Acquired Spontaneous, Nontraumatic Normal-Pressure Cerebrospinal Fluid Fistulas Originating from the Middle Fossa

Five cases of spontaneous cerebrospinal fluid (CSF) fistulas originating from the middle fossa are described, including one patient with an "empty" sella. It is suggested that acquired meningocele and meningoencephalocele progress to become CSF fistulas. The normal anatomical and physiological factors which give rise to acquired bone/dural/arachnoid dehiscences are discussed and illustrated.