MRI morphology of surgically treated lumbar canal stenosis: A retrospective study

Study Design: Retrospective cohort study. Objective: The aim of this study was to identify morphologic features on magnetic resonance imaging that might correlate with lumbar canal stenosis severe enough to warrant surgery. Summary of Background Data: None of the quantitative parameters measured on x-rays, CT scans, or magnetic resonance imaging correlates well with the severity of clinical symptoms in lumbar canal stenosis (LCS). In a patient with neurogenic claudication, we need to define what would constitute radiologic LCS and whether he needs surgical intervention. This paper attempts to define MRI features of LCS addressing the morphology rather than canal dimensions in any direction. MATERIALS AND Methods: A total of 64 consecutive patients who were operated at 113 levels of LCS were reviewed retrospectively. Their clinical notes and MRI were analyzed. Only the axial T2-weighted images were utilized for this study. The images were reviewed by 1 orthopedic surgeon and 1 radiologist and segregated into morphologic categories. No interobserver and intraobserver studies were undertaken. Results: Two types of axial image features were identified in LCS symmetrical and asymmetrical with 5 subtypes. They were trefoil, triangular, "cat's eye," "pinhole," and complete obliteration. Several subtypes were also described. Of the operated cases, 70.8% had a triangular configuration of the canal with symmetrical large triangular canal shape occurring in 49/80 levels. It was impossible to correlate the severity of symptoms, their duration, and the presence of objective neurological deficits with the morphologic picture from the documentation available. Conclusions: LCS seems to produce predictable patterns on T2 axial MRI. The triangular configuration correlates most frequently with surgical LCS. Further studies are needed in normal individuals, in prospective patients, and to determine the outcome of treatment based on MRI morphology.