How Does Resorption Differ Amongst Single- and Multi-Level Lumbar Disc Herniations? A Prospective Multi-Imaging and Clinical Phenotype Study

Study Design. Prospective, Case Series. Objective. T o identify and characterize any differences in specific patient factors, MRI findings, features of spontaneous disc resorption, and outcomes between patients with single- and multi-level LDH. Background. Lumbar disc herniation (LDH) is one of the most common spinal pathologies worldwide. Though many cases of LDH resolve by spontaneous resorption, the mechanism underlying this “self-healing” phenomenon remains poorly understood, particularly in the context of multi-level herniations. Methods. A one-year prospective study was conducted of patients presenting with acute symptomatic LDH between 2017 and 2019. Baseline demographics, herniation characteristics, and MRI phenotypes were recorded prior to treatment, which consisted of gabapentin, acupuncture, and avoidance of inflammatory-modulating medications. MRIs were performed approximately every 3 months after initial evaluation to determine any differences between patients with single- and multi-level LDH. Results. Ninety patients were included, 17 demonstrated multi-level LDH. Body mass index was higher amongst patients with multi-level LDH ( P <0.001). Patients with multi-level LDH were more like to exhibit L3/L4 inferior endplate defects ( P =0.001), L4/L5 superior endplate defects ( P =0.012), and L4/L5 inferior endplate defects ( P =0.020) on MRI. No other differences in MRI phenotypes (e.g., Modic changes, osteophytes, etc.) existed between groups. Resorption rate and time to resolution did not differ between those with single- and multi-level LDH. Conclusions. Resorption rates were similar between single- and multi-level LDH at various time points throughout one prospective assessment, providing insights that disc healing may have unique programmed signatures. Compared to those with single-level LDH, patients with multi-level herniations were more likely to have a higher BMI, lesser initial axial and sagittal disc measurements, and endplate defects at specific lumbar levels. In addition, our findings support the use of conservative management in patients with LDH regardless of the number of levels affected.