## Distinguishing Hypertensive ICH from Ruptured AVM **Key Point:** The presence of a nidus (tangle of abnormal feeding arteries, draining veins, and shunting vessels) on contrast-enhanced CT or MRI is pathognomonic for AVM and definitively separates it from hypertensive ICH. ### Comparison Table: Hypertensive ICH vs. Ruptured AVM | Feature | Hypertensive ICH | Ruptured AVM | | --- | --- | --- | | **Nidus on imaging** | Absent | Present (hallmark finding) | | **Location** | Deep structures (basal ganglia, thalamus, pons, cerebellum) | Anywhere (cortical, deep, infratentorial) | | **Age of presentation** | Typically >50 years | Any age (often younger) | | **Acute CT density** | Hyperdense | Hyperdense | | **Surrounding edema** | Present | Present | | **Feeding arteries** | Normal caliber | Enlarged, tortuous | | **Draining veins** | Normal | Enlarged, prominent | **High-Yield:** While hypertensive ICH has a predilection for deep brain structures, AVMs can occur anywhere. The **nidus** (abnormal vascular tangle) is the only imaging feature that is specific to AVM and absent in hypertensive ICH. ### Clinical Pearl **Contrast-enhanced CT or MR angiography** will show the nidus in AVM as a tangle of abnormal vessels with early arterial filling and prominent draining veins. Hypertensive ICH shows only the hematoma without any underlying vascular malformation. ### Why Location Alone Is Not Sufficient Although hypertensive ICH classically occurs in deep structures (basal ganglia, thalamus, pons, cerebellum), AVMs can rupture anywhere in the brain. Location is suggestive but not discriminating. **Warning:** Do not rely solely on location to distinguish these entities — always look for the nidus. 
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