Anomalous Vertebral Artery Research Articles

Arthroplasty-CervicalP001 - Double Crush Syndrome of the Vertebral Artery Loop and Foraminal Stenosis Causing Monoparesis

Introduction:To report a case of monoparesis caused by a vertebral artery (VA) anomaly and foraminal stenosis treated with microvascular decompression by the posterior approach.Material and Methods:A 51-year-old man was referred because of a 4-year history of progressive left shoulder pain refractory to other forms of treatment and a 7-month history of arm weakness. Clinical and radiologic evaluation showed an abnormally tortuous loop of left C5-6 cervical foramina with foraminal stenosis causing direct C6 nerve root compression.Results:Left posterior cervical C5-6 facetectomy and fusion was done to decompress the nerve root. The C6 nerve root was identified and well decompressed. The patient’s symptoms resolved after surgery, supporting the posterior decompression of a cervical nerve root compressed by a vertebral artery loop and stenosis for the relief of pain and weakness.Conclusion:Cervical root compression by an anomalous extracranial VA accompanied with foraminal stenosis is a rare cause of radiculopathy and weakness. The best management of such lesions combined with arterial compression and stenosis, is the posterior approach with bony and nerve root decompression.

Atlantoaxial Stabilization Using C1 and C2 Laminar Screw Fixation.

We describe the use of a C1 laminar screw in combination with a C2 laminar screw as a salvage technique to treat two patients, one with persistent first intersegmental artery and the other with vertebral artery occlusion after cervical spine fracture. The combined use of C1 and C2 laminar screws allows for good fixation of the atlantoaxial joint with a lower risk of vertebral artery injury; therefore, it can be an alternative surgical procedure for patients with congenital or traumatic anomalous vertebral artery.

Delineate, Yet not Dread: Anomalous Vertebral Artery in Pediatric Congenital Atlantoaxial Dislocation and Basilar Invagination.

Introduction:The deformed joints seen in congenital atlantoaxial dislocation (CAAD) are often associated with vascular anomalies. It is important to identify these vascular anomalies and address them appropriately without compromising the manipulation and fusion of C1–C2 joints. The small bones in pediatric age group pose an additional challenge.Materials and Methods:Data of fifty-six children with CAAD operated in the last 4 years was analyzed. A computed tomography angiogram was obtained preoperatively to assess for the course of the third segment of vertebral artery (VA). The anomalous VA was dissected and safeguarded during drilling and manipulation of the C1–C2 joints.Results:Of the 112 VAs, 5 were aplastic, 21 crossed the joint posteriorly. Only one patient with reducible atlantoaxial dislocation (AAD) had anomalous VA crossing the joint posteriorly, the remaining VA anomalies were seen with irreducible AAD. Anomalous VA was seen on both sides in 2 patients. The most common anomaly was an inverted VA seen in seven sides. In all patients, the anomalous VA could be dissected and safeguarded without compromising the C1–C2 dissection and manipulation and fusion. In children, even the normal VA may occasionally pose difficulties while manipulation of joints. Challenges while addressing the anomalous and normal VA in pediatric age group have been described. Techniques to overcome these have been discussed.Conclusion:It is important to delineate the anomalous VA. However, the presence of such an artery is not a deterrent to the manipulation of C1–C2 joint, essential for best results. Special attention needs to be paid to the extent of distraction, medial C2 transverse foramen, and dissection/drilling of the area superior to the anomalous VA in the pediatric age group.

Revisiting the differences between irreducible and reducible atlantoaxial dislocation in the era of direct posterior approach and C1-2 joint manipulation.

OBJECTIVE The current management of atlantoaxial dislocation (AAD) focuses on the C1-2 joints, commonly approached through a posterior route. The distinction between reducible AAD (RAAD) and irreducible AAD (IrAAD) seems to be less important in modern times. The roles of preoperative traction and dynamic radiographs are questionable. This study evaluated whether differentiating between the 2 groups is important in today's era. METHODS Ninety-six consecutive patients with congenital AAD (33 RAAD and 63 IrAAD), who underwent surgery through a posterior approach alone, were studied. The preoperative and follow-up clinical statuses for both groups were studied and compared using Japanese Orthopaedic Association (JOA) scores. The radiological findings of the 2 groups were compared, and the intraoperative challenges described. RESULTS A poor preoperative JOA score (clinical status) was seen in one-fifth of patients with IrAAD, although the mean JOA score was nearly similar in the RAAD and IrAAD groups. There was significant improvement in follow-up JOA score in both groups. However, segmentation defects (such as an assimilated arch of the atlas and C2-3 fusion) and anomalous vertebral arteries were found significantly more often in cases of IrAAD compared with those of RAAD. Os odontoideum was commonly seen in the RAAD group. The C1-2 joints were acute in IrAAD compared with RAAD. Preoperative traction in IrAAD resulted in vertical distraction and improvement in clinical and respiratory status. Surgery for IrAAD required much more drilling and manipulation of the C1-2 joints while safeguarding the anomalous vertebral artery. CONCLUSIONS Bony and vascular anomalies were much more common in patients with IrAAD, which made surgery more challenging than it was in RAAD despite similar approaches. An irreducible dislocation seen on preoperative radiographs made surgeons aware of difficulties that were likely to be encountered and helped them to better plan the surgery. Distraction achieved through preoperative traction reaffirmed the feasibility of intraoperative reduction. This made the differentiation between the 2 groups and the use of preoperative traction equally important.

Neurological outcomes following iatrogenic vascular injury during posterior atlanto-axial instrumentation

BackgroundIatrogenic vascular injury is a feared complication of posterior atlanto-axial instrumentation. A better understanding of clinical outcome and management options following this injury will allow surgeons to better care for these patients. The object of the study was to systematically review the neurologic outcomes after iatrogenic vascular injury during atlanto-axial posterior instrumentation. MethodsWe performed a systematic review of the Medline database following PRISMA guidelines. In our analysis, we included any retrospective cohort studies, prospective cohort studies, case reports, cases series, or systematic reviews with patients who had undergone posterior atlanto-axial fusion via screw rod constructs (SRC) or transarticular screws (TAS) that reported a patient with an injury to an arterial vessel directly attributable to the surgical procedure. ResultsSixty cases of vascular injury were reported in 2078 (2.9%) patients over 27 publications. The average age for this patient population was 55.7+/−17.9. Vascular injury following posterior C1/2 instrumentation resulted in ipsilateral stroke in 10.0% (n=6/60) and non-persistent neurologic deficit in 6.7% (n=4/60) of cases with the deficit being permanent (not including death) in 1.7% (n=1/60) of cases. Four patients (6.7%) died. Arteriovenous fistula or pseudoaneurysm occurred in 8.3% (n=5/60) and 3.3% (n=2/60) of cases, respectively. Eight patients (13.3%) underwent endovascular repair of the injury with no permanent deficit. ConclusionNeurological morbidity after iatrogenic vascular injury during posterior C1/2 fixation is higher than previously reported in literature. Some patients may benefit from endovascular treatment. Surgeons should be aware of normal and anomalous vertebral artery anatomy to avoid this potentially catastrophic complication.

A Study Of Variations In The Origin Of Vertebral Artery And Its Clinical Significance

Objectives: An understanding of anatomy is essential to surgeons and knowledge of variations is of practical importance. The anatomic and morphologic variations of great vessels are significant for diagnostic and surgical procedures in the neck and thorax region. Vertebral artery is a branch of subclavian artery, generally arising from the first part of subclavian artery on both the sides. Multiple variations in the origin of vertebral artery have been reported in the literature, most common being directly from the arch of aorta, as a branch of thyrocervical trunk, as a branch of common carotid or external carotid artery. Material and methods: Study was carried out among 30 formalin fixed cadavers procured from Dr. D.Y.Patil Medical College, to note down the variations in the origin of vertebral artery. Results: Origin of right vertebral artery was normal in all the cases while the left vertebral artery showed varied origin. Conclusions: Anomalous vertebral artery origins may predisposes an individual to cerebrovascular disorders.

Neurological Outcomes following Iatrogenic Vascular Injury during Posterior Atlanto-axial Instrumented Fusion

Introduction Iatrogenic vascular injury is a feared complication of posterior atlanto-axial instrumented fusion. A better understanding of clinical course following this injury will allow surgeons to better care for these patients. The object of the study was to systematically review the neurologic outcomes after iatrogenic vascular injury during atlanto-axial posterior instrumented fusion. Methods A systematic review of the PubMed database was performed, following the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The extracted data was recorded in an excel spreadsheet. To be included, the patients must have undergone fusion of the C1/C2 joint using posterior instrumentation with injury to an arterial vessel directly attributable to the surgical procedure. Results 86 incidences of vascular injury were found in 41 articles with 11200 patients. The average age of included patients was 46.4 +/− 24.1 for the screw rod construct (SRC) group and 36.2 +/− 28.2 for the transarticular screw (TAS) group. Vascular injury in SRC cases resulted in ipsilateral stroke in 15.9% ( n = 7/44) of patients and neurologic deficit in 22.7% ( n = 10/44) of patients with a permanent neurologic deficit occurring in 11.4% ( n = 5/44) of patients. Vascular injury following TAS fixation resulted in ipsilateral stroke in 11.9% of cases ( n = 5/42) and neurologic deficit in 23.8% of cases with the deficit being permanent in 9.5% ( n = 4/42) of cases. Death was the result of injury in 9.1% ( n = 4/44) of SRC cases and 7.1% ( n = 3/42) of TAS cases. Conclusions Neurological morbidity after iatrogenic vascular injury during posterior C1/2 fixation is higher than previously reported in literature. There has been no large-volume studies aimed at identifying a rate of neurologic complications after iatrogenic injury. Surgeons should be aware of the normal and anomalous vertebral artery anatomy to avoid this potentially catastrophic injury.

Comprehensive drilling of the C1-2 facets to achieve direct posterior reduction in irreducible atlantoaxial dislocation.

The cause of irreducibility in irreducible atlantoaxial dislocation (AAD) appears to be the orientation of the C1-2 facets. The current management strategies for irreducible AAD are directed at removing the cause of irreducibility followed by fusion, rather than transoral decompression and posterior fusion. The technique described in this paper addresses C1-2 facet mobilization by facetectomies to aid intraoperative manipulation. Using this technique, reduction was achieved in 19 patients with congenital irreducible AAD treated between January 2011 and December 2013. The C1-2 joints were studied preoperatively, and particular attention was paid to the facet orientation. Intraoperatively, oblique C1-2 joints were opened widely, and extensive drilling of the facets was performed to make them close to flat and parallel to each other, converting an irreducible AAD to a reducible one. Anomalous vertebral arteries (VAs) were addressed appropriately. Further reduction was then achieved after vertical distraction and joint manipulation. Adequate facet drilling was achieved in all but 2 patients, due to VA injury in 1 patient and an acute sagittal angle operated on 2 years previously in the other patient. Complete reduction could be achieved in 17 patients and partial in the remaining 2. All patients showed clinical improvement. Two patients showed partial redislocation due to graft subsidence. The fusion rates were excellent. Comprehensive drilling of the C1-2 facets appears to be a logical and effective technique for achieving direct posterior reduction in irreducible AAD. The extensive drilling makes large surfaces raw, increasing fusion rates.

Prevalence of C7 level anomalies at the C7 level: an important landmark for cervical nerve ultrasonography.

Recently, various examination and intervention techniques using cervical nerve ultrasonography have been developed. The specific shapes of the C7 transverse process and vertebral artery in front of the C7 transverse process have become landmarks. To determine the prevalence of anomalies and anomalous vertebral artery entrances at the C7 transverse process. The records of patients who underwent plain or contrast-enhanced neck or cervical spine computed tomography (CT) were reviewed. The examinations were scored for the anomalous presence of anterior tubercles or cervical ribs as well as vertebral artery entrances in the C7 transverse process. The prevalence of anomalies was compared based on patient sex and age. Evaluating the examinations from 2067 patients (1046 men; 1021 women), 1% of patients exhibited an anomalous presence of anterior tubercles, and 0.3% of patients displayed cervical ribs at the C7 transverse process. The prevalence of anomalies process was significantly higher in men aged less than 40 years than in older men (P < 0.001), whereas the prevalence was not higher in women aged less than 40 years than in older women. The prevalence of vertebral artery entry into the C7 transverse foramen was 0.6%. Although an anomalous vertebral artery entry into the C7 transverse foramen was rare, the prevalence of an anomaly at the C7 transverse process was higher in men aged less than 40 years. Therefore, we recommend performing CT in younger men before cervical nerve ultrasonographic intervention to avoid misinterpretations at the cervical level.

CT-based morphometric analysis of C1 laminar dimensions: C1 translaminar screw fixation is a feasible technique for salvage of atlantoaxial fusions.

Background:Translaminar screw fixation has become an alternative in the fixation of the axial and subaxial cervical spine. We report utilization of this approach in the atlas as a salvage technique for atlantoaxial stabilization when C1 lateral mass screws are precluded. To assess the feasibility of translaminar fixation at the atlas, we have characterized the dimensions of the C1 lamina in the general adult population using computed tomography (CT)-based morphometry.Methods:A 46-year-old male with symptomatic atlantoaxial instability secondary to os odontoideum underwent bilateral C1 and C2 translaminar screw/rod fixation as C1 lateral mass fixation was precluded by an anomalous vertebral artery. The follow-up evaluation 2½ years postoperatively revealed an asymptomatic patient without recurrent neck/shoulder pain or clinical signs of instability. To better assess the feasibility of utilizing this approach in the general population, we retrospectively analyzed 502 consecutive cervical CT scans performed over a 3-month period in patients aged over 18 years at a single institution. Measurements of C1 bicortical diameter, bilateral laminar length, height, and angulation were performed. Laminar and screw dimensions were compared to assess instrumentation feasibility.Results:Review of CT imaging found that 75.9% of C1 lamina had a sufficient bicortical diameter, and 63.7% of C1 lamina had sufficient height to accept bilateral translaminar screw placement.Conclusions:CT-based measurement of atlas morphology in the general population revealed that a majority of C1 lamina had sufficient dimensions to accept translaminar screw placement. Although these screws appear to be a feasible alternative when lateral mass screws are precluded, further research is required to determine if they provide comparable fixation strength versus traditional instrumentation methods.

Commentary on: "Vertebral Artery Anomalies at the Craniovertebral Junction: A Case Report and Review of the Literature".

The authors report a case of an unstable C1 fracture with magnetic resonance imaging demonstrating rupture of the transverse ligament. Posterior vertebral artery anomaly in the form of a right persistent first intersegmental artery was identified preoperatively in the region of the right posterior C1–C2 lateral mass interval. The surgical plan was altered to avoid the anomalous vertebral artery and the patient was successfully managed with an uncomplicated occiput to C3 instrumentation and fusion procedure. The literature review includes a discussion of the work by Uchino et al who have reported a persistent first intersegmental artery in up to 3.2% of normal subjects and an overall prevalence of craniovertebral junction vertebral artery anomalies of 5%.1 This article is an important addition to the existing literature as it highlights the relatively high prevalence of vertebral artery anomalies at the craniovertebral junction. The case described involves an aberrant vertebral artery with an anomalous course located posteriorly between the C1 and C2 lateral masses. This particular vertebral artery anomaly poses great risk to the conventional placement of C1 lateral mass screws through previously described techniques involving the exposure of the C1 lateral mass or placement of the screw through the C1 posterior ring. The anomaly was identified preoperatively by computed tomography angiography in this case, and intraoperative vertebral artery injury was avoided. The utility of the use of routine of preoperative imaging studies to demonstrate the course of the bilateral vertebral arteries before any planned exposure of the craniocervical junction is clearly implied in this case report. The significance of this case report and review of the literature lies in the identification of the increased risk of complication involving vertebral artery injury through a routine posterior cervical spine surgical exposure. Much of the existing literature involving vertebral artery injury in cervical spinal surgery has focused on injuries incurred with anterior cervical spinal surgical procedures. Tortuous anterior course of the vertebral artery in the subaxial cervical spine has been well described by Curylo et al in approximately 5.5% of subjects.2 Multiple reports of injury to the vertebral artery during anterior cervical decompression surgery exist in the literature.3 Five studies reported rates of 0.10 to 1.96%, depending on the type of anterior cervical spine procedure.3 There remains, however, a paucity of literature with respect to vertebral artery injury incurred with a posterior cervical surgical exposure. Molinari et al recently reported vertebral artery injury in two cases involving a persistent first intersegmental artery in the region of C1–C2. Both injuries were incurred with routine posterior exposure of the C1–C2 anatomy. A review of the existing literature demonstrates few publications on this topic.3 The authors should be applauded for this work, which raises a greater sense of awareness as to the increased potential for vertebral artery injury during posterior cervical spine exposure in the region of the craniocervical junction. Their work underscores the need for thorough preoperative evaluation of the course of the vertebral artery before performing operative procedures on the cervical spine.

Vertebral artery anomalies at the craniovertebral junction in the US population.

Retrospective review. To evaluate the prevalence of anatomical variations of the vertebral artery at the craniovertebral junction and the posterior arch of the atlas in the US population. Recent studies from Asia have reported a 5% to 10% prevalence of a persistent first intersegmental vertebral artery and 1% to 2% prevalence of a fenestrated artery. These anomalous vertebral artery courses lie directly over the starting point for atlas lateral mass screw insertion. The relatively high reported prevalence of these anomalies suggests that routine preoperative computed tomographic angiogram be considered prior to upper cervical fixation. We have not observed this anomaly as commonly as reported. The authors analyzed the records of 975 patients from a level I trauma center and adjacent university hospital who underwent computed tomographic angiography to evaluate the incidence of anomalous variations in the third segment of the vertebral artery. These results were compared with similar studies performed in Korea and Japan. The mean age of the patients was 52.9 years. The ethnic distribution of the patients was as follows: 69.3% of the patients were Caucasian, 11% Asian, 10.8% African American, and 6% Hispanic. The prevalence of a persistent intersegmental artery was 0.01% (1/975); a fenestrated vertebral artery was 0.01% (1/975); and origin of a posterior inferior cerebellar artery was 0.4% (4/975). The incidence of these anomalies was significantly lower than those previously published from Korea and Japan. Vertebral artery course anomalies in the upper cervical spine were rare (0.42%) in our patient population. This finding contrasts with recent published reports from Asia, citing as high as a 10% rate of vertebral artery presence over the starting point for C1 lateral mass screw insertion. On the basis of the infrequent occurrence of this anomaly, we do not recommend routine computed tomographic angiography when planning upper cervical instrumentation. N/A

Intraoperative Computed Tomography With an Integrated Navigation System in Stabilization Surgery for Complex Craniovertebral Junction Malformation

This study was designed to report our preliminary experience with stabilization procedures for complex craniovertebral junction malformation (CVJM) using intraoperative computed tomography (iCT) with an integrated neuronavigation system (NNS). To evaluate the workflow, feasibility and clinical outcome of stabilization procedures using iCT image-guided navigation for complex CVJM. The stabilization procedures in CVJM are complex because of the area's intricate geometry and bony structures, its critical relationship to neurovascular structures and the intricate biomechanical issues involved. A sliding gantry 40-slice computed tomography scanner was installed in a preexisting operating room. The images were transferred directly from the scanner to the NNS using an automated registration system. On the basis of the analysis of intraoperative computed tomographic images, 23 cases (11 males, 12 females) with complicated CVJM underwent navigated stabilization procedures to allow more control over screw placement. The age of these patients were 19-52 years (mean: 33.5 y). We performed C1-C2 transarticular screw fixation in 6 patients to produce atlantoaxial arthrodesis with better reliability. Because of a high-riding transverse foramen on at least 1 side of the C2 vertebra and an anomalous vertebral artery position, 7 patients underwent C1 lateral mass and C2 pedicle screw fixation. Ten additional patients were treated with individualized occipitocervical fixation surgery from the hypoplasia of C1 or constraints due to C2 bone structure. In total, 108 screws were inserted into 23 patients using navigational assistance. The screws comprised 20 C1 lateral mass screws, 26 C2, 14 C3, or 4 C4 pedicle screws, 32 occipital screws, and 12 C1-C2 transarticular screws. There were no vascular or neural complications except for pedicle perforations that were detected in 2 (1.9%) patients and were corrected intraoperatively without any persistent nerves or vessel damage. The overall accuracy of the image guidance system was 98.1%. The duration of interruption during the surgical process for the iCT was 8±1.5 minutes. All patients were clinically evaluated using Nurick grade criteria and for neurological deficits 3 months after surgery. Twenty-one patients (91.3%) improved by at least 1 Nurick grade, whereas the grade remained unchanged in 2 (8.7%) patients. Craniovertebral stability and solid bone fusion was achieved in all patients. NNS was found to correlate well with the intraoperative findings, and the recalibration was uneventful in all cases and had an accuracy of 1.8 mm (range, 0.6-2.2 mm). iCT scanning with integrated NNS was found to be both feasible and beneficial in the stabilization procedures for complex CVJM. In this unusual patient population, the technique seemed to be of value for negotiating complex anatomy and for achieving more control over screw placement.

Vertebral artery anomaly and injury in spinal surgery.

Study Design Systematic review. Study Rationale The purpose of this review is to further define the published literature with respect to vertebral artery (VA) anomaly and injury in patients with degenerative cervical spinal conditions. Objectives In adult patients with cervical spine or degenerative cervical spine disorders receiving cervical spine surgery, what is the incidence of VA injury, and among resulting VA injuries, which treatments result in a successful outcome and what percent are successfully repaired? Materials and Methods A systematic review of pertinent articles published up to April 2013. Studies involving traumatic onset, fracture, infection, deformity or congenital abnormality, instability, inflammatory spinal diseases, or neoplasms were excluded. Two independent reviewers assessed the level of evidence quality using the Grades of Recommendation Assessment, Development and Evaluation criteria; disagreements were resolved by consensus. Results From a total of 72 possible citations, the following met our inclusion criteria and formed the basis for this report. Incidence of VA injuries ranged from 0.20 to 1.96%. None of the studies reported using preoperative imaging to identify anomalous or tortuous VA. Primary repair and ligation were the most effective in treating VA injuries. Conclusion The incidence of VA injuries in degenerative cervical spinal surgery might be as high as 1.96% and is likely underreported. Direct surgical repair is the most effective treatment option. The most important preventative technique for VA injuries is preoperative magnetic resonance imaging or computed tomography angiographic imaging to detect VA anomalies. The overall strength of evidence for the conclusions is low.

Zone II Coverage in the Context of an Anomalous Left Vertebral Artery

Anomalous left vertebral arteries are uncommon occurring in roughly 4% of the population. Typically of no clinical consequence, they become very important in the context of endovascular repair of an arch aneurysm with Zone II coverage, requiring a deliberate strategy tailored to the anatomy. We describe three cases of aortic arch aneurysms with an anomalous vertebral artery, and discuss the different approaches available depending upon the anatomy.

Scapular Pain Caused By an Anomalous Vertebral Artery

Scapular Pain Caused By an Anomalous Vertebral Artery A 39-year-old woman presented to my office with neck pain after a motor vehicle accident. The neck pain described radiated into her left periscapular region, consistent with a c4 dermatome. The patient did not demonstrate weakness or numbness during the physical examination and is an otherwise healthy middle-aged female.

Optimal measurement for "posterolateral protrusion" of the vertebral artery at the craniovertebral junction using computed tomography angiography.

Purpose:Among extraosseous abnormalities of the vertebral artery (VA) at the craniovertebral junction (CVJ), available evidence regarding “posterolateral protrusion,” the VA running distant from the groove over the superior surface of the posterior arch of the atlas, is limited. The purpose of this study was to determine the optimal measurement to indicate posterolateral protrusion of the VA.Materials and Methods:Computed tomography angiography (CTA) images of 40 consecutive patients with cervical disease were reviewed. Ultimately, 66 arteries were included in this study. Five parameters predicted to indicate posterolateral protrusion of the VA were defined (A–E) and measured by two surgeons twice over a 2-week interval. Intraclass correlation coefficients (ICC) were used to examine intra-observer reproducibility and inter-observer reliability. Receiver operating characteristic (ROC) curve analysis was performed to determine the most optimal parameter to predict posterolateral protrusion of the VA.Results:Excellent inter-observer reliability and intra-observer reproducibility were obtained for all parameters (ICC = 0.87-0.99). Among them, parameter A, defined as the maximal length from the outer surface of the VA to the outer surface of the posterior arch of the atlas, was most accurately described posterolateral protrusion of the VA. The optimal cut-off value of parameter A obtained with ROC curves was 8.3 mm (sensitivity 97.5%, specificity 100%).Conclusions:The measurement in this study can quantitatively evaluate the posterolateral protrusion of the VA. Before posterior surgery at the CVJ, pre-operative CTA can help surgeons detect anomalous VA and reduce the risk of intra-operative VA injury.

Operative nuances to safeguard anomalous vertebral artery without compromising the surgery for congenital atlantoaxial dislocation: untying a tough knot between vessel and bone

Stabilization of the craniovertebral junction (CVJ) by using lateral masses requires extensive dissection. The vertebral artery (VA) is commonly anomalous in patients with congenital CVJ anomaly. Such a vessel is likely to be injured during dissection or screw placement. In this study the authors discuss the importance of preoperative evaluation and certain intraoperative steps that reduce the chances of injury to such vessels. A 3D CT angiogram was obtained in 15 consecutive patients undergoing surgery for congenital atlantoaxial dislocation. The course of the VA and its relationship to the C1-2 facets was studied in these patients. The anomalous VA was exposed intraoperatively, facet surfaces were drilled in all, and the screws were placed according to the disposition of the vessel. A skeletal anomaly was found in all 10 patients who had an anomalous VA. Four types of variations were noted: 1) the first intersegmental artery in 5 patients (bilateral in 1); 2) fenestration of VA in 1 patient; 3) anomalous posterior inferior cerebellar artery crossing the C1-2 joint in 1 patient; and 4) medial loop of VA in 5 patients. The anomalous vessel was dissected and the facet surfaces were drilled in all. The C-1 lateral mass screw was placed under vision, taking care not to compromise the anomalous vessel, although occipital screws or sublaminar wires were used in the initial cases. A medial loop of the VA necessitated placement of transpedicular or C-2 lateral mass screws instead of pars interarticularis screws. The anomalous vessel was injured in none. Preoperative 3D CT angiography is a highly useful method of imaging the artery in patients with CVJ anomaly. It helps in identifying the anomalous VA or its branch and its relationship to the C1-2 facets. The normal side should be surgically treated and distracted first because this helps in opening the abnormal side, aiding in dissection. In the posterior approach the C-2 nerve root is always encountered before the anomalous vessel. The defined vascular anatomy helps in choosing the type of screw. The vessel should be mobilized so as to aid the drilling of facets and the placement of screws and spacers under vision, avoiding its injury (direct or indirect) or compression. With these steps, C1-2 (short segment) rigid fusion can be achieved despite the presence of anomalous VA.

Anomalous Vertebral Artery Injured During Anterior Cervical Discectomy

Case report. To describe treatment and injury prevention from discectomy with a newly described vertebral artery anomaly. Cervical segment vertebral artery (VA) anomalies of various types are described with the least common type involving erosion into the vertebral body medial to the uncinate process. The morphology of these includes return to the lateral position at the disc level where they have been immune to anterior cervical discectomy surgery. This case report demonstrates the first published account of a medial vertebral artery adjacent to a disc and injured by discectomy alone.VA injury is a serious complication with a significant percentage of neurological injury and death. The lesion was missed by a neuroradiologist reading the thin slice preoperative magnetic resonance imaging (MRI) study. Subsequently, 6 additional specialists blinded to the study all missed the diagnosis. The difficulty of diagnosis is similar to another study where 6 neuroradiologists missed 100% of diagnosis of similar lesions on 49 MRI studies. A 55-year-old female with left-sided weakness in the neck and shoulder and C5-C6 stenosis underwent anterior cervical microdiskectomy. When a fine-tipped drill bit was used to smoothen a slight convexity on the C6 endplate, high pressure and volume hemorrhage started. After tamponade, the patient was brought directly to angiography and CT scanning. Several days later, the patient underwent endovascular evaluation and stenting for a pseudoaneurysm. No neurological deficits occurred from the complication. Cervical discomfort and headache symptoms partially improved. A previously undescribed medial vertebral artery anomaly involving the cervical disc level is documented with near disastrous hemorrhage from simple anterior discectomy. The rate of preoperative diagnosis from MRI scans is dismal. Preoperative studies should be scrutinized with suspicion and any questionable area studied further regardless of a negative diagnosis. N/A.

A novel sling technique for microvascular decompression of a rare anomalous vertebral artery causing cervical radiculopathy

Cervical radiculopathy secondary to compression from congenital anomalous vertebral arteries (VAs) is a known entity. Patients present with a variety of symptoms ranging from upper-extremity numbness to true occipital neuralgia. Treatment options for extracranial tortuous VAs include conservative management or some form of surgical microvascular decompression (MVD). The authors report on a patient with a congenital anomalous VA loop causing cervical nerve root compression. Successful MVD was conducted with relief of the patient's symptoms. A novel sling technique was used for mobilization of the VA. To the authors' knowledge, this is the first MVD described utilizing this technique.