Cerebrospinal fluid leakage after dacryocystorhinostomy.

The authors have encountered two presumptive cases of cerebrospinal fluid leakage associated with dacryocystorhinostomy. To understand better the pathophysiology, bilateral dacryocystorhinostomies and anatomic dissections were performed on three fresh cadaver specimens. The average distance from the superior bony nasal window to the floor of the anterior cranial fossa was 5.0 mm. The frontal sinus floor overlies the anterior portion of the nasal window, while the thinnest portion of cribriform plate overlies the posterior portion of the nasal window. A bony fracture of the anterior cranial fossa floor and/or cribriform plate resulted from (1) applying a rotational force to the Kerrison ronguer while enlarging the posterior nasal window or (2) fracturing an attenuated superior wall of an ethmoid air cell which has eroded into the orbital roof.