Otitis externa may be caused by otitis externa or cerebrospinal fluid leakage. Otitis externa is associated with ear itching, ear pain, burning sensation and a small amount of secretion. Cerebrospinal fluid ear leakage is mainly caused by trauma or chronic otitis media invading the skull base. It is recommended to do endoscopy to check whether there is fluid flowing out from the tympanic membrane perforation. If not, it is caused by otitis externa. Water-based otolaryngitis mostly occurs in craniocerebral trauma, skull base fracture, tympanic membrane rupture, and the slow flow of water-like fluid from the external ear canal is mixed with blood, which is the characteristic of cerebrospinal fluid otolaryngitis and can cause meningitis.