Summary Statement. Tandem stenosis is a prevalent condition in an Asian population with the narrowest cervical canal diameters and risk factors include advanced age and increased levels of lumbar canal stenosis. Introduction. Tandem spinal stenosis (TSS) is defined as patient with concomitant spinal canal stenosis found in both cervical (C) and lumbar (L) spinal region. Few studies have reported the incidence of TSS is ranged from 5–25%, but these are all noncomparative, small cohort studies. To the best of author knowledge this is the 1st study aims to compare the prevalence of TSS and its risk factors of development in a large multiracial Asian population. Methods. A retrospective review of all mid-sagittal T2MRI whole spine image was carried out at a University hospital in year 2007. Patients with spinal tumour, fracture and congenital stenosis were excluded. Spinal stenosis was defined as canal diameter of ≤10mm, measured from the posterior cervical vertebral/disc wall to anterior surface of the corresponding lamina. Patients were divided into 4 groups, no stenosis(NS), lumbar stenosis only(LS), cervical stenosis only(CS) and TSS. Patients’ demographics, race, co-morbidities and lumbar radiological report data were examined. Potential risk factors for the development of TSS were analyzed using SPSS software. Results. 926 (479 male, 447 female) patients with average age 50 (20–96) yrs were studied. Cervical canal diameters (mm) in TSS patients were the narrowest among the 4groups with C2/3 disc: 11.6, C3/4: 9.7, C4/5: 9.4, C5/6: 8.9, C6/7: 10.0 and C7T1: 11.4mm. The incidence of TSS was 26.2%. The prevalence of TSS in Chinese was 30.7%, Indian 12.5%, Malay 22.5%. The TSS prevalence in patients with 1 level lumbar canal stenosis was 12.5%, 2 levels lumbar stenosis was 6.4% and 3 levels was 4.1%. Multivariate analysis showed patients aged between 40–59 yrs (p=0.000, Exp(B):5.8, 95%CI 2.8–12.0), aged > 60yrs (p=0.000, Exp(B): 10.5, 95%CI 4.8–22.9), Chinese race (p=0.008, Exp(B): 2.5, 95%CI 1.3–4.9), patients with 1 level lumbar stenosis (p=0.000, Exp(B): 63.3, 95%CI 29.2–137.3), 2 levels lumbar stenosis (p=0.000, Exp(B): 67.7, 95%CI 29.4–155.7) and 3 levels lumbar stenosis (p=0.000, Exp(B): 106.6, 95%CI 43.6–260.5) are statistical significant risk factors for TSS development. Conclusion. The incidence of TSS was 26.2%. TSS patients have the narrowest cervical canal measurements among the studied groups. The prevalence of TSS in Chinese is the highest (30.7%). Patients advancing in age or have increased levels of lumbar canal stenosis are at risk of developing TSS

We retrospectively examined the prevalence and natural history of asymptomatic lumbar canal stenosis in patients treated surgically for cervical compressive myelopathy in order to assess the influence of latent lumbar canal stenosis on the recovery after surgery. Of 214 patients who had undergone cervical laminoplasty for cervical myelopathy, we identified 69 (32%) with myelographically documented lumbar canal stenosis. Of these, 28 (13%) patients with symptomatic lumbar canal stenosis underwent simultaneous cervical and lumbar decompression. Of the remaining 41 (19%) patients with asymptomatic lumbar canal stenosis who underwent only cervical surgery, 39 were followed up for ≥ 1 year (mean 4.9 years (1 to 12)) and were included in the analysis (study group). Patients without myelographic evidence of lumbar canal stenosis, who had been followed up for ≥ 1 year after the cervical surgery, served as controls (135 patients; mean follow-up period 6.5 years (1 to 17)). Among the 39 patients with asymptomatic lumbar canal stenosis, seven had lumbar-related leg symptoms after the cervical surgery.

Kaplan–Meier analysis showed that 89.6% (95% confidence interval (CI) 75.3 to 96.0) and 76.7% (95% CI 53.7 to 90.3) of the patients with asymptomatic lumbar canal stenosis were free from leg symptoms for three and five years, respectively. There were no significant differences between the study and control groups in the recovery rate measured by the Japanese Orthopaedic Association score or improvement in the Nurick score at one year after surgery or at the final follow-up.

These results suggest that latent lumbar canal stenosis does not influence recovery following surgery for cervical myelopathy; moreover, prophylactic lumbar decompression does not appear to be warranted as a routine procedure for coexistent asymptomatic lumbar canal stenosis in patients with cervical myelopathy, when planning cervical surgery.