Effectiveness of Interventional Pain Management on Disc Herniation Resorption: Radiological Evidence

Abstract

Background:

The purpose of this study is to evaluate the change in disc herniation over time, as assessed on MRI images, in those patients who are receiving epidural steroid injections. The concept of reduction in the size of the disc, in other words, spontaneous resorption/regression will be explored and whether it has any link with administration of epidural steroid injections.

Objective:

The purpose of this study is to evaluate the change in disc herniation over time, as assessed on MRI images, in those patients who are receiving epidural steroid injections. The concept of reduction in the size of the disc, in other words, spontaneous resorption/regression will be explored and whether it has any link with administration of epidural steroid injections.

Methods:

This retrospective study investigates the potential link between changes in the natural history of disc morphology, specifically disc resorption, and various IPM treatments. For 449 patients the inclusion criteria encompassed LDH patients who Underwent IPM at KAUH from the period between January 2022 and January 2024 for the patient who had at least two lumbar spine MRI scans (one before and one after IPM). Patients with disc surgery after IPM and pre-or post-MRI follow-up exceeding two years were excluded.

Results:

Among the 128 LDH patients included in the study, 48 cases (37.5%) exhibited varying degrees of LDH resorption following IPM treatments, while 80 cases (62.5%) showed no significant change in LDH size.

Conclusion:

The findings suggest that IPM therapies may influence the natural history of LDH morphology by decreasing disc size in a subset of patients. These results underscore the potential benefits of IPM treatments in LDH management and warrant further exploration in clinical practice and research settings.

1. BACKGROUND

Lumbar disc herniation (LDH) stands as a prevalent global health concern, with its incidence surpassing 50% in certain populations (1, 2). Symptomatic LDH inflicts significant socioeconomic burdens on patients, leading to activity limitations, participation restrictions, and career setbacks (2). The economic toll of LDH-related conditions, such as low back pain (LBP), radiating pain, and disability, is consider-able, with the US healthcare system alone expending $1 billion annually on back-related conditions and $300 million on discectomy procedures (1).

Treatment options for LDH pain encompass both surgical and conservative methods, with surgical intervention offering expedited symptom relief (3). However, studies indicate that both surgical and conservative treatments demonstrate simi-lar long-term efficacy (1, 3, 4). Notably, conservative treatments, particularly interventional pain management (IPM) procedures, are increasingly favoured over surgical interventions for managing LDH-related pain symptoms, with a reported rise in the avoidance of surgeries (5).

The phenomenon of spontaneous resorption of LDH was initially reported by Guinto et al. in 1984 (6), and subsequent studies have documented numerous cases of spontaneous herniation resorption. For instance, Hong et al. observed a reduction in LDH size in 85.7% of 28 patients with massive LDH (7), while Shen et al. reported 8 cases of LDH resorption following non-surgical treatment (8). Additionally, Kesikburun et al. enrolled 40 patients with LDH in MRI follow-up and noted partial regression in 15% of cases and complete resolution in 75% (10). Moreover, Chang et al. and others reported cases of LDH regression (9, 11, 12). Meta-analyses have reported high incidence rates of spontaneous LDH resorption, ranging from 66.66% (13) to 70.39% (14).

Numerous studies suggest that conservative treatments can prompt the resorption process of LDH. The underlying mechanisms of LDH resorption involve inflammation, macrophage infiltration, angiogenesis, and enzymatic activity (16). Furthermore, the presence of vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) in herniated discs material indicates a relationship with neovascularization processes in LDH (17). Neo-vascularization levels in disc herniation entering the epidural space correlate with the severity of histodegenerative changes of disc hernias (18). However, the effect of IPM treatments on these factors remains unclear.

Despite the wealth of research on LDH resorption, few studies have examined its relationship with IPM procedures, and many of them lack sufficient case numbers. Previous studies, such as those by Buttermann et al. and Wilson et al., have suggested that while IPM procedures can alleviate patient symptoms, they may not significantly alter the natural history of LDH morphology (14, 15), , whilee Zhijia et al. suggested that the conservative treatments may have more significant effect on the natural history of larger protrusions of LDH (19). However, some studies have predicted a negative effect of IPM treatments on the process of LDH resorption (16).

2. OBJECTIVE

The primary aim of this study is to evaluate changes in disc herniation over time, as assessed on MRI images, in LDH patients undergoing various IPM procedures. Specifically, we aim to explore the concept of resorption/regression and its potential linkage with the administration of IPM procedures. We hypothesize that IPM procedures may contribute to disc herniation resorption in LDH patients.

3. MATERIAL AND METHODS

A retrospective study design was employed to investigate changes in LDH following interventional pain management treatments, including epidural steroid injection, facet joint block, radio-frequency small Joint, and nerve block, at King Abdullah University Hospital (KAUH) between January 2022 and January 2024.

A list of 449 patients was extracted from KAUH radiology archive according to the following inclusion criteria: a) Underwent IPM at KAUH at period from January 2022 to January 2024, b) Had at least two lumbar spine MRI scans (one before and one after IPM).

The patients who underwent IPM were injected with dexamethasone or methylprednisolone steroids and normal saline and either Marcaine or Bupivacaine as local anesthetics.

From this list, a sample of 128 patients was selected based on the following exclusion criteria:

a) Patients who undergone disc surgery after the IPM.

b) Patients with pre- or post-MRI scans conducted more than 2 years before or after IPM.

c) MRI scans that were not for the lumbar region or were not clear enough for evaluation.

Changes in LDH were assessed using pre- and post-IPM MRI images, specifically axial and sagittal T2-weighted images. The degree of change in LDH was categorized as “Decrease” or “Same”; the decrease was detected at any degree. The level of herniation (e.g., L1-L2, L2-L3) and the presence of multiple level of LDH were recorded as well (ie. Single, Multiple). Demographic information including age and gender was collected. Age was categorized into three groups: 25-45, 46-65, and 66-85. The mean age of the study population was 52.6 years (+-12), with 65 female and 63 male participants.

The post-MRI timing in relation to IPM procedure was divided into intervals of less than3 months, 3-6 months, 6-9 months, 9-12 months, and more than 12 months to assess changes in LDH over time. Table-1 shows the frequency distribution of different categories of variables.

SPSS software was used for the analysis of data to know the relationship between MRI changes and IPM and the effect of age and gender on that change. Then we compared resorption rates between different levels of herniation, And the P-value <0.05. Considered statistical significance for all statistical tests.

Table 1 presents the frequency distribution of different categories of variables, including Gender, Herniation Status, Age group, post-MRI scan, providing a comprehensive overview of the study sample.

Table 1. Frequency distribution of different categories of variables.

Category	Subcategory	Count	Percentage
Gender	Male Female	63 65	49.2% 50.8 %
Herniation status	Multiple Single	118 10	92.2% 7.8%
Age category	25 – 45 46 – 65 66 – 85	38 73 17	29.7% 57.0% 13.3%
Post-MRI timing	Less than 3 months 3 – <6 months 6 – <9 months 9 – <12 months More than 12 months	41 24 18 16 29	32.0% 18.8% 14.1% 12.5% 22.7%

4. RESULTS

Data from 449 patients who underwent pre- and post-MRI scans between January 2022 and January 2024 were ana-lysed. Among the 128 patients meeting inclusion criteria, with a mean age of 52.6 (±12), 65 patients were female and 63 males. Of these, 48 cases (37.5%) demonstrated reduction in the size of herniation after treatment, while 80 cases (62.5%) did not. Resorption percentages were almost similar between genders (36.9% female, 38.1% male) and varied across age categories (39.4% for 25-45 group, 35.6% for 46-65 group, and 41.1% for 66-85 group) with no statistically significant differences (Table 2).

Table 2. Percentages of LDH Resorption cases.

Category	Subcategory	Absorption percentage %	P-value
Gender	Male Female	38.1 36.9	0.891
Post-MRI timing	Less than 3 months 3 – 6 months 6 – 9 months 9 – 12 months More than 12 months	29.3 25 50 43.8 48.3	0.224
Age category	25 – 45 46 – 65 66 – 85	39.4 35.6 41.1	0.873
Herniation status	Multiple Single	36.4 50	0.395

Examining LDH resorption percentage in relation to the post-MRI timing showed that the resorption percentage was 29.3% when it’s less than 3 months, 25% when it’s between 3-6 months, 50% when it’s between 6-9 months, 43.8% when it’s between 9-12 months and 48.3 when it’s more than 12 months. Additionally, in cases where patients had multiple discs, the resorption percentage was 50% in single herniation status and 36% in multiple with no statistically significant differences.

Table 2 presents the percentages of LDH Resorption cases according to different characteristics, gender, post-MRI timing, age category and herniation status.

Examining LDH resorption percentage at each herniation level independently, the percentages were: 8.6% for L1-L2, 12.5% for L2-L3, 18.7% for L3-L4, 18.8% for L4-L5, and 22.2% for L5-S1 (Table 3). Pre- and post-MRI images pro-vided examples of LDH resorption for three patients (Figure 1). Table 3 presents the percentages of LDH Resorption in every level alone.

Table 3. Percentages of LDH Resorption.

Herniation level	Count	Resorption percentage
L1-L2	35	8.6
L2-L3	56	12.5
L3-L4	91	18.7
L4-L5	101	18.8
L5-S1	81	22.2

Figure 1. Molecular dynamic analysis of ligand stability (a), RMSF (b), and gyrate / Rg (c) from compounds 12, 13, and 15 against HBV.

5. DISCUSION

To investigate the potential correlation between IPM treatment and LDH resorption, the findings of this study contribute to our understanding of the potential relationship between interventional pain management (IPM) procedures and the natural history of lumbar disc herniation (LDH)., our results showed 37.5% of patients who underwent IPM showed LDH resorption and there was no relationship between the patient demographic characteristics and the LDH resorption. However. Which is relatively low compared to recent meta-analysis (13) , that is suggested by Pengfei et al. because of mechanism of action of steroids on impairing the degradation process of inflammation around the herniation (16) and we believe that patients’ lifestyle, along with whether they return for another MRI scan due to pain recurrence or persistence (with the majority not returning because they felt well), are the most significant factors influencing the likelihood of resorption.

Although none of the results was significant but an observed variation in LDH resorption rates according to gender, age, and follow-up timing provided additional insights into the potential factors influencing the effectiveness of IPM treatments. Although the differences in resorption rates between genders were not statistically significant, there was a slightly higher percentage of LDH reduction in males compared to females. Additionally, the highest resorption rate was observed in the 45-65 age group, indicating a potential age-related effect on treatment outcomes. Furthermore, the timing of post-MRI scans appeared to influence the likelihood of LDH resorption, with higher rates observed in patients with longer follow-up periods.

The analysis of LDH resorption rates according to herniation level and status revealed interesting patterns. Higher resorption rates were observed in herniations located at the L5-S1 level then L4-L5 level. Additionally, patients with single-level herniation exhibited a higher resorption rate compared to those with multiple-level herniations, suggesting that the extent and location of LDH may impact treatment outcomes. These findings underscore the im-portance of considering individual patient characteristics, including gender, age, herniation level, and follow-up timing, when assessing the effectiveness of IPM treatments for LDH.

The basic treatment of LDH should be conservative according to the results of this study. However, surgery may be necessary for large central protruding hernias and patients who show severe motor deficits (20). The IPM procedures are commonly utilized for the temporary pain relief through steroid injection near the region of nerve com-pression which blocks the inflammation and pain pathways, and many reported no effect on natural history of LDH (14, 15). While IPM procedures offer a promising approach for managing LDH-related pain symptoms, further re-search is needed to confirm its effect on the LDH natural history.

During a person’s lifetime, the intervertebral disc (IVD) goes through a number of changes that are key to its slow breakdown. One of the key changes occurs in the nucleus pulposus (NP), which initially has a gel-like consistency essential for the shock-absorbing function of the disc. Over time, the NP undergoes a transformation into a more fibrous tissue. This change largely matches the depletion of proteoglycans and modifications in the extracellular matrix, which all together contribute to a substantial decrease in water content. Finally, the disc loses height, flexibility, and overall hydration, impairing its ability to cushion spinal movements effectively. As individuals age, degenerative changes in the intervertebral disc are enhanced by the natural aging process. With advancing age, the number of progenitor cells in the nucleus pulposus (NP) declines, while the proportion of senescent cells rises significantly. This accumulation of senescent cells promotes an inflammatory microenvironment that accelerates disc degeneration. An important factor in this process is the senescence-associated secretory phenotype (SASP), which triggers the release of inflammatory cytokines. These cytokines are highly linked to discogenic pain and they are closely associated with discogenic pain and play a crucial role in the breakdown of the extracellular matrix, perpetuating a self-sustaining cycle of inflammation and degeneration.

Disc degeneration is often associated with symptomatic herniations, which occur due to the displacement of the disc material. This displaced tissue can mechanically compress or chemically irritate the lumbosacral nerve roots, resulting in radiating pain, such as sciatica.

In more severe cases, it could also lead to nerve weakness or sensory abnormalities in the lower extremities, which significantly affects the quality of life (21, 22). Because these processes are so complicated, therapies that target cellular senescence, metabolic dysfunction, and inflammatory factors, such as cytokines, are getting more attention as possible ways to slow down disc degeneration. By focusing on these molecular pathways, it may be possible to slow down or even reverse the degenerative process, ultimately improving patient outcomes (24).

This study aimed to find the potential correlation between interventional pain management (IPM) treatment and lumbar disc herniation (LDH) resorption, which helps to a deeper understanding of how IPM procedures might influence the natural history of LDH. Our findings revealed that 37.5% of patients who underwent IPM experienced LDH resorption. Notably, no significant association was found between patient demographic characteristics and the likelihood of LDH resorption. However, this resorption rate is relatively low when we compare it to recent meta-analyses (13). One possible explanation for this discrepancy, as suggested by Pengfei et al., lies in the mechanism of action of corticosteroids used in IPM. These steroids may impair the degradation process of inflammation surrounding the herniated disc material (16). Inflammation plays a crucial role in creating an environment that facilitates spontaneous regression of LDH, as it activates macrophages that help resorb the herniated tissue (23). Therefore, the anti-inflammatory effects of corticosteroids, while beneficial for pain relief, might inadvertently hinder the natural resorption process.

These findings highlight the significance of using IPM treatments for LDH and underscore the need for a balanced approach that considers both pain management and the potential impact on disc resorption. Further research is necessary to explore alternative strategies that optimize both pain relief and the promotion of spontaneous LDH regression. We believe that patients’ lifestyle choices, along with their decision to return for a follow-up MRI scan due to pain recurrence or persistence, are key factors influencing the likelihood of LDH resorption. Notably, the majority of patients did not return for a follow-up MRI scan because they experienced sufficient symptom relief, which may have underestimated the observed resorption rates.

Although no statistically significant results were found which is consistent with findings from most previous cohorts (27) the observed variation in LDH resorption rates according to gender, age, and follow-up timing provides valuable insights into potential factors affecting the effectiveness of IPM treatments. For example, while the differences in resorption rates between genders were not statistically significant, males showed a higher percentage of LDH resorption compared to females. This shows that biological or lifestyle-related differences might play a role in the resorption process. Age also appeared to influence treatment outcomes, with the highest resorption rate observed in patients aged 45-65. This finding suggests a possible age-related effect, potentially linked to variations in disc composition, immune response, or activity levels within this age group. Moreover, the timing of follow-up MRI scans seemed to affect resorption rates, when we have longer follow-up periods associated with higher rates of LDH resorption. This trend highlights the importance of adequate monitoring duration when assessing treatment effectiveness.

Some patient factors, such as smoking, depression, or concomitant joint issues, may be associated with worse functional outcomes, independent of whether surgical or nonoperative therapy is sought, according to a prior randomized and observational study. Remarkably, individuals who had sequestered disc fragments, symptoms that lasted longer than six months, more low back pain, or who were unemployed or incapacitated at baseline showed greater benefits from surgical treatment (28). These results undervalue the intricate interactions between patient-specific variables that can affect LDH resorption and overall treatment results, underscoring the necessity of a customized strategy for lumbar disc herniation management.

The analysis of LDH resorption rates based on the herniation level showed several sign patterns. Markedly, higher resorption rates were found in herniations at the L5-S1 level compared to those at the other levels. This finding may be related to the special anatomical properties of the L5-S1 segment, which has greater mobility and stress, which could potentially be affecting the resorption process.

Additionally, patients who have single-level herniation showed a higher resorption rate in comparison with those who have multiple-level herniations. This indicates that the extent and location of LDH play a significant role in treatment outcomes. Wang et al,, also reported the same findings as ours, they reported that patients with single-level SLDH are more likely to experience spontaneous regression compared to those with multiple-level SLDH (31).

The difference in the volume of herniated disc tissue may be a proposed explanation for the pattern of difference we found. Single-level SLDH typically involves a larger amount of herniated material than multiple-level SLDH, which may trigger a more inflammatory response. This inflammatory reaction is believed to be a key mechanism underlying disc resorption, as the body develops an immune response against the extruded disc material (32, 33). The recruitment of macrophages and the subsequent release of inflammatory cytokines facilitate the breakdown and phagocytosis of the herniated tissue, resulting in the gradual resorption of the affected area.

These findings highlight the importance of considering herniation level and status when predicting the outcomes.

These findings may underline the importance of considering individual patient characteristics such as gender, age, herniation level, and follow-up timing when evaluating the effectiveness of interventional pain management (IPM) treatments for lumbar disc herniation (LDH). Recognizing these variables can help tailor treatment approaches, leading to more personalized and potentially effective care strategies.

The literature on post-operative recurrent LDH following surgical procedures like discectomy reports recurrence rates ranging from as low as 1% to as high as 25%, reflecting a significant variability and highlighting the potential for high recurrence rates and relatively low long-term benefits, particularly in non-complicated cases (29, 30). According to these statistics, the results of this study - along with evidence from other research - support the recommendation that initial treatment should prioritize conservative management. This includes using nonsteroidal anti-inflammatory drugs (NSAIDs) or narcotic medications, engaging also in physical therapy, and considering epidural transforaminal injections before undergoing the surgical intervention. Surgery should be reserved firstly just for more severe cases, such as those presenting with neurological deficits or cauda equina syndrome, where conservative measures are insufficient (25, 26). In spite of that, surgical intervention remains necessary for patients with large central protruding hernias or those exhibiting severe motor deficits, where nonoperative treatments are unlikely to provide adequate relief or functional recovery (20). In contrast, IPM procedures are commonly employed to provide temporary pain relief by administering steroid injections near the site of nerve compression. These steroids effectively block inflammation and disrupt pain signaling pathways, offering symptomatic relief. However, multiple studies have reported that IPM procedures have minimal to no impact on the natural history of LDH, particularly regarding long-term disc resorption or structural improvement (14, 15).

While IPM offers a non-surgical option for managing pain associated with LDH, its influence on the underlying degenerative process remains uncertain. As such, further research is required to clarify the long-term effects of IPM on LDH progression and to determine whether it can contribute to disc resorption or merely provide temporary symptomatic relief. These investigations will be essential for optimizing treatment approaches and improving patient outcomes in the management of lumbar disc herniation.

The study was limited by many factors that could be improved to have more reliable results, that could be used in more clinical relative research in the future. First, the study population was limited to a small number of patients due to the low adherence of patients to have a second MRI after the IPM treatment, prospective studies are more appropriate to have a sufficient number of patients with specified criteria of MRI images, patients characteristics, and IPM procedures. Second, the LDH characteristics such as the protrusion direction (Central, lateral…etc) and protrusion size were limited to the LDH level. Third, The changes in LDH size were limited to “decreased” or “Not”, as it could be more specified in numerical data (eg, in millimeters). Fourth, clinical symptom improvement should be incorporated into future studies to have more realistic results related to the clinical improvement of patients. Sixth, other factors should be measured in these studies such as physical activity, physiotherapy adherence, and lifestyle.

6. CONCLUSION

This retrospective study provides evidence of a potential association between interventional pain management (IPM) treatments and the reduction in the size of lumbar disc herniation (LDH) on MRI images. The findings suggest that IPM therapies may influence the natural history of LDH morphology by decreasing disc size in a subset of patients. However, the effectiveness of IPM treatments appears that there is no obvious relation between the individual patient characteristics, including gender, age, herniation status, and follow-up timing with the probability of resorption.

These results highlight the importance of personalized treatment like the lifestyle and daily tasks in managing LDH-related pain symptoms and we emphasize the need for further research to better understand the mechanisms underlying LDH resorption. By optimizing treatment strategies based on patient-specific factors, healthcare providers can enhance the effectiveness of IPM interventions and improve outcomes for LDH patients.

Data availability declaration:

The data supporting the findings of this study are available from the corresponding author upon reasonable request.

Ethics Declaration

This research was conducted in accordance with the Declaration of Helsinki. Ethical approval was obtained from the Institutional Review Board of Jordan University of Science and Technology at Jordan with reference number (9/124/2019).

Participate Declaration

Consent to participate was waived by an Institutional Review Board of Jordan University of Science and Technology with reference number (9/124/2019).

Author’s contribution

The all authors were involved in all steps of preparation this article including final proofreading.

Conflict of interest

None to declare.

Financial support and sponsorship

None.