Transient Ischemic Attack and Stroke Etiology

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Questions and Answers

What is a characteristic feature of a transient ischemic attack (TIA)?

There is evidence of cerebral infarction.

Symptoms persist beyond 24 hours.

Symptoms resolve within a few hours. (correct)

Symptoms do not resolve completely.

What distinguishes recurrent nonstereotypic TIAs from stereotypic TIAs?

They differ in character from event to event. (correct)

They are always caused by large artery occlusion.

They are caused by the same site of embolism.

They manifest with identical clinical features.

What percentage of strokes is attributed to ischemia due to occlusion?

90% (correct)

10%

35%

Which structure is supplied by the posterior circulation of the brain?

Brainstem Signup and view all the answers

Which artery is NOT part of the anterior (carotid) circulation?

Posterior cerebral artery (PCA) Signup and view all the answers

What is the primary function of the Circle of Willis?

To provide redundancy in cerebral circulation. Signup and view all the answers

What is a common risk factor for stroke?

High blood pressure Signup and view all the answers

What technique is crucial for distinguishing between ischemic and hemorrhagic strokes?

CT scan or MRI Signup and view all the answers

What is a potential role of new neurons generated in response to cerebral ischemia?

They migrate to ischemic regions to release growth factors. Signup and view all the answers

What is one of the observed effects of angiogenesis following ischemia?

Enhancement of local blood supply through capillary sprouting. Signup and view all the answers

Which mechanism describes the ability of mild ischemia to protect against subsequent ischemic events?

Ischemic tolerance. Signup and view all the answers

What are common pathological findings in a brain affected by large artery occlusion?

Swelling and softening of brain tissue with necrosis. Signup and view all the answers

During which phase after stroke is cerebral edema usually maximized?

1-2 days after the stroke. Signup and view all the answers

In the chronic phase of a stroke from large artery occlusion, what typically characterizes the infarct site?

Appearance as a cavitary lesion. Signup and view all the answers

Which of the following contributes to spontaneous post-ischemic repair?

Changes in gene expression and axonal sprouting. Signup and view all the answers

Which of the following is NOT a characteristic of acute ischemic changes observed under microscopy?

Increased vascular integrity. Signup and view all the answers

Which structures are primarily supplied by the anterior circulation?

Basal ganglia and internal capsule Signup and view all the answers

What characterizes pure motor hemiparesis?

Hemiparesis affecting face, arm, and leg without sensory disturbance Signup and view all the answers

Where are lacunes typically located in a pure motor hemiparesis condition?

Contralateral internal capsule or pons Signup and view all the answers

Which syndrome involves hemisensory loss associated with paresthesia?

Pure sensory stroke Signup and view all the answers

What type of infarct causes sensorimotor stroke?

Small, deep infarct Signup and view all the answers

Ataxic hemiparesis primarily affects which part of the body?

Leg predominantly Signup and view all the answers

What does dysarthria-clumsy hand syndrome include?

Dysarthria, facial weakness, and hand clumsiness Signup and view all the answers

What is a common cause for lacunar syndromes?

Vascular disorders and cardiac disorders Signup and view all the answers

What structural features are observed in an atherosclerotic common carotid artery as shown by contrast-enhanced black blood MRI?

Thick fibrous cap and focal calcification Signup and view all the answers

Which of the following is NOT a common definition for hypertension?

Systemic blood pressure > 130 mm Hg systolic Signup and view all the answers

What method is recommended for measuring blood pressure to reduce confounding factors?

Take measurements after 3 readings at 1-minute intervals Signup and view all the answers

What is a major risk factor for stroke associated with chronic hypertension?

Lipohyalinosis and fibrinoid necrosis Signup and view all the answers

Which type of diabetes is associated with an increased risk of both ischemic stroke and intracerebral hemorrhage?

Both type 1 and type 2 diabetes Signup and view all the answers

Which aspect of diabetes affects small arteries and arterioles, potentially leading to lacunar infarction?

Microvascular damage Signup and view all the answers

What is a characteristic of vasculitis as a cause of stroke?

It is a treatable condition. Signup and view all the answers

Which treatment approach is indicated to reduce stroke risk in both diabetic and non-diabetic patients?

Antihypertensive drugs and statins Signup and view all the answers

What type of strokes do children with moya moya typically present with?

Ischemic strokes Signup and view all the answers

Which drug is most commonly associated with intracerebral hemorrhage?

Cocaine hydrochloride Signup and view all the answers

In which demographic is migraine with aura most common?

Smokers using oral contraceptives Signup and view all the answers

What typically occurs in drug users within hours of using certain drugs?

Acute ischemic stroke Signup and view all the answers

Which mechanism is NOT proposed as a cause of stroke in drug users?

Myocardial infarction Signup and view all the answers

What percentage of strokes in drug users is thought to be associated with infective endocarditis?

Minority of cases Signup and view all the answers

What relation does sporadic hemiplegic migraine have with stroke?

Not associated with stroke but with cerebellar atrophy Signup and view all the answers

What does the middle cerebral artery transformation in moya moya resemble?

Puff of smoke Signup and view all the answers

Study Notes

Transient Ischemic Attack (TIA)

TIA symptoms resolve completely within 1 hour, with no cerebral infarction.
Recurrent TIAs can be classified into stereotytic (identical features from the same site) and non-stereotypic (varied features from different sites).

Vascular Etiology of Ischemia

90% of ischemic strokes result from occlusion:
- 35% due to large artery occlusion
- 25% from small artery occlusion
- 20% caused by cardiac embolism
- 15% are cryptogenic (unknown causes)
- 5% from other processes, like inflammation
10% of strokes are hemorrhagic due to rupture.

Diagnostic Techniques

Distinguishing between ischemia and hemorrhage can be challenging through history and neurologic exam; CT scan or MRI provides definitive diagnosis.

Arterial Circulation in the Brain

Anterior circulation consists of internal carotid artery and branches, supplying most cerebral cortex and subcortical white matter.
Major branches include anterior choroidal artery, anterior cerebral artery (ACA), and middle cerebral artery (MCA).
Posterior circulation involves vertebral arteries and basilar artery, supplying brainstem, cerebellum, thalamus, and parts of occipital and temporal lobes.

Neurogenesis and Angiogenesis

Cerebral ischemia can stimulate neurogenesis, with new neurons migrating to ischemic areas, promoting survival through growth factor release.
Angiogenesis results from ischemia prompting capillary sprouting, potentially aiding tissue protection during acute stroke.

Ischemic Tolerance

Mild ischemia can precondition brain tissue, offering protection against future ischemic events through extensive gene expression changes.

Pathology of Large Artery Occlusion

Recent infarcts present as swollen brain areas, affecting both gray and white matter.
Microscopic examination reveals acute ischemic changes, including neuron shrinkage and destruction of glial cells.
Cerebral edema peaks within the first 2-3 days post-stroke.

Lacunar Syndromes

Various lacunar syndromes result from small, deep infarcts:
- Pure motor hemiparesis: equal hemiparesis without sensory disturbances.
- Pure sensory stroke: hemisensory loss potentially with paresthesia.
- Sensorimotor stroke: motor and sensory deficits due to thalamus lesions.
- Ataxic hemiparesis: combined pure motor hemiparesis and ataxia, typically affects the leg.
- Dysarthria-clumsy hand syndrome: includes dysarthria and facial weakness with hand clumsiness.

Stroke Risk Factors

Vascular disorders and cardiac disorders are primary contributing factors.
Hypertension: defined as BP above 140/90 mmHg, a major risk factor; chronic hypertension leads to small arterial degeneration, increasing stroke risk.
Diabetes: both type 1 and 2 increase risks for both ischemic stroke and hemorrhage.
Vasculitis: uncommon but treatable cause of stroke.

Drug Abuse and Migraine

Cocaine and amphetamines are associated with stroke onset shortly after use, with various proposed mechanisms, including endothelial dysfunction and vasospasm.
Migraine with aura: a rare ischemic stroke cause, primarily affecting women and younger individuals; links to thrombotic and cardioembolic mechanisms exist.

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Description

This quiz covers key concepts related to Transient Ischemic Attacks (TIAs) and the vascular causes of ischemic strokes. It discusses TIA symptoms, classification, and the major contributing factors to ischemic strokes along with diagnostic techniques. Test your understanding of these crucial neurological topics.