A 58-year-old hypertensive man on irregular antihypertensive therapy presents with sudden onset severe headache, vomiting, and focal neurological deficits. CT brain shows a hyperdense lesion in the basal ganglia with intraventricular extension. What is the most common site of hypertensive intracerebral hemorrhage?

Explanation

## Most Common Site of Hypertensive ICH **Key Point:** Hypertensive intracerebral hemorrhage (ICH) has a characteristic distribution pattern based on the location of lipohyalinosis in small penetrating arteries. ### Anatomical Distribution of Hypertensive ICH | Site | Frequency | Artery Involved | Clinical Features | |------|-----------|-----------------|-------------------| | **Putamen & external capsule** | **50–60%** | Lenticulostriate (lateral) | Contralateral hemiparesis, hemisensory loss, homonymous hemianopia | | Thalamus | 15–25% | Thalamoperforating arteries | Contralateral sensory loss, vertical gaze palsy, aphasia (dominant) | | Pons | 5–10% | Pontine perforating arteries | Pinpoint pupils, locked-in syndrome, bilateral signs | | Cerebellum | 5–10% | Superior cerebellar artery | Ataxia, headache, hydrocephalus | | Lobar (cortical) | 10–20% | Cortical branches | Seizures, cortical deficits | **High-Yield:** The **putamen and external capsule** account for approximately **50–60% of all hypertensive ICH cases**. This is the single most common site and is a high-frequency exam question. ### Pathophysiology **Key Point:** Chronic hypertension causes lipohyalinosis of small penetrating arteries (lenticulostriate arteries), leading to microaneurysm formation (Charcot–Bouchard aneurysms). These rupture spontaneously, typically in the distribution of the lateral lenticulostriate branches. ### Clinical Pearl **Clinical Pearl:** A patient with putaminal hemorrhage classically presents with **contralateral hemiparesis** (internal capsule involvement) and **hemisensory loss** (thalamic radiation). If the hemorrhage extends medially into the thalamus, vertical gaze palsy may develop. Intraventricular extension (as in this case) indicates a larger, more severe bleed and carries a worse prognosis. ### Why Putaminal ICH Is Most Common 1. Lenticulostriate arteries (especially lateral branches) are the most vulnerable to lipohyalinosis in chronic hypertension. 2. These arteries are terminal branches with poor collateral supply, making them prone to rupture. 3. The putamen lies directly in the distribution of these high-pressure vessels. [cite:Harrison 21e Ch 296]