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Eur Spine J. 2018 Sep 6. doi: 10.1007/s00586-018-5750-6. [Epub ahead of print]

Clinically significant radiographic parameter for thoracic myelopathy caused by ossification of the ligamentum flavum.

Author information

1
Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro43-gil, Songpa-gu, Seoul, 05505, South Korea.
2
Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro43-gil, Songpa-gu, Seoul, 05505, South Korea. grandblue@gnah.co.kr.
3
Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43 gil, Songpa-gu, Seoul, 05505, Korea. grandblue@gnah.co.kr.
4
Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro43-gil, Songpa-gu, Seoul, 05505, South Korea. swroh@amc.seoul.kr.
5
Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43 gil, Songpa-gu, Seoul, 05505, Korea. swroh@amc.seoul.kr.

Abstract

PURPOSE:

To investigate radiographic parameters to improve the accuracy of radiologic diagnosis for ossification of ligamentum flavum (OLF)-induced thoracic myelopathy and thereby establish a useful diagnostic method for identifying the responsible segment.

METHODS:

We classified 101 patients who underwent surgical treatment for OLF-induced thoracic myelopathy as the myelopathy group and 102 patients who had incidental OLF and were hospitalized with compression fracture as the non-myelopathy group between January 2009 and December 2016. We measured the thickness of OLF (TOLF), cross-sectional area of OLF (AOLF), anteroposterior canal diameter, and the ratio of each of these parameters.

RESULTS:

Most OLF cases with lateral-type axial morphology were in the non-myelopathy group and most with fused and tuberous type in the myelopathy group. Most grade-I and grade-II cases were also in the non-myelopathy group, whereas grade-IV cases were mostly observed in the myelopathy group. The AOLF ratio was found to be the best radiologic parameter. The optimal cutoff point of the AOLF ratio was 33.00%, with 87.1% sensitivity and 87.3% specificity. The AOLF ratio was significantly correlated with preoperative neurological status.

CONCLUSIONS:

An AOLF ratio greater than 33% is the most accurate diagnostic indicator of OLF-induced thoracic myelopathy. In cases of multiple-segment OLF, confirmation of cord signal change on MRI and an AOLF measurement will help determine the responsible segment. AOLF measurement will also improve the accuracy of diagnosis of OLF-induced thoracic myelopathy in cases of grade III or extended-type axial morphology. These slides can be retrieved under Electronic Supplementary Material.

KEYWORDS:

Area of ligamentum flavum; Optimal cutoff point; Ossification of ligamentum flavum; Thickness of ligamentum flavum; Thoracic myelopathy

PMID:
30191306
DOI:
10.1007/s00586-018-5750-6

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