Pneumocephalus: NEET PG Radiology
1. Pathophysiology & Presentation
Presence of air or gas within the cranial cavity. It is most commonly associated with trauma involving the skull base or paranasal sinuses.
- Trauma: Fracture of the skull base, particularly involving the frontal or ethmoid sinuses.
- Iatrogenic: Post-craniotomy, endoscopic sinus surgery, or lumbar puncture (rare).
- Tension Pneumocephalus: A surgical emergency where intracranial air accumulates under pressure, causing a mass effect.
2. High-Yield Radiographic Signs
| Sign | Description |
|---|---|
| Mount Fuji Sign | Bilateral air collections in the frontal region cause compression and separation of the frontal lobes. Highly suggestive of tension pneumocephalus. |
| Peek-a-boo Sign | Air bubbles seen within the sulci or ventricles on CT imaging. |
3. Clinical Pearls
- Imaging Modality: CT scan is the diagnostic gold standard, as it is highly sensitive to even small amounts of intracranial air.
- Tension Pneumocephalus: A medical emergency; patients often present with deteriorating neurological status, headache, and vomiting. Requires immediate surgical decompression.
- Meningitis Risk: Any patient with post-traumatic pneumocephalus is at high risk for meningitis due to a persistent CSF fistula. Prophylactic antibiotics may be considered, and serial imaging is often required.
- Differential Diagnosis: Ensure that the “Mount Fuji” sign is distinguished from simple pneumocephalus by the presence of a mass effect on brain parenchyma.