Technical Aspects of Intra-Operative Ultrasound for Spinal Cord Injury and Myelopathy: A Practical Review.

OBJECTIVES: To compile intra-operative techniques, established imaging parameters, available equipment and software, and clinical applications of intraoperative ultrasound imaging (IOUSI) for spinal cord injury (SCI) and myelopathy.

METHODS: PubMed and Google Scholar were searched for relevant articles. The articles were reviewed and selected by two independent researchers. After article selection, data was extracted and summarized into research domains. PRISMA systematic review process was followed.

RESULTS: Of the 2,477 articles screened, sixteen articles met the inclusion criteria. In patients with SCI and myelopathy, common quantitative measurements obtained using IOUSI were noted: ultrasound elastography (USE), midsagittal anteroposterior diameter (APD), transverse APD, transverse diameter (TD), maximum spinal cord compression (MSCC), and compression ratio (CR). To ensure adequate decompression and to look for residual compression, the lateral and the craniocaudal margins of the laminectomy site were inspected in both axial and sagittal planes. In instances where quantitative assessment was not possible, cord decompression and degree of residual compression were gauged by inspecting the interface between the ventral border of the spinal cord and any potentially compressive elements, and by searching for symmetric and rhythmic CSF pulsations. Use of contrast-enhanced ultrasound (CEUS) and molecular imaging are additional advances in objective assessments for SCI and myelopathy.

CONCLUSION: This review outlines the potential of IOUSI in patients presenting with SCI and myelopathy. Moreover, by identifying potential for inter-operator variability in certain subjective measurements, we illustrate the need for further research to quantify and standardize those assessments.