A 72-year-old woman with a history of dementia and falls presents with acute headache and confusion. CT head reveals a crescent-shaped hyperdense collection between the brain surface and the inner table of the skull. What is the most common location of this hemorrhage?

Explanation

## Most Common Location of Subdural Hematoma **Key Point:** Acute subdural hematomas (SDH) from head trauma preferentially occur over the convexities of the brain, particularly the frontal and parietal regions, due to the anatomy of bridging veins. ### Anatomical Distribution of Subdural Hematoma | Location | Frequency | Mechanism | Clinical Significance | |----------|-----------|-----------|----------------------| | **Frontal and Parietal Convexities** | **70–80%** | Tearing of bridging veins crossing subdural space | Most common; often bilateral | | Temporal region | 15–20% | Trauma to temporal bone; middle meningeal artery involvement | Can progress rapidly | | Posterior fossa | <5% | Rare; usually from severe trauma | High mortality; difficult to access surgically | | Falx/Interhemispheric | <5% | Rare; deep head trauma | Often associated with severe brain injury | **High-Yield:** The **frontal and parietal convexities** account for 70–80% of subdural hematomas. This is because bridging veins crossing the subdural space are most numerous and vulnerable in these regions, especially in elderly patients with brain atrophy. ### Why the Convexities Are Most Vulnerable 1. **Bridging vein anatomy:** Veins crossing from brain surface to dural sinuses are most prominent over convexities 2. **Brain atrophy in elderly:** Increased subdural space → greater traction on bridging veins with minor head trauma 3. **Rotational forces:** Frontal and parietal regions most exposed to acceleration-deceleration injury 4. **Venous pressure gradient:** Subdural veins have lower pressure than epidural vessels → slower bleeding but persistent ooze **Clinical Pearl:** In elderly patients with dementia and a history of falls, **always suspect subdural hematoma** even with minor head trauma. The crescent-shaped appearance on CT (following brain contour) is pathognomonic. Bilateral subdural hematomas are common in this population. **Mnemonic:** **CFPV** — Convexities (most common), Frontal-Parietal (specific regions), Posterior fossa (rare), Vertex (only part of convexity distribution). ### Imaging Characteristics - **Acute SDH (0–3 days):** Hyperdense on CT; crescent-shaped; follows brain surface - **Subacute SDH (3–20 days):** Isodense to brain; may be missed on CT; MRI shows T1 hyperintensity - **Chronic SDH (>20 days):** Hypodense on CT; may have fluid-fluid levels - **Location clue:** Crescent shape (follows dural reflection) = subdural; lens-shaped (biconvex) = epidural **Warning:** Do not confuse subdural hematoma location with epidural hematoma. Epidural hematomas are typically temporal (middle meningeal artery) and lens-shaped; subdural hematomas are convexity-based and crescent-shaped. [cite:Robbins 10e Ch 28]