Laminoplasty after anterior spinal fusion for cervical spondylotic myelopathy

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1 Journal of Orthopaedic Surgery 2009;17(3): Laminoplasty after anterior spinal fusion for cervical spondylotic myelopathy Chun-Hong Pang, Hon-Bong Leung, Chi-Hung Yen Department of Orthopaedics and Traumatology, Kwong Wah Hospital, Hong Kong ABSTRACT Purpose. To review outcomes of laminoplasty after anterior spinal fusion () in 8 patients with cervical spondylotic myelopathy (CSM). Methods. Records of 3 men and 5 women aged 49 to 80 (mean, 60) years who underwent laminoplasty after for CSM were reviewed. Before and after and laminoplasty, the causes of CSM, mechanical instability, the Pavlov Torg ratio, the numbers of levels of stenosis, myelomalacia,, and laminoplasty, the modified Japanese Orthopaedic Association (JOA) score, and the Hirabayashi recovery rate were recorded in all the patients. Results. After, the mean modified JOA score improved to 9.6 from 8.3 (p=0.05), with a mean Hirabayashi recovery rate of 12.5% at the 12-month follow-up. However, it deteriorated to 9 after a mean of 25 (range, 3 54) months follow-up. Indications for a secondary laminoplasty included inadequate (n=5), progression of prolapsed discs (n=4), osteophytes (n=3), ossification of the posterior longitudinal ligament (n=1), and hypertrophy of the ligamentum flavum (n=4). The mean interval between and laminoplasty was 30 (range, 14 55) months. The mean number of levels of laminoplasty was 4.5 (range, 4 5). After laminoplasty, all patients had adequate spinal with no cord compromise, neck pain or stiffness, despite the signal change remaining the same. Two patients improved, 2 deteriorated, and 4 remained unchanged with respect to walking status. The mean modified JOA scores improved to 9.7 from 9 (p=0.38); the mean Hirabayashi recovery rate was -1.5%. All patients had persistent myelomalacia, which was not reflected in the improved modified JOA score. Conclusions. Initial surgery (such as ) is more effective in relieving cord compromise and myelopathy. and progression of disease may necessitate secondary laminoplasty, which conferred additional benefits that 5 of our 8 patients enjoyed despite persistence of myelomalacia. Key words: cervical vertebrae; spinal cord diseases; spondylosis Address correspondence and reprint requests to: Dr Chi-Hung Yen, Department of Orthopaedics and Traumatology, Kwong Wah Hospital, 25 Waterloo Road, Kowloon, Hong Kong. chihungyenyen@yahoo.com.hk

2 270 CH Pang et al. Journal of Orthopaedic Surgery INTRODUCTION Surgical using an anterior or posterior approach for severe or progressive cervical spondylotic myelopathy (CSM) has achieved goodto-excellent results. 1 4 Laminoplasty is comparable to anterior spinal fusion () in terms of neurological improvement, functional status, and overall pain relief. 5,6 After, outcome may remain the same or even deteriorate in some patients, 7 because of inadequate, permanent neurological damage, new cord compromise (as the disease progresses owing to prolapsed discs), osteophytes, ossification of the posterior longitudinal ligament (OPLL), and hypertrophy of the ligamentum flavum (HLF). Further using laminoplasty may be indicated. We reviewed the clinical results of 8 patients who underwent laminoplasty after for CSM. MATERIALS AND METHODS Records of 3 men and 5 women aged 49 to 80 (mean, 60) years who underwent laminoplasty (using the modified Kurokawa spinous process splitting method) 8 after (using the Southwick and Robinson approach with autologous iliac crest bone grafting) for CSM between 1999 and 2008 were reviewed. Comorbidities included diabetes mellitus (n=2), hypertension (n=3), and benign prostate hypertrophy (n=1). No patients had a psychiatric illness or dementia or endured a cerebrovascular accident. In all patients, radiographs and magnetic resonance images (MRIs) obtained before and after and laminoplasty were reviewed (Fig.). The causes of CSM, mechanical instability, the Pavlov Torg ratio, the numbers of levels of stenosis, myelomalacia, and details pertaining to the and laminoplasty were also recorded. 9 Stenosis was defined as spinal cord compromise at the level of disc or body. Cord compromise at 2 disc levels was considered as 2 stenosis levels. This definition also applied to measurement of the level of myelomalacia. The modified Japanese Orthopaedic Association (JOA) scores were evaluated by one observer to avoid inter-observer variability. The Hirabayashi recovery rate (%) 10,11 = (postoperative preoperative JOA scores) / (17 preoperative JOA (a) (b) (c) Figure Magnetic resonance images showing (a) disc prolapse at C3/4 with myelomalacia and at C5/6 with cord compromise, (b) inadequate after anterior spinal fusion of C3/4, and (c) adequate cord with persistent myelomalacia after modified Kurokawa laminoplasty.

3 Vol. 17 No. 3, December 2009 Laminoplasty after anterior spinal fusion for cervical spondylotic myelopathy 271 score) x 100. The paired sample 2-tailed t test was used. A p value of 0.05 was considered statistically significant. RESULTS All patients had a normal cervical lordosis except one; none was mechanically instable; all had cord signal changes and were continent. The causes of CSM included disc prolapse (n=6), osteophytes (n=3), OPLL (n=4) and HLF (n=1). The mean numbers of levels of stenosis and myelomalacia were 2.6 (range, 1 4) and 1.6 (range, 1 3), respectively. Patients 5, 6, and 8 had congenital cervical stenosis with a Pavlov Torg ratio of <0.8 (Table 1). After, all patients achieved bony union. At the 12-month follow-up, the mean modified JOA score improved to 9.6 (standard deviation [SD], 1.8) from 8.3 (SD, 2.5) [p=0.05, paired sample t test, Table 2]. This improvement was not related to the preoperative Pavlov Torg ratio, or the presence of disc prolapse, osteophytes, OPLL, or HLF. The mean Hirabayashi Patient No. Pavlov Torg ratio Table 1 Radiological findings of the 8 patients before anterior spinal fusion () and laminoplasty Disc prolapse Osteophytes Ossification of posterior longitudinal ligament Hypertrophy of ligamentum flavum C C4/5, C3/ C C4/5, + - C4/5, - - C4/ C5/6 C5/ C3/4, - + C4/5, - - C C4/5, C4/ C3/4, C5/6 - + Table 2 The modified Japanese Orthopaedic Association (JOA) scores before and after anterior spinal fusion () and laminoplasty Patient No. Mean modified JOA score * Hirabayashi recovery rate (%) Interval between and laminoplasty Mean modified JOA score Post- (months) Prelaminoplasty Postlaminoplasty Hirabayashi recovery rate (%) Levels of myelomalacia before and after laminoplasty C C C C C C C C4 Mean (SD) 8.3 (2.5) 9.6 (1.8) (3.2) 9.7 (2.5) * p=0.05, paired sample t test p=0.38, paired sample t test

4 272 CH Pang et al. Journal of Orthopaedic Surgery recovery rate was 12.5% (range, %) and was positive in patients 1, 2, 5, 6, and 8 (who had subjective feeling of neurological improvement). Patients 1 and 3 had a worse walking status; others remained unchanged (Table 3). At a mean of 25 (range, 3 54) months of follow-up, the mean modified JOA score decreased to 9 from 9.6, with an absolute decrease in patients 1, 3, 5, and 8 (Table 2). The MRI showed the same mean numbers of levels of stenosis and myelomalacia as pre-. Indications for a secondary laminoplasty included inadequate after (n=5: 2 improved, 2 remained unchanged, and one deteriorated), progression of disc prolapse (n=4), osteophytes (n=3), OPLL (n=1), and HLF (n=4). The mean interval between the and laminoplasty was 30 (range, 14 55) months. The mean number of levels of laminoplasty was 4.5 (range, 4 5). The mean follow-up period after laminoplasty was 27 (range, 8 49) months. After laminoplasty, all patients had adequate spinal with no cord compromise and neck pain or stiffness, despite the signal change remaining the same. Two patients improved, 2 deteriorated, and 3 remained unchanged with respect to walking status. The mean modified JOA score improved to 9.7 from 9 (p=0.38, paired sample t test); the mean Hirabayashi recovery rate was -1.5% and was positive in patients 1, 2, 3, 5, and 8. All patients had persistent myelomalacia, which was not reflected on the improved modified JOA score. No major complication occurred after or laminoplasty. DISCUSSION The pathophysiology of CSM involves both mechanical and vascular factors. 12,13 Anterolateral discectomy with interbody fusion is the procedure of choice for patients with single-level disc herniation causing anterior cord compromise without spinal canal stenosis. 14 Its use has extended to multiple-level CSM with good long-term results. 3,15 In our series, improved the Hirabayashi recovery rate by 12.5% at the one-year follow-up, compared to -1.5% after laminoplasty. Therefore, initial surgery (such as ) was more effective in relieving cord compromise and myelopathy. 16 Secondary laminoplasty did not enable recuperation from the detrimental effects to the cord, despite adequate. 17 merely decompressed (rather than enlarged) the spinal canal anteriorly, as the number of stenosis levels remained the same. Its complications include dislodgement or nonunion of bone grafts, donor-site morbidities, prolonged immobilisation, inadequate for disc prolapse and OPLL and adjacent segment disease, and visceral complications related to the anterolateral approach Progression of the degenerative cervical spondylosis was inevitable, particularly in patients with congenital spinal stenosis In our series, the frequency of new HLF after was relatively high. Initial surgery (such as ) is more effective in relieving cord compromise and myelopathy. and progression of disease may necessitate secondary laminoplasty, which conferred additional benefits that 5 of our 8 patients enjoyed despite persistence of myelomalacia. The Kurokawa laminoplasty is superior to laminectomy. Although both achieve the same neurological improvement, laminoplasty has a lower rate of complications such as segmental instability, kyphosis, perineural adhesions, and late neurological deterioration Although laminoplasty and confer the risk of chronic neck pain and bone graft complication, respectively, both procedures achieve Table 3 Walking status of the 8 patients Patient No. Walking status * Post- Post-laminoplasty 1 Walking frame Wheelchair Walking frame Wheelchair 2 Walking stick Walking stick Walking stick Quadripods 3 Quadripods Walking frame Walking frame Walking frame 4 Walking stick Walking stick Walking stick Walking stick Quadripods Quadripods Quadripods Walking stick 7 Walking stick Walking stick Walking stick Walking stick 8 Walking frame Walking frame Wheelchair Walking frame * Patients 1 and 3 deteriorated after, patients 6 and 8 improved after laminoplasty, patients 1 and 2 deteriorated after laminoplasty

5 Vol. 17 No. 3, December 2009 Laminoplasty after anterior spinal fusion for cervical spondylotic myelopathy 273 the same neurological improvement, 6 and can reliably arrest myelopathic progression in multiple cervical myelopathy and reduce pain. 5 In our series, cerebrospinal fluid was adequate to cushion the spinal cord in all patients after laminoplasty. Nonetheless, adequate cord did not guarantee significant improvement in outcomes. The poor outcome after laminoplasty was due to spinal cord insult, which persisted without any MRI signal change. 27 Myelomalacia indicated a poor prognosis in patients with CSM. Our retrospective study had limitations. The number of patients was small and results were inconclusive. Intra-observer errors in recording the modified JOA scores were inevitable. Prospective randomised controlled studies of matched CSM patients are needed to compare the treatment outcomes following conservative treatment,, or laminoplasty. ACKNOWLEDGEMENTS We thank Dr WM Lee for providing secretarial support and Ms Kian Chong for statistical analysis. REFERENCES 1. Sampath P, Bendebba M, Davis JD, Ducker TB. Outcome of patients treated for cervical myelopathy. A prospective, multicenter study with independent clinical review. Spine (Phila Pa 1976) 2000;25: Carol MP, Ducker TB. Cervical spondylitic myelopathies: surgical treatment. J Spinal Disord 1988;1: Ikenaga M, Shikata J, Tanaka C. Long-term results over 10 years of anterior corpectomy and fusion for multilevel cervical myelopathy. Spine (Phila Pa 1976) 2006;31: Chiba K, Ogawa Y, Ishii K, Takaishi H, Nakamura M, Maruiwa H, et al. Long-term results of expansive open-door laminoplasty for cervical myelopathy average 14-year follow-up study. Spine (Phila Pa 1976) 2006;31: Edwards CC 2nd, Heller JG, Murakami H. Corpectomy versus laminoplasty for multilevel cervical myelopathy: an independent matched-cohort analysis. Spine (Phila Pa 1976) 2002;27: Sakaura H, Hosono N, Mukai Y, Ishii T, Iwasaki M, Yoshikawa H. Long-term outcome of laminoplasty for cervical myelopathy due to disc herniation: a comparative study of laminoplasty and anterior spinal fusion. Spine (Phila Pa 1976) 2005;30: LaRocca H. Cervical spondylotic myelopathy: natural history. Spine (Phila Pa 1976) 1988;13: Tomita K, Kawahara N, Toribatake Y, Heller JG. Expansive midline T-saw laminoplasty (modified spinous process-splitting) for the management of cervical myelopathy. Spine (Phila Pa 1976) 1998;23: White AA 3rd, Johnson RM, Panjabi MM, Southwick WO. Biomechanical analysis of clinical stability in the cervical spine. Clin Orthop Relat Res 1975;109: Hirabayashi K, Miyakawa J, Satomi K, Maruyama T, Wakano K. Operative results and postoperative progression of ossification among patients with ossification of cervical posterior longitudinal ligament. Spine (Phila Pa 1976) 1981;6: Hirabayashi K, Watanabe K, Wakano K, Suzuki N, Satomi K, Ishii Y. Expansive open-door laminoplasty for cervical spinal stenotic myelopathy. Spine (Phila Pa 1976) 1983;8: Batzdorf U, Flannigan BD. Surgical decompressive procedures for cervical spondylotic myelopathy. A study using magnetic resonance imaging. Spine (Phila Pa 1976) 1991;16: Taylor AR. Vascular factors in the myelopathy associated with cervical spondylosis. Neurology 1964;14: Southwick WO, Robinson RA. Surgical approaches to the vertebral bodies in the cervical and lumbar regions. J Bone Joint Surg Am 1957;39: Ikenaga M, Shikata J, Tanaka C. Anterior corpectomy and fusion with fibular strut grafts for multilevel cervical myelopathy. J Neurosurg Spine 2005;3: Matz PG, Holly LT, Mummaneni PV, Anderson PA, Groff MW, Heary RF, et al. Anterior cervical surgery for the treatment of cervical degenerative myelopathy. J Neurosurg Spine 2009;11: Matsumoto M, Nojiri K, Chiba K, Toyama Y, Fukui Y, Kamata M. Open-door laminoplasty for cervical myelopathy resulting from adjacent-segment disease in patients with previous anterior cervical and fusion. Spine (Phila Pa 1976) 2006;31: Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am 1999;81: Shinomiya K, Okamoto A, Kamikozuru M, Furuya K, Yamaura I. An analysis of failures in primary cervical anterior spinal cord and fusion. J Spinal Disord 1993;6: Teramoto T, Ohmori K, Takatsu T, Inoue H, Ishida Y, Suzuki K. Long-term results of the anterior cervical spondylodesis. Neurosurgery 1994;35: Iwasaki M, Okuda S, Miyauchi A, Sakaura H, Mukai Y, Yonenobu K, et al. Surgical strategy for cervical myelopathy due to ossification of the posterior longitudinal ligament: part 1: clinical results and limitations of laminoplasty. Spine (Phila Pa 1976) 2007;32: Iwasaki M, Okuda S, Miyauchi A, Sakaura H, Mukai Y, Yonenobu K, et al. Surgical strategy for cervical myelopathy due to ossification of the posterior longitudinal ligament: part 2: advantages of anterior and fusion over

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