Mac Ewan sign is seen in:
**Core Concept**
MacEwan sign is a clinical indicator of increased intracranial pressure (ICP) due to a decrease in the jugular venous pressure (JVP) upon coughing or straining. This phenomenon is observed in patients with pseudotumor cerebri or other conditions causing elevated ICP.
**Why the Correct Answer is Right**
When a patient with increased ICP coughs or strains, the increased intrathoracic pressure compresses the jugular veins, causing a temporary decrease in jugular venous pressure (JVP). However, in patients with increased ICP, the compression of the jugular veins is incomplete due to the increased pressure inside the cranium. As a result, the JVP does not decrease as much as it would in normal individuals, leading to the absence of the normal decrease in JVP upon coughing (MacEwan sign). This is because the increased ICP prevents the normal transmission of increased intrathoracic pressure to the jugular veins.
**Why Each Wrong Option is Incorrect**
* **Option A:** MacEwan sign is not seen in conditions with decreased intracranial pressure, but rather those with increased ICP.
* **Option B:** The MacEwan sign is not related to the patient's position or posture, but rather the underlying pathophysiology of increased ICP.
* **Option C:** MacEwan sign is not a specific indicator of pseudotumor cerebri, but rather a general indicator of increased ICP.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the MacEwan sign is not a definitive diagnostic tool, but rather a clinical indicator that should prompt further investigation for increased ICP.
**Correct Answer: C.**