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Published on: February 9, 2024
Mismatch Between MRI-Defined Stenotic Level and Epidurographic Block in Lumbar Degenerative Disorders: A
Daigo Arimura1, Akira Shinohara1, Mitsuru Saito1
1Department of Orthopaedic Surgery, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan.
Background:
Trans-sacral canalplasty (TSCP) is a minimally invasive epidural adhesiolysis technique positioned between conventional block therapy and open surgery. However, the relationship among MRI-defined levels of stenosis, epidurographic block patterns, and clinical effectiveness remains unclear.
Objectives:
To investigate the clinical significance of mismatch between MRI-defined levels of stenosis and epidurographic block as well as to evaluate the short-term outcomes and feasibility of adhesiolysis in patients undergoing TSCP.
Study Design:
A retrospective observational study.
Setting:
A university hospital in Japan and an affiliated institution.
Methods:
We reviewed all patients who underwent TSCP between October 2024 and August 2025. Baseline characteristics, diagnosis, surgical history, and minimum dural sac area at L3/4, L4/5, and L5/S (measured on MRI using ImageJ2) were assessed. Epidurography was performed to identify block levels, and cases were categorized as concordant (MRI-defined level of stenosis = block level) or discordant (mismatch). Discordant cases were subclassified into a "tail-stop" type (in which contrast stopped in a position caudal to the MRI-defined level of stenosis) and a "pass-through" type (in which these levels differed). Clinical effectiveness was defined as an improvement in low back pain or leg pain at one week after the procedure. Feasibility of adhesiolysis was also evaluated.
Results:
Twenty-eight patients underwent TSCP during the study period. Nine (32.1%) showed concordance between MRI-defined levels of stenosis and epidurographic block sites, and 19 patients (67.9%) showed discordance (tail-stop, n = 11; pass-through, n = 8). Overall, 23 patients (82.1%) experienced clinical improvement. The effectiveness rate was 66.7% (6/9) in the concordance group and 89.5% (17/19) in the discordance group; however, the difference was not statistically significant (P = 0.290). In the discordance group, there was a significant difference in gender distribution between subgroups, with men predominating in the tail-stop subtype and women in the pass-through subtype (P = 0.024), but not in age, diagnosis, surgical history, or minimum dural sac area. Epidural dissection was successful in 21 patients (75.0%), with no significant difference between the effective and noneffective groups (73.9% vs 80.0%, P > 0.999).
Limitations:
A single-center retrospective design, small sample size, and short-term follow-up of only one week.
Conclusions:
TSCP demonstrated favorable short-term clinical effectiveness, even in cases with mismatches between MRI and epidurographic findings. The feasibility of adhesiolysis may contribute to the clinical success of TSCP. Epidurographic mismatch should not be considered a contraindication for TSCP, and our findings support its role as a minimally invasive option for patients with degenerative disorders of the lumbar spine who are unsuitable for open surgery.
