SPONTANEOUS CEREBROSPINAL-FLUID LEAKS FRO M THE TYMPANOMASTOID TEGMEN

The author's experience with spontaneous cerebrospinal fluid (CSF) oto rrhea from the tympanomastoid tegmen is based on the management of two clinical cases, the temporal bone histopathological findings in a thi rd case suffering fatal meningitis and a review of the literature. Cha racteristically, the disorder occurs in otherwise healthy ears and is the consequence of embryogenic faults in the dura mater and adjacent t egmen. After years of exposure to physiologically normal CSF pressures , these faults may fistulize into the tympanomastoid compartment. The onset may be at any age, but is more common after age 40. About 20% of cases have a history of one or more bouts of meningitis. The site of the leak is characterized by one or more defects measuring 2-5 mm in t he dura mater and adjacent bony plate, usually in the area of the petr ous ridge. About 25% of defects are associated with small meningoceles or meningoencephaloceles. Computed tomographic and magnetic resonance imaging, as well as testing with fluorescein dye, provide confirming diagnostic data. Corrective surgery employs transmastoid exploration. After any existing meningoceles or meningoencephaloceles have been cau terized or amputated, small grafts of autogenous fascia or cartilage a re used to plug defects found. The area is covered with temporalis fas cia graft, reinforced by a pedicled muscle-fascia graft and, if needed to obliterate the mastoid cavity, a free graft of subcutaneous abdomi nal adipose tissue.