Cauda Equina Occupation Ratio as a New Imaging Parameter for the Evaluation of Spinal Dural Arteriovenous Fistulae

Hitoshi Yamahata, Satoshi Yamaguchi, Toshiya Osanai, Masaaki Takeda, Takafumi Mitsuhara, Masanao Mori, Shunichi Tanaka, Masanori Yonenaga, Akira Taguchi, Yosuke Watanabe, Masaru Abiko, Toshitaka Seki, Toru Sasamori, Kazunori Arita, Koji Yoshimoto

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Background: Because spinal dural arteriovenous fistulae (SDAVF) are rare and their clinical presentation is nonspecific, they are often overlooked during diagnostic evaluations. Typical magnetic resonance imaging (MRI) findings are intramedullary T2-weighted signal hyperintensity and perimedullary flow voids. There are few reports on the characteristic signs of the cauda equina. We assessed the significance of a new imaging parameter, the cauda equina occupation ratio (CEOR), for the evaluation of SDAVF. Methods: We retrospectively analyzed the clinical charts and radiological findings of 20 SDAVF patients treated at our institutions. We evaluated sagittal T2-weighted MRI scans and assessed the CEOR, the occupation ratio of the cauda equina compared to the sagittal diameter of the corresponding lumbar spinal canal. The controls were 21 age- and sex-matched subjects. Results: Of the 20 SDAVF, 10 were at the thoracic and 10 at the lumbar spine. There was no significant difference between the preoperative CEOR and the spinal level of the fistulae or the neurological signs. On preoperative MRI scans, the mean CEOR was 56.0 ± 7.8; postoperatively, it was 37.1 ± 7.4 (P = 0.000). The preoperative CEOR was significantly larger in SDAVF patients than in the controls (P = 0.000); postoperatively, it was smaller than in the controls (P = 0.14). Conclusions: The preoperative CEOR was larger in patients with SDAVF than in the controls. It normalized after successful occlusion of the fistula. Our findings indicate that the CEOR is a useful parameter for the pre- and postoperative evaluation of SDAVF.

Original languageEnglish
Pages (from-to)e1020-e1027
JournalWorld Neurosurgery
Publication statusPublished - Oct 2019
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Surgery
  • Clinical Neurology


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