Clinical Results And Prognostic Factors for Thoracic Myelopathy Caused by Ossification of Yellow Ligament after Surgical Treatment

Whoan Jeang Kim; Dae Geon Song; Kun Young Park; Je Yun Koo; Won Cho Kwon; Kyung Hoon Park; Won Sik Choy

doi:10.4184/jkss.2014.21.3.116

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Kim, Song, Park, Koo, Kwon, Park, and Choy: Clinical Results And Prognostic Factors for Thoracic Myelopathy Caused by Ossification of Yellow Ligament after Surgical Treatment

Original Article

Journal of Korean Spine Surg 2014;21(3):116-122.

Published online: 21 September 2014

DOI: https://doi.org/10.4184/jkss.2014.21.3.116

Clinical Results And Prognostic Factors for Thoracic Myelopathy Caused by Ossification of Yellow Ligament after Surgical Treatment

Whoan Jeang Kim, M.D., Dae Geon Song, Kun Young Park, M.D., Je Yun Koo, M.D., Won Cho Kwon, M.D., Kyung Hoon Park, M.D., Won Sik Choy, M.D.

Department of Orthopedic Surgery, Eulji University College of Medicine, Daejeon, Korea

Corresponding author: Dae Geon Song, M.D. Department of Orthopaedic Surgery, Eulji University College of Medicine, 1306, Dunsan-dong, Seo-gu, Daejeon, Korea TEL: +82-42-611-3280, FAX: +82-42-611-3283 E-mail: jaystar4u@eulji.ac.kr

Received 18 February 2014 Revised 1 April 2014 Accepted 19 June 2014

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Study Design

Retrospective study.

Objectives

We analyzed the clinical results of thoracic myelopathy caused by ossification of yellow ligament (OYL) and to explore prognostic factors after surgical treatment.

Summary of Literature Review

Thoracic myelopathy due to OYL is difficult to treat; surgery is considered as treatment of choice. However, studies of the clinical results and prognostic factors are few due to its rare presentation.

Materials and Methods

Twenty six patients who had surgery for thoracic myelopathy caused by OYL were evaluated from February 2002 to April 2012. We describe the analysis of the clinical results after surgery and prognostic factors.

Results

Modified Japanese orthopedic association (JOA) score was recorded in all patients by 5.7±1.3 points (range, 2-9 points) preoperatively, 7.8±1.7 points (range, 4-10 points) postoperatively, and 8.4±2.1 points (range, 5-11 points) at final followup. Hirabayashi recovery rate was recorded by 60.2±20.2% (range, 45.5-72.0%) postoperatively, 64.5±17.3% (range, 50.2-75.1%) at final followup. The Visual Analogue Scale (VAS) score was also improved by 7.6±1.8 points (range, 7-10 points) preoperatively, 4.5±1.3 points (range, 3-6 points) postoperatively, and 3.8±1.6 points (range, 2-5 points) at final followup. Both modified JOA score and VAS score improved significantly (p<0.05). In prognostic factor analysis, OYL type on CT axial image, duration of symptom, and preoperative severity of myelopathy was significant (p<0.05).

Conclusion

We showed the effectiveness of surgery on patients who suffer from thoracic myelopathy caused by OYL and that OYL type identified by CT axial image, duration of symptom, and preoperative severity of myelopathy were significant prognostic factors.

Keywords: Ossification of yellow ligament, Thoracic myelopathy, Clinical result, Prognostic factor

REFERENCES

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3. Kurosa Y, Yamaura I, Nakai O, et al. Selecting a surgical method for thoracic myelopathy caused by ossification of the posterior longitudinal ligament. Spine (Phila PA 1976). 1996; 21:1458–66.

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16. Lazorthes G, Gouaze A, Zadeh JO, Santini JJ, Lazorthes Y, Burdin P. Arterial vascularization of the spinal cord. Recent studies of the anastomotic substitution pathways. J Neurosurg. 1971; 35:253–62.

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Figures and Tables%

Fig. 1.

A 57-year-old man suffered from thoracic myelopathy T2-3-4 by OYL. (A) This CT sagittal image shows OYL with protrusion into the spinal canal at T2-3 and T3-4 level (arrow). (B) CT axial image displays localized type of OYL with spinal canal encroachment (arrow). (C) T2-wighted MRI sagittal image demonstrates OYL of beak type which encroaches spinal canal on T2-3 and T3-4 level. (D) He underwent surgery of T2-3-4 posterior decompression and postoperative CT sagittal image shows well-decompressed spinal canal.

Fig. 2.

A 66-year-old man had thoracic myelopathy T10-11 by ossification of yellow ligament. (A) CT sagittal image demonstrates OYL lesion between T10 and T11 level (B) T2-weighted MRI sagittal image shows hypointense signal of OYL with beak type on T10-11 level and intramedullary hypertense signal change on T11-12 level just beneath the level of lesion. (C) Preoperative plain lateral radiograph shows OYL with projection to the spinal canal at T10-11 level (arrow). (D) He had an operation of T10-11 posterior decompression and posterolateral fusion. The patient had to get a wide laminectomy including facet joint because of large size of OYL. This is the reason he had to have a surgery of fusion.

Table 1.

Demographics of the Patients

Variable	Value
Total number (cases)	26
Mean age (year)	64.6
Sex
M	17
F	9
Location of ossification of yellow ligament (cases)
Upper thoracic spine (T1-4)	6
Middle thoracic spine (T5-9)	4
Lower thoracic spine (T10-12)	16
Myelopathy symptom (cases)
Lower limb weakness	21
Lower limb pain	17
Gait disturbance	16
Trunk or lower limb sensory dysfunction	12
Lower limb spasticity	8
Sphincter dysfunction	6
Surgical method (cases)
Posterior decompression	17
Posterior decompression & PLF	9
Mean preoperative modified JOA score (points)	5.7±1.3

PLF: Posterolateral fusion, JOA: Japanese orthopedic association.

Table 2.

Modified Japanese Orthopedic Association (JOA) Scoring Sys Tem in Thoracic Myelopathy

Neurologic status	Score (points)
Lower limb motor dysfunction
Unable to walk	0
Able to walk on flat floor with walking aid	1
Able to walk up/down stairs with handrail	2
Lack of stability and smooth reciprocation of gait	3
No dysfunction	4
Lower limb sensory deficit
Severe sensory loss or pain	0
Mild sensory deficit	1
No deficit	2
Trunk sensory deficit
Severe sensory loss or pain	0
Mild sensory deficit	1
No deficit	2
Sphincter dysfunction
Unable to void	0
Marked difficulty in micturition	1
Minor difficulty in micturition	2
No dysfunction	3
Total	11

Table 3.

Clinical Data in 26 Patients with Surgical Treatment

Variable	Value
Mean followup period (month)	38.3
Mean preoperative duration of symptom (month)	16.3
Mean modified JOA score (points)
Preoperative	5.7±1.3
Postoperative	7.8±1.7
Last followup	8.4±2.1
Hirabayashi recovery rate (%)
Postoperative	60.2±20.2
Last followup	64.5±17.3
VAS score (points)
Preoperative	7.6±1.8
Postoperative	4.5±1.3
Last followup	3.8±1.6

JOA: Japanese orthopedic association, VAS: Visual analogue scale.

Table 4.

Results of Univariate Analysis of Postoperative Modified JOA Score and Various Factors

Factors	No. of patients	Postoperative modified JOA score	P value
Intramedullary signal change on MRI			0.552
Yes	5	7.83
No	21	8.01
Surgical method			0.283
Posterior decompression	17	8.23
Posterior decompression & PLF	9	8.31
Age (year)			1.000
<60	9	8.37
≥60	17	8.13
Location of lesions			0.311
Upper thoracic spine (T1-4)	6	7.78
Middle thoracic spine (T5-9)	4	7.89
Lower thoracic spine (T10-12)	16	8.12
OYL type on MRI sagittal image			0.425
Beak	6	7.82
Non-beak	20	8.23
OYL type on CT axial image			0.027*
Diffuse	7	7.23
Localized	19	8.32
Preoperative duration of symptom (month)			0.000*
≤6	10	9.34
7 to 12	6	8.16
13 to 24	7	7.89
>24	3	6.34
Preoperative severity of myelopathy			0.001*
Mild(modified JOA score≥7)	8	9.87
Moderate(modified JOA score 4 to 6)	15	7.52
Severe(modified JOA score≤3)	3	4.83

MRI: Magnetic resonance imaging, PLF: Posterolateral fusion, OYL: Ossification of yellow ligament, CT: Computed tomography, JOA: Japanese orthopedic association, * statistically significant.

Table 5.

Results of Multiple Regression Analysis of Last Followup Modified JOA Score and Various Factors

Factors	Correlation with last followup modified JOA score
Factors	Coefficient	P value
Preoperative modified JOA score	0.735	0.012*
Preoperative duration of symptom	-0.331	0.007*
Intramedullay signal change on MRI	0.037	0.637
OYL type on MRI sagittal image	0.025	0.741
OYL type on CT axial image	-0.012	0.134
Location of lesions	0.045	0.447
Surgical method	0.089	0.281

JOA: Japanese orthopedic association, MRI: Magnetic resonance imaging, OYL: Ossification of yellow ligament, CT: Computed tomography.

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