We reviewed the medical records of patients who underwent PDD using L’DISQ following a diagnosis of lumbar discogenic pain between January 2015 and July 2020 at a tertiary university hospital. All procedures were performed by a single physician (Y.H.K.). The study was approved and informed consent was waived by The Catholic University of Korea, Seoul St. Mary’s Hospital Institutional Review Board (IRB No. KC21IRSI0101). This retrospective cohort study was registered with CRIS (Clinical Research Information Service of the Korea National Institute of Health, https://cris.nih.go.kr/cris/index.jsp, KCT0005967). All methods were performed in accordance with the relevant guidelines and regulations. All medical data were collected by a standardized protocol, and only analysed after anonymisation. The inclusion criteria were as follows: (1) age at least 20 years old; (2) numeric rating scale for pain (NRS pain) score of 5 or more; (3) diagnosis of lumbar intervertebral disc herniation confirmed using magnetic resonance imaging (MRI) and patient-reported concordant back pain or radicular pain in the lower extremity, or both; (4) pain duration of 3 months or more; (5) failure to respond to previous epidural injections combined with exercise and pharmacotherapy. The exclusion criteria were as follows: (1) absence of lumbar spine MRI; (2) poorly controlled coexisting psychiatric diagnosis; (3) postherpetic neuralgia in the lumbar spinal nerve, or any other condition potentially accounting for the signs and symptoms; (4) lumbar myelopathy or any evidence of central nervous system injury; (5) presence of coagulopathy, malignancy, fever, or local infection at the puncture site.
PDD using the L’DISQ.
Intravenous access was prepared in advance, and prophylactic antibiotics were injected 30 min before the start of the procedure. The vital signs of the patient, including pulse oximetry, electrocardiogram, and blood pressure, were monitored continuously during the procedure. The patient was kept in a prone position, and a pillow was placed under the abdomen to minimise lumbar lordosis. The skin was disinfected with povidone-iodine and draped in a sterile manner. The endplate of the target disc was aligned and the C-arm was then rotated until the lateral margin of the contralateral superior articular process passed the posterior 3/5th of the vertebral body. Local anaesthesia was administered in this view, while ensuring the needle entry site was 12–15 cm from the midline. The introducer needle was directed toward the lateral edge of the contralateral superior articular process, where it would meet the disc margin at the line drawn between the medial borders of the adjacent pedicles in the anteroposterior view. When the needle passed through the annulus fibrosus, the physician felt a sudden loss of resistance. When the needle reached the border of the annulus fibrosus and nucleus pulposus, it stopped advancing. The stylet was then removed, and only the introducer was retained. The wand of the L’DISQ was placed into the introducer. Depending on the position of the target disc, the lever was pulled and the tip of the wand was adjusted to finally reach the target area of the lesion. After reaching the target area, a low-voltage (0.5–1 V) electrical stimulation was applied. If the patient experienced a momentary, sharp, or sudden aching sensation in the back or the buttock, the tip of the wand was repositioned. The ablation and coagulation modes were used as per established protocols27,28. All adverse events that occurred during and after the procedure were recorded. After the procedure, the patient was transferred to the recovery room, and vital signs were monitored. After a few hours of recovery, the patient was discharged once a neurological examination confirmed the absence of any abnormalities.
Patient demographic and clinical data, including age, sex, height, weight, smoking history, pain duration, and history of surgery, were recorded. The NRS pain scores before and at 1, 2, 3, and 6 months after the procedure were assessed. The functional status was estimated using the Oswestry disability index (ODI) before and at 1, 2, 3, and 6 months after the procedure. The findings of radiographic examinations, including plain radiography and lumbar MRI, were thoroughly reviewed to assess the side of the lesions (unilateral or bilateral), migration of the herniated disc, broadly herniated discs, decreased intensity of the disc on T2-weighted MRI, as well as the presence of high-intensity zones (HIZs), thecal sac compression, spondylolisthesis, central stenosis, and foraminal stenosis. Decreased intensity of the disc on T2-weighted MRI indicated a lack of homogeneity with a hypointense grey or black signal intensity and the loss of distinction between the nucleus and annulus29,30. Procedure-related variables, including the number of treatment levels and post-procedural complications over 6 months after the procedure, were also recorded.
Definition of a successful outcome.
The NRS pain and ODI scores before and at 1, 2, 3, and 6 months after the procedure were determined through chart reviews. Patients whose NRS pain scores decreased by 50% or more and whose ODI scores decreased by 40% or more at 6 months after the procedure than before the procedure were grouped into the successful outcome group. Patients who were lost during the 6-month follow-up (n = 4) were grouped into the unsuccessful outcome group. According to these definitions, 80 patients had successful outcomes and 26 had unsuccessful outcomes at 6 months after the procedure.
Normality of data was analysed using the Kolmogorov–Smirnov test for all continuous parameters. Continuous variables were presented as mean and standard deviation (SD) or median and interquartile range, depending on normality. Categorical demographic variables were reported as a number or a percentage. For continuous variables, comparisons of patient characteristics between the groups were made using Student’s t-tests or the Mann–Whitney U test. Categorical demographic data were analysed using Pearson’s chi-square test or Fisher’s exact test. P values less than 0.05 were considered statistically significant. To compare the NRS pain and ODI scores before and after the procedure, the Wilcoxon signed-rank test was performed. The P level was adjusted (0.05/4 = 0.0125) for the multiple comparisons of the differences in the scores at 1, 2, 3, and 6 months versus those before the procedure. To quantify the relationship between successful outcomes and the patients’ clinical and demographic characteristics, binary logistic regression techniques were used. To determine independent positive prognostic factors of the procedure, multivariable logistic regression analysis was performed using variables that were statistically significant in the univariable analysis. By implementing the Hosmer–Lemeshow goodness-of-fit test, the regression model was determined to be appropriate. All data were analysed using IBM SPSS Statistics for Windows/Macintosh, Version 24.0 (IBM Corp., Armonk, NY).