The most common cause of CSF rhinorrhea is?

Trauma to the floor of anterior cranial fossa cause disruption of the arachnoid, tear in dura and fracture of the bone leading to CSF leakage. Trauma to middle cranial fossa cause leakage of CSF into the nose sphenoid. CSF leakage may also occur from posterior cranial fossa due to fracture of clivus or petrous bone. (Ref: Textbook of ent surgeries by P Hazarika D R Nayak pg 361)