CSF rhinorrhea is defined as passage of CSF from the subarachnoid space through osseous and dural defect at skull base into the nasal cavity.~Causes of CSF rhinorrhea are classified into traumatic (including iatrogenic) and non traumatic (including spontaneous leak).~Patients are presented by variable symptoms including clear nasal discharge, headache or with complications like meningitis or even brain abscess, so closure of the defect is of great importance with required accurate localization of the defect and its dimensions.~CSF rhinorrhea can be also classified into active when with active dripping or inactive when dripping is intermittent.~Different imaging modalities have been employed to localize and characterize skull base defects responsible for CSF leakage including computed tomography (CT), CT cisternography (CTC), magnetic resonance imaging (MRI), MR cisternography (MRC) and radionuclide cisternography (RNC). However, there is still no gold standard imaging modality.~High resolution computed tomography (HRCT) provides accurate bone details, but difficult to differentiate para nasal sinus secretions from CSF leak. contrast enhancing CT cisternography has an advantage of definite proof of CSF leak and definite anatomical localization of the bony defect, but side effects like headache and meningeal irritation may occur.~Magnetic resonance imaging (MRI) with 3D- constructive interference in steady state (3D-CISS) (MR cisternography) instead of the invasive CT cisternography shows CSF as a bright signal without intra thecal contrast injection. Also MRI provides intra cranial details, but it lacks of bony details.~In the present prospective study, we will assess the use of HRCT, CTC and MRC imaging modalities in definite diagnosis and localization of active CSF leak.
To assess the diagnostic accuracy of combined high resolution CT, CT cisternography and MR cisternography in pre operative assessment of active CSF leak, compared by endoscopic sinus surgery.