Evaluation of CSF leaks: high-resolution CT compared with contrast-enhanced CT and radionuclide cisternography

Abstract

Background and purpose: Radiologic evaluation of CSF leaks is a diagnostic challenge that often involves multiple imaging studies with the associated expense and patient discomfort. We evaluated the use of screening noncontrast high-resolution CT in identifying the presence and site of CSF rhinorrhea and otorrhea and compared it with contrast-enhanced CT cisternography and radionuclide cisternography.

Methods: We retrospectively reviewed the imaging studies and medical records of all patients who were evaluated for CSF leak during a 7-year period. Forty-two patients with rhinorrhea and/or otorrhea underwent high-resolution CT of the face or temporal bone and then had CT cisternography and radionuclide cisternography via lumbar puncture. The results of the three studies were compared and correlated with the surgical findings in 21 patients.

Results: High-resolution CT showed bone defects in 30 of 42 patients (71%) with CSF leak. High-resolution, radionuclide cisternography and CT cisternography did not show bone defects or CSF leak for 12 patients (29%) who had clinical evidence of CSF leak. Among the 30 patients with bone defects, 20 (66%) had positive results of their radionuclide cisternography and/or CT cisternography. For the 21 patients who underwent surgical exploration and repair, intraoperative findings correlated with the defects revealed by high-resolution CT in all cases. High-resolution CT identified significantly more patients with CSF leak than did radionuclide cisternography and CT cisternography, with a moderate degree of agreement.

Conclusion: Noncontrast high-resolution CT showed a defect in 70% of the patients with CSF leak. No radionuclide cisternography or CT cisternography study produced positive results without previous visualization of a defect on high-resolution CT. CT cisternography and radionuclide cisternography may be reserved for patients in whom initial high-resolution CT does not identify a bone defect or for patients with multiple fractures or postoperative defects.

fig 1.

Two patients with bone defects on high-resolution CT and normal results of radionuclide cisternography and CT cisternography. A, Coronal CT scan shows a defect (arrow) in the right cribriform plate with adjacent mucosal thickening. B, Coronal CT scan of the temporal bone shows a large defect (arrow) in the tegmen mastoideum and mucosal thickening in the postsurgical mastoid bowl. No contrast accumulation is seen in the mastoid defect. Surgery confirmed the defect and leak in this patient.

fig 2.

Patient with a defect revealed by CT and a leak revealed by radionuclide cisternography but not by CT cisternography. A, Radionuclide cisternogram of the head, anterior planar view, shows an abnormal accumulation of radionuclide (arrow) in the left mastoid region. B, Coronal CT scan of the temporal bone shows a defect (arrow) in the tegmen tympani with adjacent mucosal thickening. The bone and dural defect were confirmed at surgery.

fig 3.

Patient with a bone defect revealed by CT and a leak evident by CT cisternography but not by radionuclide cisternography. A, Coronal CT scan of the face shows a large defect (straight arrow) in the right cribriform plate with adjacent mucosal thickening. Nasal pledgets can be seen within the nasal cavity (curved arrow). B, Coronal CT cisternogram of the same region shows accumulation of contrast medium at the defect and extending into the ethmoidal sinus (arrow). The results of radionuclide cisternography and nasal pledgets were normal. There was no surgical confirmation.

fig 4.

Patient with a bone defect revealed by CT and positive results of radionuclide cisternography and CT cisternography. A, Coronal CT scan of the face shows a defect (arrow) of the lateral sphenoidal sinus roof with mucosal thickening filling the sphenoidal sinus. B, Coronal contrast-enhanced CT cisternogram shows contrast medium extending through the defect (arrow) and within the right sphenoidal sinus (curved arrow). The nasal pledgets indicated a leak in the region of the right sphenoethmoidal recess, although the cisternogram did not show abnormal accumulation of the radionuclide. The defect and CSF leak were confirmed at surgery.