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CSF rhinorrhoea
Clear one-sided nasal discharge, especially after trauma or sinus surgery, is a CSF leak until proven otherwise; it is confirmed by beta-2 transferrin, the defect is located on high-resolution CT, and it is repaired — usually endoscopically — when the leak does not close with conservative care, because of the risk of meningitis.
Why it matters in the exam
The commonest cause is trauma (about 80%), including surgical trauma during FESS — the most vulnerable point is the lateral lamella of the cribriform plate, the thinnest part of the skull base. The Keros classification describes the depth of the olfactory fossa: type I — 1 to 3 mm, II — 4 to 7 mm, III — 8 to 16 mm; the deeper the fossa, the greater the surgical risk. Spontaneous leak appears mainly in a middle-aged woman with obesity and idiopathic intracranial hypertension (sometimes with an "empty sella" on imaging), and sometimes from the lateral recess of the sphenoid sinus.
Diagnosis: beta-2 transferrin is the most specific test (beta-trace protein is an alternative); glucose testing and the "halo sign" are unreliable. High-resolution CT locates the bony defect; T2-weighted MRI (cisternography) shows fluid and raises suspicion of a meningoencephalocele. Intrathecal fluorescein is sometimes used during surgery to locate the leak. The anterior ethmoidal artery crosses the ethmoid roof behind the frontal recess, and sometimes hangs below the skull base — a surgical danger.
A leak after trauma closes in most cases with 7 to 10 days of conservative care: rest with the head raised, avoiding straining, nose blowing and constipation, and sometimes lumbar drainage. When the leak persists — endoscopic repair, with success over 90%, using layered grafts; in large defects a vascularised septal flap (nasoseptal flap, Hadad-Bassagasteguy) is used, based on the posterior septal artery — a branch of the sphenopalatine artery. Bleeding from this artery is the danger when the sphenoid opening is widened downward. In spontaneous leak the intracranial pressure must also be treated (acetazolamide, weight loss), otherwise the leak recurs. Prophylactic antibiotics have not been proven effective; pneumococcal vaccination is advised.
Key points
- Clear one-sided discharge — a leak until proven otherwise.
- Beta-2 transferrin to confirm.
- High-resolution CT to locate.
- After trauma — conservative for 7 to 10 days.
- Endoscopic repair over 90% success.
Summary table
| Aspect | Detail | Meaning |
|---|---|---|
| Common cause | Trauma, including sinus surgery | About 80% |
| Diagnosis | Beta-2 transferrin | The most specific |
| Localisation | High-resolution CT, T2-weighted MRI | Bony defect and meningoencephalocele |
| Conservative care | 7 to 10 days, head raised, lumbar drain | Most post-traumatic leaks close |
| Repair | Endoscopic, nasoseptal flap for a large defect | Success over 90% |
| Spontaneous leak | Obesity, raised intracranial pressure | Treat the pressure too |
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Sources
- Cummings Otolaryngology: Head and Neck Surgery, 7th edition (2021) — Cerebrospinal fluid rhinorrhoea and skull base repair
- Hadad G, Bassagasteguy L et al. A novel reconstructive technique after endoscopic expanded endonasal approaches: vascular pedicle nasoseptal flap, 2006 — Technique
- Oakley GM et al. Management of CSF rhinorrhea: an evidence-based review, 2016 — Diagnosis and repair outcomes
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.