MRI Evaluation of Cervical Spondylotic Canal Stenosis and Change in its Severity on Flexion and Extension Positioning: A Cross-sectional Study

Introduction: Cervical spondylosis is a degenerative disorder of the cervical spine and has varied pathological forms of presentation. It presents as either varying degrees of intervertebral disc bulge, spinal cord compression, altered cord signals, neural exit foraminal stenosis, annular tears, facet joint degeneration and ligamentum flavum hypertrophy in combination or isolation. Magnetic Resonance Imaging (MRI) being known for its excellent soft tissue resolution helps assess and grade these pathologies efficiently.

Aim: To evaluate the flexion-extension MRI in regular cervical spondylosis imaging by assessing the effect of flexion and extension positioning on the severity of cervical spondylotic canal stenosis and spinal canal dimensions. Also, to compare the change in cervical canal dimensions on flexion and extension with that of neutral positioning.

Materials and Methods: A cross-sectional study was conducted in the Department of Radiodiagnosis, JSS Medical College, Mysuru, Karnataka, India, from January 2021-June 2022. A total of 50 participants, aged above 18 years with a clinical suspicion of cervical spondylosis and without history of trauma, tumour, infection, prior cervical surgery and with Nurick grade <3 were included in the present study. In all the subjects, spinal canal dimension, degree of stenosis was assessed and graded, further assessment for presence of foraminal stenosis, ligamentum flavum hypertrophy and facetal arthropathy were also documented. Data were statistically analysed using Chi-square test and Mc Nemer’s test.

Results: Out of total 50 cases, 26 (52%) were males and the rest were females with mean age of 46 years. Least cervical canal space dimension of 0.4 cm at C6-7 level in the neutral position and at C3-4, C5-6 and C6-7 levels in extension were noted thus, proving the importance of extension positioning in recognising maximum levels and severity of involvement. Narrowest diameter was demonstrated on flexion and extension. Additionally, the elderly was seen more affected by central disc bulge, foraminal stenosis, facetal arthropathy and ligamentum flavum hypertrophy as compared to the middle aged and the younger patients, more so in extension (12%).

Conclusion: Disc bulge and grade of stenosis vary extensively and are more conspicuous on additional flexion and extension imaging. Severity of the grade of stenosis and demonstration of maximum number of levels involved on extension as compared to flexion or neutral positioning thereby, benefitting clinical management plan.