04/08/2025
Just published 🔥
Digital pain diagrams to identify common lumbar spinal stenosis pain distribution patterns
✅ Lumbar spinal stenosis (LSS) is a prevalent degenerative condition affecting approximately one-third of patients in secondary spine care settings, contributing significantly to disability and reduced quality of life [1]. While classic clinical descriptions distinguish between central canal stenosis (typically bilateral posterior lower extremity pain) and lateral recess/foraminal stenosis (often unilateral radicular pain in a dermatomal distribution) [2,3], real-world presentations are often heterogeneous. Pain diagrams (PDs) have long been used to document pain distribution, offering insight into the subjective pain experience and aiding diagnosis [4]. Digital PDs now allow for large-scale, quantitative analysis of pain patterns, and latent class analysis (LCA) has emerged as a valuable data-driven approach for identifying distinct clinical phenotypes [5–7].
📘 Prior studies have demonstrated the validity of PDs for musculoskeletal conditions [4,6], but LSS-specific pain distribution phenotypes have not been systematically mapped. The aim of this brand-new study by Young and colleagues (https://pubmed.ncbi.nlm.nih.gov/40751839/) was to identify and characterize common pain distribution patterns in patients with LSS using digital PDs and LCA.
✅ Methods
This was a cross-sectional study using baseline data from the SpineData registry at the Spine Centre of Southern Denmark [10] between February 2019 and April 2021. Inclusion criteria were age ≥18 years, LSS diagnostic code post-consultation, and completion of a digital PD. Exclusion criteria included diagnostic codes for malignancy, fracture, neurological disorders, chronic widespread pain, or lower extremity musculoskeletal/vascular conditions.
👫 Patients completed an electronic questionnaire before consultation, including demographic data, psychosocial screening (anxiety, depression, pain catastrophizing, fear of movement, risk of pain persistence, social isolation) [12], numeric rating scales (NRS) for back and leg pain, and the Oswestry Disability Index (ODI).
📷 PD data were processed using MATLAB polyshape functions to map pain areas to predefined anatomical regions [13,14]. Unilateral right-sided pain was mirrored to the left for analysis. LCA tested models with 2–7 classes, selecting the optimal model based on Bayesian Information Criterion (BIC), posterior probabilities (>0.9), class size (>5%), and clinical interpretability [15–17].
📊 Results
👉 From 16,114 patients presenting with low back pain, 2,379 met inclusion criteria. The mean age was 66.6 years, 50.7% were female, and mean ODI was 39.0. Pain duration exceeded 12 months in 52% of patients.
A six-class LCA model provided the best fit (relative entropy 0.92), identifying distinct LSS pain distribution patterns:
1️⃣ Bilateral posterior leg pain – 11.4% (n=272)
2️⃣ Bilateral posterior & anterior leg pain – 8.7% (n=207)
3️⃣ Unilateral posterior leg pain – 26.1% (n=620)
4️⃣ Unilateral posterior leg pain with low back pain – 21.0% (n=499)
5️⃣ Unilateral anterior & posterior leg pain – 22.9% (n=545)
6️⃣ Multisite pain – 9.9% (n=236)
💡 Mean NRS scores for back and leg pain were consistent across classes, with slight variation in Class 4 (lower leg pain). Multisite pain was associated with higher social isolation and longer pain duration.
Discussion 💬
▶️ This study is the first to map LSS pain phenotypes using digital PDs and LCA, revealing substantial heterogeneity beyond “textbook” bilateral or unilateral posterior leg pain patterns [2,3]. Notably, unilateral anterior and posterior leg pain (22.9%) was more prevalent than any bilateral pattern. This underscores the diagnostic complexity of LSS and the potential value of PDs in differentiating it from conditions like hip osteoarthritis.
▶️ The findings support the concept of LSS clinical phenotypes, which could improve diagnostic accuracy, guide treatment selection, and facilitate patient–clinician communication. However, limitations include reliance on diagnostic codes (risk of misclassification), absence of imaging correlation, and lack of pain quality descriptors in PDs. Future research should validate these phenotypes in diverse settings and assess prognostic and therapeutic implications.
✅ Conclusion
Six clinically recognizable pain distribution patterns were identified in LSS patients, reflecting significant heterogeneity in presentation. These patterns may represent distinct clinical phenotypes with potential diagnostic and therapeutic relevance. Further validation and longitudinal outcome studies are needed.
📚 References
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