Selective Angiography to Detect Anterior Spinal Artery Stenosis in Thoracic Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN: Single-center prospective study. PURPOSE: To investigate anterior spinal artery (ASA) status using preoperative selective angiography in patients undergoing surgery for thoracic ossification of the posterior longitudinal ligament (T-OPLL). OVERVIEW OF LITERATURE: Surgery for T-OPLL has a high risk of neurological complications, which might be associated with insufficient spinal cord blood flow. METHODS: This study prospectively examined nine T-OPLL patients who underwent posterior thoracic decompression with kyphosis correction and instrumented fusion at Hamamatsu University School of Medicine between 2017 and 2019. All underwent preoperative selective angiography to detect and evaluate the Adamkiewicz artery and ASA. Intraoperative neuromonitoring and Doppler ultrasonography were performed to analyze neurological complications and spinal cord blood flow. RESULTS: All nine patients showed ASA stenosis in the area of T-OPLL. In all patients, the Adamkiewicz artery was located between T7 and L2 and the area of ASA stenosis corresponded to the level of T-OPLL and greatest spinal cord compression; intraoperative Doppler ultrasonography confirmed the ASA defect at the same spinal level. The number of spinal levels from the Adamkiewicz artery to the most compressive OPLL lesion was greater in the two patients who developed postoperative neurological deficit compared to those who did not (5.5 vs. 2.3, p=0.014). CONCLUSIONS: This is the first study to report detection of ASA stenosis in patients with T-OPLL. Maintaining spinal cord blood flow is important in these patients to avoid neurological deterioration.