CSF Leak Following COVID-19 Swab: A Case Report and Literature Review

Abstract

Millions of nasopharyngeal swabs have been performed during the COVID-19 pandemic. Although generally considered a safe diagnostic test, rare adverse events have been reported. We describe a case of cerebrospinal fluid (CSF) leak in an otherwise well woman. A literature search of Pubmed and Ovid Embase was also performed, with the aim of identifying all reported cases of CSF leak following COVID-19 swabs. Extracted data points included demographics, pre-existing risk factors, past trauma, site of injury, meningitis, and management. This case report concerns a 54-year-old woman with no known risk factors. She had 10 nasopharyngeal swabs performed. Three days following the last swab, she developed persistent rhinorrhea. CTB demonstrated focal defect in the left lamella and cribriform plate, with associated soft tissue prominence. An MRI identified a meningocele arising from the left side of the cribriform plate. The patient underwent endoscopic repair without complications. A total of 17 reported cases of CSF leak following a COVID-19 swab were identified. Majority of the patients were female (65%), and most did not have any risk factors. Four patients had a preexisting skull base deformity and three had benign intracranial hypertension. The most common site of injury was the cribriform plate (11/17). Four cases were complicated by meningitis. Most patients were surgically managed with endoscopic repair while the remaining three patients were successfully managed conservatively. CSF leaks following nasopharyngeal swabs are rare but need to be promptly identified by clinicians, even in patients without known pre-existing risk factors.

Keywords

CSF leak - nasopharyngeal swab - COVID-19 - case report

Background and Importance

Millions of nasopharyngeal swabs have been performed since the start of the COVID-19 pandemic. Nasopharyngeal swabs have been used as the primary diagnostic test for detection of SARS-CoV-2 particles using polymerase chain reaction (PCR) techniques.[1] Although generally considered a safe diagnostic test, rare adverse events have been reported, including cerebrospinal fluid (CSF) leaks. Although not common, CSF leaks need to be promptly identified as they can be further complicated by meningitis. We describe a case of post-swab CSF leak secondary to the rupture of an undiagnosed pre-existing meningocele. We review this case in the context of all reported cases of CSF leaks following PCR swabs in the literature to date.

Case Report

Informed consent was obtained from the patient whose case we will discuss. This case concerns a 54-year-old woman, who was previously well prior to presentation to the emergency department. She had no known history of sinus-related comorbidities or known skull base defects. Her only significant past medical history includes migraines, which she reports experiencing once every 3 months, that respond well to simple oral analgesia. In 2021, the patient traveled overseas, where 10 nasopharyngeal swabs were performed to screen for COVID-19 during her travels. Three days following the last swab, the patient developed rhinorrhea, described as a persistent leak of clear salty fluid from her left nostril which increased in volume over the next few days, prompting the patient to seek urgent medical attention. One week after the onset of rhinorrhea, she presented to the emergency department where a sample of her nasal discharge tested positive for β 2 transferrin. Neurological examination of the patient was unremarkable, including a normal fundoscopy. A plain CT scan of the brain demonstrated a focal bony defect in the region of the left lamella and cribriform plate, with prominence of the soft tissue. An MRI of the brain confirmed the finding of a meningocele arising from the region of the left side of the cribriform plate, with evidence of recent rupture causing the CSF leak ([Fig. 1]). A CT scan of the brain performed 2 years prior was reviewed and demonstrated a skull base defect in the corresponding region with features suggestive of a possible meningoencephalocele. This was not documented in the radiologist's report.

Fig. 1 Preoperative imaging demonstrating the pre-existing meningocele. (A) Coronal CT bone window demonstrating dehiscent bone at the left lateral lamella and meningocele. (B) Coronal T2 MRI demonstrating meningocele at the left superior nasal cavity.

The presumed diagnosis was of a ruptured meningocele secondary to a traumatic nasopharyngeal swab, complicated by a persistent CSF leak. The meningocele was likely pre-existing, as it was an incidental finding on a previous scan. The patient underwent successful endoscopic repair of the ruptured meningocele, with no complications experienced postoperatively ([Fig. 2]).

Fig. 2 Endoscopic repair of ruptured meningocele. (A) Ethmoidal mucosa lifted by CSF. (B) CSF seeping through ethmoidal cavity. (C) Skull base dehiscence. (D, E) Bath plug repair. (F) Free mucosal graft overlay. (G) Duraseal applied.

Literature Review and Discussion

A literature search was conducted using the Pubmed central and Ovid Embase databases. Keywords of the search strategy included the terms CSF leak, rhinorrhea, COVID-19 swab, and varying nomenclatures of these terms. Relevant data points extracted included demographics, pre-existing skull base deformities or previous sinus surgery, past trauma, site of injury, meningitis complication, and management. A total of 17 cases of CSF leak following a COVID-19 swab were identified in the literature.[2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] Results are summarized in [Table 1]. Most patients were female (65%), and patient's age ranged between 34 and 67 years. The cribriform plate was injured in most cases (11/17). The right side was the most common side of injury (11/17). Three cases received more than one swab, up to a total of four swabs compared with 10 swabs in our reported case. Some patients had self-administered their swab (2/17). A total of 41% of patients had a risk factor for CSF leak. Four patients had a preexisting skull base deformity, including three encephalocele and one meningocele. Three patients had a history of idiopathic intracranial hypertension (IIH), two of which had an associated meningocele or encephalocele. IIH has been theorized to increase the risk of meningoceles and associated CSF leak through increased intracranial pressure if left untreated.[19] The remaining patients had no documented history of any predisposing factors. Four out of all cases of CSF leak were further complicated by meningitis. The treatment approach varied between endoscopic repair or conservative management, with 14/17 patients managed surgically and 3/17 cases of CSF leak resolved with conservative management. Most patients were endoscopically managed with an overlay repair using a nasoseptal or middle turbinate flap. One case used an overlay graft from the anterior sheath of the rectus abdominis.

Table 1 Summary of 17 cases of CSF leak following a PCR swab for COVID-19

Article	Date of issue	Country	Patient profile	Known skull base deformity 1–Yes 0–No	If yes, please specify	Idiopathic intracranial hypertension 1–Yes 0–No	Risk factors for CSF fistula	Presenting complaint at time of diagnosis	Site of injury	Number of swabs	Self-administered swab 1–Yes 0–No	Meningitis after leak 1–Yes 0–No	Management of leak
Agamawi et al	Nov 2021	USA	40Y M	0	N/A	0	0	Large amount of clear rhinorrhea at time of swab, persisted	Superior and lateral wall of right sphenoid sinus	1	0	0	Endoscopic repair—nasoseptal flap overlay
Alberola et al	Jan 2021	Spain	41 Y F	0	N/A	0	0	Holocranial headache and low grade fever on background of unilateral rhinorrhea and metallic taste	Cribriform plate - at lamina cribrosa	1	0	1	Conservative management
Asiri et al	October 2021	Saudi Arabia	36Y F	0	N/A	1	0	Fever, headache and altered consciousness, agitation on background of rhinorrhea	Right sphenoid sinus	1	0	1	Conservative management
Douglas et al	July 2021	USA	Middle aged F	0	N/A	0	0	Severe headache and clear rhinorrhea	Cribriform plate	2	1	0	Endoscopic repair—mucosal flap overlay from middle turbinate
Hill et al	Dec 2021	UK	60Y F	0	N/A	0	0	16 days of right-sided rhinorrhea, metallic taste and constant headache	Posterior ethmoid air cells	1	1	0	Endoscopic repair—mucosal flap overlay from middle turbinate
Holmes et al	May 2021	USA	54 Y F	1	Congenital meningocele	0	0	Severe headache and neck stiffness on background of 2 months of rhinorrhea and headaches since swab	Cribriform plate	1	0	1	Endoscopic repair
Knizek et al	September 2021	Czech Republic	40s Y M	0	N/A	0	0	Persistent rhinorrhea	Cribriform plate	1	0	0	Endoscopic repair—temporal muscle fascia underlay
Ku et al	Oct 2021	USA	41 Y M	0	N/A	0	0	5-day history of rhinorrhea	Cribriform plate	Multiple, unspecified	0	0	Endoscopic repair—overlay graft harvested from anterior sheath of rectus abdominis
Mistry et al	May 2021	Australia	67 Y F	0	N/A	0	0	Meningitis on a background of 48 hours of unilateral rhinorrhea following swab	Cribriform plate	1	0	1	Endoscopic repair—fat plug and free mucosal overlay
Ovenden et al	April 2021	Australia	34 Y F	0	N/A	0	0	2 days of upper respiratory tract symptoms on background of clear rhinorrhea	Cribriform plate	1	0	0	Conservative management
Paquin et al	Sept 2021	USA	38 Y F	1	Encephalocele	0	0	2 days of clear rhinorrhea, persistent headache and metallic tasting, postnasal drip	Cribriform plate	1	0	0	Endoscopic repair—free mucosal overlay
Rajah et al	April 2021	Australia	59 Y M	1	Encephalocele	0	0	Unilateral rhinorrhea	Lateral sella turcica wall of sphenoid	1	0	0	Endoscopic repair—nasoseptal flap overlay
Sadashiva et al	Oct 2021	India	48Y M	0	N/A	0	0	Unilateral rhinorrhea	Lateral wall of right sphenoid sinus	1	0	0	Endoscopic repair—multilayered repair with synthetics
Sullivan et al	Oct 2020	USA	40s Y F	1	Encephalocele	1	Removal of nasal polyps 20 years before presentation	Unilateral rhinorrhea, metallic taste, headache, neck stiffness and photophobia	Right sphenoid wing pseudomeningocele	1	0	0	Endoscopic repair
Uz et al	May 2023	Turkey	45 Y F	0	N/A	0	0	Left-sided unilateral rhinorrhea for 1 month post-swab	Lamina fibrosa of the left olfactory groove	1	0	0	Endoscopic repair—overlay septal cartilage, abdominal fat and fascia lata grafts
Vasilica et al	Sept 2022	UK	54 Y F	0	N/A	1	0	2 weeks of rhinorrhea following the swab, right-sided	Cribriform plate	1	0	0	Endoscopic repair—fat graft reinforced with Spongostan onlay
Yilmaz et al	June 2021	Turkey	47Y M	0	N/A	0	Minor head trauma 4 years ago—no medical attention sought	Unilateral rhinorrhea	Right fovea ethmoidalis	4	0	0	Endoscopic repair—nasoseptal flap overlay

Conclusion

This is the second reported case of CSF leak post-COVID-19 PCR swab in a patient with a pre-existing meningocele. This case report and literature review demonstrate that CSF leaks following nasopharyngeal swabs are rare but patients with pre-existing risk factors or multiple swab administration may be at a slightly higher risk of this complication. However, it is important to highlight that most patients who developed a CSF leak did not have any predisposing factors as most cases are a result of mechanical complications of nasopharyngeal swabs. It is essential for clinicians to remain vigilant of symptoms suggestive of a leak in patients without established risk factors. Treatment modalities may vary with some successfully recovering with conservative management; however, most have required endoscopic surgical repair. With nasopharyngeal swab testing becoming increasingly common, it is important to ensure adequate precautions in patients with known risk factors and appropriate education on safe PCR administration techniques for healthcare workers.

Conflict of Interest

None declared.

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Publication History

Received: 22 December 2024

Accepted: 06 October 2025

Article published online:
31 October 2025