Introduction: Degenerative Cervical Myelopathy [DCM] is a slow-motion spinal cord injury. Compression and dynamic compression have been considered disease hallmarks. However, this is likely an oversimplification, as compression is more commonly incidental and has only modest correlation to disease severity. MRI studies have recently suggested spinal cord oscillation could play a role.
Research question: To determine if spinal cord oscillation could contribute to spinal cord injury in degenerative cervical myelopathy.
Material and methods: A computational model of an oscillating spinal cord was developed from imaging of a healthy volunteer. Using finite element analysis, the observed implications of stress and strain, were measured in the context of a simulated disc herniation. The significance was bench marked by comparison to a more recognised dynamic injury mechanism; a flexion extension model of dynamic compression.
Results: Spinal cord oscillation altered both compressive and shear strain on the spinal cord. Following initial compression, compressive strain moves from within the spinal cord to the spinal cord surface, whilst shear strain is magnified by 0.1-0.2, depending on the amplitude of oscillation. These orders of magnitude are equivalent to a dynamic compression model.
Discussion and conclusion: Spinal cord oscillation could significantly contribute to spinal cord damage across DCM. Its repeated occurrence with every heartbeat, draws parallels to the concept of fatigue damage, which could reconcile differing theories on the origins of DCM. This remains hypothetical at this stage, and further investigations are required.
Keywords: Biomechanics; Cervical spondylotic myelopathy; Computational case control study; Degenerative cervical myelopathy; Finite element analysis; Oscillation.
© 2023 The Authors.