Misplaced intraspinal venous stent causing cauda equina syndrome: illustrative case

Vaibhavi Shah Department of Neurosurgery, Stanford University Medical Center, Stanford, California
School of Medicine, Stanford University, Stanford, California; and

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Thomas Johnstone Department of Neurosurgery, Stanford University Medical Center, Stanford, California
School of Medicine, Stanford University, Stanford, California; and

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Ghani Haider Department of Neurosurgery, Stanford University Medical Center, Stanford, California

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Neelan J Marianayagam Department of Neurosurgery, Stanford University Medical Center, Stanford, California

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Martin N Stienen Department of Neurosurgery & Spine Center of Eastern Switzerland, Cantonal Hospital, St. Gallen, Switzerland

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Venita Chandra School of Medicine, Stanford University, Stanford, California; and

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Anand Veeravagu School of Medicine, Stanford University, Stanford, California; and
Department of Neurosurgery & Spine Center of Eastern Switzerland, Cantonal Hospital, St. Gallen, Switzerland

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BACKGROUND

Endovenous stents for deep venous thrombosis treatment can be unintentionally placed in the spinal canal, resulting in neurological deficit.

OBSERVATIONS

The authors report the case of a patient presenting to our institution with intraspinal misplacement of an endovenous stent, resulting in cauda equina syndrome. The authors also performed a systematic literature review, evaluating the few previously reported cases. This review was performed according to the updated Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. In four of five cases describing stent misplacement into the spinal canal, the authors report that only anteroposterior monoplanar imaging modalities were utilized for venous localization and stent deployment. The anteroposterior plane cannot assess the relative depth of structures, nor can it distinguish between superimposed structures well. Therefore, the use of biplanar imaging should at least be considered before stent deployment, as intraspinal stent placement can lead to disastrous consequences.

LESSONS

This report should serve as an impetus for the use of biplanar or three-dimensional imaging modalities for iliac venous stent placement. Additionally, this work should increase spine surgeons’ awareness about management and operative techniques when faced with this complication.

ABBREVIATIONS

CT = computed tomography; DVT = deep venous thrombosis; PRISMA = Preferred Reporting Items for Systematic Reviews and Meta-Analyses

BACKGROUND

Endovenous stents for deep venous thrombosis treatment can be unintentionally placed in the spinal canal, resulting in neurological deficit.

OBSERVATIONS

The authors report the case of a patient presenting to our institution with intraspinal misplacement of an endovenous stent, resulting in cauda equina syndrome. The authors also performed a systematic literature review, evaluating the few previously reported cases. This review was performed according to the updated Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. In four of five cases describing stent misplacement into the spinal canal, the authors report that only anteroposterior monoplanar imaging modalities were utilized for venous localization and stent deployment. The anteroposterior plane cannot assess the relative depth of structures, nor can it distinguish between superimposed structures well. Therefore, the use of biplanar imaging should at least be considered before stent deployment, as intraspinal stent placement can lead to disastrous consequences.

LESSONS

This report should serve as an impetus for the use of biplanar or three-dimensional imaging modalities for iliac venous stent placement. Additionally, this work should increase spine surgeons’ awareness about management and operative techniques when faced with this complication.

ABBREVIATIONS

CT = computed tomography; DVT = deep venous thrombosis; PRISMA = Preferred Reporting Items for Systematic Reviews and Meta-Analyses

Endovenous stenting has become the standard of care for iliofemoral venous outflow obstruction in patients with deep venous thrombosis (DVT) because of its safety, minimal morbidity, short hospital stay, and faster recovery.1 However, there have been previous reports of a rare but serious complication of this stenting procedure.2–5 These stents can be unintentionally placed in the spinal canal, resulting in neurological deficit. The common iliac vein connects to the iliolumbar vein and then to the epidural venous plexus superiorly. This plexus connects directly to the spinal canal in the L4–5 region. When these stents are placed in the iliac system, they can migrate up through this venous tract directly into the spinal canal, which is the supposed method of injury in these previously reported cases.6,7

We report the case of a patient presenting to our institution with intraspinal misplacement of an endovenous stent, resulting in cauda equina syndrome, and who was managed surgically. This rare clinical presentation has been sparsely reported in the literature. Thus, we provide a systematic literature review of all previously reported cases. This review aims to comprehensively compare the operative courses and outcomes so that future providers can appropriately manage this unique complication.

Illustrative Case

History and Presentation

A 68-year-old male with a previous medical history of chronic obstructive pulmonary disease and extensive DVT in the lower left extremity who underwent venous stenting of the left common iliac vein while under general anesthesia at another facility. After the procedure, he developed sudden-onset progressive bilateral lower-extremity numbness and weakness. He was transferred to our institution for emergency management of this neurological condition. The patient was admitted and on examination was found to have sensory deficits at approximately the L1 sensory level and below, bilateral lower-extremity weakness with foot drop, urinary retention, and saddle anesthesia consistent with cauda equina syndrome.

Preoperative Imaging

Computed tomography (CT) scanning of the abdomen and pelvis revealed misplacement of the vascular stent from the left common iliac vein through the left L5–S1 neural foramen into the spinal canal (Fig. 1). The tip of the stent terminated at the superior endplate of the L4 vertebra. There was severe stenosis of the spinal canal at the L4 and L5 levels. The diagnosis of an extradural foreign body, epidural hematoma, and cauda equina syndrome was confirmed.

FIG. 1
FIG. 1

CT of the misplaced endovenous stent, which was inserted through the L5–S1 neural foramen and into the spinal canal, sagittal (A), coronal (B), and axial (C) views.

Surgical Procedure

The patient was emergently taken to the operating room, and an L4–5 laminectomy was conducted. Intraoperatively, an extremely taut and immobile dura was observed. There was a large epidural hematoma at the lateral and ventral aspects of the spinal canal. Intradural hemorrhage was also noted. To achieve complete exposure of the left L5 neural foramen and better mobilize the stent, the procedure was extended to include a partial S1 laminectomy. The left S1 nerve root was gently medialized and preserved, but the left L5 nerve root was found to be severely injured and transected. With hematoma removal and meticulous dissection, the thecal sac was progressively mobilized until the intraspinal part of the stent was exposed. It was in the extradural space, in direct contact with the medial and inferior aspect of the left L5 pedicle and extending into the left L5 neural foramen. Also, the right L5 nerve root was injured, resulting from the contralateral extension at the level of the L4–5 disc space, where the stent led to ventral compression of the dura and neural structures (Fig. 1). The dura appeared to be under great pressure, likely resulting from suspected intradural hemorrhage. After exposure, the surgical strategy included manual compression of the stent from both sides, to induce its collapse, which then allowed the dura to reexpand under less tension. The stent was mobilized and dissected away from the dura on both sides and cut at the level of the neural foramen. It was then removed in one piece from the ventral aspect of the spinal canal. The stent was truncated at the extraforaminal segment. The length of the removed intraspinal part of the stent was approximately 4 cm (Fig. 2). The stent appeared to have traversed the iliac vein through the venous plexus via the neural foramen, terminating in the epidural veinous complex. The venous plexus through which the stent migrated had clotted and closed off. No leakage of cerebrospinal fluid was noted. The remaining hematomas were evacuated, hemostasis was achieved, and the wound was closed in a standard manner.

FIG. 2
FIG. 2

Excised spinal portion of the vascular stent, approximately 4 cm in length.

Postoperative Course and Outcome

Postoperative CT revealed expected findings after the L4–S1 laminectomy, decompression, and removal of the endovenous stent (Fig. 3). There were no fractures or misalignments of the lumbar spine.

FIG. 3
FIG. 3

Lateral scout view of the postoperative CT, showing no evidence of residual stent material.

Immediate postoperative neurological examination demonstrated weakened knee flexion and extension (3/5) on the left side and 0/5 dorsiflexion, plantarflexion, and extensor hallucis longus function bilaterally. The patient was able to tolerate standing three minutes at a time and could ambulate forward and take side steps. He continued to take part in physical therapy sessions in the hospital and was discharged to an acute rehabilitation facility on postoperative day 7.

At the 1-month postoperative follow-up appointment, he reported continued weakness, although much improved, in the bilateral lower extremities. The patient could ambulate with the aid of a walker. Bilateral lower-extremity plantar and dorsiflexion continued to be severely weakened. He reported swelling and burning sensation on his left foot when walking and was self-catheterizing.

Patient Informed Consent

The necessary patient informed consent was obtained in this study.

Discussion

Study Description

A systematic review of the literature was conducted to identify articles related to misplaced venous stents that had migrated to the spinal canal, causing cauda equina syndrome. This review was performed according to the updated Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The review was not registered and had no formal prepared protocol.

A comprehensive literature search of PubMed was conducted up until March 10, 2023. The search strategy consisted of the following key words: “venous,” “stent,” “misplacement,” “spinal” in various AND/OR combinations and tenses. Manual combing of references and citations was also conducted to ensure there were no missed articles. Articles were imported into Zotero and reviewed.

All studies detailing this very rare complication of venous stent migration into the spinal canal were included. To be comprehensive, no exclusion criteria were applied. Two independent reviewers verified the relevance of all articles.

Given the nature of the articles, data were extracted from all parts of the article (text, tables, images). No quantitative analysis was conducted; the findings of each case study were qualitatively described and compared.

The review produced 97 article results. Of the 97 screened, 11 progressed to full-text review. Of these articles, 4 were eligible and relevant to the case report at hand. The PRISMA search strategy is outlined in Fig. 4. Case reports were from France, Belgium, Finland, and the United States (Arizona).

FIG. 4
FIG. 4

PRISMA search strategy.

Results of the data extraction can be found in Table 1 and are further discussed below.

TABLE 1

Literature review of all cases of accidental intraspinal stent placement

VariableWhiting et al., 20185 Schwartz et al., 20203 Di Santo et al., 20202 Zaldivar-Jolissaint et al., 20204 Shah et al., 2023
Age/sex67/M42/M20/F58/F68/M
Neural foramen impactedRt L5–S1 & lt S1–2Lt S1Lt L5Lt L4Lt L5
Underlying conditionPADIVC atresiaBilat PEDVTDVT
Vein leading to spinal canalLt external iliac veinLt paravertebral plexusLt common iliac veinLt common iliac veinLt common iliac vein
Exam findingsRt foot drop, rt L5 radiculopathy, CESLt DF (1/5), lt L5 radiculopathyLt EHL paralysis, decreased LLE sensationLt L4/5 radiculopathy, lt foot drop (1/5)Bilat foot drop, bilat LE pain, CES
Op conducted to retrieve stentL5–S1 decompression & fusionLt L5 hemilaminectomyLt L5–S1 hemilaminectomy + facetectomyL3–4 laminectomyL4–S1 laminectomy
Postop examBilat DF 2/5, pain resolved, CES resolvedLt DF 4/5, pain resolvedImproved sensationLt DF 4/5, pain resolvedBilat leg weakness improved
Imaging used for stent placementNot reportedMonoplanar (ant-pst angiography)Monoplanar (ant-pst radiography)Monoplanar (ant-pst fluoroscopy)Monoplanar (ant-pst angiography)
Time to op (after misplacement)DaysHrsDaysHrsHrs

ant-pst = anteroposterior; CES = cauda equina syndrome; DF = dorsiflexion; EHL = extensor hallucis longus; IVC = inferior vena cava; LLE = left lower extremity; PAD = peripheral artery disease; PE = pulmonary embolism; PF = plantar flexion.

Observations

Malposition of a venous stent through the common iliac vein into the spinal canal can be a devastating complication, leading to severe neurological sequelae such as cauda equina syndrome. Several articles report similar complications, each with different clinical presentations, however.2–5 We aimed to describe our unique operative experience and to systematically review the available literature regarding similar cases, so that other surgeons might be wary of this hazardous complication if confronted with a similar clinical presentation.

Table 1 reviews all known previous reports of venous stent migration into the spinal canal. It is interesting to note that these reports all occurred after 2017, with four cases occurring in 2020. This increase likely corresponds to the increased use of venous stenting over the past decade.8 Four of the five patients were male and over the age of 40 years old. In all cases, the stent had migrated into the spinal canal through veins on the left side, with four of the five cases occurring through the left iliac vein complex, and one occurring through the left paravertebral plexus. In each case, lumbar and lumbosacral sensory and motor levels were affected, leading to classic neurological deficits and/or cauda equina syndrome. Common symptoms included lower-extremity weakness, foot drop, saddle anesthesia, urinary retention and incontinence, and debilitating back pain.

Regarding the time to decompression and stent removal, two patients underwent emergency stent removal, whereas two other reports described an interval of several days between accidental intraspinal stent placement and removal. This time interval seems to depend primarily on the rapidity of the development of neurological symptoms. Patient outcomes after decompression have been variable, with partial recovery in some cases.

Lessons

In every case describing stent misplacement or migration into the spinal canal so far, the authors reported that only anteroposterior monoplanar imaging modalities were utilized for venous localization and stent deployment. Although the anteroposterior plane is critical for identifying the correct vascular segment for iliac venous stent deployment, it cannot assess the relative depth of different structures, nor can it discriminate between superimposed structures well. Similarly, many modalities (e.g., fluoroscopy, radiography) cannot assess collateral vessels traveling primarily in the anteroposterior plane. This limitation creates a sense of false security; a stent may look like it is placed correctly even though it is impinging on critical neurological structures. Therefore, the use of biplanar imaging should at least be considered before stent deployment, as intraspinal stent placement is possible—as evident from the five reported cases—and can lead to disastrous consequences. In fact, each case report that diagnosed and later surgically corrected stents misplaced in the spinal canal used biplanar or three-dimensional imaging to localize the stent and affected structures.

We present a case in which a stent intended for the left common iliac vein was misplaced into the spinal canal, which can largely be attributed to the use of monoplanar fluoroscopic imaging during stent deployment, preventing adequate depth assessment and stent localization. The misplaced stent led to cauda equina syndrome due to epidural and potentially intradural hemorrhage and severe nerve injury requiring emergency spinal decompression with stent removal. In this paper, we compiled the previous rare reports of this complication and detailed the various presentations that patients can have in the emergency department. This study is limited by the number of formally reported cases, as there may be more variable incidences of this presentation that have not been published and could inform management. However, given the literature, we aimed to provide the aforementioned recommendations on multiview imaging. This review should alert other providers to the potential development of this serious complication and serve as an impetus for the use of biplanar or three-dimensional imaging modalities for iliac venous stent placement. Additionally, this work, by sharing our own institutional experience and highlighting previous cases, should increase awareness in spine surgeons about management and operative techniques when faced with this complication.

Author Contributions

Conception and design: Shah, Haider, Veeravagu. Acquisition of data: Shah, Johnstone, Haider, Chandra, Veeravagu. Analysis and interpretation of data: Shah, Johnstone, Haider, Marianayagam, Stienen, Veeravagu. Drafting the article: Shah, Johnstone, Haider, Veeravagu. Critically revising the article: Shah, Johnstone, Haider, Marianayagam, Stienen, Chandra. Reviewed submitted version of manuscript: Shah, Johnstone, Haider, Marianayagam, Stienen, Veeravagu. Approved the final version of the manuscript on behalf of all authors: Shah. Administrative/technical/material support: Haider. Study supervision: Haider, Stienen.

References

  • 1

    Breen K Role of venous stenting for venous thromboembolism. Hematology Am Soc Hematol Educ Program. 2020;2020(1):606611.

  • 2

    Di Santo M, Belhaj A, Rondelet B, Gustin T Intraspinal iliac venous stent migration with lumbar nerve root compression. World Neurosurg. 2020;137:372375.

  • 3

    Schwartz C, Hafez A, Lönnrot K, et al. Microsurgical removal of a misplaced intraspinal venous stent in a patient with inferior vena cava atresia. J Neurosurg Spine. 2020;32(5):763767.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Zaldivar-Jolissaint JF, de Schlichting E, Haller C, Morard M Foot drop after iliocaval vein stenting: radicular syndrome from stent misplacement in spinal canal. World Neurosurg. 2020;137:4345.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Whiting BB, Mulholland CB, Daniels L, Kakarla UK, Theodore N, Snyder LA Misplacement of stent into epidural venous plexus with resultant cauda equina syndrome and open surgical treatment: a case report. Oper Neurosurg (Hagerstown). 2018;15(3):E23E26.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Jasani V, Jaffray D The anatomy of the iliolumbar vein. A cadaver study. J Bone Joint Surg Br. 2002;84(7):10461049.

  • 7

    Kunakornsawat S, Prasartritha T, Korbsook P, Vannaprasert N, Tungsiripat R, Tansatit T Variations of the iliolumbar and ascending lumbar veins. J Spinal Disord Tech. 2012;25(8):433436.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Oropallo A, Andersen CA Venous Stenting. In: StatPearls. StatPearls Publishing; 2023. Accessed March 30, 2023. http://www.ncbi.nlm.nih.gov/books/NBK574515/

    • PubMed
    • Export Citation
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  • FIG. 1

    CT of the misplaced endovenous stent, which was inserted through the L5–S1 neural foramen and into the spinal canal, sagittal (A), coronal (B), and axial (C) views.

  • FIG. 2

    Excised spinal portion of the vascular stent, approximately 4 cm in length.

  • FIG. 3

    Lateral scout view of the postoperative CT, showing no evidence of residual stent material.

  • FIG. 4

    PRISMA search strategy.

  • 1

    Breen K Role of venous stenting for venous thromboembolism. Hematology Am Soc Hematol Educ Program. 2020;2020(1):606611.

  • 2

    Di Santo M, Belhaj A, Rondelet B, Gustin T Intraspinal iliac venous stent migration with lumbar nerve root compression. World Neurosurg. 2020;137:372375.

  • 3

    Schwartz C, Hafez A, Lönnrot K, et al. Microsurgical removal of a misplaced intraspinal venous stent in a patient with inferior vena cava atresia. J Neurosurg Spine. 2020;32(5):763767.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Zaldivar-Jolissaint JF, de Schlichting E, Haller C, Morard M Foot drop after iliocaval vein stenting: radicular syndrome from stent misplacement in spinal canal. World Neurosurg. 2020;137:4345.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Whiting BB, Mulholland CB, Daniels L, Kakarla UK, Theodore N, Snyder LA Misplacement of stent into epidural venous plexus with resultant cauda equina syndrome and open surgical treatment: a case report. Oper Neurosurg (Hagerstown). 2018;15(3):E23E26.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Jasani V, Jaffray D The anatomy of the iliolumbar vein. A cadaver study. J Bone Joint Surg Br. 2002;84(7):10461049.

  • 7

    Kunakornsawat S, Prasartritha T, Korbsook P, Vannaprasert N, Tungsiripat R, Tansatit T Variations of the iliolumbar and ascending lumbar veins. J Spinal Disord Tech. 2012;25(8):433436.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Oropallo A, Andersen CA Venous Stenting. In: StatPearls. StatPearls Publishing; 2023. Accessed March 30, 2023. http://www.ncbi.nlm.nih.gov/books/NBK574515/

    • PubMed
    • Export Citation

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