Original ArticleIs the Cervical Anterior Spinal Artery Compromised in Cervical Spondylotic Myelopathy Patients? Dual-Energy Computed Tomography Analysis of Cervical Anterior Spinal Artery
Introduction
Cervical spondylotic myelopathy (CSM), wherein the spinal cord is compromised within the vertebral canal by degenerative changes, is the most common acquired cause of spinal cord dysfunction among those older than 55 years.1 Teresi et al.2 identified 26% of general subjects older than 64 years old with spinal cord compression on magnetic resonance imaging.2 It has been widely accepted that the pathophysiology of cervical spondylotic myelopathy (CSM) involves static factors, resulting in acquired or developmental stenosis, and dynamic factors that involve repetitive injury to the cervical spinal cord.3, 4
The signs and symptoms are widely dependent on the relative degree to which the posterior, dorsolateral and ventrolateral columns, the ventral horns, and the cervical nerve root of the spinal cord are involved.2 However, there is still a lack of understanding why some patient develops severe symptomatology, whereas others have few or no symptoms despite radiographic evidence confirming similar degrees of compression. Histologic examination of the spinal cord in patients with spondylotic myelopathy revealed flattening of the cord, swelling of myelin and axons, demyelination in the posterolateral and anterolateral columns, neuronal loss in the anterior horns, and gliosis.5 As a basis of reasoning, it was assumed that the chronic degenerative changes can compress major feeding arteries of the cervical spine, resulting in pathologically reduced blood flow and compromised spinal cord perfusion.5 A cadaveric study that supports this theory has demonstrated a curved and stretched anterior spinal artery and branches of lateral pial plexus around the degenerative spondylo-osteophytes.6
In light of ongoing concerns about altered blood flow in cervical spondylotic myelopathy, a radiographic tool to detect compromised blood flow in patients with CSM in a clinical setting would be valuable. Attempts to detect altered anterior spinal artery (ASA) blood flow have been reported previously using the present-day availability of computed tomography (CT) angiography, and they have been unsuccessful.7 The concept of dual-energy CT (DECT) involves the acquisition of 2 datasets using different X-ray energy spectra.8, 9 The potential for material decomposition using a dual-energy method has been known since the late 1970s; however, clinical implementation of this technique was limited on early-generation CT scanners.10, 11
The goal of the present study was to use DECT as a screening tool to identify and compare the blood flow in cervical anterior spinal artery in CSM patients and volunteers without cervical spondylotic myelopathy, to discuss the effect of surgical decompression for cervical spondylotic myelopathy on the cervical ASA, and to acknowledge and highlight the changes in blood flow of cervical anterior spinal artery after surgical treatment with the improvement in the Japanese Orthopedic Association (JOA) score of CSM patients.
Section snippets
Patients with Cervical Spondylotic Myelopathy
Between June 2016 and April 2017, a total of 50 patients were prospectively included in our study. The inclusion criteria for this study was: 1) Patient presented with typical symptom of cervical myelopathy that were not alleviated after at least 6-month conservative treatment; 2) Obvious single disc-level cervical spinal cord compression as shown by magnetic resonance imaging studies; 3) Patient agreed to receive surgical treatment and cooperate with follow-up visits after surgery. These
Results
The study included 50 patients with CSM patients (29 men and 21 women) with an average age (and standard deviation) of 56.24 ± 10.435 years (range, 31–72 years) and 10 volunteers without cervical spondylotic myelopathy (7 men and 3 women) with an average age (and standard deviation) of 53 ± 9.24 years (range, 31–64 years). The average length of symptoms in CSM patients was 10.26 ± 2.44 months. The demographic features and radiologic parameters are shown in Table 1. The JOA scores (Table 1) for
Discussion
Chronic degenerative changes in the cervical spine cause an interruption in the blood supply to the spinal cord that may be a significant component in the initiation and progression of CSM.14 The cadaveric study conducted by Breig et al.6 supports the suggestion of compromised ASA blood flow by degenerative changes in the cervical spine to axonal pathways, including corticospinal tracts. Clinical attempts to identify compromised ASA in patients with CSM have been unsuccessful.7
In this study
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Shiyang Wu, Suraj Chandoo, and Minyu Zhu contributed equally to this work.
This work was supported by grants from the National Natural Science Foundation of China (81571190, 81771348) and Wenzhou Public Welfare Science and Technology Project (Y20170082).