Microvascular decompression of a vertebral artery loop causing cervical radiculopathy: illustrative case

Abstract

BACKGROUND

Vertebral artery loops are a rare cause of cervical radiculopathy. Surgical options for nerve root decompression include an anterior or posterior approach, with or without additional microvascular decompression.

OBSERVATIONS

The authors describe a case of a 49-year-old man with a long-standing history of left-sided neck pain and migraines, who was found to have a vertebral artery loop in the left C3–4 neural foramen compressing the left C4 nerve root. The patient underwent a posterior cervical decompression with instrumented fusion and macrovascular decompression of the left C4 nerve root via Teflon felt insertion. In a literature review, we identified 20 similar cases that had also been managed surgically.

LESSONS

Although the anterior approach is more frequently described in the literature, a posterior approach for nerve compression by a vertebral artery loop is also a safe and effective treatment. The authors report the third case of this surgical approach with a good outcome.

An ectatic or tortuous vertebral artery course is a rare cause of cervical radiculopathy.^1–4 These lesions can be congenital or acquired. The natural incidence of vertebral artery loops is estimated to be 1%–5.9%, based on cadaveric studies and retrospective reviews of databases of cervical vessel imaging. It remains unknown how frequently these lesions cause symptomatic compression of the neural elements.^5–7 Symptomatic cases typically present with neck pain, occipitocervical pain, cervical radiculopathy, and, in some cases, vertebrobasilar insufficiency.^2,8,9 Asymptomatic cases can be discovered incidentally on cervical spine imaging after traumatic injury.⁸

First-line therapy with conservative management is unlikely to provide lasting symptom relief. Various surgical options have been described in the literature, including anterior and posterior approaches to the affected level for bony decompression, with or without direct manipulation of the vertebral artery loop away from the affected nerve root using typical techniques for microvascular decompression (MVD).^8,10–14 These approaches also have adapted techniques specific to MVD for trigeminal neuralgia, including Teflon felt and sling transposition.^15–17 Rare cases of vertebral artery transection with end-to-end anastomosis or sacrifice have also been described.^18,19

Illustrative Case

A 49-year-old man presented with a decades-long history of left-sided neck pain and migraines, which had acutely worsened over the past few years. The pain was exacerbated by neck extension and head turn to the contralateral side. On physical examination, the patient had full strength in all extremities with a positive Spurling’s sign and tenderness to palpation over the left midcervical region. The pain was refractory to several lines of conservative management, including physical therapy and peripheral nerve blocks.

Computed tomography (CT) angiography showed a dominant left vertebral artery with an ectatic vertebral artery loop that coursed through the left C3–4 foramen and compressed the anterior aspect of the C4 nerve root (Fig. 1A and B).

FIG. 1.

Preoperative axial (A) and sagittal (B) CT angiography sequences showing a left vertebral artery loop occupying an enlarged left C3–4 neuroforamen.

The risks and benefits of an anterior versus posterior surgical approach were discussed extensively with the patient prior to surgery. To aid in this discussion, a customized three-dimensional model of the patient’s cervical spine was created. On the basis of this model, our surgical team recommended a posterior approach to visualize the affected nerve root before the vertebral artery and minimize direct manipulation of the vertebral artery in our decompression. The patient was counseled that cervical fusion would allow more complete decompression than foraminotomy alone because of the ability to remove the entire facet.

A standard posterior left C3–4 hemilaminectomy, facetectomy, and foraminotomy was performed to visualize the area of neurovascular compression (Video 1). Intraoperative neuronavigation was used to plan a trajectory length and angle that would allow sufficient lateral mass screw purchase after laminectomy. The C4 nerve root was skeletonized from its origin at the thecal sac to the lateral edge of the foramen. A microvascular Doppler probe was used to localize the vertebral artery within the working space. Doppler signals from the vertebral artery could be transduced through the nerve itself. Next, a plane was developed between the nerve root and vertebral artery. The vertebral artery was mobilized inferiorly away from the nerve, and two Teflon pledgets were inserted (Fig. 2). Doppler ultrasound confirmed that arterial signals could no longer be transduced from the nerve. Finally, the posterior fusion was completed at C3–4 with lateral mass screws under navigation, and an autograft was harvested from an iliac crest graft site. A subfascial surgical drain was placed.

FIG. 2.

Intraoperative views of the C4 nerve root before (A) and after (B) MVD involving microdissection of the nerve root away from the vertebral artery and placement of a Teflon interposition graft (asterisk).

VIDEO 1. Clip showing MVD of a vertebral artery loop causing cervical radiculopathy via a posterior cervical approach. Click here to view.

Postoperatively, the patient remained neurologically intact on examination. Postoperative radiographic images confirmed that his cervical fusion instrumentation was in good position (Fig. 3). In the immediate postoperative setting, the patient was unable to tell if his neck pain had improved. At the 1-year follow-up, however, the patient reported that his migraines were less frequent and that his neck pain had entirely resolved.

FIG. 3.

Postoperative anteroposterior (A) and lateral (B) radiographs of the cervical spine showing posterior instrumentation in good position.

Patient Informed Consent

The necessary patient informed consent was obtained in this study.

Discussion

Observations

In a review of the literature, we identified 18 articles describing 20 patients who had undergone surgical management for a vertebral artery loop causing cervical radiculopathy between 1970 and 2021 (Table 1). Summary statistics describing the results of our literature review are shown in Table 2.

TABLE 1.

Literature review of surgical management for symptomatic cases of vertebral artery loops causing neurovascular compression

Authors & Year	Age (yrs), Sex	Presenting Symptoms	Pertinent Exam Findings	Side, Level Affected	Surgical Approach	Outcome at Last FU
Zimmerman & Farrell,197013	50, F	Lt occipital & cervical pain	None	Lt C4–5	Pst decompression	Asymptomatic at 10 mos
Anderson & Shealy, 197014	54, F	Migraines, lt neck & facial pain	None	Lt C3–4	Pst decompression	Asymptomatic at several mos
Sharma et al., 199323	75, F	Occipital neuralgia, cervical myelopathy	Generalized hyperreflexia, spasticity, reduced sensation at/below C2 dermatome	Lt C2–3	Pst decompression & fusion, MVD w/ Surgicel plug	Improvement in symptoms & exam (some residual spasticity) at 1.5 yrs
Satoh et al., 199320	59, F	Lt neck & arm pain	None	Lt central canal C1	Suboccipital decompression, C1 laminectomy	Asymptomatic at 2 yrs
Duthel et al., 199422	37, F	Lt shoulder & arm radicular pain, paresthesias	Diminished lt triceps reflex	Lt C5–6	Anterolat decompression, MVD w/ Teflon	Asymptomatic, normal exam at 3 mos
Detwiler et al. 19988	70, M	Rt neck pain	Rt shoulder girdle muscle atrophy	Rt C3–4	Pst decompression, MVD	Asymptomatic, normal muscle bulk at 2 yrs
Sakaida et al. 200119	62, M	Lt shoulder & arm radicular pain	Decreased biceps jerk, deltoid weakness, paresthesias	Lt C4–5	Anterolat decompression, vertebral loop transection w/ end-to-end anastomosis	Asymptomatic, normal exam at 2 yrs
Korinth & Mull, 200715	68, F	Cervical radiculopathy	Decreased biceps jerk, deltoid	Rt C4–5	Anterolat decompression, MVD w/ Teflon pledget	Asymptomatic, normal exam (FU length not reported)
Dahdaleh et al., 201012	55, M	Presyncope, lt neck & shoulder pain	None	Lt C2–3, C3–4	Pst cervical fusion w/o decompression	Asymptomatic at 6 mos
Hage et al., 201210	27, F	Cervical radiculopathy	Rt finger extension weakness	Rt C6–7	Anterolat decompression, MVD	Asymptomatic, normal exam at 13 mos
Chibbaro et al., 20121	50, F	Cervical radiculopathy	None	Lt C5–6	Anterolat decompression, MVD	Asymptomatic, normal exam at 1 yr
Tandon et al., 201317	52, F	Neck pain, radicular arm pain	None	Rt C4–5	Anterolat decompression, MVD w/ sling	Asymptomatic at 1 yr
Ekși et al., 20166	60, M	Neck pain, lt arm weakness	Lt deltoid & biceps weakness	Lt C5–6	Pst decompression	Improvement in symptoms, change in neurological exam & FU length not reported
Wood et al., 20214	35, M	Cervical radiculopathy	Decreased sensation in C6–8 dermatomes	Lt C5–6	Anterolat decompression, MVD w/ Dacron graft	Asymptomatic, persistent weakness on exam, FU length not reported
	48, F	Lt shoulder pain, cervical radiculopathy	Lt upper-extremity hyperreflexia, positive Spurling’s	Lt C3–4, C4–5	Anterolat decompression, MVD w/ Dacron graft	Asymptomatic, persistent weakness on exam, FU length not reported
Wang et al., 20172	51, F	Cervical radiculopathy	Wrist extensor weakness, reduced sensation	Lt C5–6	Anterolat decompression, MVD w/ Teflon graft	Asymptomatic, residual numbness at 4 mos
	49, F	Lt occiput, neck, biceps pain	Reduced sensation over fingers	Lt C3–4	Anterolat decompression, MVD	Improved symptoms at 6 mos
Venteicher et al., 20197	72, F	Cervical radiculopathy	Deltoid weakness	Rt C4–5	Anterolat decompression, MVD w/ pledget	Asymptomatic, normal exam at 1 yr
Khansuheb et al., 202018	62, F	Cervical radiculopathy	None	Lt C6–7	Endovascular coiling for VA sacrifice	Asymptomatic at 9 mos
Farshad et al., 202221	76, F	Cervical radiculopathy	None	Rt C5–6	Ant discectomy & fusion, foraminotomy w/ VA manipulation	Asymptomatic at 1 yr; cage subsidence on FU imaging

ant = anterior; FU = follow-up; pst = posterior; VA = vertebral artery.

TABLE 2.

Summary of presentation, surgical management, and outcomes of 20 cases of vertebral artery loops causing neurovascular compression

Characteristic	Value
Mean age in yrs	55.6
Female sex	15 (75.0%)
Median duration of symptoms in yrs (IQR)	3 (2–7)
Lt VA affected	14 (70.0%)
Level affected
C1	1 (5.0%)
C2–3	2 (10.0%)
C3–4	5 (25.0%)
C4–5	6 (30.0%)
C5–6	6 (30.0%)
C6–7	2 (10.0%)
Surgical management
Ant approach plus MVD	11 (55.0%)
Pst approach	4 (20.0%)
Pst approach plus MVD	2 (10.0%)
VA sacrifice	2 (10.0%)
Suboccipital craniotomy, partial C1 laminectomy	1 (5.0%)
Status of presenting symptoms, neurological deficits at last FU
Total resolution	14 (70.0%)
Partial resolution	6 (30.0%)
No improvement	0 (0%)

FU = follow-up; IQR = interquartile range; VA = vertebral artery.

From our review, we found that most (75.0%) patients were female. The mean age at the time of surgical consultation was 55.4 years (range 27–76 years). Patients typically presented with a yearslong history of poorly controlled symptoms (median 3 years, interquartile range 2–7 months). Common symptoms included occipital pain, cervical radiculopathy, and neck or arm radicular pain.

On physical examination, 7 patients had a completely normal neurological status (35.0%). Neurological findings encountered on examination included hyperreflexia, cervical myelopathy, radiculopathy, and paresthesias that localized to the affected level on neuroimaging.

Neuroimaging obtained for diagnostic work-up and surgical planning included radiographs, CT myelograms, CT angiograms, magnetic resonance imaging of the cervical spine, and catheter angiography of the vertebral artery. These studies showed that the left vertebral artery was most frequently affected (68.4%). Vertebral artery loops were found between C1 and C7. The most frequently affected levels were C4–5 and C5–6 (n = 6, 30% each).

Our findings are consistent with those of other published studies showing left-sided dominance, presentation within the 5th–6th decades of life, and affects to the C4–5 level.^6,7

In the literature, 9 patients (45.0%) had documented failure of conservative management. Attempted conservative therapies included anti-inflammatories, epidural steroid injections, suprascapular nerve block, acupuncture, trigger point injections, and physical therapy.^{2,4,7,8,15,17,18,20} Three patients (15.0%) had undergone previous surgeries without resolution of symptoms. These surgeries included anterior cervical discectomy and fusion, multiple shoulder surgeries, and posterior cervical foraminotomy.^1,4,7

From our literature review, we found that the majority (n = 11, 55.0%) of patients underwent an anterior approach for bony decompression and MVD.^{1,2,4,7,10,15,17,19–23} In terms of the MVD technique, 6 of these cases used an interposition graft (Teflon or Dacron), and 1 used an allograft sling; in 4 cases, the artery was transpositioned via microdissection alone. Only 1 case underwent additional anterior discectomy and fusion. Seven patients (35.0%) underwent a posterior cervical decompression and fusion procedure, and only 2 underwent concurrent MVD.^{6,8,12–14,22} In 1 case, the artery was dissected away from the nerve. In the second case, a Surgicel plug was placed between the artery and nerve. In the second case, a suboccipital decompression and partial C1 laminectomy was performed for central stenosis caused by an ectatic left vertebral artery.

In rare instances, patients underwent a procedure to either excise the vertebral artery loop entirely or to sacrifice the affected artery (n = 2, 10.0%).^18,19 In each case, a balloon occlusion test was performed beforehand to estimate the safety of vertebral artery temporary occlusion or sacrifice.

Our illustrative case is the third case reported using a posterior approach with MVD. A posterior approach is more likely to require cervical fusion but decompresses the nerve root directly. Advantages of the anterior approach include direct visualization of the vertebral artery anterior to the nerve. The risk of vascular injury from direct manipulation of the vertebral artery versus the risk of nerve root injury by more direct manipulation of the nerve root depends on the surgeon’s expertise and comfort.

All 20 patients identified in the literature tolerated surgery well, with good outcomes in terms of symptom resolution. The median follow-up time after surgical intervention was 12 months (interquartile range 7.5–15.5 months). At the last follow-up, 14 patients (70.0%) had total resolution of all symptoms and physical examination findings, whereas 6 (30.0%) had partial resolution. Among 20 procedures, the only noted complication was cage subsidence in the patient undergoing anterior decompression, MVD, and discectomy with fusion at the affected level.²⁰ In this case, the patent remained asymptomatic, so no reoperation was performed.

Lessons

An ectatic vertebral artery loop is an uncommon cause of cervical radiculopathy but should be considered in the differential diagnosis. An updated literature review of symptomatic cases showed a predominance in women, in the left vertebral artery, and at the C4–5 and C5–6 levels. Surgical management typically involves an anterior or posterior approach to the site of neurovascular compression, with or without MVD.

Although the anterior approach is more frequently described, a posterior approach can also be efficacious. Each case should be addressed according to the surgeon’s comfort, the patient’s preference, and relevant anatomy.

Author Contributions

Conception and design: Abla, Semonche. Acquisition of data: Abla, Semonche, Matles, Chou, Chang. Analysis and interpretation of data: Abla, Semonche, Rinaldo, Lee, Chang. Drafting the article: Abla, Semonche, Rinaldo, Chang. Critically revising the article: Abla, Semonche, Rinaldo, Lee, Matles, Chou, Chang. Reviewed submitted version of manuscript: Abla, Semonche, Rinaldo, Lee, Chang. Approved the final version of the manuscript on behalf of all authors: Abla. Statistical analysis: Semonche. Administrative/technical/material support: Abla, Semonche, Dubnicoff. Study supervision: Abla, Semonche, Chang. Patient care: Matles.

Supplemental Information

Videos

• Video 1. https://vimeo.com/901908520.