CSF leaks through the nasal cavities can be post-traumatic, following skull base surgery, or simply spontaneous — the latter being the most common cause. They result from a defect in the skull base, both in the bony and dural planes, that allows CSF to escape outward. With the brain having a communication to the exterior, there is a risk of ascending bacterial meningitis from common nasal cavity organisms.
Clinically they present as loss of a transparent water-like fluid — non-viscous, unilateral, odorless, with a salty taste — and the flow increases when the patient sits up and leans the head forward. They can be continuous or intermittent, present with recurrent meningitis, or with seizures when associated with brain tissue herniated through the defect, forming a meningoencephalocele.
Imaging studies to localize the defect are multiaxial CT and MRI. The most frequently affected sites, in decreasing order, are the ethmoid, sphenoid sinus, frontal sinus, and lastly the clivus.
With the development of endoscopic endonasal surgery, this is currently the access route of choice for the treatment of this pathology, without the need for craniotomy. The surgery involves localizing the dural defect and interposing multiple layers of tissue to seal the fistulous tract, providing vascularization with a pediculated nasoseptal flap.
