A 68-year-old man with chronic alcoholism presents to the emergency department with a 3-week history of progressive confusion, gait disturbance, and left-sided weakness. His daughter reports he had a minor head injury from a fall 3 weeks ago, which he did not consider serious at the time. On examination, he is drowsy, has a left extensor plantar response, and mild left hemiparesis. CT head (non-contrast) shows a crescent-shaped collection that crosses the midline and compresses the lateral ventricles. What is the most likely diagnosis?

Explanation

## Clinical Presentation & Timeline **Key Point:** The 3-week interval between minor head trauma and symptom onset is pathognomonic for chronic subdural hematoma (CSDH). Acute subdural presents within 72 hours; subacute (3–20 days) is intermediate. ## Imaging Findings | Feature | Epidural | Acute Subdural | Chronic Subdural | |---------|----------|----------------|------------------| | **Shape** | Lens-shaped (biconvex), does NOT cross suture lines | Crescent-shaped, follows brain contour | Crescent-shaped, may cross midline | | **Crosses midline?** | No | Rarely | Yes (common) | | **Crosses suture lines?** | No (bounded by dura) | Yes (follows brain surface) | Yes | | **CT density (acute)** | Hyperdense | Hyperdense | Mixed or hypodense | | **Typical age** | Younger (head trauma) | Any age, acute trauma | Elderly, alcoholics, anticoagulated | | **Time to symptom** | Hours to 1–2 days | < 72 hours | 3–20 days (subacute) or > 20 days (chronic) | **Clinical Pearl:** Chronic subdural hematoma is the "great imitator" — insidious onset, vague symptoms (confusion, gait disturbance, personality change), and often a **trivial or forgotten head injury**. Elderly and alcoholic patients are at highest risk due to brain atrophy and coagulopathy. ## Why This Patient Has Chronic Subdural 1. **3-week delay** — rules out acute epidural (hours) and acute subdural (< 72 hours) 2. **Crescent shape crossing midline** — subdural, not epidural (which is lens-shaped and respects suture lines) 3. **Risk factors:** Age 68, chronic alcoholism (coagulopathy + brain atrophy = bridging vein rupture) 4. **Progressive neurological decline** — typical of mass effect from expanding collection **High-Yield:** Chronic subdural can present with **fluctuating consciousness**, **dementia-like picture**, or **focal deficits** weeks after a minor fall that the patient may not even remember. ## Management Implication Chronic subdural requires **burr hole drainage** (often bilateral if bilateral collections). Unlike acute subdural (which may be managed conservatively if small), CSDH with mass effect and neurological decline is a surgical emergency.