Clinical Outcomes of Intraoperative Contrast-Enhanced Ultrasound Compared with Intraoperative Neurophysiological Monitoring During Circumferential Decompression for Myelopathy Associated with Thoracic-Ossification of the Posterior Longitudinal Ligament

BACKGROUND: Circumferential decompression (CD) is an essential treatment option for myelopathy associated with thoracic-ossification of the posterior longitudinal ligament (T-OPLL) when laminectomy cannot achieve sufficient ventral decompression. Although intraoperative neurophysiological monitoring (IONM) is widely used, the operation has a relatively high risk. This study is the first to describe the use of contrast-enhanced ultrasound (CEUS) to evaluate the spinal cord blood flow (SCBF) during thoracic spine surgery in humans. The objective of this study was to compare clinical outcomes between intraoperative CEUS and IONM during CD. MATERIAL/METHODS: Sixty-eight T-OPLL patients who received CD from 2007 to 2014 were reviewed. All patients underwent IONM. CEUS was used on the following 2 occasions on 18 patients to evaluate SCBF: the first measurement was performed after laminectomy and the second after ventral decompression. Outcomes were evaluated by the Hirabayashi recovery rate (HRR). RESULTS: The overall HRR of all patients was 56.7%. Regarding CEUS, the HRR was 20.0% in Group A (SCBF decreased) and 63.6% in Group B (SCBF increased), indicating a significantly poorer neurological outcome in Group A (P<0.01). Regarding IONM, the HRR did not significantly differ between Groups C (no meaningful change in potential), D (potential changed up to alert criteria), and E (potential improved). CONCLUSIONS: IONM is relatively effective in detecting impending spinal cord dysfunction. Intraoperative CEUS is a safe and reliable method for assessing SCBF changes, which may be used as a supplement to IONM, thus reducing the incidence of false-negative results.