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.
