Optimum imaging and diagnosis of cerebrospinal fluid rhinorrhoea

Imaging is an important component in the investigation of unilateral watery rhinorrhoea suspicious of cerebrospinal fluid (CSF). Whilst the demonstrat ion of the presence of beta 2 transferrin confirms that CSF is present it m ay prove difficult to demonstrate the exact site of origin. Fine detail cor onal computed tomography (CT) with sections of 1-2 mm thickness through the anterior skull base may show small dehiscences and fractures. The commones t site for congenital dehiscences is the cribriform niche adjacent to the v ertical attachment of the middle turbinate anteriorly and the superior and lateral walls of the sphenoid posteriorly. In the presence of frequent or c onstant CSF rhinorrhoea a CT cisternogram can be helpful in defining the ex act site of the leak. Magnetic resonance imaging (MRI) is reserved for defi ning the nature of soft tissue Le. inflammatory tissue, meningoencephalocel e or tumour. Finally, per-operative intrathecal fluorescein is helpful when imaging does not prove positive. A management algorithm for CSF rhinorrhoe a is presented.