The prevalence of tandem spinal stenosis and its characteristics in a population-based MRI study: The Wakayama Spine Study

Purpose Tandem spinal stenosis (TSS) is a condition of combined spinal stenosis in the cervical and lumbar regions. The purpose of this study was to determine the prevalence of radiographic TSS and its association with developmental canal stenosis (DCS). The second purpose was to investigate the extent to which radiographic TSS is associated with cervical myelopathy and symptomatic LSS. Methods We recruited 1011 (336 men and 675 women) participants in this population-based study. After excluding those with a pacemaker, a history of cervical or lumbar surgery, disqualification, the MRI data of whole spine was analysed in 931 (mean, 67.3 years) participants. Cervical cord compression (CCC) and radiographic lumbar spinal stenosis (LSS) were evaluated by MRI. The canal-to-body ratio was also measured by plain X-ray. DCS was diagnosed as canal-to-body ratio <0.75. The diagnosis of cervical myelopathy and symptomatic LSS was made by presentation of both symptoms and radiographic compression using MRI. Results The prevalence of CCC was 24.7%, that of radiographic LSS was 30.2%, and that of radiographic TSS was 11.0% (men, 14.1%; women, 9.4%). The prevalence of TSS was significantly higher in the DCS group than in the non-DCS group (p < 0.001). Among the participants with radiographic TSS, the prevalence of cervical myelopathy and symptomatic LSS was 9.8 and 18.6%, respectively. The coexisting cervical myelopathy and symptomatic LSS was 6.1% in the participants with LSS. Conclusions The present study is the first population-based study to clarify TSS characteristic using whole-spine MRI.