Localization of inactive cerebrospinal fluid fistulas

Because of the importance of preoperative localization of dural fistulas, many imaging modalities have been critically evaluated for their role in pinpointing the site of cerebrospinal fluid (CSF) leakage. Twenty-one consecutive patients who were suspected of having a CSF fistula were studied to evaluate magnetic resonance (MR) imaging in locating the fistula. These patients were also studied independently by fine-slice computerized tomography (CT). The MR images demonstrated lesions compatible with dural fistulas in 19 patients, whereas CT demonstrated only seven of these lesions. All of these patients underwent surgical dural repair. The remaining two patients underwent surgical exploration on the basis of the CT findings but no dural fistula was found in either patient. All patients made a good postoperative recovery. One patient developed a postoperative wound infection and in another CSF leakage recurred. Although MR imaging was very precise in locating the CSF fistulas, CT missed a significant number of these lesions and was falsely positive in 9.5% of cases. Therefore, it is concluded that MR imaging is an essential investigation in patients with a suspected dural fistula and should be performed before embarking upon surgery and before assuming natural healing of the CSF fistula.