Selective laminoplasty for cervical spondylotic myelopathy: a comparative study with a minimum 5-year follow-up

Transcription

1 Selective laminoplasty for cervical spondylotic myelopathy: a comparative study with a minimum 5-year follow-up Minori Kato*, Hiroaki Nakamura**, Koji Tamai**, Kazunori Hayashi**, Akira Matsumura**, Sadahiko Konishi**. *Department of Orthopaedic Surgery Osaka City General Hospital **Department of Orthopaedic Surgery Osaka City General Hospital

2 Introduction Conventional expansive laminoplasty (C3 7) is an established and standard treatment for cervical spondylotic myelopathy (CSM) involving multiple levels, and satisfactory longterm results have been obtained with it. However, compared with anterior procedures, some postoperative complications such as restriction of cervical spine range of motion (ROM), loss of cervical lordosis, C5 root paresis, and persistent axial pain have been reported. Operative invasion to the posterior extensor mechanism has been considered a cause of these complications. Recently, less invasive methods such as selective decompression and/or reconstruction of posterior elements have been reported. The clinical outcome of selective laminoplasty (e.g., C3 6 laminoplasty), which decreases postoperative complications, has been reported to be similar to that of conventional C3 7 laminoplasty. To our knowledge, no comparative study has evaluated the medium-term clinical outcome of selective laminoplasty vs. conventional C3 7 laminoplasty.

3 Purpose The purpose of this study is to examine the mediumterm clinical outcome of selective laminoplasty (C4 7 laminoplasty and C3 6 laminoplasty) in comparison with conventional C3 7 laminoplasty for treating CSM over a minimum follow-up of 5 years.

4 Materials & Methods The study population included 73 CSM patients (51 males; age range, years; average, 61.6 years) who had undergone spinous process-splitting laminoplasty between 1999 and 2004 at our institution. The duration of follow-up was >5 years (mean follow-up period: 7.1 years). The levels at which dural sac compression were observed on preoperative T2-weighted MRI was chosen for decompression. In the present series, the extent of laminoplasty was C3 7 in 42 cases (Group A), C4 7 in 16 (Group B), and C3 6 in 15 (Group C). Thus, 31 patients (Groups B and C) underwent selective laminoplasty. The patient demographics are shown in Table 1. C3-7:42 C3-6:15 C4-7:16 Group A:42case C3-7 laminoplasty Group B:31case Selective laminoplasty

5 Patient demographics Group A Group B Number Age (yo) Gender (Men/Women) 31/11 20/11 Time of operation (min) Blood loss (ml) Duration of symptom (mo) Preoperative diameter of the canal at C5 (mm) Follow up period (mo)

6 Outcome evaluation - Clinical outcome - X-ray findings Clinical outcomes were evaluated by comparing Japanese Orthopedic Association (JOA) scores, and X-ray findings (cervical sagittal alignment and ROM) before surgery, 2 years after surgery, and at final follow-up. - Axial pain Axial pain was defined as pain from the nuchal to the scapular regions. Axial pain was classified as follows: never; grade 0, mild; grade I, moderate; grade II, or severe; grade III. Postoperative axial pain was defined as newly developed pain or progression of the grade of pain.

7 Surgical procedure cf. C3-6 laminoplasty Re-suture Preservation of muscles attached at the spinous process of C7 All patients underwent spinous process-splitting open-door laminoplasty. After exploration of the laminae with detachment and retraction of the posterior paraspinal muscles. All detached attachments of the posterior paraspinal muscles were resutured to the original spinous process after elevation. The level of detachment of deep extensor muscles, including the semispinalis cervicis muscle, from the spinous processes was from 1 level cranial to the cranialmost decompressed lamina and to the same level as the caudalmost decompressed lamina.

8 Results Clinical outcome (JOA score) :Group A Point recovery ratio: 53.6% 13.8 N.S. :Group B % Pre-op. Post-op after 2Y Final follow-up No patient showed postoperative neurological deficits and none required a second surgery because of worsening symptoms. At final follow-up, mean recovery ratio of JOA scores were 53.6% in Group A and 50.6% in Group B. There was no significant deference between that of Group A and B. Medium-term clinical outcome was maintained in both groups over 5 years.

9 Cervical lordosis degree :Group A :Group B N.S. degree 20 Range of motion :Group A :Group B *: P < * 18.5 Pre-op. Post-op after 2Y Final follow-up Pre-op. Post-op after 2Y Final follow-up Cervical lordosis was maintained both groups at final follow-up. Meanwhile, C2 7 ROM decreased from 38.9 and 42.2 before surgery to 18.5 and 25.6 at final follow-up in Group A and B, respectively. The percentage of cervical range of motion retained after surgery was significantly higher in Group B than in Group A at final follow-up.

10 Pre-op. Pre-op. Pre-op. Pre-op. Axial pain Post-op. 2 years Final follow-up C3-7 laminoplasty C3-7 laminoplasty Post-op. 2 years Final follow-up grade 0 (never) I (mild) II (moderate) III (severe) grade 0 (never) I (mild) II (moderate) III (severe) I I II and III 1 1 II and III 1 1 Selective laminoplasty Selective laminoplasty Post-op. 2 years Final follow-up grade 0 I II III grade 0 I II III I 3 2 I 3 3 II and III 1 II and III 1 improve unchanged worsen Among all the cases, postoperative axial pain was observed in 11 patients, with its incidence being 15.1% at 2 years after surgery. At final follow-up, 9 patients had postoperative axial pain (12.3%). In Group A, 9 patients had postoperative axial pain 2 years after surgery and 7 patients had axial pain at the final follow-up. In Groups B, only 2 patient had postoperative axial pain at 2 years after surgery and at final follow-up.

11 Discussion Recently, many authors have reported less invasive methods such as selective laminoplasty for treating CSM. However, few studies have examined long- or mediumterm results of selective laminoplasty. Sakaura et al. reported 31 CSM patients who underwent C3 6 laminoplasty with preservation of all muscles attached to the C2 and C7 spinous processes bilaterally and were followed up for 5 years; they observed low incidence of persistent axial neck pain with a decreased loss of cervical lordosis 5 years after laminoplasty (Eur Spine J. 2011;20:928-33). The present study evaluated the clinical and radiological outcome of selective laminoplasty (C3 6 laminoplasty or C4 7 laminoplasty) vs. conventional C3 7 laminoplasty. Over a duration of >5 years, selective laminoplasty showed good neurological outcome and resulted in little postoperative axial neck pain and a decreased limitation of ROM. However, this study did not describe the inclusion criteria of selective laminoplasty for CSM because the preoperative parameters of each group were not very similar. A potential limitation of the present study is the fact that the total number of cases included in this study is small. To investigate essential indications of the selective range of laminoplasty, further research is needed using prospective randomized designs with larger sample sizes.

12 Conclusion Medium-term neurological recovery following selective laminoplasty (C4 7 laminoplasty and C3 6 laminoplasty) was satisfactory compared with that following conventional C3 7 laminoplasty. Our presentation has no potential conflict of interest disclosure.