Low meningitis-incidence in primary spontaneous compared to secondary cerebrospinal fluid rhinorrhoea

OBJECTIVE: Spontaneous cerebrospinal fluid (CSF) rhinorrhoea is a separate clinical entity with elevated intracranial pressure as its most probable pathophysiological mechanism. Having the clinical impression of distinct courses of diseases in primary spontaneous (PS) compared to secondary CSF rhinorrhoea, our objective was to identify whether the two forms differ in the duration of CSF rhinorrhoea and the incidence of meningitis. METHODS: Chart review performed on all patients referred with a CSF leak to our tertiary-care medical center over a 20-year period from 1990 to 2010. RESULTS: In total, 58 cases suffering from CSF rhinorrhoea could be included. The aetiology was primary spontaneous in 23 (40%) and secondary in 35 (60%) patients. The duration of CSF rhinorrhoea was notably longer in patients with PS CSF rhinorrhoea. Moreover, we could show a significantly lower incidence of meningitis with PS CSF rhinorrhoea compared to the secondary group (annual incidence of 0.12 vs. 1.22 episodes). CONCLUSION: A significantly lower incidence and delayed onset of meningitis in patients suffering from PS CSF rhinorrhoea could be explained by an elevated intracranial pressure that hinders the ascension of bacteria. The closure of a leak in secondary CSF fistula seems more urgent than in PS CSF fistulas