Which of the following is the most common pathological mechanism of ischemic stroke in the Indian population?

Explanation

## Pathological Mechanisms of Ischemic Stroke in the Indian Population **Key Point:** Large artery atherosclerosis (LAA) is the most common pathological mechanism of ischemic stroke in the Indian population, accounting for approximately 30–40% of all ischemic strokes. This is supported by multiple Indian stroke registries including the Indo-US MOU Stroke Project and the Trivandrum Stroke Registry. ### Epidemiological Distribution (Indian Data) | Mechanism | Prevalence (India) | Prevalence (Western) | Pathology | | --- | --- | --- | --- | | Large artery atherosclerosis | 30–40% | 25–35% | Atherosclerotic plaque in carotid/vertebral/intracranial arteries | | Small vessel disease (lacunar) | 25–35% | 20–25% | Lipohyalinosis of penetrating arteries | | Cardioembolism | 15–25% | 20–30% | Thrombus from cardiac source (AF, MI, valve disease) | | Other/Cryptogenic | 10–15% | 10–15% | Patent foramen ovale, hypercoagulable states | | Arterial dissection | <5% | <5% | Spontaneous or traumatic vessel wall dissection | ### Why Large Artery Atherosclerosis Predominates in India **High-Yield:** A distinctive feature of Indian stroke epidemiology is the high prevalence of **intracranial large artery atherosclerosis** (as opposed to extracranial carotid disease more common in Western populations). Risk factors such as hypertension, diabetes mellitus, dyslipidemia, and tobacco use — all highly prevalent in India — drive accelerated atherosclerosis of both extracranial and intracranial vessels. The Indo-US MOU Stroke Project and other Indian registries consistently identify LAA as the leading TOAST category. **Clinical Pearl:** Intracranial atherosclerotic disease (ICAD) is particularly prominent in South Asian populations. Stenosis of the middle cerebral artery, basilar artery, and intracranial internal carotid artery is more common in Indians than in Western Caucasians, where extracranial carotid stenosis predominates (Harrison's Principles of Internal Medicine, 21st ed.). **Why Small Vessel Disease is NOT the top answer:** While small vessel disease is indeed more prevalent in Asian vs. Western populations and is the second most common mechanism in India, Indian stroke registry data place large artery atherosclerosis at the top. The claim that SVD accounts for 40–50% of Indian strokes is not consistently supported by published Indian registry data. **TOAST Classification Reminder:** The Trial of Org 10172 in Acute Stroke Treatment (TOAST) classifies ischemic stroke into: (1) Large artery atherosclerosis, (2) Cardioembolism, (3) Small vessel occlusion, (4) Other determined etiology, (5) Undetermined etiology. **Reference:** Kaul S et al., Indo-US MOU Stroke Project; Sridharan SE et al., Trivandrum Stroke Registry; Harrison's Principles of Internal Medicine, 21st ed., Chapter on Cerebrovascular Diseases.