CSF Fistulas (Cerebrospinal Fluid Leak)
A CSF fistula is the leakage of cerebrospinal fluid (CSF) into the nose, ear or a wound through a defect in the skull base bone and dura. It is a serious condition that carries a risk of meningitis, so diagnosis and treatment are important.
마지막 업데이트: 2026-06-07
Definition
A CSF fistula is the leakage of cerebrospinal fluid to the exterior through the paranasal sinuses, mastoid air cells or a surgical wound, owing to a defect in the skull base bones and dura. Leakage from the nose is termed rhinorrhea and from the ear otorrhea. It is most often located at the ethmoid bone and cribriform plate and carries a risk of serious complications such as meningitis.
Causes and Classification
CSF fistulas fall into three main groups. Traumatic fistulas are the most common and follow skull base fractures; iatrogenic fistulas after surgery (for example endoscopic sinus surgery, transsphenoidal pituitary surgery or skull base tumor surgery) also belong to this group. Spontaneous fistulas often arise on a background of idiopathic intracranial hypertension (IIH), where chronic raised pressure thins the skull base. Congenital fistulas are due to inborn dura and bone defects such as encephalocele.
Symptoms
The most common symptom is a unilateral, clear, watery nasal discharge, typically worsening with bending forward or straining (sneezing, coughing). Depending on the integrity of the eardrum, fluid may also drain from the ear. A postural headache that worsens on standing and eases on lying down may occur due to CSF loss. Spontaneous fistulas may be accompanied by signs of idiopathic intracranial hypertension (chronic headache, pulse-synchronous tinnitus, blurred vision). Fever, severe headache and neck stiffness suggest meningitis and require urgent assessment.
Diagnosis
The gold-standard laboratory test is the beta-2 transferrin assay, which identifies the discharge as CSF with high accuracy; beta-trace protein is a faster alternative. A glucose measurement provides a quick screen. For imaging, thin-slice high-resolution CT (coronal and sagittal views) is used to localize the defect, and brain MRI assesses encephalocele and brain herniation. When needed, MR cisternography or intrathecal contrast studies define the site of an active fistula.
Treatment
Small traumatic fistulas may initially be managed conservatively: bed rest, head elevation and avoidance of straining (sneezing, coughing, heavy lifting); some close on their own. Spontaneous fistulas and large, refractory or recurrent defects require surgical repair. The preferred method today is endoscopic endonasal repair using multilayer reconstruction and a vascularized flap (nasoseptal flap); an intracranial approach is used in selected complex cases. In spontaneous fistulas, treating the underlying intracranial hypertension (weight control, medication and a shunt when needed) is important to prevent recurrence.
Prognosis
An untreated CSF fistula carries a serious risk of recurrent bacterial meningitis; early diagnosis and repair markedly reduce this risk. Endoscopic repair has a high success rate, and failed cases can reach high cumulative success with repeat repair. Persistent effects such as loss of smell may occur. In spontaneous fistulas, recurrence risk rises if the underlying pressure problem is not treated. Outcomes vary by patient and cannot be guaranteed.
참고 문헌
- Greenberg MS. Greenberg's Handbook of Neurosurgery. 10th ed. Thieme; 2023:414-425.
- Oakley GM, Alt JA, Schlosser RJ, Harvey RJ, Orlandi RR. Diagnosis of cerebrospinal fluid rhinorrhea: an evidence-based review with recommendations. Int Forum Allergy Rhinol. 2016;6(1):8-16.
- Schlosser RJ, Bolger WE. Nasal cerebrospinal fluid leaks: critical review and surgical considerations. Laryngoscope. 2004;114(2):255-265.
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