  • Anticoagulation after stroke from atrial fibrillation