Spontaneous resorption of herniated lumbar discs: illustrative cases

Abstract

BACKGROUND

It is well recognized that symptoms of lumbar disc herniation often improve with conservative management. It is less well understood that the disc herniation resolves over time.

OBSERVATIONS

The authors present several cases demonstrating the natural history of resolution of lumbar disc herniation. All cases also experienced symptomatic improvement of their radicular pain.

LESSONS

These findings provide radiological evidence of the pathophysiology behind symptom resolution with conservative management of lumbar disc herniation and provide support for conservative management of lumbar disc herniation.

https://thejns.org/doi/10.3171/CASE24873

Lumbar disc herniation (LDH) affects 1%–3% of the global population annually and predominantly affects those aged between 30 and 50 years.¹ LDH is estimated to impact 9% of people worldwide.² Distal lumbar vertebral segments are most commonly affected with 95% of LDH occurring at the L4–5 or L5–S1 levels.³ Multiplanar motion occurs at these levels and significant biomechanical stress is imposed on L4–5 and L5–S1, with these segments accounting for the majority of the natural lumbar lordosis.⁴ Common symptoms of herniated lumbar discs include lumbar back pain, radicular pain, and sensory and motor dysfunction. Management of herniated discs ranges from conservative management such as physiotherapy, exercise and strengthening, analgesia, and corticosteroid injection to surgical intervention.

The various treatment options for LDH pose a challenging question for clinicians: when to operate and when to manage conservatively. A 2017 meta-analysis found that two-thirds (66.67%) of LDHs spontaneously resorbed with conservative management.⁵ Furthermore, long-term follow-up of patients with LDH over 2–5 years, showed little difference between persistent symptoms experienced in patients who underwent surgical intervention and those who were conservatively managed.⁵ Pain reduction is generally experienced within 6–12 weeks of conservative management in 85%–90% of patients.^3,6,7 Patients experiencing radicular pain without motor impairment are often best suited to conservative management, as motor impairment is an indication for surgical intervention.^6,–,8 In severe cases of LDH, patients may experience significantly debilitating intractable pain as their sole symptom, limiting their ability to perform their activities of daily living. In these circumstances, some patients are offered surgical intervention to enable a return to normal function through pain minimization.^7,8

This limited case series discusses 3 cases of patients experiencing radicular pain from LDH. Patients were followed up over a 2-year period and were found to have symptomatic and radiological resolution of their disc herniations.

Illustrative Cases

Case 1

A 53-year-old professional woman presented to her general practitioner with a 12-month history of bilateral lower limb paraesthesia and radiating pain in the L5 and S1 distributions. MRI of the lumbar spine revealed a large central disc herniation at L4–5 (Fig. 1A and B). She had no motor impairment and was managed by specialist spinal physiotherapists. Interval MRI conducted 19 months later (Fig. 1C and D) confirmed complete retraction of the L4–5 disc bulge. Her neuropathic symptoms had resolved.

FIG. 1.

Sagittal (A) and axial (B) T2-weighted MR images of the lumbar spine (August 2019). Sagittal (C) and axial (D) T2-weighted MR images of the lumbar spine (February 2021).

Case 2

A 24-year-old male laborer presented to his general practitioner with a 5-month history of lumbar back pain and left L5 radicular pain. MRI of the spine demonstrated a large L4–5 central disc protrusion with canal stenosis (Fig. 2A and B). He had no motor deficit and opted for conservative management. MRI completed 13 months after presentation (Fig. 2C and D) demonstrated complete resorption of the offending disc. He showed symptomatic improvement at follow-up.

FIG. 2.

Sagittal (A) and axial (B) T2-weighted MR images of the lumbar spine (December 2021). Sagittal (C) and axial (D) T2-weighted MR images of the lumbar spine (January 2023).

Case 3

A 38-year-old male laborer presented to his general practitioner after sudden-onset lumbar back pain and left leg pain after weight lifting. He experienced urinary urge incontinence; however, he had intact saddle sensation and no fecal incontinence. He had no motor impairment. MRI showed a large disc protrusion at L5–S1 (Fig. 3A and B). He was managed conservatively and a repeat MRI study (Fig. 3C and D) demonstrated resorption of the disc protrusion. He had persistent lumbar back pain but no residual radicular pain.

FIG. 3.

Sagittal (A) and axial (B) T2-weighted MR images of the lumbar spine (February 2023). Sagittal (C) and axial (D) T2-weighted MR images of the lumbar spine (July 2023).

Informed Consent

The necessary informed consent was obtained in this study.

Discussion

Landmark studies conducted to understand the role of conservative versus surgical management of LDHs include the Maine Lumbar Spine Study,^9,10 Spine Patient Outcomes Research Trial (SPORT),¹¹ and Leiden–The Hague Spine Intervention Prognostic Study Group.¹² These important trials, conducted more than 15 years ago, allow longitudinal assessment of patient outcomes between intervention groups. All 3 studies found more rapid improvement in patient symptomatology in the groups assigned to surgical intervention;^9–12 however, the longitudinal improvements were similar between groups, suggesting that conservative management is an appropriate management strategy in the long term.

The Maine Lumbar Spine Study was a prospective cohort study published in 1996 that assessed 507 patients with sciatica from Maine. A total of 275 patients were initially treated surgically and 232 were initially treated conservatively. Results showed that patients initially treated surgically reported greater symptomatic improvement than those treated conservatively at the 1-year follow-up.¹⁰ However, long-term data collected at the 10-year follow-up of 400 of the 477 surviving patients from the study found that predominant symptom improvement, lumbar back pain relief, and work and disability status were similar between surgically treated and conservatively treated groups.⁹ Overall satisfaction (71% vs 56%, p = 0.002) and leg pain reduction (56% vs 40%, p = 0.006) were significantly improved in the initially surgically treated group at 10 years of follow-up.⁹ There are numerous limitations of this study, including differences in severity of initial presentation between groups, with the surgically treated group overall experiencing more severe symptoms than the conservatively managed group at presentation. Furthermore, a large proportion of both groups required subsequent operations (25% in each group).⁹

The SPORT study, conducted between 2000 and 2004, was a randomized clinical trial of 501 Americans with lumbar radiculopathy persisting more than 6 weeks and radiologically confirmed LDH.¹³ Patients were drawn from 13 clinics in 11 US states.¹³ Primary outcomes were deviation from baseline health survey and Oswestry Disability Index at 6 weeks and 3, 6, 12, and 24 months.¹³ Secondary outcomes included satisfaction with symptoms, self-reported improvement, sciatica severity, and employment status.¹³ No significant conclusions were able to be elucidated between groups at the 2-year mark, due to significant crossover between groups, with only 50% of patients assigned to surgical intervention proceeding with surgery within 3 months, and 30% of patients from the conservative treatment group having undergone surgery within the first 3 months.¹³ At the 10-year follow-up, an as-treated analysis took place, demonstrating greater improvement in primary outcomes at 4 and 8 years in those who had undergone surgery.¹¹

The Leiden–The Hague Spine Intervention Prognostic Study Group trial assessed 283 Dutch patients from 9 different hospitals between 2002 and 2005 who experienced severe sciatica after failure of 6–12 weeks of conservative management.¹² A total of 141 patients were assigned to early surgical intervention and 142 were assigned to ongoing conservative treatment. At the 1-year follow-up, the overall disability scores were not significantly different between the groups; however, those assigned to the early surgical intervention group reported faster pain relief and perceived recovery.¹² At the 5-year follow-up, outcomes were not statistically significant between surgically treated and nonsurgically treated groups.¹⁴ The only significant predictors of unsatisfactory outcome at 5 years were age (> 40 years; OR 2.42, 95% CI 1.16–5.02), severity of leg pain (visual analog scale score > 70; OR 3.32, 95% CI 1.69–6.54), and McGill affective score (score > 3; OR 6.23, 95% CI 2.23–17.38).¹⁴ The limitations of this study included cohort crossover, with a significant number of patients (39%) who were initially assigned to the conservative management group undergoing surgery within the 1st year of follow-up.¹²

In 2024, the World Federation of Neurosurgical Societies (WFNS) Spine Committee published a consensus statement on the role of surgical intervention for LDHs.⁸ The WFNS recommendations were in keeping with the available literature and common international clinical practices, with surgery indicated only in the case of failed conservative treatment, unrelenting severe pain, or neurological deficit.⁸ While the vast majority of patients with LDHs experience symptomatic improvement within 6–12 weeks,^3,6,7 the duration over which the disc herniations resolve is not yet clearly defined. A 2024 systematic review suggests that the average duration of spontaneous resorption may be between 3 and 6 months.¹⁵

The suggested physiological mechanisms via which herniated lumbar discs resorb include dehydration of extruded tissue,^15,16 mechanical traction,¹⁶ macrophage-mediated phagocytosis,^2,15,16 neovascularization,^2,15,16 inflammatory cascades^2,15,16 and matrix protease activation.¹⁵ As a result of this, herniations that more readily expose the nucleus pulposus to the bloodstream tend to better spontaneously resorb.^16,17 Extrusion of intervertebral disc fragments into the epidural space readily induces neovascularization and subsequently results in increased inflammatory cascades.¹⁶ This in turn induces macrophage-mediated phagocytosis and contributes to resorption of the herniated material.¹⁶ Therefore, disc fragments that are larger,^15–17 sequestered,¹⁶ involve the posterior longitudinal ligament,¹⁷ or are ring enhancing on gadolinium-based MRI^15–17 may represent positive indicators of resorption likelihood. Via different mechanisms, it has been suggested that the integrity of the annulus fibrosus is also viewed as a positive predictive factor for resorption, due to the associated smaller size of protrusion and increased likelihood of dehydration of herniated material.¹⁵

New and emerging conservative management therapies have been trialed for the management of LDH, targeting the suggested physiological mechanisms mentioned above.¹⁸ A 2025 paper reviewed the use of transforaminal, epidural, or intradiscal injection of platelet-rich plasma (PRP) to induce neovascularization and immune response. PRP was found to provide symptomatic relief for patients with radicular pain and improvements in disc height; however, further research is needed to support this treatment.¹⁸

Furthermore, there are multiple contributors to symptomatic improvement, including weight loss, supportive muscle strengthening, activity, and inflammation modulation. Challengingly, clinical symptoms do not always correlate with radiological evidence of neurological compression or with radiological improvement. As such, history taking and clinical examination remain important factors in treatment choice.

Observations

This limited case series demonstrates marked reduction in the size of LDHs with conservative management alone. It is widely accepted that conservative management of LDH is appropriate in the case of radicular pain without motor dysfunction.^1,3,5,6 Furthermore, reduction in radicular pain has been found to be equivalent at 2 years after pain onset between surgically and conservatively treated patients.³ All patients in this case series demonstrated significant symptomatic resolution and radiological improvement to their disc herniations during 2 years of follow-up.

Lessons

This case series highlights the efficacy of conservative management of LDHs from a symptomatic and radiological viewpoint. While this is a very small limited series of 3 patients, the significant radiological and symptomatic improvements are widely applicable and support the practice of conservative management for LDHs among patients presenting with radicular pain in the absence of motor dysfunction, in keeping with WFNS guidelines.

Delayed imaging of LDHs managed conservatively demonstrates spontaneous resolution. Clinical review of patients at these time points confirmed symptomatic improvement. These findings provide imaging evidence of the pathophysiology behind symptom resolution with conservative management of LDH. Conservative management shows excellent resolution of symptomatic pathology and is a safe alternative to surgical intervention.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Jeffree. Acquisition of data: both authors. Analysis and interpretation of data: both authors. Drafting the article: both authors. Critically revising the article: both authors. Reviewed submitted version of manuscript: both authors. Approved the final version of the manuscript on behalf of both authors: Jeffree. Administrative/technical/material support: both authors. Study supervision: Jeffree.

Correspondence

Rosalind L. Jeffree: Alfred Hospital, Monash University, Melbourne, Victoria, Australia. l.jeffree@alfred.org.au.