CSF rhinorrhoea refers to the drainage of cerebrospinal fluid through the nose. Measures of CSF components such as glucose have been used in the past, but are neither sensitive nor specific; beta-2 transferrin, however, has been shown to have a high positive predictive value. It has also been noted to be characterized by unilateral discharge.
It is a sign of basal skull fracture. Management includes watchful waiting - leaks often stop spontaneously; if this does not occur then neurosurgical closure is necessary to prevent the spread of infection to the meninges.
Other signs of basal skull fracture includes CSF otorrhoea (drainage of CSF through the ear). It can have devastating complications in some patients, as the communication between the nasal cavity and the cerebrospinal fluid and CNS can result in bacterial infections of the CNS that can have catastrophic effects on the patient.
^Kerr, Julie T.; Chu, Felix W.K.; Bayles, Stephen W. (2005). "Cerebrospinal Fluid Rhinorrhea: Diagnosis and Management". Otolaryngologic Clinics of North America38 (4). doi:10.1016/j.otc.2005.03.011. PMID16005720.