Abstract and Introduction
Study Design: Retrospective cross-sectional cohort.
Objective: To investigate the prevalence and predictive factors of concurrent cervical spinal cord compression (CSCC) in patients with adult spinal deformity (ASD).
Summary of Background Data: In patients with ASD undergoing major thoracolumbar realignment surgery, concurrent CSCC potentially increases the risk of progression of myelopathy or cervical cord injury due to various perioperative factors including poor intraoperative neck positioning and hypotension. However, the prevalence of CSCC in ASD patients has not been previously studied.
Methods: This study included ASD patients who were indicated for major thoracolumbar corrective surgery (>5 levels). The presence of CSCC was determined using the modified Cord Compression Index (Grades 0–3) based on the cervical magnetic resonance imaging (MRI). Significant CSCC was defined as Grade>2, and the distribution of compression level as well as the number of Grade>2 segments were investigated in each patient. A multivariate regression analysis was performed to identify the predictors of CSCC with variables being the patients' characteristics including radiographic sagittal alignment parameters.
Results: Of 121 patients with ASD, 41 patients (33.8%) demonstrated significant CSCC on MRI. Intramedullary T2 hyper-intensity (myelomalacia) was present in eight patients (6.6%). Thirty-five of 41 patients were asymptomatic or with myelopathy that is difficult to detect. Significant CSCC was most commonly observed at C4/5 level. Four patients (3.3%) underwent cervical decompression and fusion prior to thoracolumbar reconstruction. Multivariate regression analysis revealed old age, increased body mass index (BMI), and PI-LL mismatch independently predicted the CSCC grade.
Conclusion: The prevalence of concurrent significant cervical cord compression in patients with ASD is relatively high at 33.8%. Preoperative evaluation of cervical MRI and examinations for signs/symptoms of myelopathy are essential for patients with (1) older age, (2) increased BMI, and (3) high PI-LL mismatch to avoid progressive myelopathy or cord injury during ASD surgery.
Level of Evidence: 4
As the population continues to grow older and the incidence of adult spinal deformity (ASD) has become more prevalent, scientific interest in this condition has increased. Patients with ASD undergoing complex thoracolumbar surgical procedures requiring aggressive osteotomies are at an increased risk for cervical cord injury (if preexisting cord compression is present) due to trauma from intraoperative positioning or reduced cord perfusion, e.g., intraoperative hypotension due to acute blood loss. In addition, concurrent cervical spinal cord compression (CSCC) in patients with ASD can potentially increase the risk of progression of myelopathy or cervical cord injury. However, clinical signs and symptoms of mild myelopathy due to CSCC, especially gait disturbance or hyperreflexia, might be subtle and masked by the clinical manifestations of thoracolumbar deformity, including spinal imbalance or simultaneous lumbar stenosis. Therefore, making a diagnosis based on patients' history and physical examination can sometimes be problematic, especially in elderly patients with severe thoracolumbar deformity.
Some reports have described the relationship between radiographic cervical degeneration and thoracolumbar spinal alignment in patients with ASD.[2,3] Fujimori et al reported that the prevalence of degenerative changes in the cervical spine was higher in patients with ASD than those without ASD, and the severity of degenerative change in the cervical spine varied depending on the type of thoracolumbar deformity: flat-back syndrome induced compensatory kyphotic changes in cervical alignment, showing significant degenerative changes on radiography. However, to our knowledge, magnetic resonance imaging (MRI)-based prevalence of CSCC in patients with ASD has not been previously studied.
Preoperatively, spinal deformity surgeons should be aware that CSCC can be present in patients with ASD who are undergoing major thoracolumbar realignment surgery to minimize the chance of perioperative cervical cord injury. This study seeks to identify the prevalence and characteristics of CSCC in patients with ASD based on MRIs. We hypothesized that the incidence of CSCC is relatively high in patients with ASD and its severity differs depending on the extent of sagittal malalignment of thoracolumbar deformity.
Spine. 2019;44(15):1049-1056. © 2019 Lippincott Williams & Wilkins