A 68-year-old man with chronic alcoholism presents to the emergency department following a minor head injury from a fall 2 weeks ago. CT brain shows a crescent-shaped hematoma that crosses the midline. What is the most common cause of subdural hematoma in elderly patients?

Explanation

## Most Common Cause of Subdural Hematoma **Key Point:** Subdural hematomas result from tearing of bridging veins that traverse the subdural space between the cerebral cortex and dural venous sinuses. ### Pathophysiology Bridging veins are particularly vulnerable because they: 1. Cross the subdural space under relatively low pressure 2. Have thin walls with minimal muscular support 3. Are prone to tearing with even minor head trauma, especially in elderly patients with brain atrophy ### Why Elderly Patients Are at Risk - Cerebral atrophy creates increased subdural space - Bridging veins are stretched and more fragile - Chronic alcoholism impairs coagulation and increases fall risk - Minor trauma (often not remembered) is sufficient to cause bleeding ### Clinical Presentation - **Acute SDH:** Symptoms within 72 hours (rare in elderly) - **Chronic SDH:** Symptoms weeks to months after minor trauma - Crescent-shaped appearance on CT that crosses suture lines (key distinguishing feature from epidural) ### Comparison with Epidural Hematoma | Feature | Subdural | Epidural | |---------|----------|----------| | **Vessel injured** | Bridging veins | Meningeal artery (esp. middle meningeal) | | **Location** | Between dura and arachnoid | Between skull and dura | | **Shape on CT** | Crescent (crosses sutures) | Lens-shaped (respects sutures) | | **Common age** | Elderly, chronic alcoholics | Young adults | | **Trauma severity** | Minor (often forgotten) | Usually significant | | **Prognosis** | Often better (lower pressure) | More acute, higher mortality if untreated | **High-Yield:** The crescent shape crossing the midline is pathognomonic for subdural hematoma and distinguishes it from the lens-shaped epidural hematoma that respects dural attachments. **Clinical Pearl:** Chronic subdural hematomas in elderly patients may present with subtle cognitive decline, gait disturbance, or personality changes — easily mistaken for dementia or stroke. [cite:Robbins 10e Ch 28]