Abstract
Study design
Randomized controlled trial.
Objectives
There are no high-quality studies that evaluate the impact of intraoperative epidural steroids on early outcomes of patients undergoing full-endoscopic lumbar spine surgery. We aimed to assess the effect of intraoperative epidural steroid application on early clinical outcomes.
Methods
We evaluated adult patients submitted to full-endoscopic discectomy at a neurosurgery department from September 2022 to January 2025. The primary endpoint was the mean Oswestry Disability Index (ODI) reduction 3 months after surgery. The secondary endpoints were mean ODI reduction 1 month post-op and lumbar and leg pain reduction using a numeric rating scale (NRS, 0-10) following surgery at different timepoints. After randomization and following disc herniation removal, the intervention group was given 2 mL (8 mg) of dexamethasone, and the control group was given 2 mL of saline. Outcome measures were collected at 2, 14, 30 and 90 postoperative days.
Results
Ninety patients were randomized (45 for each group) and results were obtained for 78 patients (39 in each group). Mean age was 45.1 years and 50 (64%) were females. Both groups shared similar clinical characteristics and preoperative scores, and both groups achieved significant improvement following surgery. There was no difference between groups regarding mean improvement in the ODI at 1 and 3 months postoperatively. No differences were found between groups regarding mean improvement in NRS back and leg pain at different time points.
Conclusions
In this study, intraoperative administration of epidural steroid had no effect in early clinical outcomes after full-endoscopic lumbar discectomy.
Keywords: full-endoscopic lumbar discectomy, endoscopy, lumbar spine, intraoperative steroids, steroids
Introduction
Lumbar transforaminal and interlaminar epidural steroid injections have long been applied to treat and alleviate leg pain in patients with degenerative disease of the lumbar spine.1,2
Percutaneous epidural steroids may contribute to pain reduction by decreasing inflammation and possibly reducing both intraneural oedema and venous congestion. 3
Meta-analyses have demonstrated that compared to control groups, epidural steroid injections provided significant short-term (3 months) and medium-term (6 months) pain relief but had limited long-term effects.4,5
The use of epidural corticosteroids perioperatively has been studied with positive results. In 2014 Jamjoom performed a systematic review on the intraoperative epidural use of steroids in patients submitted to open lumbar discectomy and found that nine of the eleven trials report less early postoperative pain in patients given intraoperative steroids. 6 Song et al performed a randomized study assessing the clinical effect of epidural steroid application in patients undergoing transforaminal lumbar interbody fusion (TLIF) and found patients given intraoperative steroids to have less early postoperative back pain and radiculopathy-related symptoms. 7
To our knowledge, no high-quality studies have evaluated the impact of epidural steroids on the early clinical outcomes of patients undergoing endoscopic lumbar decompression.
With this randomized controlled trial (RCT) we aimed to ascertain whether intraoperative epidural application of steroids led to better early clinical outcomes in patients submitted to full-endoscopic lumbar discectomy (FELD). 8
Methods
Trial Design, Participants and Setting
This prospective double-blinded randomized controlled trial was approved by the ethics committee of our institution and followed the CONSORT statement for RCTs. 9
Adult patients who gave written consent to enroll in this study that underwent endoscopic lumbar discectomy at our department between September 2022 to January 2025 were included in this study.
Exclusion criteria included previous lumbar surgery at the same level, foraminal and extra-foraminal disc herniations, multilevel surgery, intraoperative conversion into microdiscectomy and dural tear precluding steroid application.
Intervention
In this study we used dexamethasone, a non-particulate corticosteroid, which is generally considered safer than particulate steroids and equally or more effective in pain reduction for lumbar epidural injections. 10 According to group allocation, dexamethasone or saline was administered at the end of the surgery after hernia removal, nerve root decompression and hemostasis revision. Saline infusion was stopped, and residual saline solution was aspirated until air was visible at the depth of the working cannula. The product of intervention was then injected through the working cannula, after which the instruments were removed and the skin closed.
Surgical Procedure
A spine surgeon with experience in FELD performed all procedures under general anesthesia at the ambulatory center of our institution. An interlaminar or transforaminal approach was used according to level, characteristics of disc herniation and degenerative pathology. All patients were discharged in the same day of the surgery.
Pilot Study
A pilot study with 36 patients was initially conducted in which 3 groups were evaluated: a control group was administered 2 mL saline, in group 1 was administered 1 mL (4 mg) of dexamethasone and group 2 was administered 2 mL (8 mg) of dexamethasone. The median reduction for leg pain measured with a numeric rating scale (NRS) at 3 months was 5 for control group, 5.5 for group 1 and 7 for group 2. Although without statistical significance there was a tendency for greater reduction in leg pain in group 2 patients and therefore a decision was taken to proceed with the study and compare the 8 mg dose to the control group.
Baseline Data and Outcomes
Patients’ clinical characteristics including age, gender, degree of degeneration of the operated disc measured by the Pfirrmann grade, Modic changes adjacent to the operated disc, endoscopic approach (transforaminal or interlaminar), symptom duration, preoperative lumbar and leg pain measured by NRS, preoperative functional disability measured by the Oswestry Disability Index (ODI) were retrieved both from the clinical registries at our institution and the EUROSPINE Spine Tango registry.
The lumbar and leg NRS were evaluated at 2, 14, 30 and 90 postoperatively days while the ODI was completed 30 and 90 days after surgery. Lower values in the back and leg NRS represent lower levels of pain whilst higher ODI scores represent higher disability. Additionally, return to work and analgesic medication consumption were assessed at 3 months. Adverse events in the first 90 days possibly related to dexamethasone were also registered.
The first author collected all the data and did not take part in any of the surgeries and was blind to whether patients had received saline or steroid. All procedures were performed by the same spine specialist who was also blind to the treatment plan.
Outcomes
The primary endpoint of the study was the ODI mean reduction at 3 months after surgery. The secondary endpoints were ODI mean reduction 1 month after surgery and postoperative lumbar and leg NRS mean reduction 2, 14, 30 and 90 days following surgery.
Sample Size
Effect size was obtained according to the quotient of minimal clinically important difference (MCID) for ODI (12.8) and the standard deviation (7.78). 11
Sample size was calculated using G*Power 3.1.9.7 for a 2-sided Wilcoxon-Mann-Whitney test, with significance level of 0.05 and a power of 0.80 to a final value of 66 patients. The enrollment accounted for a 20%−30% expected loss of patients to follow-u P during study completion.
Randomization
A simple randomization procedure was performed using a random number generator (Microsoft Excel) to 2 independent lists corresponding to “2 mL saline” and “2 mL dexamethasone”. Only the nursing team had access to this information and provided the solution at the end of the surgery according to the predefined number attributed to each patient. The randomization was undertaken by a third-party while the main surgeon conducted the implementation of the randomization. All authors were blind to the randomization.
Statistical Methods
R software (R Foundation for Statistical Computing, Vienna, Austria) version 4.0.3 was used for data analysis.
Wilcoxon rank sum test was used for mean comparison between groups, Fisher’s test was used for associations between categorical variables.
A mixed effects linear model was used for back and leg NRS and ODI to evaluate group effects adjusted for time, baseline NRS/ODI and subject-specific variability.
Results
Participant Flow and Recruitment
From September 2022 to January 2025 92 patients underwent one-level endoscopic lumbar hernia removal at our department. Two patients were excluded, one due to dural tear and another due to intraoperative conversion into microdiscectomy (Figure 1).
Figure 1.
CONSORT flow diagram illustrating patient enrolment, randomization, allocation, follow-up, and final analysis. Ninety patients were randomized to receive either intraoperative epidural dexamethasone (8 mg) or saline. Seventy-eight patients completed follow-up and were included in the final analysis
Ninety patients were enrolled in the study from which twelve were lost to follow-up or unfulfilled questionnaires. Valid results were obtained for 78 patients (39 in the intervention and control groups), from which 50 (64%) were females, with a median age of 45.1 years (Table 1).
Table 1.
Baseline Characteristics and Outcome Regarding Returning do Work and Medication
| Sham (N = 39) | Steroid (N = 39) | Total (N = 78) | P value | |
|---|---|---|---|---|
| Age | .36 a | |||
| Mean (SD) | 46.4 (11.6) | 43.8 (12.3) | 45.1 (12.0) | |
| Sex | .81 b | |||
| Male | 15 (38%) | 13 (33%) | 28 (36%) | |
| Female | 24 (62%) | 26 (67%) | 50 (64%) | |
| BMI | .33 a | |||
| Mean (SD) | 26.2 (4.7) | 26.8 (3.8) | 26.5 (4.3) | |
| Current smoker | .57 b | |||
| No | 30 (77%) | 33 (85%) | 63 (81%) | |
| Yes | 9 (23%) | 6 (15%) | 15 (19%) | |
| Level | .82 b | |||
| L3-L4 | 0 (0%) | 1 (3%) | 1 (1%) | |
| L4-L5 | 20 (51%) | 18 (46%) | 38 (49%) | |
| L5-S1 | 19 (49%) | 20 (51%) | 39 (50%) | |
| Pfirrmann grade - operated level | .08 a | |||
| Mean (SD) | 4.2 (0.6) | 4.4 (0.7) | 4.3 (0.7) | |
| Modic changes - upper adjacent plate | .17 b | |||
| 0 | 12 (31%) | 17 (44%) | 29 (37%) | |
| 1 | 6 (15%) | 1 (3%) | 7 (9%) | |
| 2 | 20 (51%) | 19 (49%) | 39 (50%) | |
| 3 | 1 (3%) | 2 (5%) | 3 (4%) | |
| Modic changes - lower adjacent plate | .54 b | |||
| 0 | 14 (36%) | 20 (51%) | 34 (44%) | |
| 1 | 2 (5%) | 1 (3%) | 3 (4%) | |
| 2 | 22 (56%) | 16 (41%) | 38 (49%) | |
| 3 | 1 (3%) | 2 (5%) | 3 (4%) | |
| Approach | .48 b | |||
| Endoscopic interlaminar | 23 (59%) | 27 (69%) | 50 (64%) | |
| Endoscopic transforaminal | 16 (41%) | 12 (31%) | 28 (36%) | |
| Symptoms duration | .60 b | |||
| <3 months | 6 (15%) | 6 (15%) | 12 (15%) | |
| 3-6 months | 10 (26%) | 6 (15%) | 16 (21%) | |
| >6 months | 23 (59%) | 27 (69%) | 50 (64%) | |
| Previous surgery | 1.00 b | |||
| No | 36 (92%) | 35 (90%) | 71 (91%) | |
| Yes | 3 (8%) | 4 (10%) | 7 (9%) | |
| Preoperative NRS back | .78 a | |||
| Mean (SD) | 5.6 (2.8) | 5.4 (3.2) | 5.5 (3.0) | |
| Preoperative NRS leg | .84 a | |||
| Mean (SD) | 7.2 (2.2) | 7.0 (2.5) | 7.1 (2.3) | |
| Preoperative ODI | .45 a | |||
| Mean (SD) | 49.5 (16.7) | 46.3 (16.7) | 47.9 (16.7) | |
| Return to work90d | .84 b | |||
| No | 10 (27%) | 9 (24%) | 19 (25%) | |
| Yes | 22 (59%) | 25 (66%) | 47 (63%) | |
| Not applicable | 5 (14%) | 4 (11%) | 9 (12%) | |
| Medication90d | .80 b | |||
| No | 24 (67%) | 26 (70%) | 50 (68%) | |
| Yes | 12 (33%) | 11 (30%) | 23 (32%) |
aWilcoxon rank sum test.
bFisher’s Exact Test for Count Data.
There were no differences between groups regarding mean preoperative variables including demography, lumbar level, degenerative changes, endoscopic approach, ODI and back and leg NRS. Patients lost to follow-up in both groups also displayed similar characteristics.
Postoperative ODI
Functional disability 1 month after surgery measured by the ODI was 17.1 (15.9) in the control group and 18.8 (15.7) in the intervention group (P = .56) and at 3 months 22.1 (20.6) and 15.6 (14.2) respectively in the control and intervention groups (P = .15) (Figure 2).
Figure 2.
Oswestry Disability Index (ODI) scores in the sham (saline) and steroid (dexamethasone) groups at 1 and 3 months postoperatively. Higher scores indicate greater disability. Error bars represent standard deviation
Both groups had clinical improvement well above the MCID for this questionnaire. Mean postoperative ODI improvement at 1-month was 34.4 (22.6) for the control group and 30.5 (22.4) in the intervention group (P = .68) and at 3-month mean ODI improvement was 28.1 (28.3) and 33.2 (18.8) respectively for the control and intervention groups (P = .50) (Table 2).
Table 2.
Outcomes According to Groups
| Sham (N = 39) | Steroid (N = 39) | P value | |
|---|---|---|---|
| NRS back - 2 days postop | .02 a | ||
| Mean (SD) | 2.2 (2.2) | 3.7 (2.8) | |
| NRS leg - 2 days postop | .65 a | ||
| Mean (SD) | 1.5 (2.0) | 2.2 (2.9) | |
| NRS back - 14 days postop | .72 a | ||
| Mean (SD) | 2.8 (2.4) | 3.0 (2.5) | |
| NRS leg - 14 days postop | .51 a | ||
| Mean (SD) | 3.8 (2.9) | 3.4 (2.8) | |
| NRS back - 30 days postop | .33 a | ||
| Mean (SD) | 2.1 (2.4) | 2.7 (2.8) | |
| NRS leg - 30 days postop | .65 a | ||
| Mean (SD) | 2.6 (2.8) | 2.9 (3.3) | |
| NRS back - 90 days postop | .76 a | ||
| Mean (SD) | 3.5 (3.2) | 3.5 (2.7) | |
| NRS leg - 90 days postop | .22 a | ||
| Mean (SD) | 2.8 (3.0) | 2.2 (3.0) | |
| ODI – 1 month postop | .56 a | ||
| Mean (SD) | 17.1 (15.9) | 18.8 (15.7) | |
| ODI – 3 months postop | .15 a | ||
| Mean (SD) | 22.1 (20.6) | 15.6 (14.2) | |
| NRS back improvement at 2 days | .04 a | ||
| Mean (SD) | 3.4 (3.0) | 1.8 (3.6) | |
| NRS leg improvement at 2 days | .60 a | ||
| Mean (SD) | 5.7 (2.9) | 5.0 (4.0) | |
| NRS back improvement at 14 days | .49 a | ||
| Mean (SD) | 2.9 (3.0) | 2.4 (3.4) | |
| NRS leg improvement at 14 days | .85 a | ||
| Mean (SD) | 3.4 (3.0) | 3.6 (3.7) | |
| NRS back improvement at 30 days | .31 a | ||
| Mean (SD) | 3.6 (2.8) | 2.6 (4.1) | |
| NRS leg improvement at 30 days | .45 a | ||
| Mean (SD) | 4.8 (3.0) | 4.1 (3.9) | |
| NRS back improvement at 90 days | .81 a | ||
| Mean (SD) | 2.1 (3.7) | 1.9 (3.9) | |
| NRS leg improvement at 90 days | .54 a | ||
| Mean (SD) | 4.4 (3.5) | 4.9 (3.6) | |
| ODI improvement at 1 month | .68 a | ||
| Mean (SD) | 34.4 (22.6) | 30.5 (22.4) | |
| ODI improvement at 3 months | .50 a | ||
| Mean (SD) | 28.1 (28.3) | 33.2 (18.8) |
aWilcoxon rank sum test.
A mixed effects model also showed no differences between groups when different timepoints, baseline ODI and subject-specific variability were considered (P value for estimate of the group: .366).
Postoperative Leg NRS
The mean postoperative leg NRS for the control group was 1.5 (SD 2.0) at 2 days, 3.8 (2.9) at 14 days, 2.6 (2.8) at 30 days and 2.5 (3.0) at 90 days which compared to 2.2 (2.9; P = .65), 3.4 (2.8; P = .51), 2.9 (2.3; P = .65) and 2.2 (3.0 P = .22) in the intervention group for the respective time periods (Figure 3).
Figure 3.
Mean postoperative leg pain measured using the Numeric Rating Scale (NRS, 0-10) in the sham (saline) and steroid (dexamethasone) groups at 2, 14, 30, and 90 days after surgery. Lower scores indicate less pain. Error bars represent standard deviation
At all time periods there were no significant differences between groups regarding mean improvement in leg pain (Table 2) and a mixed effects model also showed no differences between groups when different timepoints, baseline NRS and subject-specific variability were considered (P value for estimate of the group: .175).
Postoperative Back NRS
The mean postoperative back NRS for the control group was 2.2 (SD 2.2) at 2 days, 2.8 (2.4) at 14 days, 2.1 (2.4) at 30 days and 3.5 (3.2) at 90 days which compared to 3.7 (2.8; P = .02), 3.0 (2.5; P = .72), 2.7 (2.8; P = .33) and 3.5 (2.7; P = .76) for the intervention group for the respective time periods (Figure 4).
Figure 4.
Mean postoperative back pain measured using the Numeric Rating Scale (NRS, 0-10) in the sham (saline) and steroid (dexamethasone) groups at 2, 14, 30, and 90 days after surgery. Lower scores indicate less pain. Error bars represent standard deviation
At all time periods there were no significant differences between groups regarding mean improvement in back pain (Table 2) and a mixed effects model also showed no differences between groups when different timepoints, baseline NRS and subject-specific variability were accounted for (P value for estimate of the group: .937).
Return to Work and Pain Medication
Twenty-two (59%) and 25 (66%) patients had returned to work 3 months after surgery respectively in the control and intervention groups (P = .84). In the same timeframe 24 (67%) patients in the control group and 26 (70%) patients in the intervention group had completely ceased analgesia for their lumbar pathology (P = .80).
Discussion
To our knowledge, this RCT is the first study of the kind to assess the impact of intraoperative epidural steroids on the outcomes of patients submitted to endoscopic discectomy. Contrary to a broad range of literature reporting favourable outcomes following perioperative steroid application with microdiscectomy, we did not find differences in early clinical outcomes at all examination points between groups.12,13
In 2003 Lundin et al performed a prospective randomized double-blinded trial that compared patients who had a fat graft soaked with Depo-Medrol placed in the epidural space following microdiscectomy to a control group not given topical steroids. They found lower pain scores and improved functional outcomes and faster return to work in those administered epidural steroids. 12
Waqas et al. performed a systematic review on RCTs that evaluated the impact of perioperative epidural steroids for lumbar disc surgery and the findings pointed to a positive effect of topical steroids on early post-surgical back and leg pain improvement as well as shorter hospitalization times and faster return to work. 13
In our RCT both groups achieved very good clinical outcomes with 1- and 3-month improvements in functional disability (ODI) well above the MCID for this questionnaire. 11 Similarly, at all-time points the MCID (1.2 for back pain and 1.6 for leg pain) defined by Copay et al was reached in both groups. 11
Possible reasons for the lack of clinical differences between groups in our study may be due to less tissue damage induced by endoscopic surgery. Additionally, the main bulk of the treatment was achieved through nerve root decompression and hernia removal in all patients. Those factors may have contributed to the low postoperative back and leg pain scores in the control group, therefore lowering the threshold for further clinical improvement with steroid therapy. Another factor could be related to epidural steroid washout by saline. Although saline perfusion was stopped before intraoperative steroid epidural instillation, considerable amounts of saline may have remained in the epidural space and cause dilution and/or washout of the dexamethasone.
Limitations
This study has some limitations; firstly, and although saline was removed at the end of the procedure, we could not quantify the amount of residual saline left and do not know whether the dose of dexamethasone (8 mg) used in this study was sufficient to cause a clinically relevant effect. Secondly, memory bias was not addressed during fulfilment of the postoperative patient-reported outcome measures (PROMs) as patients were not provided their preoperative pain scores and this may limit interpretation of postoperative PROMs. 14
Interpretation
Clinical meaningful improvement following endoscopic lumbar discectomy was obtained for both groups in our study but no differences in early clinical outcomes were encountered between the control group and patients given intraoperative epidural steroids.
Prospective studies with larger samples are needed to consolidate these findings and ascertain whether intraoperative epidural steroids can lead to better clinical outcomes in patients undergoing endoscopic lumbar discectomy.
Additionally, how best to apply epidural steroids following endoscopic discectomy should be addressed in future studies.
Author Notes: All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest, or non-financial interest in the subject matter or materials discussed in this manuscript.
Funding: The authors received no financial support for the research, authorship, and/or publication of this article.
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Trial Registration: Trial is registered at clinicaltrials.gov ID: ULSSJOAO_80/23.
ORCID iDs
Pedro Valente Aguiar https://orcid.org/0000-0002-4279-3315
Osvaldo Sousa https://orcid.org/0000-0002-1953-1640
Paulo Pereira https://orcid.org/0000-0001-6961-9213
Pedro Santos Silva https://orcid.org/0000-0002-7523-5782
Ethical Considerations
This research was approved by the ethics committee of our institution with the following reference: CES/CHUSJ: 80/23. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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