Prevalence and Associated Risk Factors of Tandem Spinal Stenosis

Background: Tandem spinal stenosis (TSS) is a complex, multi-level degenerative condition that is notoriously underdiagnosed due to overlapping symptoms and diagnostic masking.The true prevalence and predictive risk factors of this condition remain inadequately characterized in patients presenting with focal spinal symptoms.Objective: This study aimed to determine the prevalence of TSS and identify its associated demographic, anthropometric, clinical, and radiological factors in symptomatic patients.Methods: A cross-sectional study was conducted at a tertiary neurosurgical center.Patients with symptomatic spinal stenosis were consecutively enrolled.Those with prior spinal surgery, MRI contraindications, or unrelated neurological deficits were excluded.Data collected included sociodemographic variables, anthropometrics, symptom duration, and comorbidities.All participants underwent whole-spine MRI, evaluated using the Lee grading system (0-3).TSS was defined as stenosis (Lee Grade ≥ 1) in ≥2 non-contiguous spinal regions, with a pre-specified sensitivity analysis using Grade ≥ 2. Predictors were identified using bivariate and binary logistic regression analyses.Results: Between March 2025 and January 2026, 226 patients were enrolled (mean age 56.3 ± 13.9 years; 54.0% female).Overall, TSS prevalence was 80.1% (181/226; 95% confidence interval (CI): 74.9%-85.3%),with cervico-lumbar TSS as the dominant subtype (97.2%).A pre-specified sensitivity analysis (Lee Grade ≥ 2) yielded a substantially lower TSS prevalence of 45.6% (103/226; 95% CI: 39.1%-52.1%).In multivariate analysis, older age (adjusted odds ratio (aOR) 1.06, 95% CI: 1.03-1.08,p < 0.001) and longer leg pain duration (aOR 1.13, 95% CI: 1.04-1.23,p = 0.004) were independently associated with TSS.Conclusions: TSS is highly prevalent (80.1%) among symptomatic stenosis patients.These findings suggest that a low threshold for whole-spine MRI may be clinically warranted in older patients presenting with chronic radicular symptoms to facilitate earlier detection and surgical planning.