Three-dimensional Spinal Canal Morphometric Analysis and Relevant Spinal Cord Occupational Ratios in Congenital Cervical Spinal Stenosis: A Classification Algorithm of the Stenosis Phenotypes and Data-driven Decompression Approach.

OBJECTIVES: No standardized magnetic resonance imaging (MRI) parameters have defined the 3-dimensional morphoanatomy and relevant spinal cord occupation ratios (occupation of spinal cord dimensions/similar dimensions within the spinal canal) in congenital cervical stenosis (CCS). METHODS: A retrospective, comparative analysis was conducted on 200 patients >18 years of age with myelopathy and CCS (mean age, 52.4 years) and 200 age-matched controls with no myelopathy or radiculopathy. The variables assessed from high resolution MRI included sagittal and axial spinal canal dimensions (MRI Torg-Pavlov ratios) from C3 to C7. Morphometric dimensions from the sagittal retrodiscal and retrovertebral regions as well as axial MRI dimensions were compared. Sagittal and axial spinal cord occupation ratios were defined and correlated with spinal canal dimensions. RESULTS: Multivariate analyses indicated reduced sagittal and axial anteroposterior (AP) spinal canal dimensions and a large reduction in transverse spinal canal dimensions at all spinal levels. There was a small significant correlation between AP sagittal spinal canal dimensions and axial transverse spinal canal dimensions at C3-C5, but not at C5-C6. Small correlations were noted between AP sagittal spinal canal dimensions and AP axial spinal cord and axial cross-sectional area occupation ratios at C3-C6, but there was no correlation with axial mediolateral spinal cord occupation ratios. CONCLUSIONS: The stenosis effect can involve any dimension, including the transverse spinal canal dimension, independent of other dimensions. Owing to the varied observed morphoanatomies, a classification algorithm that defines CCS specific phenotypes was formulated. Objectivizing the stenosis morphoanatomy may allow for data-driven patient-focused decompression approaches in the future.

Redefining lumbar spinal stenosis as a developmental syndrome: does age matter?

OBJECTIVE: Age is commonly thought to be a risk factor in defining lumbar spinal stenosis (LSS) degenerative or developmental subtypes. This article is a follow-up to a previous article ("Redefining Lumbar Spinal Stenosis as a Developmental Syndrome: An MRI-Based Multivariate Analysis of Findings in 709 Patients Throughout the 16- to 82-Year Age Spectrum") that describes the radiological differences between developmental and degenerative types of LSS. MRI-based analysis of "degeneration" variables and spinal canal morphometric characteristics of LSS segments have been thought to correlate with age at presentation. METHODS: The authors performed a re-analysis of data from their previously reported prospective MRI-based study, stratifying data from the 709 cases into 3 age categories of equal size (instead of the original < 60 vs ≥ 60 years). Relative spinal canal dimensions, as well as radiological degenerative variables from L1 to S1, were analyzed across age groups in a multivariate mode. The total degenerative scale score (TDSS) for each lumbar segment from L1 to S1 was calculated for each patient. The relationships between age and qualitative stenosis grades, TDSS, disc degeneration, and facet degeneration were analyzed using Pearson's product-moment correlation and multiple regression. RESULTS: Multivariate analysis of TDSS and spinal canal dimensions revealed highly significant differences across the 3 age groups at L2-3 and L3-4 and a weaker, but still significant, association with changes at L5-S1. Age helped to explain only 9.6% and 12.2% of the variance in TDSS at L1-2 and L2-3, respectively, with a moderate positive correlation, and 7.8%, 1.2%, and 1.9% of the variance in TDSS at L3-4, L4-5, and L5-S1, respectively, with weak positive correlation. Age explained 24%, 26%, and 18.4% of the variance in lumbar intervertebral disc (LID) degeneration at L1-2, L2-3, and L3-4, respectively, while it explained only 6.2% and 7.2% of the variance of LID degeneration at L4-5 and L5-S1, respectively. Age explained only 2.5%, 4.0%, 1.2%, 0.8%, and 0.8% of the variance in facet degeneration at L1-2, L2-3, L3-4, L4-5, and L5-S1, respectively. CONCLUSIONS: Age at presentation correlated weakly with degeneration variables and spinal canal morphometries in LSS segments. Age correlated with upper lumbar segment (L1-4) degeneration more than with lower segment (L4-S1) degeneration. The actual chronological age of the patients did not significantly correlate with the extent of degenerative pathology of the lumbar stenosis segments. These study results lend support for a developmental contribution to LSS.