Modeling the Spinal Cord for DCM

Although spinal cord compression (seen on MRI scans) is the dominant cause of degenerative cervical myelopathy (DCM), spinal cord stress (pressure) and strain (stretch) during neck movement is also known to contribute to spinal cord damage. However, assessment of spinal cord stress and strain is not routinely performed in the clinic. This leads to an incomplete assessment of spinal cord damage in DCM and may affect clinical decision making.

Since direct measurements are not easy or feasible to perform in humans, we have developed finite element models (FEMs) of the cervical spine and cervical spinal cord that can measure spinal cord stress and strain during neck movement. FEMs are computational models used to analyze complex systems and can be used to measure spinal cord biomechanics during neck movement.

While similar research has been performed in the past, our research is unique in that our models are developed using a pre-surgical MRI and are therefore specific to the anatomy of the individual person with DCM. These FEMs provide a more accurate and clinically relevant measure of spinal cord stress and strain.

In addition, different surgical approaches can be simulated on these models, and we can measure the changes in spinal cord biomechanics after different surgical interventions. For those persons with DCM in whom more than one surgical option exists, the measurement of spinal cord biomechanics could potentially be incorporated into the surgical decision making.

In our preliminary work using this technique, we have found that increased spinal cord stretch is associated with increased neck motion as well as loss of the normal neck alignment.

We found that there are distinct differences in spinal cord biomechanics after different surgical approaches such as laminectomy, laminectomy with fusion, and laminoplasty. The number of levels of spinal fusion also impact spinal cord biomechanics at the levels above the fusion. We have also used this technique to predict the risk of spinal cord injury for persons with spinal cord compression who sustain minor trauma such as whiplash injury. Together, our work shows that FEMs can quantify spinal cord biomechanics in DCM and can be used to simulate different scenarios.

There are limitations to this technique and there is still more work that needs to be done. Developing a patient-specific FEM from an MRI is time-consuming, manually intensive, and requires high computational power. Advances in automated image segmentation and the use of artificial intelligence (AI) may improve this process.

Validating these models is currently challenging since direct measurement of spinal cord biomechanics is not feasible in humans. Importantly, we need to determine how spinal cord biomechanics relates to patient symptoms as well as outcomes after surgery. This is a critical piece of information that would determine the clinical value of spinal cord FEMs.

This work is a product of a close collaboration between neurosurgeons and biomedical engineers, and we are excited about exploring this novel approach to advance the care of persons with DCM.

About the Author

Dr Aditya Vedantam is an Assistant Professor in Neurosurgery at the Medical College of Wisconsin, Milwaukee.

He leads the Center for Cervical Myelopathy and runs an NIH-funded laboratory to investigate the use of advanced MRI to improve the diagnosis and prognosis for DCM. He is a part of the RECODE-DCM Perioperative Rehabilitation Incubator.

References

1: Singhal I, Harinathan B, Warraich A, Purushothaman Y, Budde MD, Yoganandan N, Vedantam A. Finite element modeling of the human cervical spinal cord and its applications: A systematic review. N Am Spine Soc J. 2023 Jul 27;15:100246. doi: 10.1016/j.xnsj.2023.100246. PMID: 37636342; PMCID: PMC10448221.

2: Vedantam A, Harinathan B, Warraich A, Budde MD, Yoganandan N. Differences in spinal cord biomechanics after laminectomy, laminoplasty, and laminectomy with fusion for degenerative cervical myelopathy. J Neurosurg Spine. 2023 Apr 7;39(1):28-39. doi: 10.3171/2023.3.SPINE2340. PMID: 37029671.

3: Vedantam A, Purushothaman Y, Harinathan B, Scripp S, Budde MD, Yoganandan N. Spinal Cord Stress After Anterior Cervical Diskectomy and Fusion: Results from a Patient-Specific Finite Element Model. Ann Biomed Eng. 2023 May;51(5):1040-1051. doi: 10.1007/s10439-022-03118-5. Epub 2022 Dec 20. PMID: 36538274.

4: Vedantam A, Harinathan B, Purushothaman Y, Scripp S, Banerjee A, Warraich A, Budde MD, Yoganandan N. Determinants of spinal cord stress and strain in degenerative cervical myelopathy: a patient-specific finite element study. Biomech Model Mechanobiol. 2023 Dec;22(6):1789-1799. doi: 10.1007/s10237-023-01732-3. Epub 2023 Jun 12. PMID: 37306885.

5: Harinathan B, Jebaseelan D, Yoganandan N, Vedantam A. Effect of Cervical Stenosis and Rate of Impact on Risk of Spinal Cord Injury During Whiplash Injury. Spine (Phila Pa 1976). 2023 Sep 1;48(17):1208-1215. doi: 10.1097/BRS.0000000000004759. Epub 2023 Jun 21. PMID: 37341525.

6: Yoganandan N, Choi H, Purushothaman Y, Vedantam A, Harinathan B, Banerjee A. Comparison of Load-Sharing Responses Between Graded Posterior Cervical Foraminotomy and Conventional Fusion Using Finite Element Modeling. J Eng Sci Med Diagn Ther. 2024 May 1;7(2):021006. doi: 10.1115/1.4063465. Epub 2023 Oct 9. PMID: 37860789; PMCID: PMC10583278.

7: Yoganandan N, Harinathan B, Vedantam A. Cervical Column and Cord and Column Responses in Whiplash With Stenosis: A Finite Element Modeling Study. J Eng Sci Med Diagn Ther. 2024 May 1;7(2):021003. doi: 10.1115/1.4063250. Epub 2023 Oct 3. PMID: 37860790; PMCID: PMC10583276.