Lumbar Disk Prolapse Complicated With an Intradural Nerve Sheath Tumor at the Same Level. A Rare Co-Incidence

Abstract

Lumbar disk disease is a common cause of low back pain and radicular pain. Nerve sheath tumors of lower lumbar spine may also present with similar symptoms. The association of a lumbar disk prolapse with a concomitant schwannoma at the same level is rare and cannot be suspected clinically. Only six similar cases have been described in literature. Contrast-enhanced magnetic resonance imaging is necessary to confirm the co-existing pathologies. We describe a case of low back pain with radicular pain due to lumbar disk prolapse at L4 − 5 with a concurrent intradural nerve sheath tumor at the same level. The patient underwent a successful discectomy and total excision of the L4–5 intradural schwannoma without any additional neurological deficit.

Keywords

lumbar disk prolapse - intradural schwannoma - same level - nerve sheath tumor - intradural lesion

Introduction

Herniated lumbar disk is a common cause of low back ache with radicular pain.[1] [2] Benign nerve sheath tumors or spinal schwannoma of the lumbar spine can produce similar symptoms.[2] [3] Schwannomas comprise approximately 15% of all spinal tumors.[4] The simultaneous occurrence of a lumbar disk prolapse and a schwannoma at the same level is extremely rare and cannot be suspected or diagnosed on clinical examination alone. Plain magnetic resonance imaging (MRI) could be confusing; a high degree of suspicion and the use of contrast-enhanced MRI help in diagnosis. We describe a case of coexisting lumbar disk disease and intradural schwannoma, operated in the same sitting and discharged without any motor deficit.

Case Report

A 41-year-old male presented with low back pain radiating to the right lower limb for a duration of 2 months. A month after the onset of symptoms, the pain started to radiate to the left lower limb as well.

There was no history of limb weakness, sensory loss, or bladder or bowel involvement. On examination, the patient had restricted straight leg raising to 45 degrees on the left side. The muscle tone was normal bilaterally; motor power was 5/5 in both lower limbs, with normal deep tendon reflexes at the knee and ankle. He had a subjective loss of pain and touch sensation by approximately 30% in bilateral L5 dermatome, with preserved joint position sense. Initially a plain MRI of the lumbar spine revealed a prolapsed lumbar disk at L4 − 5 ([Figs. 1B] and [2B]) along with a small intradural lesion at the same level. The intradural lesion was isointense on T1-weighted images ([Fig. 1A]) and hyperintense on T2-weighted images ([Figs. 1B] and [2A]) .Based on the initial MRI findings, a contrast-enhanced sequence was ordered. The intradural lesion measured approximately 12 mm in its maximum dimension and showed bright contrast enhancement ([Figs. 3] and [4]). Based on the MRI findings, a diagnosis of intradural schwannoma at L4 − 5 was made. The patient was advised to undergo L4 − 5 discectomy along with resection of the intradural pathology to completely alleviate his symptoms. The patient underwent a partial L4–5 laminectomy and L4–5 discectomy, followed by exposure of the intradural tumor ([Fig. 5A]) and its total excision in the same sitting ([Fig. 5B]). The histopathology of the resected specimen was reported as schwannoma. Postoperatively, the patient has been symptom free at 6-month follow-up.

Fig. 1 Sagittal T1-(A) and T2-weighted(B) MR image of the lumbar spine showing prolapsed disk at L4 − 5 and a well-defined T1 isointense and T2 hyperintense intradural lesion (arrow) suggestive of a tumor.

Fig. 2 Axial T2-weighted image of lumbar spine showing the hyperintense intradural tumor (A, arrow) and the disk prolapse (B, arrow) at the same level.

Fig. 3 Sagittal contrast image of lumbar spine showing the prolapsed disk at L4 − 5 and the intradural brightly enhancing lesion at the same level (arrow).

Fig. 4 (A, B) Axial MR contrast images showing the brightly enhancing intradural lesion (arrow) with the disk prolapse at the same level.

Fig. 5 (A) Intraoperative image showing the nerve sheath tumor (arrow) and (B) nerve roots after complete tumor resection.

Discussion

Patients with lumbar disk bulge or prolapse most often present with low back pain, with or without radicular symptoms. These symptoms may persist for months or years in the absence of neurological deficits, and such patients may continue with conservative treatment. During the initial months of low back pain or radicular pain, patients without any motor or sensory deficit, may not even undergo any radiological investigation including MRI, to confirm the diagnosis of a lumbar disk disease. A small nerve sheath tumor developing at the same level may cause aggravation of symptoms necessitating medical attention. The vice versa may also be true: small nerve sheath tumors of the lower lumbar spine may present with symptoms similar to those of lumbar disk disease.[4] These tumors are slow-growing and follow a long, indolent course before symptoms begin to appear.[5] The added pathology of a disk prolapse may cause the patient to seek medical attention while the tumor is still small in size. It is however extremely rare for a lumbar disk prolapse to present with a co-existing schwannoma at the same level. According to our literature search, six cases of lumbar disk disease with a lumbar intradural schwannoma co-existing at the same level have been reported.[2] [4] [5] [6] [7] A table with the previous reported cases is shown depicting the age, sex, level of the lesion, and tumor size ([Table 1]).

Table 1 Table depicting previous reported cases of lumbar disc prolapse with intradural schwannoma at the same level

	Author, year	Patient Age/Sex	Spinal level of lesions	Size of schwannoma in maximum dimension
1	Khorram and Watson 2024[2]	62/M	L 1–2	15 mm
2	Fujii et al 2019[7]	45/M	L 2–3	10 mm
3	Pan et al 2016[4]	67/M	L 3–4	14 mm
4	Baek et al 2014[5]	71/F	L 4–5	Reported as small incidental finding
5	Liu et al 2007[6]	51/M	L 2–3	9 mm
6	Albert 1988[11]	52/M	L 4–5	12 mm

It is almost impossible to clinically diagnose co-existing lumbar disk prolapse and a small intradural nerve sheath tumor at the same level as both may present with similar symptoms and clinical findings.[4] [5] [8] The plain MRI of spine performed to diagnose a suspected lumbar disk prolapse may exhibit an abnormal signal in the intradural space at the same level in the rare event of an associated intradural pathology. Therefore, it is important to order a contrast-enhanced MRI of the spine to confirm the morphology of the intradural lesion.

MRI of the spine may occasionally be misleading in these circumstances, as a posteriorly migrated disk fragment may also show peripheral enhancement on contrast imaging.[4] [9] A differential diagnosis of an intradural or extradural tumor has to be included in such cases.[4] [7] [10] However, in our case there was no continuity between the lesions. The homogenously enhancing and completely intradural lesion, suggested by the cerebrospinal fluid (CSF) signals around it, was seen as distinctly separate from the disk prolapse at that level.

Once diagnosed with coexisting lumbar disk and intradural neurofibroma, surgical decompression can be performed in the same sitting. Although previously reported cases were all operated in a single sitting, none of the authors recommended any particular sequence for surgery. Fujii et al[7] performed discectomy first followed by intradural tumor resection at L2–3, whereas Khorram and Watson[2] performed tumor resection first, followed by discectomy at L1–2. We suggest doing the discectomy first before resecting the intradural mass at lower lumbar lesions. The reason being, compression on the dural sac and the nerve root caused by the disk prolapse is better appreciated with the intact dura rather than after CSF is released on opening the dura. Also, there would be no further retraction of the dura once the disk has been removed, thus avoiding strain on the sutures if intradural pathology was addressed first. As in our case, most dual pathologies presented with a very small intradural tumor, which does not hinder dural retraction or compromise the nerve roots during discectomy. On dural retraction during discectomy, the wide CSF space at L4–5 level with relatively fewer nerve roots easily accommodates the small and soft nerves sheath tumor without compromising other roots. However, at the L1–2 level, where the canal is relatively narrow, the cauda equina roots along with the schwannoma occupy a greater volume of the intradural space. Dural retraction may be difficult or cause neural compromise and it may be prudent to operate on the intradural pathology first and thereafter address the disk prolapse.

Conclusion

When MRI findings are suggestive of a disk prolapse or a migrated disk fragment along with another noncontiguous lesion at the same level, it is important to get a contrast-enhanced scan to confirm the morphology of the lesion. Contrast MRI is also essential when the imaging study is conflicting with the clinical presentation. Surgery should be performed in the same sitting for co-existing pathologies at the same level. In the lower lumbar spine, discectomy should be performed prior to dealing with intradural lesion. At the L1–2 level, where CSF space is relatively less and dural retraction may be an issue, intradural tumor resection takes precedence.

Conflict of Interest

None declared.

Patient Consent

Patient consent was obtained with due care to maintain his/her privacy.

Authors' Contribution

All authors contributed substantially to the write-up of the article. All authors reviewed and approved the final draft of the manuscript, and all take the responsibility of the content of publication.

• References

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Publication History

Article published online:
28 January 2026