Adult-onset fluid in the tympanomastoid compartment. Diagnosis and management.

Fluid in the tympanomastoid compartment having its onset in adulthood may be caused by three pathogenic mechanisms. Serous otitis in vacuo is the result of blockage of the eustachian tube and the most frequent cause is neoplastic disease. Adult serous effusion is a disorder of unknown cause characterized by active secretion of serous fluid from the mucous membrane lining the tympanomastoid compartment. Cerebrospinal fluid otorrhea is the result of a CSF fistula in the tympanomastoid compartment and may be caused by congenital anomalies, acquired diseases, and trauma. The differential diagnosis demands a systematic approach beginning with history and examination and progressing as necessary through a series of diagnostic procedures that may include pressure-equilizing tube insertion, fluorescein dye test, and surgical exploration.