Detection of CSF leak in spinal CSF leak syndrome using MR myelography: correlation with radioisotope cisternography

Abstract

Background and purpose: Spinal CSF leak syndrome is a unique disorder caused by spinal CSF leak. In this study, we attempted to determine whether MR myelography (MRM) can detect the leakage site in the spine.

Materials and methods: We performed both MRM and radioisotope cisternography (RIC) in 15 patients with spinal CSF leak syndrome. Patients were included in this study if they had at least 2 of the following criteria: 1) orthostatic headache, 2) low CSF opening pressure, and 3) diffuse pachymeningeal enhancement on brain MR imaging. For comparison, we performed MRM in 15 subjects without symptoms of spinal CSF leak syndrome. MRM was performed with the 2D turbo spin-echo technique in the entire spine by using a 1.5T scanner. Two blinded radiologists evaluated the MRM findings in a total of 30 cases, composed of patient and control groups, with regard to the presence of leakage and the level of leakage if present. RIC was performed only in the patient group and was assessed by consensus among 3 physicians experienced in nuclear medicine. The diagnostic performance of MRM and RIC was evaluated on the basis of the clinical diagnosis of spinal CSF leak syndrome.

Results: The sensitivity, specificity, and accuracy of MR myelography for detecting CSF leak was 86.7%, 86.7%, and 86.7% for reader 1, respectively, and 80.0%, 93.3%, and 86.7% for reader 2, respectively. The sensitivity of RIC was 93.3%. Agreement between the 2 techniques for the detection of CSF leak was substantial in reader 1 and moderate in reader 2 (kappa = 0.634 and 0.444, respectively).

Conclusion: MRM is an effective tool for detecting CSF leak in the spine in patients with spinal CSF leak syndrome.

Fig 1.

Schematic drawing of 4-point-scale grading system of CSF leak on MRM (A) and RIC (B). A, Our grading scale on MRM is depicted as follows: grade zero, no leak (normal findings on MR myelogram); grade 1, possible leak (expansion of the CSF space column around the nerve root sleeve); grade 2, probable leak (streaky hyperintensity lateral to the nerve root sleeves but with length less than the transverse diameter of the thecal sac); and grade 3, definite leak (lateral extension greater than the transverse diameter of the thecal sac). However, actual grading of the case is determined on the basis of the highest grade in each level of the spine. B, Grade of CSF leak on RIC is depicted as follows: grade zero, no paraspinal activity; grade 1, possible leak (faint paraspinal activity with length under the transverse diameter of spinal canal activity); grade 2, probable leak (hot paraspinal activity with the length under the transverse diameter of spinal canal activity); and grade 3, definite leak (hot paraspinal activity with the length over the transverse diameter of spinal canal activity)

Fig 2.

A 28-year-old woman with spinal CSF leak syndrome. A, Anterior projection of RIC shows diffusion of the radioisotope into the extra-arachnoidal space in the region of the bilateral upper thoracic spine (arrowheads). B, On MR myelography, triangular-shaped CSF space expansion at multiple nerve root sleeves with reticular and streaky hyperintensities extending around the nerve root sleeves was identified in the corresponding upper thoracic spine (arrowheads). C, Normal MRM findings in a 50-year-old woman with low-back pain for comparison. Note incidental perineurial cysts in cervicothoracic junction level (arrows). They appear as round discrete hyperintensities at the nerve root sleeves in contrast to CSF leak noted on B. D, A presumed false-positive finding on MRM of a CSF leak in a 49-year-old woman with chronic back pain. The patient did not have symptoms of CSF leak syndrome. Both readers 1 and 2 reported grade 1 CSF leak at the thoracic level in this patient. There is hyperintensity at the midthoracic level (arrow). However, the shape is round, and there is no accompanying expansion at the nerve root sleeve. This may represent a perineurial cyst, but it is uncertain.

Fig 3.

A 33-year-old woman with spinal CSF leak syndrome and multiple CSF leaks in the bilateral thoracic and lumbar spine. A and B, Posterior projection of RIC shows diffusion of the radioisotope into the extra-arachnoidal space in the region of the upper thoracic spine (arrows), predominantly on the left side (A) and in the lumbar spine (B). C and D, MRM shows hyperintensities along multiple nerve root sleeves in the upper thoracic spine (arrows, C) and in the lumbar spine (arrows, D). E and F, On 1-month follow-up MRM, multiple hyperintensities around the nerve root sleeves disappeared.