The most common clinical manifestation of CSF leak is clear, unilateral rhinorrhoea, exacerbated by bending over or performing a Valsalva manoeuvreer. The presence of headache should make the clinician suspicious of raised intracranial pressure or or meningitis.

Diagnosis can be confirmed by the laboratory analysis of CSF markers such as Beta-2 transferrin, which is a sensitive and specific marker in chronic or severe cases.

More usually however, a CT Scan or MR Cysternography is performed to diagnose the presence and location of a leak.