Unilateral Clear Thin Rhinorrhea: How Often Is It a Cerebrospinal Fluid Leak?

Objectives: Determine frequencies of conditions causing unilateral clear thin rhinorrhea (UCTR), and assess whether certain clinical features are associated with CSF rhinorrhea.

Methods: This was a retrospective review identifying all patients presenting with UCTR to one rhinologist over a 6-year period. The conditions causing UCTR were recorded, and the following demographic or clinical variables were collected when available: body-mass index (BMI, kg/m2), gender, age, race, and self-reported drainage volume (whether the UCTR dripped out the nose and could be collected, or it felt like a wet nostril with intermittent running down lip that was unlikely to be collectable).

Results: Of 3,041 patients, 146 were identified with at least UCTR (4.8%). Mean age was 56.2 ± 17.6 years, and 65.8% were female. Amongst UCTR, nonallergic rhinitis (NAR) was the most common cause (45%), followed by CSF rhinorrhea (30%). On multivariate analysis, the following were significantly positively associated with CSF rhinorrhea: BMI≥30 (OR=4.95), ages 45-54 years (OR=3.67) and 55-64 years (OR=4.15), and self-reported UCTR dripping with collectability (OR=5.96)).

Conclusions: NAR was the most common cause of UCTR, representing nearly 50% of cases. However, CSF rhinorrhea still represented 30% of cases, reinforcing that UCTR should be worked up for CSF rhinorrhea, ideally with B2-Tf testing. BMI ≥30, ages 45-64 years, and patient-reported higher volume UCTR were positively associated with CSF rhinorrhea. If B2-Tf testing is negative or unobtainable, or clinical suspicion for CSF leak is low, clinicians can consider starting medical therapy for rhinitis or rhinosinusitis before pursuing further invasive CSF confirmatory testing.