**Question:** CSF rhinorrhoea is diagnosed by

A. Examining the presence of cerebrospinal fluid (CSF) on a nasal swab
B. Assessing the olfactory bulb for edema and inflammation
C. Evaluating the cerebrospinal fluid (CSF) protein level
D. Ensuring a negative pressure in the nasal cavity during Valsalva maneuver

**Correct Answer:** A. Examining the presence of cerebrospinal fluid (CSF) on a nasal swab

**Core Concept:** CSF rhinorrhoea is a clinical condition characterized by the leakage of cerebrospinal fluid (CSF) from the nasal cavity into the nasal mucosa or nasopharynx. This can occur as a result of a defect in the skull base, meninges, or nasal mucosa. CSF is the clear, colorless fluid that surrounds and protects the brain and spinal cord.

**Why the Correct Answer is Right:** The correct answer (A) involves examining the presence of CSF on a nasal swab because this method directly detects the leakage of CSF from the nasal cavity. In CSF rhinorrhoea, CSF can be seen as a clear, colorless fluid on a wet swab. This confirms the leakage and allows for diagnosis.

**Why Each Wrong Option is Incorrect:**

B. Assessing the olfactory bulb for edema and inflammation (B) is incorrect because the olfactory bulb is not the primary site of CSF leakage. Instead, the focus should be on the nasal mucosa or nasopharynx where the actual leakage occurs.

C. Evaluating the cerebrospinal fluid (CSF) protein level (C) is incorrect because assessing CSF protein levels is not a direct method for detecting CSF rhinorrhoea. Protein levels can vary due to various factors unrelated to the presence of CSF leakage.

D. Ensuring a negative pressure in the nasal cavity during Valsalva maneuver (D) is incorrect because this method is not reliable for diagnosis. The Valsalva maneuver may not consistently produce CSF leakage, and other factors affecting nasal pressure do not specifically indicate CSF rhinorrhoea.

**Clinical Pearls:**

1. **Core Concept**: The presence of CSF on a wet swab is a definitive method for diagnosing CSF rhinorrhoea as it directly detects the leakage of CSF from the nasal cavity. This is crucial for initiating appropriate treatment and preventing potential complications such as meningitis.

2. **Core Concept**: CSF rhinorrhoea can occur due to various causes, including traumatic injury, surgery, infections, or tumors. Understanding the etiology is crucial in selecting the appropriate treatment approach.

3. **Core Concept**: CSF rhinorrhoea requires prompt management to prevent complications such as meningitis, subarachnoid hemorrhage, and brain abscess. Early detection and intervention help prevent these complications and ensure the patient's well-being.

4. **Core Concept**: CSF rhinorrhoea can present with or without symptoms of