Intraoperative Myelography in Transpsoas Lateral Lumbar Interbody Fusion for Degenerative Lumbar Spinal Stenosis: A Preliminary Prospective Study

Aim. To investigate the feasibility and effectiveness of intraoperative myelography in determining adequacy of indirect spinal canal decompression during transpsoas lateral lumbar interbody fusion (LLIF). Methods. Seven patients diagnosed with degenerative lumbar spinal stenosis (DLSS) were prospectively included to this study. All patients underwent LLIF and subsequently received intraoperative myelography to determine the effect of indirect spinal canal decompression, which was visualized in both anterior-posterior and lateral images. Those patients with insufficient indirect canal decompression were further resolved by microendoscopic canal decompression (MECD). Radiological parameters, including stenosis ratio and dural sac area of operated levels, were measured and compared before and after operation. Besides, all patients were followed up for at least one year using visual analogue scale (VAS) for back and leg, Japanese Orthopaedic Association score (JOA), and Oswestry disability index (ODI). Results. Seven patients with 8 operated levels underwent LLIF safely and demonstrated significant symptom relief postoperatively. Five operated levels showed adequate indirect canal decompression intraoperatively, while the remaining three levels did not achieve the adequacy, and their residual stenosis was resolved following MECD. Radiological parameters were improved statistically when compared with preoperation (P < 0.05). Furthermore, neurological symptoms of all patients were also improved significantly (P < 0.05), shown by improved VAS (back and leg), JOA, and ODI at both two-week and one-year follow-up. Conclusions. Intraoperative myelography during LLIF is able to assess adequacy of indirect canal decompression for DLSS, thus promising favorable clinical outcomes.