Engorged venous plexus mimicking adjacent segment disease: Case report and review of the literature.

BACKGROUND: An engorged venous plexus may mimic nerve compression from a herniated disk on the magnetic resonance (MR) studies as they both have similar signal intensities. During a laminectomy, if an engorged venous plexus is encountered instead of a disk herniation, there may be marked unanticipated bleeding. CASE DESCRIPTION: A 58-year-old female who had a prior anterior lumbar interbody fusion later returned with recurrent radiculopathy. Adjacent segment disease from a spinal disk herniation was suspected based on the surgical history, physical examination, and imaging (MRI) findings. Rather than a disk, an engorged venous plexuses (EVP) was encountered intraoperatively.
CONCLUSION: Here, we discussed our findings regarding a lumbar EVP rather than a herniated disk and reviewed the current literature. Although rare, a higher index of suspicion for these vascular malformations based on combined historical information and MRI studies should allow one to better detect and/or anticipate an EVP rather than a routine disk. Copyright:

INTRODUCTION

Patients, who previously had spinal fusions, may develop recurrent lumbar radiculopathy due to adjacent-level disk herniations. However, new adjacent level disease may occasionally be attributed to engorged venous plexuses (EVP) rather than new disk herniations.[2,13,27] Furthermore, EVPs may mimic the symptoms of a new herniated disk and exhibit comparable magnetic resonance imaging (MRI) findings as they both have similar signal intensities.[2,13,17,26] Implementing EVPs among differential diagnostic considerations should enable spine surgeons to better anticipate surgical options and deal with attendant rapid intraoperative blood loss.

Here, we present a 58-year-old female patient who had previously undergone an anterior lumbar interbody fusion (ALIF) but later returned with lumbar radiculopathy. Although adjacent segment disease from a new spinal disk herniation was suspected, particularly based on relatively routine MRI findings, an EVP was discovered intraoperatively and was appropriately excised.

CASE REPORT

Clinical presentation

A 58-year-old female presented with the left lower radiculopathy. Seven years ago, she had a prior L5-S1 ALIF. On examination she had decreased the left lower-extremity 1/5 motor function in the tibialis anterior and extensor hallucis longus distributions, plus a 3/5 in the gastrocnemius. The MRI showed what appeared to be an L4-L5 left-sided disk herniation above the level of her prior fusion (i.e., adjacent L4-L5 segment disk disease) [Figure 1].

Figure 1:

Preoperative T2-weighted magnetic resonance imaging in (a) sagittal and (b) axial views demonstrating the left-sided lateral recess epidural venous plexus at the adjacent level above a fusion mimicking a herniated disk associated with adjacent segment disease.

Operative course

She subsequently underwent an L4-L5 left-sided minimally invasive microdiscectomy. After the laminotomy was completed and nerve root identified, there was a large venous plexus in the nerve root axilla extending ventrally and laterally. This was successfully coagulated with bipolar cautery. Due to the fragility of the plexus and recurrent venous bleeding, multiple hemostatic agents were repeatedly employed to control the bleeding [Figure 2]. After successful cauterization, a thorough examination of the nerve root and disk showed no free fragments or accompanying disk herniations.

Figure 2:

Intraoperative view down the minimally invasive tubular retractor showing (a) the lateral edge of the dural and nerve root with cottonoids and Surgicel® hemostatic material at both the nerve root shoulder and axilla after encountering copious venous bleeding. (b) View of the nerve root after exploration which demonstrated no herniated disk bulge or fragment.

Outcome and follow-up

Postoperatively, she reported immediate improvement of her foot strength and resolution of her left lower extremity and buttock pain. She was discharged on postoperative day 1 after a follow-up MRI confirmed an EVP as the ultimate etiology of her radiculopathy [Figure 3]. Six months later, an examination showed improvement to 4−/5 motor strength in the left tibialis anterior and extensor hallucis longus distributions, plus 4+/5 in the gastrocnemius.

Figure 3:

(a) Preoperative and (b) postoperative T2-weighted magnetic resonance imaging showing resolution of the epidural venous plexus after surgical intervention, confirming its etiology as the source of radiculopathy.

DISCUSSION

A review of the English-language literature demonstrated 25 reports ranging in publication year between 1916 and 2019 that described patients with EVPs who presented similarly to those with lumbar disk herniations [Table 1]. There were a total of 55 patients (range 15–71 years old, 25 males and 24 females) in reports where this information was available. Patients most commonly presented with radiculopathy, followed respectively by myelopathy and cauda equina syndrome. In most cases, the surgeons initially had a preoperative diagnosis other than EVP of herniated disks or lumbar stenosis; other diagnoses were: cauda equina syndrome, tumor, disk bulge, disk fragment, disk prolapse, inferior vena cava (IVC) thrombosis, and vascular origin. MRI findings consisted of herniated disk, dural sac compression, cystic lesion, spondylosis, nerve root compression, hypo-/hyperintense canal lesion, and tortuous/ dilated epidural vein. EVPs were found between T12-S1 and most often occurred between L4-S1 levels. Some of the reports did not opt for surgery, but all cases reported a final or postoperative diagnosis of EVP. Determined causes of the EVPs included: iliac vein stenosis, obesity, lumboperitoneal shunt intracranial hypotension, May-Thurner syndrome, Factor V Leiden mutation, follicular lymphoma, epidural venous throbolith, IVC thrombosis/hypoplasia, previous microdiscectomy, oral contraceptives, and pregnancy. Complications included intraoperative hemorrhage, abortion of the surgical procedure, and residual radiculopathy.

Table 1:

Case reports and series with similar case presentations to lumbar disk herniation.

Location and pathology of EVPs

EVPs are variously attributed to IVC thrombosis/hypoplasia and iliac vein stenosis. EVPs in the lumbar region represent dilations of the vertebral venous plexus system resulting from either increased blood flow or disrupted venous drainage. Notably, EVP at the cervical and thoracic levels have different regional etiologies.[1,13] EVPs are variously attributed to: vascular anomalies such as IVC thrombosis/ hypoplasia, iliac vein stenosis, obesity related IVC obstruction, bladder distention, intracranial hypotension, previous microdiscectomy, coagulopathy, Factor V Leiden mutation, protein C deficiency, Behcet’s, and Budd-Chiari syndrome.[18,22] These conditions block normal venous drainage into or through the IVC, and divert blood flow into collaterals through the vertebral venous plexus; this results in venous engorgement and compression of the thecal sac, nerve roots, or cauda equine.[22]

Encountering unanticipated EVPs during lumbar surgery

Although rare, clinicians should consider EVPs in their differential diagnosis when encountering patients with radiculopathy who also have a history of obesity, vascular conditions, current pregnancy, or are taking oral contraceptives.[18,21,22] Where EVPs are discovered intraoperatively, surgical decompression utilizing electrocautery or hemostatic techniques should be performed to relieve neural compression and radiculopathy.[2,14,15,26] However, avoiding rupture of these vessels is critical as this can contribute to marked increase difficulty in obtaining hemostasis.[2] An immediate postoperative MRI should be used to confirm adequate obliteration of the EVP. Alternatively, there are instances in which medical management with anticoagulation of those with iliac vein or IVC thrombosis will sufficiently resolve signs/ symptoms.[5,10,12,21,22]

Differentiating between EVP and disk on MRI

Differentiating between EVPs and herniated disks can be difficult, as both have similar MRI appearances. However, lumbar disk herniations typically appear hypo/hyperintense on MRI reflecting their water content.[2] EVPs on T1-weighted MRI contain low signal intensity flow voids which mimic solid mass lesions, similar to disk herniations.[19,26] However, thrombosed varices can be hyperintense on both T1- and T2- weighted MRIs (T2WI).[23] EVPs without thrombosis vary in signal intensity depending on the rate of blood flow (e.g., hypointense at normal and hyperintense at slow blood flow rates).[16,17] In this case, the sagittal T2WI showed the EVP at the posterior body of L5 seemingly in continuity with the disk, exhibiting a similar signal intensity as an extruded disk. In retrospect, the homogeneity of signal intensity in our patient’s MRI and the relatively preserved disk height should have raised the possibility that we were dealing with an EVP. Although we were able to control the venous bleeding, cases of extensive intraoperative hemorrhages have been reported.[13]

CONCLUSION

We report a 58-year-old female with a lumbar EVP above the level of a prior L5-S1 ALIF. Although rare, EVP should be anticipated if additional EVP-related MRI findings are present.