Cerebrospinal fluid otorhinorrhea in patients with defects through the lamina cribrosa of the internal auditory canal.

We describe three patients with bilateral cerebrospinal fluid (CSF) otorhinorrhea with unilateral progressive hearing loss in whom CT showed the defect to be located in the lamina cribrosa of the internal auditory canal. CT cisternography showed the CSF fistula in two of the three patients who had Mondini malformation, whereas the CSF fistula was obvious on the plain high-resolution temporal bone CT study in the third patient, who had a posttraumatic (nonsurgical) fracture of the lamina cribrosa. Fast spin-echo T2-weighted coronal MR cisternography also showed the site of leakage in the third patient. In the presence of an intact tympanic membrane, the CSF egressed to the nose via the eustachian tube in all three patients.