Cerebrospinal fluid otorrhea occurs only if a perforation in the tympanic membrane or a defect in the external ear canal is present. This is often the case when the leakage results from trauma or previous ear surgery. However, in the absence of such a defect, the fluid flows down the eustachian tube and manifests as clear rhinorrhea.
CSF otorrhea usually occurs through a petrous bone fracture with perforation of the tympanic membrane, although it can occasionally take place through a laceration of the external canal via fractured mastoid air cells.
Late-onset cerebrospinal fluid otorrhea is especially rare because most otorrhea stops immediately and naturally.
Most reports recommend immediate surgical repair for the treatment of delayed CSF leakage, but the optimal surgical approach remains controversial.