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Strokes

Study guide:

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Definition:

  • Stroke: is defined as a syndrome of rapid onset of cerebral deficit (usually focal) lasting >24 h or leading to death, with no cause apparent other than a vascular one.

  • Transient ischemic attacks (TIA): brief episode of neurological dysfunction due to temporary focal cerebral or retinal ischemia without infarction.

 

Epidemiology:

  • Annual incidence in the US between 180 and 300 per 100000.

  • Stroke is the third leading cause of death and the first leading cause of disability.

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Risk Factors:

Modifiable

  • Hypertension

  • Cigarette smoking

  • Dyslipidemia

  • Diabetes

  • Central obesity

  • Alcoholism

  • Lack of physical activity

  • High risk die (e.g., high in saturated fats, trans fats, and calories)

  • Psychosocial stress (e.g., depression)

  • Heart disorders (particularly disorders that predispose to emboli, such as acute MI, infective endocarditis, and atrial fibrillation)

  • Use of certain drugs (e.g., cocaine, amphetamines)

  • Hypercoagulability

  • Vasculitis

Non modifiable

  • Prior stroke

  • Older age

  • Family history of stroke

  • Male sex

Types and Physiology:​

Ischemic stroke (70-80%)
Damage occurs rapidly during hyperthermia and slowly during hypothermia.

  • If tissues are ischemic but not yet irreversibly damaged (penumbra), restoring blood flow may reduce or reverse injury.


Mechanisms of ischemic injury include:

  • Edema, microvascular thrombosis (by Inflammatory mediators).

  • Apoptosis and cell necrosis (mainly by the loss of ATP).
     

Atherosclerotic (thrombotic) (most common)

  • Common at areas of turbulent flow (carotid bifurcation).

  • Thrombotic occlusion occurs most often at: MCA, internal carotid near the bifurcation, and basilar artery.

  • In children, sickle cell disease is a common cause of ischemic stroke.
     

Embolic:

  • Usually cardiac thrombi, commonly in atrial fibrillation, endocarditis, and prosthetic heart valves.  
     

Lacunar infarcts:

  • Small (≤ 1.5 cm) infarcts from obstruction of small, perforating arteries that supply deep cortical structures.

  • Common cause is lipohyalinosis, common among elderly patients with DM or poorly controlled HTN.
     

Hemorrhagic stroke (20-30%)
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Intracranial hemorrhage:

  • Common cause: chronic arterial hypertension➔Charcot-Bouchard Aneurysm.

  • Large hematomas ↑ intracranial pressure.
     

Subarachnoid hemorrhage:

  • Trauma is the most common cause, spontaneous can be from ruptured aneurysms.

  • A congenital intracranial saccular or berry aneurysm is the cause in about 85% of patients.

  • Blood in subarachnoid space → chemical meningitis → ↑ intracranial pressure.

  • Secondary vasospasm → focal brain ischemia; ~ 25% develop signs of TIA or ischemic stroke.

  • A second rupture sometimes occurs, most often within 7 days.

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Clinical Syndromes and their presentation:

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Diagnosis: 

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  • FAST (simple history and examination to quickly diagnose stroke):

  • Face: sudden weakness of the face.

  • Arm: sudden weakness of one or both arms.

  • Speech: difficulty speaking, slurred speech.

  • Time: the sooner treatment can be started, the better.​

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Imaging:
CT:

  • Rule out hemorrhage (in acute hemorrhage CT will be hyper-dense).

  • Exclude underlying masses/ AVM.
     

MRI:

  • DWI: differentiate acute from chronic infracts, and better detect infracts in hyperacute phase.
     

DSA (Digital subtraction angiography)/ Cerebral Angiography:

  • Real time catheter with higher radiation risk.

  • Hemorrhage (used to assess): the presence of aneurysm, bleeding site, and vascular anatomy.
     

ECG and Holter monitoring to detect cardiac source of emboli.

Carotid doppler to detect carotid stenosis when thromboembolism is suspected.

Blood tests:

  • CBC: to detect polycythemia and infection.

  • Clotting screen

  • Blood culture➔endocarditis

  • ESR and CRP: inflammatory diseases.
     

Other: blood glucose, fasting lipids, lumbar puncture renal function and electrolytes, thyroid function test, and autoantibodies and coagulation studies

Management:

  • General measures: maintain airway and give O2, monitor BP, and assess swallowing.

  • Start thrombolysis if eligible and not contraindicated:

  • I.V (t-PA) is best given within the 3-4.5 hours of onset of ischemic stroke.

  • The patient must be > 18 years, timing of the onset must be known, CT result must exclude hemorrhagic stroke, and diagnosis of ischemic stroke must be well-established, with no contraindications.

  • Clopidogrel or aspirin and dipyridamole (if allergic or if the patient presented out of the time window for t-PA).

  • Control hypertension only if severely elevated (S>220 mmHg & D>120 mmHg)

  • Sudden drop in BP → reduce perfusion → more damage.​

  • Manage the risk factors and prevent complications.

  • Rehabilitation (physiotherapy, occupational therapy, and speech therapy)

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Management of TIAs: 

  • Secondary prevention of stroke and risk factors management.

  • Modified release dipyridamole plus Aspirin.

  • Anticoagulants for patients with cardiac source of embolus (atrial fibrillation).

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Complications: 

  • Progression of the neurological injury.

  • Dysphagia and aspiration pneumonia.

  • Cerebral edema → mass effect (managed with hyperventilation and mannitol).

  • Post-stroke epilepsy.

  • Depression.
     

Prognosis:

  • Out of 10 with stroke, 2 will die, 2 will recover, and 6 will have disabilities.

  • Risk of recurrence is 5-15% in the first year, and by 5 years, 30% have had a recurrence.

  • Dysphagia is an important independent risk factor for chest infection and death in stroke patients.

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References:

  • Kumar P, Clark M. Kumar & Clark's clinical medicine. 8th ed. Edinburgh: Saunders Elsevier; 2012.

  • Colledge N, Walker B, Ralston S. Davidson's Principles and Practice of Medicine. 21st ed. London: Elsevier; 2010.

  • Yogarajah M, Horton-Szar D, Cikurel K, Khan N. Crash Course. 4th ed. London: Elsevier Health Sciences UK; 2013.

  • Merckmanuals.com. Overview of Stroke: Stroke (CVA): Merck Manual Professional [Internet]. 2014 [cited 14 October 2014]. Available from: http://www.merckmanuals.com/professional/neurologic_disorders/stroke_cva/overview_of_stroke.html

  • Ahmed M. Imaging the Brain. Presentation presented at; 2014.

  • Al Otaibi N. Stroke Epidemiology. Presentation presented at; 2014.

  • Agabegi S, Agabegi E, Ring A. Step-up to medicine. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins; 2013.

  • Le T, Bhushan V, Sochat M, Sylvester P, Mehlman M, Kallianos K. First aid for the® USMLE.

  • Le T. First Aid for the USMLE step 2 CS. New York, NY: McGraw-Hill; 2010.

  • Vernino, S. et al. 'Cause-Specific Mortality After First Cerebral Infarction: A Population-Based Study'. Stroke 34.8 (2003): 1828-1832. Web. 26 Sept. 2015.

First author: Lama Al Luhidan      


Reviewers:  Abdullah AlAsaad                                                      Abdulrahman AlNasser

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Reviewer: Roaa Amer

Format Editor : Adel Yasky

                            Bayan Alzomaili 

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