Original ArticleThe Association of Cervical Spine Alignment with Neurologic Recovery in a Prospective Cohort of Patients with Surgical Myelopathy: Analysis of a Series of 124 Cases
Introduction
Degenerative cervical myelopathy results from extrinsic changes in the cervical spine that lead to both static and dynamic spinal cord compression. The most common 2 etiologies include cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament. Spondylotic disease in the former leads to structural compression and the abnormal spinal alignment and the spinal cord excursion leads to dynamic compression and repetitive trauma.1 Nonsurgical management has not demonstrated efficacy for this condition,2, 3 whereas surgical management provides for stabilization and improvement of neurologic disability.4 Indeed, much of the current controversy pertains not to whether surgery should be offered but rather the specific type of surgical management.3, 4, 5 Disease pathoanatomy may guide the surgical decision-making, and preoperative cervical spine global sagittal alignment has been demonstrated recently to be associated with baseline neurologic disability.6 A prospective multicenter series of surgical CSM patients reveals similar neurologic outcomes despite the selected surgical approach,7 although perioperative morbidity may be heightened among patients approached posteriorly.5, 8
It is well established that the preoperative myelopathy score is one of the strongest predictors of postoperative neurologic status in prospective cohorts of patients with CSM.4, 9 Although global sagittal alignment has been associated with the intensity of spinal cord hyperintensity on magnetic resonance (MRI) and the severity of preoperative myelopathy, an important question remains as to the impact of this alignment on the potential for postsurgical neurologic improvement. Indeed, Zhang et al. have suggested that heightened MRI T2 hyperintensity does prognosticate for a lesser degree of postoperative neurologic improvement.3, 10, 11 A secondary question is whether operative correction of sagittal deformity has an impact on the extent of neurologic improvement.
Various surgical techniques can achieve different amounts of sagittal correction, more so for differences between multilevel anterior discectomy and multilevel anterior corpectomy approaches4 and less so for anterior approaches over posterior approaches.12 Experimental models of myelopathy reveal that cervical spine kyphosis is associated with demyelination, atrophy, and neuronal loss of the anterior horn and decreased vascular supply of the anterior spinal cord.13 Tang et al.14 have suggested that efforts to correct cervical spinal alignment may be appropriate and found that postoperative favorable alignment correlates with improved Neck Disability Index (NDI) scores, although this group of patients was heterogeneous for diagnosis.
Our objective was to assess how preoperative cervical sagittal alignment correlates with postoperative neurologic improvement in a prospective series of CSM patients treated at a single, tertiary-care center. Our second objective was to define whether surgical correction of kyphotic alignment independently provided for more substantially improved neurologic disability.
Section snippets
Methods
This study was performed by an ambispective analysis of prospectively collected data of CSM patients operated at a single, tertiary-care neurosurgical center during a period of 5 years (2007–2012) by 3 spinal neurosurgeons. The study population was a surgical cohort with inclusion criteria of patients with age older than 18 years of age who had symptomatic CSM with concordant spinal MRI. Exclusion criteria included patients with ossification of the posterior longitudinal ligament, previous
Results
We performed an analysis of 124 patients with symptomatic CSM, 65% of whom were men, with an average age of 60 ± 10 years and an average body mass index of 28 ± 5. Demographic data are summarized in Table 1, with no differences in age, sex, smoking status, or comorbidity found between patients on the basis of sagittal spinal alignment. Most frequently, the severity of myelopathy was moderate by both mJOA and Nurick grades, as summarized in Table 2, again without any specific differences
Discussion
Nonoperative management of symptomatic CSM generally is associated with disease progression, whereas surgical intervention can provide for neurologic stabilization and improvement in myelopathy. The choice of surgical approaches remains controversial, although mostly include both spinal cord decompression and spinal column stabilization. Patient stratification among those who are likely to achieve postoperative symptomatic improvement is even more elusive. Previous work by Mohanty et al.6 has
Conclusion
In this cohort of surgical CSM patients, the majority of patients exhibited neurologic improvement by the various myelopathy severity scores. Patients with preoperative kyphotic alignment exhibited a lesser degree of postoperative improvement compared with those who had preserved lordosis, and this was independent of whether the alignment was corrected at the time of surgery. Those patients with preoperative kyphosis had lesser improvement and deteriorated more frequently if approached by
References (20)
- et al.
Impact of surgical approach on complications and resource utilization of cervical spine fusion: a nationwide perspective to the surgical treatment of diffuse cervical spondylosis
Spine J
(2009) - et al.
Significance of increased signal intensity on MRI in prognosis after surgical intervention for cervical spondylotic myelopathy
J Clin Neurosci
(2011) - et al.
Cervical spondylotic myelopathy: the clinical phenomenon and the current pathobiology of an increasingly prevalent and devastating disorder
Neuroscientist
(2013) - et al.
Fehlings, Predictors of surgical outcome in cervical spondylotic myelopathy
Spine
(2013) - et al.
Magnetic resonance T2 image signal intensity ratio and clinical manifestation predict prognosis after surgical intervention for cervical spondylotic myelopathy
Spine
(2010) - et al.
Predictors of outcome in patients with degenerative cervical spondylotic myelopathy undergoing surgical treatment: results of a systematic review
Eur Spine J
(2015) - et al.
The association of preoperative cervical spine alignment with spinal cord magnetic resonance imaging hyperintensity and myelopathy severity: analysis of a series of 124 cases
Spine (Phila Pa 1976)
(2015) - et al.
Perioperative and delayed complications associated with the surgical treatment of cervical spondylotic myelopathy based on 302 patients from the AOSpine North America Cervical Spondylotic Myelopathy Study
J Neurosurg Spine
(2012) - et al.
Impact of preoperative neurological status on perioperative morbidity associated with anterior and posterior cervical fusion
J Neurosurg Spine
(2008) - et al.
Functional and clinical outcomes following surgical treatment in patients with cervical spondylotic myelopathy: a prospective study of 81 cases
J Neurosurg Spine
(2011)
Cited by (68)
Assessment of cervical alignment and deformity
2023, Degenerative Cervical Myelopathy: from Basic Science to Clinical PracticeComparison of sagittal vertical axis and decompression on the clinical outcome of cervical spondylotic myelopathy
2022, Clinical Neurology and NeurosurgeryAnalysis of the impact of spinopelvic radiographic parameters on the severity of cervical spondylotic myelopathy
2020, Journal of Orthopaedic ScienceDegenerative Cervical Myelopathy: Towards a Personalized Approach
2022, Canadian Journal of Neurological SciencesMRI-based measurements of spondylolisthesis and kyphosis in degenerative cervical myelopathy
2023, BMC Medical Imaging
Conflict of interest statement: M.G.F. holds the Halbert Chair in Neural Repair and Regeneration and support from the Dezwirek Foundation.