Clinical Results and Complications of Surgical Treatment for Thoracic Myelopathy Caused by Ossification of the Posterior Longitudinal Ligament

Transcription

1 Clinical Results and Complications of Surgical Treatment for Thoracic Myelopathy Caused by Ossification of the Posterior Longitudinal Ligament - A Multicenter Retrospective Study - Mitsumasa Hayashida, Katsumi Harimaya, Takeshi Maeda, Hideki Ohta, Kenzo Shirasawa, Kuniyoshi Tsuchiya, Kazumasa Terada, Kozo Kaji, Takeshi Arizono, Yukihide Iwamoto Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University

2 Background Compression of spinal cord by thoracic ossification of posterior longitudinal ligament (T-OPLL) is well-known cause of severe thoracic myelopathy and generally requires surgical treatment. However the surgical outcome of T-OPLL is generally unfavorable. There are several anatomical and clinical features for the difficulty of surgery for T-OPLL. In the previous study, several recommendations of the surgical treatment for T-OPLL have been reported, however the clinical results are not necessarily improved and the possibility of postoperative paraplegia remains a major risk. Purpose The purpose of this study was to evaluate the surgical outcome for T-OPLL including latest procedures and related risk factors in recent years. 2

3 Methods 57 patients (32 females and 25 males) with thoracic myelopathy caused by T-OPLL who underwent operations at institutions in the Fukuoka Spine Group from 2000 to The mean age 56.0 years (range, years) The mean follow-up period 5.3 years (range, years) The modified Japanese Orthopaedic Association (JOA) scoring system and modified Frankel score were used to evaluate the clinical outcome of the patients before and after surgery. 3

4 The patient data; sex, age, disease duration, BMI, comorbidity, ossification type, anteroposterior diameter of ossification, level of maximum ossification, surgical methods, decompression and fusion levels, surgical time, total blood loss and complications. To determine the most important prognostic factors related to the surgical outcome, these factors were evaluated by uni- and multivariate analyses. 4

5 Results The ossification type Beaked Continuous waveform Continuous cylindrical Mixed Maximum ossification T1/2-T4/5 25 T5/6-T8/9 21 T9/10-T11/12 11 Surgical Procedure Posterior decompression Posterior decompression and fusion with instrumentation Anterior decompression via the posterior approach (as previously reported by Ohtsuka et al. 1987) Anterior decompression via the anterior approach

6 Surgical outcome Neurological status (according to the modified Frankel score ) Improvement Unchanged Deteriorated 33 patients (57.9%) 14 patients (24.6%) 10 patients (17.5%) Recovery rate (according to JOA score) Average 25% or higher 26.4% 30 patients (52.6%) 6

7 Multivariate analysis revealed that the use of instrumentation and CSF leakage at operation were significantly related to the recovery rate of JOA score Variables β (95% CI) p-value Age at surgery 0.30 (-1.21 to 1.82) 0.69 Gender (male) ( to 19.53) 0.83 Body height (cm) 3.65 (-3.14 to 10.43) 0.28 Body weight (kg) (-9.78 to 3.64) 0.36 Body mass index 9.34 (-8.91 to 27.59) 0.30 Diabetes mellitus (-5.14 to 3.88) 0.78 Hypertension ( to 3.52) 0.10 Disease duration (year) 5.51 ( to 30.83) 0.66 The ossification type (beak-type OPLL) 1.34 ( to 15.88) 0.85 The anteroposterior diameter of (-8.21 to 7.88) 0.97 ossification JOA score before surgery 2.71 (-5.18 to 10.60) 0.49 Surgical time (min) (-0.25 to 0.11) 0.42 Total blood loss (ml) 0.03 (-0.01 to 0.06) 0.17 Use of instrumentation (2.42 to 43.64) Postoperative hematoma ( to 18.61) 0.59 Cerebrospinal fluid (CSF) leakage ( to -2.59) R 2 = 0.51, β = unstandardized regression coefficient. 7

8 The use of instrumentation was significantly related to a better outcome Change in modified Frankel score Improved Unchanged Deteriorated The association between the spinal fixation with instrumentation and the neurological status Patients with spinal instrumentation (%) n= Patients without Spinal instrumentation (%) n= *p-value CSF leakage was observed in 14 patients (24.6%) Fisher s exact test 7 out of 14 patients (50%) with CSF leakage were neurologically deteriorated, which was not associated with the type of surgical procedure. Transient paralysis 3 Permanent paralysis 4 8

9 The Fusion levels greater than or equal to the decompression levels led to a better clinical outcome. Posterior decompression 31 patients and fusion with instrumentation The association between the fixation range and the outcome of the surgery Variables FL DL n=26 Divided into 3 groups FL < DL n=5 FL > DL FL = DL FL < DL Fusion levels with instrumentation (FL) Posterior decompression levels (DL) *p-value The JOA score before 3.96 ± ± surgery The JOA score after 6.88 ± ± surgery The JOA recovery rate ± ± Values are mean ± SEM *: Wilcoxon rank-sum test. 9

10 Discussion Even today, T-OPLL is difficult to treat and therapeutic strategy for T-OPLL is still controversial. Several recommendations and clinical features for T-OPLL treatment have been recognized according to the tendency of the recent literature. The outcome of fusion surgery for T-OPLL were relatively favorable. T-OPLL extirpation is technically demanding because the ossified ligament adheres strongly to the dura. Surgery for T-OPLL was associated with a high rate of complications. Deterioration 11.7%~33% 17.5% (This study) CSF leakage 15%~40% 24.6% (This study) (Matsuyama Y, et al J Spinal Disord Tech. 2005) (Yamazaki M, et al SPINE 2006, Spinal Cord 2006) (Matsumoto M, et al SPINE 2008, SPINE 2011) (Aizawa T, et al Neuro surg Spine 2007) (Takahata M, et al SPINE 2008) (McClendon J, et al Neurosurg Focus. 2011) In this study,the posterior decompression levels versus fusion levels related to the neurological status was described for the first time. 10

11 Why does the CSF leakage result in neurological deterioration? Unfavorable conditions of the thoracic spinal cord In the mid thoracic level, the spinal cord blood flow is very poor because of the lack of collateral blood supply, making this region more susceptible to the effect of hypotension. (William F, et al Hanai K,et al 2002 Aizawa et al. 2007) CSF leakage leads to intradural hypotension and may exacerbate the susceptibility of the spinal cord compression from the surrounding soft tissue. 11

12 Conclusions Our findings demonstrated that the use of instrumentation should be considered with surgical procedure for T-OPLL and the vertebral fusion levels with instrumentation should be not less than the decompression levels, due to the enhancement and preservation of the decompression effect. We strongly believe that the complication of CSF leakage should be avoided as far as possible due to the high possibility of postoperative deterioration, regardless of the surgical procedure used. COI: none of the authors has any potential conflict of interest 12