Introduction: Failed Back Surgery Syndrome (FBSS) refers to a subset of patients who have new or persistent pain after spinal surgery for back or leg pain. In this study, We performed retrospective analysis in the veterans suffered from FBSS to identify the possible solutions for that.
Method: The medical records of 329 patients(51 FBSS patients), who took caudal, retrodiscal, and transforaminal epidural block in Veterans health service medical center, Seoul, South Korea during March 2018 to March 2019, were analyzed retrospectively.
Result:
A epidural block was considered to be effective when NRS(numeric rating scale) based pain relief is bigger than 50% after 4 weeks from epidural blocks. There was no statistical difference in age (no back surgery vs failed back: 73.19±7.4 vs 71.14±12.36),NRS(7,27±1.6 vs 7.49±0.405), gender( male %: 79.3 vs 78.4), and pain onset(years: 8.28±6.92 vs 10.09±6.75). In underlying disease comparison, there was no statistical difference in hypertension (no back surgery vs failed back:53.8% vs 54.9%), DM(48.7%vs52.9), and heart disease (38.5%vs33.3%), but the significant difference was detected in CVA(20% vs33.3%,p=0.03) and CKD(6.2%vs17.6%,p=0.01)
To compare the structural abnormality between two groups, The severity of left, right foramen and central region was assigned into four categories (0: no stenosis, 1 : mild ,2:moderate, 3: severe). The assigned score of stenosis from L1-2 to L5-S1 was summed up to generate Spine severity index for each patient.
In this study, no statistical difference was detected in spine severity index (no back surgery vs failed back: 7.93±6.01 vs 8.079±6.76)
In pain characters, there was no significant difference in aching ,throbbing , stabbing, burning, and electric-shocking. But there was significant difference in numbness (no back surgery vs failed back: 18.5% vs 7.8% , p=0.04).
In neuropathic components of symptoms, there was no significant difference in hypoesthesia, hypoalgesia, and thermohypoesthesia. But there was significant difference in allodynia (no back surgery vs failed back: 0.7% vs 7.8% , p=0.006)
The effectiveness of epidural blocks was compared to identify the appropriate block in FBSS. In no back surgery group, no statistical difference was observed among epidural blocks( caudal, retrodiscal, transforaminal : 37% vs 44% 25% , p =0.139). But in FBSS group, significant difference was detected ( caudal, retrodiscal, transforaminal : 4% vs 17% vs 38%, p=0.016)
Conclusion:
In this study, It was found that the FBSS may be related with not only the back pain or radiculopathy symptoms but also other chronic illness such as CKD or CVA. The causal relationship between two factors are not clear, further study is necessary to confirm that. In FBSS patients, the response to caudal epidural block was worse than other blocks.