Risk factor analysis and decision-making of surgical strategy for V3 segment anomaly: significance of preoperative CT angiography for posterior C1 instrumentation

Clinical and Radiological Outcomes in C2 Recapping Laminoplasty for the Pathologies in the Upper Cervical Spine

OBJECTIVE

To evaluate C2 muscle preservation effect and the radiological and clinical outcomes after C2 recapping laminoplasty.

METHODS

Fourteen consecutive patients who underwent C2 recapping laminoplasty around C1-2 level were enrolled. To evaluate muscle preservation effect, the authors conducted a morphological measurement of extensor muscles between the operated and nonoperated side. Two surgeons measured the cross-sectional area (CSA) of obliquus capitis inferior (OCI) and semispinalis cervicis (SSC) muscle before and after surgery to determine atrophy rates (ARs). Additionally, we examined range of motion (ROM), sagittal vertical axis (SVA), neck visual analogue scale (VAS), Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) score to assess potential changes in alignment and consequent clinical outcomes following posterior cervical surgery.

RESULTS

We measured the CSA of OCI and SSC before surgery, and at 6 and 12 months postoperatively. Based on these measurements, the AR of the nonoperated SSC was 0.1% ± 8.5%, the AR of the operated OCI was 2.0% ± 7.2%, and the AR of the nonoperated OCI was -0.7% ± 5.1% at the 12 months after surgery. However, the AR of the operated side's SSC was 11.2% ± 12.5%, which is a relatively higher value than other measurements. Despite the atrophic change of SSC on the operated side, there were no prominent changes observed in SVA, C0-2 ROM, and C2-7 ROM between preoperative and 12 months postoperative measurements, which were 11.8 ± 10.9 mm, 16.3° ± 5.9°, and 48.7° ± 7.7° preoperatively, and 14.1 ± 11.6 mm, 16.1° ± 7.2°, and 44.0° ± 10.3° at 12 months postoperative, respectively. Improvement was also noted in VAS, NDI, and JOA scores after surgery with JOA recovery rate of 77.3% ± 29.6%.

CONCLUSION

C2 recapping laminoplasty could be a useful tool for addressing pathologies around the upper cervical spine, potentially mitigating muscle atrophy and reducing postoperative neck pain, while maintaining sagittal alignment and ROM.

Presurgical imaging of the subscapular artery with three-dimensional-computed tomography angiography: Application to harvesting subscapular system free-flaps

A subscapular system free-flap is extremely useful for maxillofacial reconstruction since it facilitates the simultaneous harvesting of multiple flaps using one subscapular artery (SSA) alone. However, cases of aberrations in the SSAs have been reported. Therefore, the morphology of SSA needs to be confirmed preoperatively before harvesting the flaps. Recent developments in imaging, such as three-dimensional (3D) computed tomography angiography (3D CTA), facilitate obtain high-quality images of blood vessel images. Therefore, we examined the utility of 3D CTA in navigating the course of the SSA before harvesting subscapular system free-flaps. We examined the morphology and aberrations of the SSA using 39 sides of the 3D CTA data and 22 sides of Japanese cadavers. SSAs can be classified into types S, I, P, and A. Type S SSAs are significantly long (mean length = 44.8 mm). Types I and P SSAs have short mean lengths, measuring ≤2 cm in approximately 50% of cases. In type A, the SSA is absent. The frequency of types S, I, P, and A SSAs were 28.2%, 7.7%, 51.3%, and 12.8%, respectively. Type S can be advantageous for harvesting the SSA in subscapular system free-flaps, because it is significantly longer. In contrast, types I and P might be dangerous because their mean lengths are shorter. In type A, caution is needed not to injure the axillary artery because the SSA is absent. When surgeons need to harvest the SSA, presurgical 3D CTA is recommended.

Prevalence of anatomical variations at the suboccipital (V3) segment of the vertebral artery: a systematic review

BACKGROUND AND OBJECTIVE

A recent meta-analysis on the incidence of iatrogenic injury to the VA has revealed that patients with variant anatomy are more prone to iatrogenic injury. Therefore, this review is designed to investigate the incidence of variations in the suboccipital component of the vertebral artery in different population groups according to the available literature.

METHODS

This systematic review was conducted according to PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The review is based on a comprehensive and extensive search of PubMed, Google Scholar, and ResearchGate. The following search terms were used: "vertebral artery" AND "suboccipital segment" AND "anomalies/anatomical variations of the V3 segment." Reference lists of all extracted articles were also extensively searched for references to any further relevant publications.

RESULTS

A total of 17 papers met the inclusion criteria. The 17 studies corresponded to a total of 10,820 patients. A persistent first intersegmental artery was registered in 1.8% (197 out of 10,820) of the patients. Extradural PICA origin was observed in 1.6% (175 out of 10,820) of the patients. Fenestration was detected in 0.7% (72 out of 10,820) of the patients.

CONCLUSION

The authors summarize the incidence of vascular variation at the suboccipital segment of the VA in different population groups across the Asian, European, American, and African continents. Awareness of the extent of possible anatomical variation will help interpret radiographs, which will enhance the identification of vascular pathologies and reduce the risk of iatrogenic injury.

Prevalence of Vertebral artery anomaly in upper cervical and its surgical implications: a systematic review

BACKGROUND

The presence vertebral artery (VA) abnormalities in the upper cervical may be a potential cause of catastrophic complication in the posterior approach of the upper cervical spine surgery. The aim of this study was to demonstrate the real incidence of the V3 segment anomaly in patients who need upper cervical surgery, and tried to find out the risk factors of V3 segment anomaly to evaluate the necessary of computed tomographic angiography (CTA) for upper cervical surgery.

METHOD

This systematic review was conducted following the preferred reporting items for systematic reviews and meta-Analyses (PRISMA). Retrospective studies and reports of case series involving human subjects with data on anomalies of vertebral artery in upper cervical spine were included. Data on the prevalence of persistent first intersegmental artery (PIA), fenestration of the VA (FA), posterior inferior cerebellar artery (PICA) were extracted.

RESULTS

A total of 16 articles involving 5927 subjects met the inclusion criteria. The total incidence of V3 segment anomaly in the patients with bony abnormalities was 25.9% (74/286): PIA was 17.5%, FA was 6.6% and PICA was 1.8%. The total incidence of V3 segment anomaly in the patients without bony abnormalities was 2.7% (152/5671): PIA was 1.76%, FA was 0.4% and PICA was 0.5%. The total incidence of V3 segment anomaly in Asian population without bony abnormalities was 5.8%, while in European and American population was 0.8 and 0.6%, respectively.

CONCLUSION

Patients with bone abnormalities are high risk factor for VA abnormalities, CTA is of paramount importance to evaluate the variant VA anatomy. However, regarding to the low incidence of V3 variation in normal population, we do not recommend preoperative CT angiography as mandatory part of preoperative.

An alternative way of C1 screwing: Supralaminar C1 lateral mass screws

Study Design:

This study involves literature review, technical note, and case series.

Objectives:

The objectives were to analyze indications and contraindications, advantages, and disadvantages for C1 lateral mass screw (LMS) insertion above or partially above the arch, to descript technical features, and to give examples of the practical application of this technique and investigated its safety.

Methods:

A literature review was carried out in English and Russian in PubMed, Google Scholar, and eLibrary databases. We selected four patients, treated in our clinic, which was carried out partially supralaminar C1 LMS.

Results:

Only three descriptions of supralaminar C1 LMS were found in the literature. Four adult patients underwent posterior C1–C2 screw fixation with C1 LMS along the superior edge of the C1 arch at our clinic. Partially supralaminar C1 screws were inserted on one of the sides due to the difficulties of using classical techniques. The main reasons for supralaminar screw fixation were narrow C1 lamina, hypertrophied venous plexus, and intraoperative failures of classic techniques application (broken screw trajectory, profuse venous bleeding from the plexus). The average follow-up time for the patients was 2.7 years, no complications were noted, and all had a satisfactory spinal fusion.

Conclusions:

The proposed types of C1 LMS above or partially above the C1 arch can be useful alternative method of C1 screwing in selected patients. Indications for the use of the supralaminar C1 LMS method can be narrow C1 posterior arch and pedicle, pronounced C1-C2 venous plexus, some V3 segment anomalies at C1 level, small arthritic inferior part of lateral mass, and intraoperative failures of classic techniques application.

The assessment of the frequency and arrangement of the subsegmental branches of V3 using computed tomography angiography

Background

The frequency and arrangement of the subsegmental branches of the third portion of the vertebral artery (V3) have been assessed in small samples by autopsy, but they have not been assessed by computed tomography angiography (CTA). To determine the frequency and arrangement of subsegmental branches of V3 by CTA and to analyze the interrelationships among frequency, arrangement, sex, and side-to-side.

Methods

First, the radiology records of 668 consecutive patients who underwent cervical or craniocervical CTA scans from October 1, 2017 to October 31, 2019 were retrospectively retrieved. Second, the four demarcation points were ascertained to define the three subsegments by reviewing the resource images, namely, the vertical portion of V3(V3v), horizontal portion of V3(V3h), and extradural portion of V3(V3e). Then, the numerical value and the location of the bifurcating branch in each subsegment of V3 were recorded. Third, the frequency and arrangement of the branches was assessed, and the relationships between sex, laterality and frequency and arrangement were analyzed as well as the interobserver performance.

Results

On the left, 25%, 20.21%, and 6.59% were the frequencies of one branch in the V3v, V3h, and V3e, and 1.05%, 0.00%, and 0.45% were the frequencies of two branches, respectively. On the right, 25.04%, 17.07%, and 6.44% were the frequencies of one branch in the V3v, V3h, and V3e, and 1.04%, 0.3%, and 0.15% were the frequencies of two branches, respectively. There were no differences between the side-to-side and numerical values of the branches according to the t-test (P=0.4341, P=0.7968), and there were no differences between the side-to-side variable, sex variable and number of branches according to the t-test (P=0.4474, P=0.3593). There were no differences between the side-to-side and eight arrangements (permutation of 000; 100; 110; 111; 010; 011; 001; 101) by using the two-sample KS test (P=0.942), and there were no differences between sex and the eight arrangements according to the two-sample KS test (P=0.9973, P=0.8519). The interobserver reliability was excellent (Spearman's ranked correlation: 0.9927).

Conclusions

The frequency and arrangement of V3 subsegmental branches could be displayed by source imaging with CTA, and there were no significant differences according to the sex or side of the individual. It was imperative to acquaint the subsegmental branches before the operation involving V3 in the craniocervical junction to determine the surgical approach and reduce bleeding during the surgical procedures.

Influence of dynamic neck motion on the clinical usefulness of multi-positional MRI in cervical degenerative spondylosis

PURPOSE

The purpose of this study was to find out additional indications for multi-positional MRI in cervical degenerative spondylosis (CDS) patients.

MATERIAL AND METHODS

A total of 63 patients with cervical spondylotic myelopathy that underwent multi-positional MRI and X-ray were included. Muhle's grade, C2-7 angle, and C7 slope were measured. Patients were assigned to the stenosis group (Group S) when Muhle's grades were increased by more than two or maximum grade was reached. Other patients were assigned to the maintenance group (Group M). Receiver operating characteristic (ROC) analysis was performed. Statistical significance was accepted for p values of < 0.05.

RESULTS

A total of 24 patients were assigned to the S group and 39 patients to the M group. Mean C2-7 angle difference in extension (eC27A) between S and M groups was 10.97° (p = 0.002). The mean inter-group difference between C2-7 angle in extension and neutral positions (e-nC27A) was 14.39° (p = 0.000). Mean C7 slope difference in neutral position was  - 6.53° (p = 0.002). Based on areas under ROC curves (AUCs), e-nC27A, eC27A, and negative C7 slope had AUCs of 0.934 (95% CI 0.876-0.992), 0.752 (95% CI 0.624-0.880), and 0.720 (95% CI 0.588-0.851), respectively. The optimal cutoff value of e-nC27A was 15.4 degrees, which had a diagnostic accuracy of 88.9%.

CONCLUSION

Multi-positional MRI helps to find dynamic cord compressive lesion in CDS patients. The higher eC27A, e-nC27A values and smaller C7 slope were found to increase the likelihood of cervical dynamic stenosis. Among other factors, we recommend multi-positional MRI before surgery especially when a patient's e-nC27A is > 15.4 degrees.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

A new nomenclature system for the surgical treatment of cervical spine deformity, developing, and validation of SOF system

PURPOSE

To develop and assess the reliability of new nomenclature system that systematically organizes osteotomy techniques and briefly describes the surgical approach, the surgical sequence, and the fixation technique for cervical spine deformity (CSD).

METHODS

We developed a new classification system (SOF system) for CSD surgery that describes the sequence of surgical approach (S), the grade of osteotomy (O), and the information of fixation (F) using alphanumeric codes. Twenty CSD osteotomies (8 anterior osteotomies, 12 posterior osteotomies) were included in this study to evaluate the inter- and intra-observer agreement based on operation records. Six observers performed independent evaluations of the operation records in random order. Each observer described 20 CSD surgeries using the SOF system twice (> 30 days between assessments) based on operation records to validate SOF system.

RESULTS

Overall agreement (among all six observers at the initial assessment) on the anterior and posterior osteotomy was ICC = 0.96 and ICC = 0.91, respectively. Overall agreement (repeat observations after at least 30 days) on the anterior and posterior osteotomy was ICC = 0.96 and ICC = 0.91, respectively. This data showed that both inter- and intra-observer agreement revealed 'excellent'.

CONCLUSION

This study introduces the SOF system of the CSD surgery to understand the surgical sequence, the type of osteotomy and the fixation techniques. The investigation of the inter- and intra-observer agreement revealed 'excellent agreement' for both anterior and posterior osteotomies. Thus, SOF system can provide a consistent description of the various CSD surgeries and its use will provide a common frame for CSD surgery and help communicate between surgeons.

[Treatment of locked lower cervical fracture and dislocation with anterior cervical fusion and internal fixation combined with the release of interlocking facet through the Luschka joint and anterior lamina space]

Objective

To investigate the effectiveness of treatment of locked lower cervical fracture and dislocation with anterior cervical fusion and internal fixation combined with the release of the interlocking facet through the Luschka joint and anterior lamina space.

Methods

Twelve patients with lower cervical interlocking fracture and dislocation were analyzed retrospectively between January 2013 and June 2015. There were 7 males and 5 females, aged 25-59 years with an average age of 38.4 years. The disease duration was 9.6 hours to 100 days with an average of 7.3 days. There were 8 cases of unilateral locking and 4 cases of bilateral locking; 4 cases of old injury and 8 cases of fresh injury. The injured segments were 2 cases of C _{3, 4}, 5 cases of C _{4, 5}, 3 cases of C _{5, 6}, and 2 cases of C _{6, 7}. According to Meyerding classification, there were 9 cases of grade Ⅰ and 3 cases of grade Ⅱ. According to the functional classification of American Spinal Injury Association (ASIA), there were 2 cases of grade C, 6 cases of grade D, and 4 cases of grade E. The interlocking facet was released through the Luschka joint and anterior lamina space, and the anterior cervical fusion and internal fixation were used to treat the fracture and dislocation of the lower cervical spine. The recovery of spinal cord function was judged by the functional classification of ASIA; visual analogue scale (VAS) score, neck disability index (NDI) score, modified Japanese Orthopaedic Association (m-JOA) score were used to evaluate the clinical efficacy; the Cobb angle of fusion segment were observed by X-ray film. The intervertebral bone graft fusion was evaluated at 6 months after operation.

Results

The average operation time was 78.30 minutes, the average intraoperative blood loss was 167.30 mL, and the average postoperative drainage volume was 58.12 mL. No blood transfusion was given during or after operation. During the operation, there was no accidental injury of large blood vessels, esophagus, and trachea; no laryngo edema, dysphagia, hoarseness, and cerebrospinal fluid leakage occurred after operation; no spinal cord injury or nerve root injury aggravated; the incision healed by first intention, and no infection occurred. All 12 cases were followed up 15-20 months, with an average of 16.5 months. The symptoms and function of the nerve injury were significantly improved when compared with that before operation. Re-examination of the cervical spine X-ray film at 6 months after operation showed that the Cage or bone graft was not displaced or broken, the screw was not loosened or detached, and the intervertebral graft fusion rate was up to 100%. At last follow-up, the ASIA grade, Cobb angle of fusion segment, neck pain VAS score, m-JOA score, and NDI score were significantly improved when compared with preoperative one ( P<0.05).

Conclusion

The effectiveness of treatment of locked lower cervical fracture and dislocation with anterior cervical fusion and internal fixation combined with the release of the interlocking facet through the Luschka joint and anterior lamina space is clear, which not only can make the injured segment get satisfactory reduction, immediate stability and reconstruction, and full decompression, but also can effectively prevent the secondary injury of spinal cord.

Intraoperative surveillance of the vertebral artery using indocyanine green angiography and Doppler sonography in craniovertebral junction surgeries

OBJECTIVE

The authors sought to evaluate the usefulness of indocyanine green (ICG) angiography and Doppler sonography for monitoring the vertebral artery (VA) during craniovertebral junction (CVJ) surgery and compare the incidence of VA injury (VAI) between the groups with and without the monitoring of VA using ICG angiography and Doppler sonography.

METHODS

In total, 344 consecutive patients enrolled who underwent CVJ surgery. Surgery was performed without intraoperative VA monitoring tools in 262 cases (control group) and with VA monitoring tools in 82 cases (monitoring group). The authors compared the incidence of VAI between groups. The procedure times of ICG angiography, change of VA flow velocity measured by Doppler sonography, and complication were investigated.

RESULTS

There were 4 VAI cases in the control group, and the incidence of VAI was 1.5%. Meanwhile, there were no VAI cases in the monitoring group. The procedure time of ICG angiography was less than 5 minutes (mean [± SD] 4.6 ± 2.1 minutes) and VA flow velocity was 11.2 ± 4.5 cm/sec. There were several cases in which the surgical method had to be changed depending on the VA monitoring. The combined use of ICG angiography and Doppler sonography was useful not only to monitor VA patency but also to assess the quality of blood flow during CVJ surgery, especially in the high-risk group of patients.

CONCLUSIONS

The combined use of ICG angiography and Doppler sonography enables real-time intraoperative monitoring of the VA by detecting blood flow and flow velocity. As the arteries get closer, they provide auditory and visual feedback to the surgeon. This real-time image guidance could be a useful tool, especially for high-risk patients and inexperienced surgeons, to avoid iatrogenic VAI during any CVJ surgery.

SOF System; A New Nomenclature System for the Surgical Techniques of Cervical Spine Deformity

Although cervical spinal deformity (CSD) can have a profoundly negative impact on an individual’s quality of life and there have been many advances in surgical treatment of CSD in recent years, there exists no comprehensive classification system of surgical treatment that categorizes anterior and posterior surgery separately according to the grade of surgery. The objective of this study is to introduce the new classification system of various surgical treatments for CSD. We developed a new classification system (SOF system) for CSD surgery that describes the sequence of surgical approach (S), the grade of osteotomy (O), and the information of fixation (F) using alphanumeric codes. This new classification system can provide a consistent description of the various osteotomies performed in CSD surgery. Especially, regarding research, there has been a clear benefit to this classification. Having a standardized classification that allows for common frame for cervical deformity correction surgery, communication between surgeons and the evaluation of the CSD surgeries make it possible to conduct global comparative research about surgical outcome.

Analysis of Risk Factors for Posterior C1 Screw-Related Complication: A Retrospective Study of 358 Posterior C1 Screws

BACKGROUND

Although C1 screw fixation is becoming popular, only a few studies have discussed about the risk factors and the patterns of C1 screw complications.

OBJECTIVE

To investigate the incidence of C1 screw complications and analyze the risk factors of the C1 screw complications.

METHODS

A total of 358 C1 screws in 180 consecutive patients were analyzed for C1 screw complications. Screw malposition, occipital neuralgia, major complications, and total C1 screw complications were analyzed.

RESULTS

The distribution of C1 screw entry point is as follows: inferior lateral mass, 317 screws (88.5 %); posterior arch (PA), 38 screws (10.7 %); and superior lateral mass, 3 screws (0.8 %). We sacrificed the C2 root for 127 screws (35.5 %). C1 instrumentation induced 3.1 % screw malposition, 6.4 % occipital neuralgia, 0.6 % vascular injury, and 3.4 % major complications. In multivariate analysis, deformity (odds ratio [OR]: 2.10, P = .003), traumatic pathology (OR: 4.97, P = .001), and PA entry point (OR: 3.38, P = .001) are independent factors of C1 screw malposition. C2 root resection can decrease the incidence of C1 screw malposition (OR: 0.38, P = .012), but it is a risk factor of occipital neuralgia (OR: 2.62, P = .034). Advanced surgical experience (OR: 0.09, P = .020) correlated with less major complication.

CONCLUSION

The incidence of C1 screw complications might not be uncommon, and deformity or traumatic pathology and PA entry point could be the risk factors to total C1 screw complications. The PA screw induces more malposition, but less occipital neuralgia. C2 root resection can reduce screw malposition, but increases occipital neuralgia.

Evaluation and Surgical Planning for Craniovertebral Junction Deformity

Craniovertebral junction (CVJ) deformity is a challenging pathology that can result in progressive deformity, myelopathy, severe neck pain, and functional disability, such as difficulty swallowing. Surgical management of CVJ deformity is complex for anatomical reasons; given the discreet relationships involved in the surrounding neurovascular structures and intricate biochemical issues, access to this region is relatively difficult. Evaluation of the reducibility, CVJ alignment, and direction of the mechanical compression may determine surgical strategy. If CVJ deformity is reducible, posterior in situ fixation may be a viable solution. If the deformity is rigid and the C1–2 facet is fixed, osteotomy may be necessary to make the C1–2 facet joint reducible. C1–2 facet release with vertical reduction technique could be useful, especially when the C1–2 facet joint is the primary pathology of CVJ kyphotic deformity or basilar invagination. The indications for transoral surgery are becoming as narrow as a treatment for CVJ deformity. In this article, we will discuss CVJ alignment and various strategies for the management of CVJ deformity and possible ways to prevent complications and improve surgical outcomes.

Transdiscal C7 Pedicle Subtraction Osteotomy With a Strut Graft and the Correction of Sagittal and Coronal Imbalance of the Cervical Spine

BACKGROUND

Cervical spine deformity negatively affects patients' quality of life. Pedicle subtraction osteotomy (PSO) has reported to correct cervical deformity but it is challenging and carries a significant risk of morbidity.

OBJECTIVE

To report transdiscal C7 PSO with a strut graft for the correction of sagittal and coronal imbalance in patients with fixed cervical deformity.

METHODS

After standard exposure, the spine was instrumented from C2 to T3. T1 subtotal laminectomy, and C6 to C7 total laminectomies were necessary for C7 PSO. Osteotomy was initiated with removal of C6-7 and C7-T1 facet joints to isolate C7 pedicles and identify bilateral C7/C8 roots. Bilateral C7 pediculectomies and transdiscal PSO were performed. A rectangular strut allograft was then inserted into the PSO site. The location of the strut graft was used as a fulcrum of sagittal and coronal correction. The head fixator was released and the head was extended under intraoperative neuromonitoring, and then detailed sagittal and coronal balances were controlled by compressing or distracting between the pedicle screws above and below the osteotomy.

RESULTS

This technique was applied in 2 patients with fixed subaxial cervical deformities. Transdiscal PSO could add more amount of correction and provide the additional fusion surface. The strut graft prevented sagittal translation, foraminal narrowing, and excessive focal cord kinking during PSO. Both patients showed radiologic and clinical improvements after surgery, and no neurovascular complication occurred after the surgery.

CONCLUSION

Transdiscal C7 PSO with a strut graft placement provided a safe way of correcting sagittal and coronal imbalance simultaneously and reduced neurological complication by preventing sagittal translation, foraminal narrowing and spinal cord kinking.

High Cervical Lateral Approach to Safely Remove the Cystic Retro-odontoid Pseudotumor: Technical Note

Surgery for neoplastic or vascular lesions at the craniovertebral junction remains one of the major challenges for neurosurgeons, because of issues such as the complex functional anatomy and vascular structures. We present three cases in which the high cervical lateral approach was used to safely remove the cystic retro-odontoid pseudotumor, not associated with rheumatoid arthritis, severely compressing the spinal cord. The mean age of patients was 74.7 years (range, 73–77 years). Neurological condition was assessed based on the neurosurgical cervical spine scale. A high cervical lateral approach was applied to remove the pseudotumor safely. Mean duration of follow-up after surgery was 21.3 months (range, 18–24 months). Mean recovery rate was 77.8%. All patients showed acceptable or satisfactory functional recovery, although one patient (Case 2) developed mild paralysis of the facial and spinal accessory nerve on the surgical approach side, but that completely recovered within about 1 month after surgery. Postoperative assessment at the recent follow-up suggested no significant aggravation of neck movement. This technical note suggests that the high cervical lateral approach can be considered as a surgical option for cystic retro-odontoid pseudotumor, not associated with rheumatoid arthritis, severely compressing the spinal cord. Safe management of the vertebral artery is one of the key considerations.

Surgicoanatomical aspect in vascular variations of the V3 segment of vertebral artery as a risk factor for C1 instrumentation

OBJECT

Awareness of vascular anomalies in V3 segment of vertebral artery (VA) is crucial to avoid iatrogenic injuries during surgical procedure. This study aimed to analyze the incidence of V3 segment vascular variations and demonstrate the importance of deciding the surgical strategy for C1 screw placement.

METHODS

Prevalence of vascular variations and morphometric measurements of the VA in the region of the craniocervical junction in 200 cases based on three-dimensional computed tomographic angiography (3D-CTA) scans were studied.

RESULTS

The VA has a variable course through C2 before it passes above its groove on the posterior arch of C1. Following the vascular variations of V3 segments of VA were persistent including first intersegmental artery (FIA), fenestration (FEN) of the VA, high-riding (HRVA and the posterior inferior cerebellar artery (PICA) branch originating from the C1/2 part of VA. HRVA was observed in 10.1% of patients, FIA in 1.8%, FEN in 1.3%, and PICA in 1.3%. One hundred and twenty-three (24.1%) patients were identified to have HRVA, 6% present on both sides.

CONCLUSION

The VA with FIA and FEN were rare in this study as many as a 10% the VA present over the starting point for C1 lateral screw. With respect to the vascular anatomy of V3 and more frequent left-sided VA dominancy, standard screw insertion should be started from the right side. Routine preoperative 3D-CTA evaluation is mandatory to prevent the VA injury when C1-C2 instrumentation is planned.

How to Transect the C2 Root for C1 Lateral Mass Screw Placement: Case Series and Review of an Underappreciated Variable in Outcome

BACKGROUND

The techniques for atlantoaxial arthrodesis have been modified over the years, and placing C1 lateral mass screws is a modern approach. C2 neuropathy is a complication of concern; however, sacrifice of the C2 nerve is an accepted and often favored adjunct. The impact of the technique for cutting the C2 nerve is not adequately addressed in the literature. The aim of this study was to evaluate the clinical outcomes from a series of roots sacrificed during C1-2 fusion with attention to the C2 transection method.

METHODS

Clinical data were collected from trauma patients who underwent C1 screw fixation for atlantoaxial fusion. Chart review was performed and outcome assessed through telephone surveys to patients who were at least 6 months postoperative. Quality of life, C2 nerve function, neck pain, and head pain were assessed.

RESULTS

Sixty-six roots were divided in 35 patients. There were no cases of occipital neuralgia at routine 3-month follow-up. Delayed telephone surveys were completed in 17 patients and exposed 4 cases of severe head/neck pain but none consistent with occipital neuralgia.

CONCLUSIONS

C2 neuralgia is rare when sharply dividing the C2 root with the aid of bipolar electrocautery at the midportion of the ganglion where it overlies the C1-2 joint. A literature review suggests the impact of the root sacrifice method is an underappreciated modifiable factor in outcome. In future reports, description of the root transection technique is imperative and trials comparing ganglionectomy versus transection proximal to the ganglion or through the ganglion should be considered.

Difference of Dynamic Morphometric Changes Between in Patients with Ossification of Posterior Longitudinal Ligament and Patients with Cervical Spondylosis: Assessment by Cervical Dynamic Magnetic Resonance Imaging

PURPOSE

To evaluate differences between thicknesses of the ligamentum flavum (LF) and diameter of the spinal canal in different neck positions in patients with ossification of the posterior longitudinal ligament (OPLL) and patients with cervical degenerative spondylosis (CDS) using cervical dynamic magnetic resonance imaging (MRI).

METHODS

Eighty-eight patients (66 CDS and 22 OPLL) who underwent neutral and dynamic MRI at our institute from February 2014 to July 2017 were the subjects of this retrospective study. Canal diameters and LF thicknesses were measured and Muhle's grades were determined in neutral and dynamic MRI from C2-C3 to C7-T1. Patients with CDS and OPLL were compared with respect to changes in morphometric parameters. Statistical analysis was performed using SPSS software and statistical significance was accepted for P values < 0.05.

RESULTS

Mean ages in the CDS and OPLL groups were 68.2 ± 12.27 and 63.1 ± 9.36 years, respectively. Mean canal diameters were smaller in extension than in neutral at all measured levels, especially between C3-C4 and C6-C7 in patients with CDS. LF thickness in extension was significantly greater than in neutral and flexion positions in the CDS group, but not in the OPLL group. In addition, positional changes in Muhle's grades in the CDS group were significantly greater than in the OPLL group (P = 0.042).

CONCLUSIONS

Dynamic morphometric changes were found to be significantly greater in the CDS group than in the OPLL group. The study shows dynamic MRI may provide additional information in CDS patients.

Significance of Multimodal Intraoperative Monitoring During Surgery in Patients with Craniovertebral Junction Pathology

OBJECTIVE

Although many studies have investigated the benefits of multimodal intraoperative monitoring (MIOM) during cervical spine surgery, the benefits of MIOM in craniovertebral junction (CVJ) surgery remain unclear. The objectives of the present study were to report our clinical experience in CVJ surgery with the use of MIOM and to identify risk factors that could affect MIOM changes during surgery of CVJ pathology.

METHODS

We reviewed the MIOM records of 146 patients who had undergone high cervical spinal surgery. The patients were grouped by the MIOM data recorded during surgery; the patients were included in either the MIOM or non-MIOM change group. The analyzed risk factors included demographic, myelopathy, preoperative Japanese Orthopedic Association (JOA) score, spinal cord diameter, and surgical factors. Univariate and multivariate analyses were performed to identify the risk factors for changes in MIOM data during surgery and postoperative neurological deficits.

RESULTS

Our results revealed that the incidence of postoperative neurological complications was 4.1% after CVJ surgery; this rate was significantly greater in the MIOM change group than in the non-MIOM change group (21.7% vs. 0.8%; P < 0.01). Multiple regression analysis revealed that preoperative myelopathy, preoperative JOA score, and congenital anomaly/tumor were independently associated with MIOM changes during surgery.

CONCLUSIONS

Postoperative neurological complications are not uncommon after CVJ surgery, and the incidence was significantly greater in the MIOM change group. Preoperative myelopathy, preoperative JOA score, and CVJ pathology related to congenital anomaly or tumor were independent risk factors for changes in MIOM data during surgery.