Ponticulus posticus: Morphometric analysis and Its anatomical Implications for occipito-cervical fusion

C1 Lateral Mass Screw Insertion Caudally From the C2 Nerve Root to Avoid Craniocervical Fusion in a Patient With Atlantoaxial Subluxation Associated With Ponticulus Posticus: A Case Report

This report describes the case of a 78-year-old female patient with a rare complex upper cervical spine disorder combined with atlantoaxial subluxation (AAS), ponticulus posticus (PP), and high-riding vertebral artery (HRVA), treated with posterior C1-C3 screw fixation. To avoid vertebral artery injury during screw insertion, a C1 lateral mass screw (LMS) on the PP side was inserted from the caudal side of the C2 nerve root. Preoperative three-dimensional CT angiography is important for selecting the optimal posterior screw entry point and trajectory among several screw options. C1 LMS insertion from the caudal side of the C2 nerve root may be an alternative screw trajectory in the PP with vertebral artery running variation.

Prevalence and characteristics of ponticulus posticus and its association with cervicogenic headache and migraine: A lateral cephalometric study

Background

Ponticulus posticus (PP) (arcuate foramen) is an abnormal bony bridge in the posterior arch of the atlas, which could possibly cause certain complications such as headache. Our goal was to assess the prevalence and size of PP on lateral cephalometric radiographs and its relationships with cervicogenic headache and migraine.

Materials and Methods

This cross-sectional study was a descriptive-analytical type and was performed in Isfahan Azad Dental University. Lateral cephalometric radiographs of 150 patients referred to the radiology department were selected to assess the prevalence and size of the anomaly. A checklist was prepared to evaluate cervicogenic headache and migraine among patients.

Results

Our sample consisted of 97 females and 53 males with an age range between 5 and 56 years. The prevalence of PP was 21.3% (12% complete and 9.3% incomplete), and an insignificant difference was noted between the prevalence of complete and incomplete foramen (P > 0.05). The prevalence of foramen was higher in women (59.4%), but it was not significant. The mean width of complete foramen was 6.40 mm, and the mean heights in individuals with complete and incomplete foramen were 4.71 and 4.84 mm, respectively. Among patients with the anomaly, 43.8% had cervicogenic headache and 9.4% had migraine. There was a significant association between the presence of foramen and both types of headaches (P < 0.05). However, there was no significant correlation between the shape of anomaly and the presence of cervicogenic headache and migraine (P > 0.05).

Conclusion

Our study showed a high prevalence of PP and its significant association with cervicogenic headache and migraine.

Research Progress of Ponticulus Posticus: A Narrative Literature Review

Study Design

Narrative review.

Objective

The purpose of this review was to consolidate the current literature related to ponticulus posticus (PP) and to improve the systematic understanding of this anatomical variant of atlas among spine surgeons.

Methods

Articles reviewed were searched in PubMed, Ovid MEDLINE, and Embase. All articles of any study design discussing on PP were considered for inclusion. Two independent authors read article titles and abstracts and included appropriate articles. The relevant articles were studied in full text.

Results

A total of 113 literatures were reviewed and consolidated in this narrative review. These articles are roughly divided into the following five subcategories: (1) epidemiology, (2) pathology and anatomy, (3) clinical presentation, (4) surgical significance, and (5) radiographic examination.

Conclusion

The PP is non-negligible with a high prevalence. The PP compresses the V3 segment of the artery, the suboccipital nerve, and the venous plexus, consequently contributing to the incidence of neurological pathologies. When a PP is observed or suspected on a lateral radiograph, we recommend that a computed tomography (CT) scan of a patient who is about to receive a C1 lateral mass screw (C1LMS) should be performed, which could determine a safe entry point and the right trajectory of screw insertion.

Multiple Fractures of Cervical Vertebrae Combined with Arcuate Foramen and Vertebral Artery Occlusion: A Case Report and Literature Review

BACKGROUND

The arcuate foramen is a complete or partial bony bridge over the vertebral artery groove of atlas. The mechanism of the arcuate foramen is not clearly understood. Omission of the arcuate foramen sometimes causes lethal iatrogenic injury during spinal surgery.

CASE PRESENTATION

We describe a patient who was diagnosed with multiple fractures of the cervical vertebrae, arcuate foramen, and right vertebral artery occlusion based on clinical and radiological exams. After conservative treatment, he resumed a normal and productive life.

CONCLUSIONS

Arcuate foramen is a common variation that causes symptoms such as dizziness, headache, and migraine. If the patient does not develop severe symptoms, conservative treatment can achieve very good results without the necessity to remove the bone bridge. When serious symptoms occur, surgical treatment to resect the bony ridges can relieve the symptoms dramatically.

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.

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.

The Ponticulus Posticus as Risk Factor for Screw Insertion into the First Cervical Lateral Mass

BACKGROUND

Awareness of the osseous anomaly of ponticulus posticus (PP) is crucial in avoiding vertebral artery (VA) injuries during C1 instrumentation. The aim of this study was to investigate PP and its relationship with the VA with three-dimensional computed tomography angiography.

METHODS

PP and the VA were investigated as intraoperative landmarks. The intersection of the VA to the posterior arch of C1 and the medial line and the posterior arch and VA curve around lateral masses were measured as intraoperative references.

RESULTS

PP was identified in 14.3% of samples. The anomaly was more common in women and on the right side. Of cases, 48.2% had PP bilaterally. In PP cases, the VA had variable courses through C2 before it passed under its bony bridges on the posterior arch of C1. Mean distances were found at the intersection of the VA to the posterior arch of C1 and the medial line to be larger and the posterior arch of C1 and the VA curve around lateral masses to be narrower than normal cases. Dual computed tomography scan data from C1 with PP were used to create three-dimensional patient-specific life-sized cervical spine models. Models revealed how the bone bridge affected the VA. The feasibility (>4 mm) of a safe lateral mass screw fixation was not influenced by PP anomalies.

CONCLUSIONS

The presence of the PP loop can limit space available for placement of the screw through the bony elements of C1. Standard screw techniques are contraindicated owing to the unacceptable high risk of VA injury.