Incidence of Nasal Cerebrospinal Fluid Leaks in Patients Presenting with Unilateral Clear Rhinorrhea

Objective: Cerebrospinal fluid (CSF) rhinorrhea is relatively uncommon, presenting typically as unilateral clear thin rhinorrhea. Nasal CSF leaks can lead to significant morbidity and possibly death. Understandably, concerns of CSF leak sequelae that lead many clinicians to presume unilateral clear rhinorrhea are CSF leaks until otherwise proven. However, the incidence of CSF rhinorrhea in patients presenting with unilateral clear nasal drainage has not been reported. Sinonasal inflammatory or infectious conditions can also cause clear rhinorrhea, and while these would more commonly cause bilateral rhinorrhea, the frequency with which they cause unilateral rhinorrhea has not been studied. This information would be helpful in guiding the workup and treatment of patients with unilateral rhinorrhea, as clinicians could consider the significant differences in cost and invasiveness of different diagnostic or therapeutic modalities based on the likelihood of rhinorrhea being a CSF leak versus other etiologies. The purpose of this study was to determine the incidence of CSF rhinorrhea amongst patients complaining of unilateral clear thin rhinorrhea. Methods: This was a single-institution retrospective review of patients who presented to a rhinologist (J.R.C.) at a tertiary medical center between 2015 and 2021. Electronic medical record queries were conducted according to diagnostic codes for a wide variety of rhinologic diseases, including rhinitis, rhinosinusitis, sinus neoplasia, and CSF rhinorrhea. Charts were then searched to include only patients who presented with rhinorrhea that was unilateral, clear, and thin. Charts were reviewed to record final diagnoses made, and the diagnostic studies performed to confirm or refute CSF rhinorrhea. Confirmatory studies for CSF rhinorrhea included β-2 transferrin electrophoresis, magnetic resonance cisternography, or endonasal exploration with or without intrathecal fluorescein injection. Some patients were prescribed intranasal corticosteroid or ipratropium bromide 0.06% nasal sprays, and reduction in rhinorrhea after spray use was reported. Results: From the 6-year study period, 3,041 charts were reviewed. Of these patients, 146 (4.8%) had unilateral clear thin rhinorrhea. Nonallergic rhinitis (NAR) was the most common cause of unilateral clear rhinorrhea, representing 44.5% of cases (65/146). CSF leaks were the second most common etiology, representing 29.5% of cases (43/146). The remainder of patients had allergic rhinitis (13.7%), chronic rhinosinusitis without polyps (4.8%), chronic rhinosinusitis with nasal polyps (5.5%), benign sinus tumors (0.7%), and other diagnoses (2.1%). Conclusion: Among patients presenting with unilateral clear thin rhinorrhea, NAR and CSF rhinorrhea were the most common etiologies. Interestingly, NAR was more common than CSF rhinorrhea. However, CSF rhinorrhea represented nearly a third of cases, and given its propensity to cause significant sequelae, all patients with unilateral clear rhinorrhea should initially undergo noninvasive testing to confirm or refute CSF rhinorrhea. Importantly though, if initial noninvasive confirmatory testing for CSF is negative and patients do not have concerning risk factors for CSF rhinorrhea, clinicians should consider treatments for rhinitis or rhinosinusitis rather than further invasive testing for CSF leak evaluation. Publication History Article published online: 15 February 2022 © 2022. Thieme. All rights reserved. Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany