Tethering of the vertebral artery in the congenital arcuate foramen of the atlas vertebra: a possible cause of vertebral artery dissection in children

Babinski-Nageotte syndrome after vertebral artery dissection and foramen arcuale

Vertebrobasilar ischaemia happens for a myriad of reasons. Among the rarest is the existence of a foramen arcuale (FA). This condition results from the ossification of the lateral edge of the posterior atlantooccipital membrane, closing, completely or partially, the top of this groove, turning it into a foramen or a channel. The estimated prevalence of this anatomical variant is around 9% for the complete form. It is postulated that entrapment of vertebral artery can occur. We share the case of a man in his 30s presenting with sudden imbalance, vertigo, vomiting and hiccups. Neurological observation disclosed Babinski-Nageotte syndrome. CT scan revealed left vertebral artery (VA) signs of dissection at its third segment (VA3), occlusion of its ipsilateral fourth segment (VA4) and bilateral FA. MRI confirmed ischaemic lesions in vertebrobasilar territory. The patient underwent surgical excision of contralateral FA. No new neurological adverse events occurred after 2 years of follow-up.

Does ponticulus posticus affect vertebral artery diameter

PURPOSE

Ponticulus Posticus, atlantooccipital ligament ossification-induced anomaly, surrounds the vertebral artery and the first cervical nerve root. It is believed to wrap around the first cervical nerve root and the vertebral artery, causing compression. We hypothesized that it would also reduce the diameter of the vertebral artery.

METHODS

Between January 1, 2022, and December 31, 2022, cervical spine CT scans taken for any reason were retrospectively reviewed. The images of 1365 patients suitable for evaluation were evaluated by two expert radiologists in 3 dimensions. Among patients with PP, those who underwent cervical angiography were identified for vertebral artery diameter measurement.

RESULTS

The average age of the 1365 individuals included in the study (732 males, 633 females) was 55.78 (± 18.85) with an age range of 1-96. Among this group, PP was detected in 288 individuals, resulting in a total prevalence of 21.1%. Right and left vertebral artery diameters were significantly lower in patients with complete PP compared to the absent group (p < 0,001, p < 0,001, respectively). Additionally, it was observed that width and height diameters and artery diameters were positively correlated in patients with Complete PP.

CONCLUSIONS

Ponticulus posticus can cause vertebrobasilar insufficiency by reducing the diameter of the vertebral artery. Therefore, imaging and detailed evaluation of this region are important in symptomatic patients.

Functional Anatomy and Biomechanics of the Craniovertebral Junction

The craniovertebral junction (CVJ) involves the atlas, axis, and occiput along with the atlanto-occipital and atlantoaxial joints. The anatomy and neural and vascular anatomy of the junction render the CVJ unique. Specialists treating disorders that affect the CVJ must appreciate its intricate anatomy and should be well versed in its biomechanics. This first article in a three-article series provides an overview of the functional anatomy and biomechanics of the CVJ.

Clinical response to surgical decompression in atypical pediatric Bow Hunter's syndrome suggesting alternative pathophysiology: Case report

Bow Hunter's syndrome is a rare cause of posterior circulation ischemia, produced by the mechanical and reversible occlusion of the vertebral artery during cephalic rotation. Diagnosis requires clinical suspicion and careful inspection of images with three-dimensional reconstruction. The study of choice is dynamic digital subtraction angiography (DSA). Treatment alternatives are: medical, surgical or endovascular. We report the case of an 8-year-old boy with recurrent infarctions of the posterior circulation secondary to the dissection of the vertebral artery, in association with an occipital bone spur. Dynamic DSA was negative. Conservative initial management was elected with cervical immobilization and anticoagulation, but due to persistence of symptoms, surgical decompression was decided. The patient did not repeat symptoms postoperatively and returned to his usual life. This is the first case reported to our knowledge of a surgical pediatric patient with asymptomatic atypical compression of VA secondary to BHS, whose dynamic angiography was negative, suggesting an alternative mechanism of the syndrome.

The craniovertebral junction, between osseous variants and abnormalities: insight from a paleo-osteological study

The bony components of the craniovertebral junction (CVJ) have been investigated in 172 skeletons, dug up from several archaeological sites, to define the frequency of developmental dysmorphisms, and to acquire qualitative and quantitative data about their morphology. A review of the pertinent literature is also presented. Twenty-five individuals (14.5%) exhibited at least one dysmorphism, which ranged from a condition of simple variant to a true malformation. Four individuals presented two or more anomalies at the same time (2.3% of the whole sample, 16% of the affected individuals). The most frequently observed abnormalities were: (i) the presence of a complete bony bridge in the atlas, forming a canal surrounding the vertebral artery (arcuate foramen, supertransverse foramen, and the simultaneous occurrence of arcuate foramen and supertransverse foramen); (ii) the presence of basilar processes. Basilar processes displayed a great variety in shape and dimension. They also differed with respect to their relationship with atlas and axis. The less frequently detected anomalies were: (i) complete absence of the posterior arch of C1, (ii) fusion of C2 and C3, and (iii) irregular segmentation of C2. A broad array of structural defects has been described at the CVJ. They may occur either isolated or as part of complex multisystem syndromes. Although harmless in many cases, they can notwithstanding cause severe, even life-threatening complications. When unrecognized, they may generate trouble during surgery. Hence, accurate knowledge of CVJ arrangement, including its multifarious variations, is a critical issue for radiologists, clinicians, surgeons, and chiropractors.

Bow Hunter's Syndrome in Children: A Review of the Literature and Presentation of a New Case in a 12-Year-Old Girl

BACKGROUND

Bow hunter's syndrome, or occlusion of the vertebral artery with head rotation leading to ischemia and sometimes stroke, is rarely described in children. The authors review the literature and present a new case.

METHODS

Both OVID dating back to 1946 and PubMed records were reviewed using the terms ("Bow hunter syndrome" OR "bow hunter's") OR "rotational vertebral artery occlusion" combined with "child," and limited to English language. SCOPUS and the bibliographies of cases found in the search were used to identify additional articles.

RESULTS

Twelve articles were found describing 25 patients; there were 26 patients when combined with our case. Ages ranged from 1 to 18 years. Most (88.5%, 23/26) were male. Medical treatments included aspirin, clopidogrel, abciximab, enoxaparin, warfarin, and cervical collar. Stenting was tried in 2 cases but did not work long-term. Surgical treatments included decompression, cervical fusion, or a combination. We present a new case of a 12-year-old girl with recurrent stroke who had bilateral vascular compression only visible on provocative angiographic imaging with head turn. She was referred for cervical fusion, and abnormal ligamentous laxity was noted intraoperatively.

CONCLUSIONS

Bow hunter's syndrome is a rare but important cause of stroke since many of the patients experience recurrent strokes before the diagnosis is made. Reasons for the male predominance are unclear. Provocative angiography plays a key role in diagnosis, and both medical treatment and neurosurgical intervention may prevent recurrence.

Single-center series of boys with recurrent strokes and rotational vertebral arteriopathy

OBJECTIVE

To describe a pediatric stroke syndrome with chronic focal vertebral arteriopathy adjacent to cervical abnormalities.

METHODS

At a single pediatric stroke center, we identified consecutive children with stroke and vertebral arteriopathy of the V3 segment with adjacent cervical bony or soft tissue abnormalities. We abstracted clinical presentation, treatment, and follow-up data from medical charts.

RESULTS

From 2005 to 2019, 10 children (all boys, ages 6-16 years) presented with posterior circulation strokes and vertebral arteriopathy with adjacent cervical pathology. Two children had bony abnormalities: one had a congenital arcuate foramen and one had os odontoideum with cervical instability. In children without bony pathology, vertebral artery narrowing during contralateral head rotation was visualized by digital subtraction angiography. Eight boys had recurrent ischemic events despite anti-thrombotic treatment (including 5 with multiple recurrences) and were treated surgically to prevent additional stroke. Procedures included vertebral artery decompression (n = 6), endovascular stent and spinal fusion (n = 1), and vertebral artery endovascular occlusion (n = 1). In boys treated with decompression, cervical soft tissue abnormalities (ruptured atlantoaxial bursa, ruptured joint capsule, or connective tissue scarring) were directly visualized during open surgery. No other etiology for stroke or dissection was found in any of the cases. Two boys without recurrent stroke were treated with activity restriction and antithrombotics. At a median follow-up of 51 months (range 17-84), there have been no additional recurrences.

CONCLUSIONS

Children with V3 segmental vertebral arteriopathy frequently have stroke recurrence despite antithrombotics. Cervical bone imaging and angiography with neck rotation can identify underlying pathology.

Krapina atlases suggest a high prevalence of anatomical variations in the first cervical vertebra of Neanderthals

The first cervical vertebra, atlas, and its anatomical variants have been widely studied in Homo sapiens. However, in Neanderthals, the presence of anatomical variants of the atlas has been very little studied until very recently. Only the Neanderthal group from the El Sidrón site (Spain) has been analysed with regard to the anatomical variants of the atlas. A high prevalence of anatomical variants has been described in this sample, which points to low genetic diversity in this Neanderthal group. Even so, the high prevalence of anatomical variations detected in El Sidrón Neanderthal atlases needs to be confirmed by analysing more Neanderthal remains. In this context, we analysed the possible presence of anatomical variants in the three Neanderthal atlases recovered from the Krapina site (Croatia) within the Neanderthal lineage. Two of the three Krapina atlases presented anatomical variations. One atlas (Krapina 98) had an unclosed transverse foramen and the other (Krapina 99) presented a non-fused anterior atlas arch. Moreover, an extended review of the bibliography also showed these anatomical variations in other Middle and Upper Pleistocene hominins, leading us to hypothesise that anatomical variations of the atlas had a higher prevalence in extinct hominins than in modern humans.

Craniocervical Arterial Dissection in Children: Pathophysiology and Management

BACKGROUND

Craniocervical arterial dissection is a commonly reported arteriopathy associated with stroke in children. It is characterized by a high stroke recurrence rate and variable outcomes. Here we review the pathophysiology, clinical presentation, and diagnostic neuroimaging approaches that are helpful in accurate diagnosis and follow-up of children with arterial dissection.

METHODS

MEDLINE searches (2000 to 2018) for articles that contained patients aged less than 18 years with craniocervical arterial dissection was performed, with the goal of analyzing their presenting features, pathophysiological mechanisms, and imaging characteristics and interventions.

RESULTS

Sixteen articles met the study criteria and reported 182 cases of craniocervical arterial dissection, 68% male, average age 8.6 years. Dissection was associated with head and neck trauma in 56% of the cases and frequently involved the posterior (61%) and extracranial locations (64%); the vertebral artery was the most commonly involved artery (60%). The most common clinical presentation was hemiparesis (80/160, 50%), followed by headache (64/164, 39%). Magnetic resonance imaging was the preferred neuroimaging method, followed by cerebral catheter angiography as a gold standard definitive neurovascular imaging modality when the initial vascular imaging revealed nondiagnostic findings.

CONCLUSIONS

The diagnosis of arterial dissection requires a high index of suspicion and consideration for detailed neurovascular imaging, including both the cranial and cervical regions. Neurovascular imaging challenges, especially visualization of arterial abnormalities, highlight the importance of appropriate and timely use of specific neurovascular imaging techniques. Magnetic resonance imaging appears to be the preferred neurovascular imaging modality in children with arterial dissection and may obviate the need for invasive cerebral catheter angiography.

Arcuate foramen: "Anatomical variation shape or adaptation legacy?"

PURPOSE

The groove of the vertebral artery on the posterior arch of the atlas (sulcus arteriae vertebralis) may become a complete or partial osseous foramen: the arcuate foramen. The presence of a complete or partial arcuate foramen is a rare anatomical variant described in a minority of patients and it seems to be associated with vertigo, vertebro-basilar insufficiency, posterior circulation strokes, and musculoskeletal pain. As the number and morphology of cervical vertebrae is highly preserved, we questioned about its significance from an evolutionary point of view. We thus investigated through an extensive literature review if the arcuate foramen is a pure anatomical variation shape or if it might represent an adaptation legacy.

METHODS

We observed five atlas of an extinct species, the Late Pleistocene Mammoths (M. primigenius), and we compared them with five atlas of a closely related existent species, the African elephant (L. africana).

RESULTS

All the mammoths' atlas had an arcuate foramen through which the vertebral artery passed before turning anteriorly and becoming intradural. This foramen was not present in elephants' atlas, where only a groove was observed, such as in the majority of patients.

CONCLUSION

We would like to raise the hypothesis that this peculiar morphology of mammoths' atlas might have contributed, in association with other factors, to their precocious extinction and that the arcuate foramen might represent a disadvantage in the evolutionary process, with a low prevalence in humans being the result of a natural selection.

Prevalence of anatomic variations of the atlas vertebra

BACKGROUND CONTEXT

The retrotransverse foramen (RTF), arcuate foramen (AF), unclosed transverse foramen (UTF) and posterior atlas arch defects (PAAD) are anatomic variations of the atlas vertebra that surgeons must be aware of before spine surgery is performed.

PURPOSE

To analyze the prevalence of the AF, RTF, UTF, and PAAD.

STUDY DESIGN

Ex-vivo anatomical study.

PATIENT SAMPLE

Two hundred eighteen atlas vertebrae obtained from 100 Caucasian subjects and 118 sub-Saharan African subjects (48 Sotho subjects, 35 Xhosa subjects and 35 Zulu subjects).

METHODS

We studied 218 atlas vertebrae from skeletons of the Raymond A. Dart Collection in order to analyze the prevalence of AF, RTF, UTF, and PAAD in both Caucasian and sub-Saharan African subjects.

OUTCOME MEASURES

Not applicable.

RESULTS

Sixty-nine (31.2%) atlases presented anatomical variants: 64 (29.3%) presented one anatomical variant, 4 (1.8%) presented two, and 1 (0.5%) presented three. AF, RTF, UTF, Type A and Type E defects were present in 35 (16.1%), 17 (7.8%), 17 (7.8%), 5 (2.3%), and 1 (0.5%) vertebrae, respectively. The vertebrae with two anatomical variants presented a bilateral UTF and a Type A defect, a bilateral AF and a Type A defect, a right UTF and a left AF, and a right UTF and a Type E defect. The vertebra with three anatomical variants presented a bilateral RTF, a left UTF, and a left AF. No sex differences in prevalence of the RTF (p=.775), AF (p=.605), UTF (p=.408) and Type A defects (p=1.000) were found in the sub-Saharan African and Caucasian groups (RTF, p=.306; AF, p=.346; UTF, p=.121; Type A defects, p=.561). Comparison between the sub-Saharan African (all subjects) and the Caucasian group revealed no differences in the UTF (p=.105), AF (p=.144), RTF (p=.542) and Type A defects (p=.521) prevalence. Also, no differences in the prevalence of the UTF (p=.515), AF (p=.278), and RTF (p=.857) between Zulu, Xhosa and Sotho subjects were found. Neither were found sex differences in the prevalence of UTF, RTF and AF in Zulu (p=.805, p=.234, p=.129), Xhosa (p=.269, p=.181, p=.309), and Sotho subjects (p=.062, p=.590, p=.106).

CONCLUSIONS

The present study has revealed no sex differences in the prevalence of AF, UTF, RTF or PAAD in both Caucasian and sub-Saharan African subjects. This research has also indicated no differences in the prevalence of the UTF, AF and RTF between Zulu, Xhosa and Sotho subjects. In addition, this study has revealed no differences in the Type A, UTF, AF, and RTF prevalence between the sub-Saharan African (all subjects) and the Caucasian subjects. These variations may be known by surgeons before spine surgery for better planning.

Atlases with Arcuate Foramen Present Cortical Bone Thickening That May Contribute to Lower Fracture Risk

BACKGROUND

To date, no information about the cortical bone microstructural properties in atlas vertebrae with arcuate foramen has been reported. As a result, we aimed to test in an experimental model if there is a cortical bone thickening in an atlas vertebra which has an arcuate foramen that may play a protective role against bone fracture.

METHODS

We analyzed by means of micro-computed tomography the cortical bone thickness, the cortical volume, and the medullary volume (SkyScan 1172 Bruker micro-CT NV, Kontich, Belgium) in cadaveric dry atlas vertebrae with arcuate foramen and without arcuate foramen. We also reviewed a case series of 31 posterior atlas arch fractures to correlate the possible presence in the same atlas of both fracture and arcuate foramen.

RESULTS

The micro-computed tomography study revealed significant differences in cortical bone thickness (P < 0.001), cortical volume (P < 0.004), and medullary volume (P = 0.013) values between the arcuate foramen vertebrae and the nonarcuate foramen vertebrae. The clinical series found no coexistence in the same vertebra of a posterior atlas arch fractures and the arcuate foramen.

CONCLUSIONS

An atlas with arcuate foramen presents cortical bone thickening. This advantage in bone microarchitecture seems to contribute to a lower fracture risk compared to subjects without arcuate foramen as no coexistence in the same vertebra of a posterior atlas arch fractures and arcuate foramen was found.

Prevalence of foramen arcuale and its clinical significance: a meta-analysis of 55,985 subjects

OBJECTIVE

The foramen arcuale (FA) is a bony bridge located over the vertebral artery on the posterior arch of the atlas. The presence of an FA can pose a risk during neurosurgery by providing a false impression of a broader posterior arch. The aim of this study was to provide the most comprehensive investigation on the prevalence of the FA and its clinically important anatomical features.

METHODS

Major electronic databases were searched to identify all studies that reported relevant data on the FA and the data were pooled into a meta-analysis.

RESULTS

A total of 127 studies (involving 55,985 subjects) were included. The overall pooled prevalence of a complete FA was 9.1% (95% CI 8.2%–10.1%) versus an incomplete FA, which was 13.6% (95% CI 11.2%–16.2%). The complete FA was found to be most prevalent in North Americans (11.3%) and Europeans (11.2%), and least prevalent among Asians (7.5%). In males (10.4%) the complete FA was more common than in females (7.3%) but an incomplete FA was more commonly seen in females (18.5%) than in males (16.7%). In the presence of a complete FA, a contralateral FA (complete or incomplete) was found in 53.1% of cases.

CONCLUSIONS

Surgeons should consider the risk for the presence of an FA prior to procedures on the atlas in each patient according to sex and ethnic group. We suggest preoperative screening with computerized tomography as the gold standard for detecting the presence of an FA.

Bow hunter's syndrome in a patient with vertebral artery atresia, an arcuate foramen, and unilateral deafness: a case report

Bow hunter's syndrome (BHS) is a rare cause of vertebrobasilar insufficiency that occurs when the vertebral artery (VA) is occluded on rotation of the head and neck. This dynamic occlusion of the VA can occur anywhere along its course after it arises from the subclavian artery. Although most cases are associated with compression by osteophytes, cervical spondylosis, or lateral disc herniation, BHS has a highly variable clinical course that depends on the patient's specific anatomy. Therefore, it may be important for clinicians to be aware of anatomical variants that predispose individuals to BHS. Here, we report on a patient with BHS who was found to have two uncommon anatomical anomalies: an atretic right VA and a left-sided arcuate foramen.

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

OBJECTIVE

The purpose of this study was to evaluate the morphometric characteristics of ponticulus posticus (PP) and determine the impact of two promising high cervical operations (posterior arch to lateral mass screw fixation (PALMSF) and occipital condyle fixation (OCF)).

PATIENTS AND METHODS

We evaluated retrospective data from a total of 2628 head and neck 3-dimensional CT-angiographies (3D-CTA) that did not have bony or vascular abnormalities. The PP anomaly cases were confirmed, then we measured vertebral artery groove height (VAGH), arch to vertebral artery distance (AVD) and posterior arch height (PAH) for PALMSF. We also measured the vertebral artery to occipital bone distance (VOD) for OCF.

RESULTS

In 186 patients (7.1%), 227 PP (complete or near complete) were identified and this anomaly was more common in males and on the left side. The mean VAGH and PAH values ranged from 5.0 to 6.0mm and from 7.0 to 8.8mm, respectively. The VAGH value was not statistically different, regardless of the presence of PP, and the feasibility (>4mm) of a safe PALMSF (range, 87.7-100%) was not influenced by PP anomalies. The mean value of VOD in the anomaly side (range, 6.0-8.0mm) was much higher than for normal side (range, 4.2-5.7mm) and the proportion of patients that had a safe OCF (>3.5mm) was also much higher (range, 90.8-96.9%) than for the normal side.

CONCLUSIONS

A PP anomaly might have some anatomical feasibility and advantage during PALMSF and OCF, due to the relatively sufficient bony (VAGH) and spatial regions (VOD). However, there are gender differences in anatomical dimensions (VAGH, VOD and AVD); therefore, surgery in female patients should be approached more cautiously in the future.

An anatomical study of arcuate foramen and its clinical implications: a case report

BACKGROUND

The objective of this paper is to describe the relationship of the vertebral artery (VA) to the Atlas (C1) in the sub-occipital region in the presence of arcuate foramen; and discuss the clinical implications related to manual therapies and surgical implications related to screw placement. This study is an anatomical cadaveric case report of symmetrical bilateral lateral and dorsal arcuate foramina on the C1 dorsal arch.

CASE PRESENTATION

Out of 40 cadavers that were available for use in teaching anatomy in the university setting, three presented with anomalies of the C1 dorsal arch. The sub-occipital regions were skillfully prosected to preserve related structures, especially VAs, sub-occipital and greater occipital nerves. Visual observations, photographs, measurements, and radiographic examinations were performed between January 15, 2014 and August 25, 2014. One cadaver (Specimen A) presented with complete bilateral ossified arcuate foramina, and two presented with partial ossification of the atlanto-occipital membrane. Specimen A presented the bilateral anomaly which is almost symmetrical. The VAs were found passing through double foramina (lateral and dorsal) on each side.

CONCLUSIONS

Arcuate foramina have been shown to be commonly found anomalies with highly variable shapes and sizes, even in the same individual with a bilateral condition. This study found a rare type of the anomaly associated with the C1 dorsal arch, which protected the VA against manual pressure. However, VA, in this case, would be more susceptible to dissection. The presence of the arcuate foramen would also complicate screw placement during surgery. Clinical pre-screening for signs of vertebrobasilar insufficiency is important for chiropractic and manual therapies.

Anatomical Variant of Atlas : Arcuate Foramen, Occpitalization of Atlas, and Defect of Posterior Arch of Atlas

Objective

We sought to examine anatomic variations of the atlas and the clinical significance of these variations.

Methods

We retrospectively reviewed 1029 cervical 3-dimensional (3D) CT images. Cervical 3D CT was performed between November 2011 and August 2014. Arcuate foramina were classified as partial or complete and left and/or right. Occipitalization of the atlas was classified in accordance with criteria specified by Mudaliar et al. Posterior arch defects of the atlas were classified in accordance with criteria specified by Currarino et al.

Results

One hundred and eight vertebrae (108/1029, 10.5%) showed an arcuate foramen. Bilateral arcuate foramina were present in 41 of these vertebrae and the remaining 67 arcuate foramina were unilateral (right 31, left 36). Right-side arcuate foramina were partial on 18 sides and complete on 54 sides. Left-side arcuate foramina were partial on 24 sides and complete on 53 sides. One case of atlas assimilation was found. Twelve patients (12/1029, 1.17%) had a defect of the atlantal posterior arch. Nine of these patients (9/1029, 0.87%) had a type A posterior arch defect. We also identified one type B, one type D, and one type E defect.

Conclusion

Preoperative diagnosis of occipitalization of the atlas and arcuate foramina using 3D CT is of paramount importance in avoiding neurovascular injury during surgery. It is important to be aware of posterior arch defects of the atlas because they may be misdiagnosed as a fracture.

Prevalence of ponticuli posticus among patients referred for dental examinations by cone-beam CT

BACKGROUND CONTEXT

Ponticulus posticus (PP) is the bony bridge that can completely or partially embrace the vertebral artery and the suboccipital nerve root at the atlas posterior arch. The PP can be a possible cause of vertigo, vertebrobasilar insufficiency, neck pain, shoulder pain, and cervicogenic headache. Moreover, the vertebral artery injury may happen during atlas lateral mass screw insertion in the presence of PP.

PURPOSE

The purpose of this study was to determine the prevalence of PP in a population of patients undergoing dental cone-beam computed tomography (CBCT) and the association between PP and atlas superior articular facet (SAF).

STUDY DESIGN

This is a retrospective study.

PATIENT SAMPLE

Five hundred consecutive patients who had undergone dental CBCT scans were included.

OUTCOME MEASURES

Outcome measures were age, sex, and radiologic measures.

METHODS

The maximum anteroposterior and transverse dimensions of atlas SAF were measured on the axial image, and then the area was calculated by using the formula for an elliptical area. The left-right differential ratios of the SAF in patients with unilateral PP were compared with those in age- and gender-matched patients without PP. The relationships among imaging findings, age, and sex were assessed with the two-tailed paired t test, χ(2) test, and logistic regression model, as appropriate.

RESULTS

The overall prevalence of PP was 7% (35 of 500 patients). There were no significant differences in the prevalence of PP with gender and age. The anteroposterior dimension, transverse dimension, and area of atlas SAF on the PP side were significantly larger than those on the non-PP side in the 18 unilateral complete PP patients (p<.001, p<.001, and p<.001, respectively) and in the 11 unilateral partial PP patients (p=.001, p=.007, and p<.001, respectively). The SAF area differential ratios in patients with unilateral PP were greater than those in the patients without PP (29.8% vs. 2.9%, p=.002 for 18 complete lesions, and 23.5% vs. 1.8%, p<.001 for 11 partial lesions).

CONCLUSIONS

The prevalence of PP and the measurement of SAF can be assessed by CBCT. The imaging findings show the larger SAF on the PP side and greater left-right difference of SAF area in the patients with unilateral PP.

Normal anatomy and anatomic variants of vascular foramens in the cervical vertebrae: a paleo-osteological study and review of the literature

We investigated 923 cervical vertebrae belonging to late-antiquity and medieval skeletal remains and assessed the qualitative and quantitative structural characteristics of transverse foramens (TF) and additional vascular canals. We also reviewed the pertinent literature. Double TF were chiefly observed in C6 (with a right/left side prevalence of 35.7 and 44.4%, respectively) and C5 vertebrae (23.6 and 23.9%, right/left side, respectively), while unclosed TF were mainly documented in C1 vertebrae (8.4%). Retrotransverse canal and retrotransverse groove were present in 8.5 and 17.8%, respectively, of C1 vertebrae examined, while arcuate foramens and supertransverse foramens were found in 7.3 and 3.7% of specimens, respectively. TF diameter decreased from C6 to C2 vertebrae, being smallest in C7 and greatest in C1 vertebrae, with no left/right significant difference. There was a significant correlation between TF diameter and stature, but only on the right side. The mean area of the arcuate foramen was lower than the mean area of the ipsilateral TF (24.5 ± 5.7 vs 28.5 ± 7.7 mm(2), respectively; p = 0.048), possibly causing compression of the vertebral artery within the arcuate foramen. The study of human vertebrae excavated from archaeological sites is a simple and effective way to analyze the morphology and quantitative anatomy of vascular foramens.

Arterial ischemic stroke in children: risk factors and etiologies

Stroke is increasingly recognized as a significant cause of morbidity and mortality in children, and as a financial burden for families and society. Recent studies have identified and confirmed presumptive risk factors, and have identified novel associations with childhood arterial ischemic stroke. A better understanding of risk factors for stroke in children, which differ from the atherosclerotic risk factors in adults, is the first step needed to improve strategies for stroke prevention and intervention, and ultimately minimize the physical, mental, and financial burden of arterial ischemic stroke. Here, we discuss recent advances in research for selected childhood stroke risk factors, highlighting the progress made in our understanding of etiologic mechanisms and pathophysiology, and address the future directions for acute and long-term treatment strategies for pediatric stroke.

A cone beam CT investigation of ponticulus posticus and lateralis in children and adolescents

OBJECTIVES

To determine the prevalence and pathogenesis of ponticulus posticus (PP) and ponticulus lateralis (PL) in children and adolescents.

METHODS

Cone beam CT scans of 576 patients were examined for PP and PL. The patients were divided into three age groups: 10 years and younger, 11-13 years and 14 years and older. Ponticulus formation was categorized as absent, partial or complete. Gender, race and location (right, left or bilateral) were recorded. Data were analysed with the χ(2) test, with significance at p < 0.050. Institutional review board approval was granted.

RESULTS

Overall prevalence of PP was 26.2%, with complete lesions in 10.4%. The frequency of PP was greater in patients aged 14 years and older (p ≤ 0.038). The occurrence of complete PP was greater in patients aged 11 years and older (p = 0.028). Lesions were more common in males (p = 0.014) and in blacks compared with other non-white races (p = 0.035). Bilateral PP was more common than right-sided lesions (p = 0.008) and more frequent in the oldest cohort (p = 0.006). Overall prevalence of PL was 6.1% (3.0% complete), with no differences between age groups, genders, races or by location.

CONCLUSIONS

PP is not uncommon even in the first decade and increases in frequency, completeness of calcification and numbers in mid-adolescence. It appears to be more common in males and in blacks. PP may be a congenital osseous anomaly of the atlas that mineralizes at various times. PL is less frequent with no demographic predilections.

Cervical abnormalities causing vertebral artery dissection in children

Vertebral artery dissection (VAD) is rare in children but is increasingly recognized as a cause of stroke in the pediatric population. Traditionally, VAD was thought to be attributable to either trauma or spontaneous dissections. Recently, several underlying causes, such as bony cervical abnormalities, connective tissue diseases, and infection, have been determined to account for spontaneous VAD or those cases associated with only minor trauma. Two pediatric cases of VAD are presented, both caused by bony cervical abnormalities and each treated with different surgical procedures for symptom resolution. The first case required suboccipital decompression and endovascular sacrifice of the vertebral artery. The second case was treated with surgical decompression of the foramen transversarium at C-1 and C-2. The treatment of both of these patients required accurate diagnosis via cervical spine CT to define the bone anatomy and delineate a cause for what was originally theorized to be spontaneous VAD.

Rotational vertebral artery occlusion in a child with multiple strokes: a case-based update

INTRODUCTION

Rotational vertebral artery occlusion (RVAO), sometimes known as "Bow hunter syndrome," is an important and diagnostically challenging cause of posterior circulation stroke in children. It is caused by impingement of osseous and/or ligamentous structures on the vertebral artery.

DISCUSSION

We review the differential diagnosis and recommended workup for posterior circulation stroke in children. The anatomical cause for pediatric RVAO is most commonly an anomalous bone formation of the rostral vertebral column. Many bony anomalies have been associated with RVAO, including the "ponticulus posticus," a common anomaly of the C1 vertebrae. The definitive diagnosis of RVAO is made with dynamic angiography, and surgical decompression of the vertebral artery prevents recurrent strokes.

ILLUSTRATIVE CASE

We report a 15-year-old boy with recurrent posterior circulation ischemic strokes caused by an anomalous ossification of the C1 vertebrae. Three-dimensional (3D) and multiplanar reconstructed CT images showed the anomalous C1 ossification, and cervicocerebral digital subtraction angiography (DSA) revealed an associated vertebral artery (VA) dissection. The patient was initially managed by head immobilization in a hard collar and anticoagulation for 3 months. After healing of the dissection that was confirmed angiographically, dynamic DSA demonstrated reversible occlusion of the VA during contralateral head turn. Surgical decompression of the VA was performed and confirmed by intra-operative DSA with head turning.

CONCLUSIONS

RVAO is an important diagnosis in children with posterior circulation stroke. Our case demonstrates the need for high clinical suspicion and careful analysis of 3D cervical spine CT images in children with posterior circulation stroke.

The prevalence of posticus ponticus: retrospective analysis of radiographs from a chiropractic health center

OBJECTIVE

The potential clinical significance of posticus ponticus is controversial because the majority of patients with this finding are asymptomatic. This study sought to estimate the prevalence of posticus ponticus in a chiropractic college clinic patient population.

METHODS

From the archived records in the College Health Center, 304 lateral cervical spine radiographs were randomly selected and assessed by 2 independent examiners for the presence of posticus ponticus in any of its forms. The number of radiographs showing posticus ponticus, as well as analysis of agreement between examiners, was obtained.

RESULTS

There were 60 radiographs where the examiners disagreed as to the presence or absence of posticus ponticus. These 60 were not counted for prevalence of posticus ponticus but were included in the κ analysis. Among the remaining 246 radiographs, 112 (46%) showed some type of posticus ponticus, whereas 132 (54%) did not show any posticus ponticus finding. Examiners A and B showed a κ score agreement of 0.72, and examiners C and D showed a κ score agreement of 0.51.

DISCUSSION

The κ scores for both sets of examiners show acceptable agreement. Within this population, the finding of 45.9% prevalence of some type of posticus ponticus was determined. Compared with other studies, the prevalence of posticus ponticus was found to range between 9% and 72%.

CONCLUSION

Within this sample, 45.9% of radiographs showed some type of posticus ponticus.

Prevalence of ponticulus posticus in Indian orthodontic patients

OBJECTIVES

The purpose of this study was to investigate the prevalence of complete ponticulus posticus in Indian orthodontic patients.

METHODS

The presence and types of ponticuli posticus were investigated on 858 lateral cephalograms.

RESULTS

Complete ponticulus posticus was found in 4.3% of the subjects studied with a male (5.33%) predominance over female in the population (3.76%).

CONCLUSIONS

Ponticulus posticus is not a rare anomaly and the patient must be told of the implications and importance of detecting ponticulus posticus on a lateral cephalogram. This information can prove beneficial for the diagnosis of head and neck symptoms later.

Radiological analysis of ponticulus posticus in Koreans

PURPOSE

Since there has been little reporting on the prevalence or morphologic characteristics of ponticulus posticus in Asians, we retrospectively reviewed cervical 3-dimensional CT scan images and plain radiographs which had been ordered by neurosurgeons or orthopaedic surgeons for evaluation of cervical spine problems to investigate the prevalence and morphologic features of the ponticulus posticus in Koreans.

PATIENTS AND METHODS

The presence and types of ponticulus posticus were investigated on 200 consecutive cervical 3-D CT scans.

RESULTS

Thirty-one patients, 48 ponticulus posticus, complete or partial, bilateral or unilateral, were identified on the 200 cervical 3-D CT scans; therefore, the prevalence was 15.5% in our patient population. In plain radiographs analysis, the prevalence was 6.95%.

CONCLUSION

The ponticulus posticus is a relatively common anomaly in Koreans. Therefore, proper identification of this anomaly on preoperative lateral radiographs should alert surgeons to avoid using the ponticulus posticus as a starting point for a lateral mass screw. Because of its size and shape have wide variation, 3-D CT scanning should be considered before lateral mass screw placement into the posterior arch if its presence is suspected or confirmed on radiographs.

Posterolateral protrusion of the vertebral artery over the posterior arch of the atlas: quantitative anatomical study using three-dimensional computed tomography angiography

Object

The vertebral artery (VA) often takes a protrusive course posterolaterally over the posterior arch of the atlas. In this study, the authors attempted to quantify this posterolateral protrusion of the VA.

Methods

Three-dimensional CT angiography images obtained for various cranial or cervical diseases in 140 patients were reviewed and evaluated. Seven patients were excluded for various reasons. To quantify the protrusive course of the VA, the diameter of the VA and 4 parameters were measured in images of the C1–VA complex obtained in the remaining 133 patients. The authors also checked for anomalies and anatomical variations.

Results

When there was no dominant side, mean distances from the most protrusive part of the VA to the posterior arch of the atlas were 6.73 ± 2.35 mm (right) and 6.8 ± 2.15 mm (left). When the left side of the VA was dominant, the distance on the left side (8.46 ± 2.00 mm) was significantly larger than that of the right side (6.64 ± 2.0 mm). When compared by age group (≤ 30 years, 31–60 years, and ≥ 61 years), there were no significant differences in the extent of the protrusion. When there was no dominant side, the mean distances from the most protrusive part of the VA to the midline were 30.73 ± 2.51 mm (right side) and 30.79 ± 2.47 mm (left side). When the left side of the VA was dominant, the distance on the left side (32.68 ± 2.03 mm) was significantly larger than that on the right side (29.87 ± 2.53 mm). The distance from the midline to the intersection of the VA and inner cortex of the posterior arch of the atlas was ~ 12 mm, irrespective of the side of VA dominance. The distance from the midline to the intersection of the VA and outer cortex of the posterior arch was ~ 20 mm on both sides. Anatomical variations and anomalies were found as follows: bony bridge formation over the groove for the VA on the posterior arch of C-1 (9.3%), an extracranial origin of the posterior inferior cerebellar artery (8.2%), and a VA passing beneath the posterior arch of the atlas (1.8%).

Conclusions

There may be significant variation in the location and branches of the VA that may place the vessel at risk during surgical intervention. If concern is noted about the vulnerability of the VA or its branches during surgery, preoperative evaluation by CT angiography should be considered.

Prevalence and Morphologic Features of Ponticulus Posticus in Koreans: Analysis of 312 Radiographs and 225 Three-dimensional CT Scans

Study Design

A retrospective review of three-dimensional CT scan images and radiographs.

Purpose

To investigate the prevalence and morphologic features of ponticulus posticus in Koreans.

Overview of Literature

There has been little reported on the prevalence or morphologic characteristics of ponticulus posticus in Asians, predisposing them to vertebral artery injury during screw placement in the lateral mass of the atlas.

Methods

The presence and types of ponticulus posticus were investigated on 225 consecutive cervical three-dimensional CT scans and 312 consecutive digital lateral cephalometric head radiographs.

Results

Various spectra of ponticulus posticus were found in 26% of the CT scans and 14% of the radiographs.

Conclusions

Ponticulus posticus is a relatively common anomaly in Koreans. Therefore, the presence of this anomaly should be carefully examined for on radiographs before lateral mass screw placement. If ponticulus posticus is suspected or confirmed on radiographs, three-dimensional CT scanning should be considered before placement of lateral mass screws into the posterior arch, especially given its wide variation of size and shape.

Foramen arcuale: anatomical study and review of the literature

Object

The neurosurgical literature is lacking information on the so-called foramen arcuale. When this foramen is present, the vertebral artery (VA) travels through it after exiting the transverse foramen of the atlas and prior to entering the cranium.

Methods

The authors performed a study in 60 cadavers to determine the incidence of the foramen arcuale and ascertain morphometric information on its anatomy. In specimens in which the foramen arcuale was observed, the authors studied the relationship between it and the VA.

The authors identified a foramen arcuale in 5% of specimens. The mean length and thickness of the osseous struts that converted the groove for the VA into the foramen arcuale were 7.0 and 2.0 mm, respectively. The mean area of the identified foramina was 14.2 mm2. The mean area of the ipsilateral C-1 transverse foramina was 18 mm2 in specimens with a foramen arcuale. The mean measurements of the proximal, intraforaminal (foramen arcuale), and distal diameter of the V3 segment of the VA at the level of the foramen arcuale were 6, 4, and 5 mm, respectively. In all specimens the authors noted that the intraforaminal part of the V3 segment was grossly compressed.

Conclusions

The authors found that the foramen arcuale may compress the V3 segment of the VA. Based on their postmortem study, however, they cannot conclude that compression at this location results in symptomatic VA insufficiency. Based on their review of the literature, it seems that symptomatic compression of the VA at this location may be alleviated in some patients with decompressive procedures.

Vertebral artery injury after blunt cervical trauma: an update

BACKGROUND

Vertebral artery injury (VAI) after blunt cervical trauma has been considered to be rare. The incidence of VAI has increased dramatically within the last decade after a heightened awareness of this entity on the part of spine surgeons. Diagnostic or therapeutic guidelines for VAI have not been established fully, however.

METHODS

A review of the literature published between 1990 and 2004 was conducted.

RESULTS

The incidence of VAI among total blunt trauma admissions ranged from 0.20% to 0.77%. Most VAI patients remained asymptomatic, but sudden unexpected deterioration was often reported. Distraction/extension, distraction/flexion, and lateral flexion injuries were the major mechanisms of injury. Dissection and occlusion were the frequent vascular injury patterns. Facet joint dislocations and the fractures extending into the transverse foramen were the spine injury patterns closely associated with VAI. Digital subtraction angiography was the most sensitive imaging study, but because of invasiveness, its role as a screening study remained questionable. Neuroradiological intervention was used successfully to treat hemorrhagic VAI and progressing vertebrobasilar stroke. Systemic anticoagulation with heparin was the preferred treatment for mild ischemia. Treatment of asymptomatic patients has been controversial because the natural history of VAI has not been elucidated. Prophylactic anticoagulation with heparin or the use of antiplatelet agents was advocated in recent studies.

CONCLUSIONS

Preemptive treatment may be reasonable in selected patients considering the devastating potentials of VAI. The potential risks of heparin or antiplatelet agents in relation to early cervical spine surgery have not been addressed fully, however, and spine surgeons have to weigh the risk and benefit of such treatment cautiously.

Craniocervical arterial dissection in children: clinical and radiographic presentation and outcome

Craniocervical arterial dissection is a recognized cause of arterial ischemic stroke in children. Whether children with craniocervical arterial dissection have dissection characteristics different from those of adults is unclear. A retrospective review of children, 1 month to 18 years of age, with dissection from two Canadian pediatric ischemic stroke registry centers was conducted. From 213 patients with arterial ischemic stroke, 16 (7.5%) were identified with dissection, 37.5% had warning symptoms, and 50% had a history of head or neck trauma. The clinical presentation included headache (44%), altered consciousness (25%), seizures (12.5%), and focal deficits (87.5%). Dissection involved extracranial vessels in 75% and anterior circulation in 56%. Follow-up included complete recovery in 43%, mild to moderate deficits in 44%, and severe deficits in 13%. Fourteen (87.5%) children received antithrombotic treatment. Follow-up angiography showed resolution of abnormalities in 60% of vessels. Total occlusion had the worst outcome for recanalization. In conclusion, the etiology of arterial dissection in the majority of children appears to be either trauma or idiopathic. Long-term angiography shows variable outcomes, depending on the initial findings. The relationship of angiographic outcomes with recurrent strokes requires further study in pediatric dissection. (J Child Neurol 2006;21:8-16).

Bony ponticles of the atlas (C1) over the groove for the vertebral artery in humans and primates: Polymorphism and evolutionary trends

The aim of this study was to ascertain the distribution in primates of the three possible bony ponticles over the groove for the vertebral artery (ventral, lateral, and dorsal ponticles), in order to attempt to understand the variants observed in humans and to ascertain possible evolutionary trends in primates. The material consisted of 393 atlases of extant nonhuman primates representative of 41 genera, and of 500 human atlases (dried bones of adults). For each atlas, we studied the existence and morphology of the ponticles, and the type of association of these three ponticles on a given side, which are theoretically of eight in number (types A-H). The occurrence of these ponticles varied from complete absence to constant presence, according to the genera and taxa of primates. The presence of each of these ponticles in primates can be interpreted as a primitive or plesiomorphic character, and their absence as a derived or apomorphic character. The strepsirhines-platyrrhines-cercopithecines group, presenting a predominant primitive pattern (type A), appeared to be separated from the colobines-hominoids group, presenting predominant derived patterns (type C in colobines, Pongo pygmaeus, and Pan troglodytes, and the more derived type D in Hylobates, Gorilla gorilla, and Homo sapiens). The last derived stage, corresponding to the disappearance of the three atlantal ponticles (type H), was only observed in some individuals in hominoids. A marked intraspecific polymorphism characterized the hominoids. The presence of lateral and dorsal ponticles in humans appeared to correspond to their persistence within the progressive disappearance of the atlantal ponticles, constituting an evolutionary tendency characteristic of primates and particularly of hominoid evolution.