Long-Term Sustainability of Functional Improvement Following Central
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SPINE Volume 43, Number 12, pp E703–E711 ß 2018 Wolters Kluwer Health, Inc. All rights reserved. CERVICAL SPINE Long-Term Sustainability of Functional Improvement Following Central Corpectomy for Cervical Spondylotic Myelopathy and Ossification of Posterior Longitudinal Ligament Sauradeep Sarkar, MBBS and Vedantam Rajshekhar, MCh more years (P < 0.001). Early improvement in functional status Study Design. Retrospective study. was maintained in 90.5% and 76.3% of patients at 5 and Objective. To examine predictors of long-term outcome and 10 years follow-up, respectively. On survival analysis, patients sustainability of initial functional improvement in patients with shorter preoperative symptom duration (<1 yr) were more undergoing corpectomy for cervical spondylotic myelopathy likely to demonstrate sustained improvement in functional status (CSM) or ossification of the posterior longitudinal ligament after surgery (P ¼ 0.022). (OPLL). Conclusion. Initial gains in functional status after central Summary of Background Data. There are limited data on corpectomy for CSM and OPLL are maintained in more than the predictors of outcome and sustainability of initial functional 75% of patients at 10 years after surgery. Overall, the most improvement on long-term follow-up after cervical corpectomy. Methods. We studied the functional outcome at more than 1- favorable long-term outcomes are achieved in younger patients year follow-up after central corpectomy in 352 patients with who present early and with good preoperative functional status. Key words: cervical spine, cervical spondylotic myelopathy, CSM or OPLL. Functional status was evaluated with the Nurick corpectomy, myelopathy, ossification of the posterior grading system. Analysis was directed at identifying factors longitudinal ligament, outcomes, prognostic factors, spondylosis, associated with both improvement in functional status and the sustainability. achievement of a ‘‘cure’’ (improvement to a follow-up Nurick Level of Evidence: 4 grade of 0 or 1). A survival analysis was performed to identify Spine 2018;43:E703–E711 factors associated with sustained functional improvement in patients with serial follow-up evaluations. Results. Nurick grade improved from 3.2 Æ 0.1 to 1.9 Æ 0.1 over a mean follow-up period of 57.1 months (range 12–228 ervical cord compression due to cervical spondy- mo). On multivariate analysis, age 50 years (P ¼ 0.008) and lotic myelopathy (CSM) or ossification of the pos- symptom duration 1 year (P < 0.001) were negatively associ- C terior longitudinal ligament (OPLL) frequently ated with functional improvement by 1 Nurick grade. Indepen- results in debilitating symptoms that significantly impair 1 dent factors negatively associated with ‘‘cure’’ after surgery both neurological function and quality of life. The patho- included age 50 years or older (P ¼ 0.005), preoperative Nurick physiology of degenerative cervical myelopathy is complex, grade of 4 or higher (P < 0.001) and symptom duration of 1 or involving both static and dynamic processes that usually result in progressive neurological dysfunction.2–5 Thus sur- gical decompression is recommended for the vast majority From the Department of Neurological Sciences, Christian Medical College, of patients with CSM and OPLL who present with progres- Vellore, India. sive functional impairment. Surgical decompression may be Acknowledgment date: August 2, 2017. First revision date: October 5, 2017. Acceptance date: October 16, 2017. accomplished by using a number of approaches, both ante- The manuscript submitted does not contain information about medical rior and posterior. Central corpectomy is an anterior decom- device(s)/drug(s). pressive procedure, which is ideally suited for multilevel No funds were received in support of this work. CSM or OPLL. It directly addresses the ventral compression No relevant financial activities outside the submitted work. that is seen in more than 75% of patients with CSM and all Address correspondence and reprint requests to Vedantam Rajshekhar, patients with OPLL. MCh, Department of Neurological Sciences, Christian Medical College, Although most contemporary reports testify to excellent Vellore 632004, India; E-mail: [email protected] outcomes after surgery, a small proportion of patients fail to 6–14 DOI: 10.1097/BRS.0000000000002468 achieve a complete functional recovery. Most published Spine www.spinejournal.com E703 Copyright © 2018 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. CERVICAL SPINE Long-Term Outcomes After Cervical Corpectomy Sarkar and Rajshekhar studies on the prognostic predictors of surgical outcome in each follow-up visit. Fusion status was assessed at the upper patients with CSM and OPLL suffer from small patient and lower ends of the graft, and stability was defined by lack cohorts, multiple surgeon involvement, short follow-up of sagittal translation on flexion-extension lateral cervical periods, or a heterogeneous choice of surgical spine radiographs. Patients unable to review in person were approaches.14–21 Even studies which report long-term out- periodically requested to send us postoperative radiographs comes often do not clarify whether there was a change in along with the follow-up questionnaire. function from the early postoperative period to late follow- up. Thus the proportion of patients who show a sustained Functional Evaluation improvement of function is unclear. Functional status before surgery and at all follow-up visits The objective of this study was to determine the sustain- was evaluated with the Nurick grading system. Follow-up ability of initially favorable postoperative outcome over details in the majority of cases had been obtained from long-term follow-up. We also planned to study the impact evaluation in the outpatient clinic and in the remainder by a of various preoperative clinical, imaging, and surgical fac- self-administered postal questionnaire. tors on long-term functional outcomes in a large single- surgeon cohort of patients undergoing the same surgical Outcome Measures and Prognostic Variables procedure, namely cervical corpectomy for CSM or OPLL. The primary outcome measures for this study were: (1) Functional improvement by at least one Nurick grade at MATERIALS AND METHODS last follow-up and (2) ‘‘Cure’’ (defined as improvement to a postoperative Nurick grade of 0 or 1). Patients with a Inclusion Criteria preoperative Nurick grade of 0 or 1 who retained their We consider cervical corpectomy for all patients with CSM Nurick grade after surgery were not considered ‘‘cured.’’ or OPLL, regardless of cervical alignment, unless the com- The prognostic variables studied were age at presentation, pression extends across more than three vertebral bodies or preoperative Nurick grade, symptom duration, the presence behind C2. We have been practicing uninstrumented fusion of diabetes mellitus, preoperative bladder dysfunction, pre- with a bone graft for nearly 3 decades and have achieved operative and postoperative sagittal alignment, a primary satisfactory neurological outcomes with acceptable graft diagnosis of OPLL, number of levels decompressed, and the migration and donor site morbidity rates, encouraging us occurrence of a perioperative complication. to maintain this practice.22,23 Between 1991 and 2008, 482 We sought to study whether improvement in functional patients underwent uninstrumented central corpectomy, status was sustained at long-term follow-up after CC for with all procedures performed by the senior author CSM. We identified 218 patients in whom serial evaluations (V.R.). For this study, we included only patients with a of postoperative functional status (i.e., two or more assess- primary diagnosis of CSM or OPLL and with >1 year ments performed at least 12 months apart). We then follow-up. Data were extracted from a prospectively excluded patients who had initially failed to improve or maintained database. worsened after surgery (n ¼ 24) or in whom the first follow- up evaluation was performed >2 years after surgery Surgical Technique (n ¼ 19). In this subcohort of 175 patients, we defined The surgical technique has been described in detail in several deterioration as a Nurick grade equal to or worse than that prior publications,24,25 and involved reconstruction of the before surgery or Nurick grade of 5 regardless of preopera- corpectomy defect with a tricorticate iliac bone or fibular tive status, on serial follow-up. For example, a patient with a strut graft, without instrumentation or anterior cervical preoperative Nurick grade of 3 who improved to Nurick plating. After confirming proper graft placement with an grade 1 at the first follow-up visit but later worsened to a immediate postoperative lateral cervical spine radiograph, Nurick grade of 3 at a subsequent visit was considered to patients were mobilized and discharged on a cervical collar have failed to sustain improvement in his/her functional that was maintained for 3 to 6 months. status. Radiographic Evaluation Statistical Analysis Cervical spine curvature was classified by using a line drawn Continuous and categorical variables are presented as mean from the posterior end of the inferior endplate of the C2 Æ standard error and frequencies, respectively. The Student t vertebral body to a similar point on C7. The spine was test or ANOVA and the chi-squared test were used to study described as lordotic if all the intervening vertebral bodies differences between continuous and categorical