Article

Variants and deformities of atlas vertebrae in Eastern Anatolian people

Ataturk University, Kalikala, Erzurum, Turkey
Saudi medical journal (Impact Factor: 0.59). 04/2004; 25(3):322-5.
Source: PubMed

ABSTRACT

At the craniocervical junction, developmental anomalies of the atlas may produce clinical symptoms by compressing on the vertebral artery, particularly during extreme rotational movements of the cervical spine. The aim of the present study was to investigate several varieties and deformities of the atlas vertebra from the skeletal specimens of Eastern Anatolian people.
This study was carried out over a 3-year period, 2000 through to 2002 in the Department of Anatomy, Firat, Yuzuncu Yil and Ataturk University, Turkey. Developmental anomalies and the variants of the first vertebrae were investigated on 86 atlas.
Ponticulus posterior was observed with a low frequency on right as 2.3%. The bilateral localization was 10.5% and the left-side localization was 9.3%. Ponticulus lateralis showed an equal localization as 1.2% on the right, 1.2% on the left and 1.2% bilateral. In the present study, a complete subdivision of the joint surface was observed in 11 atlases (12.8%). Processus infratransversarius atlantis with a frequency between 1.2-7%, arthrotic formation and corona atlantis peridentals in 8 cases (9.3%) were also found.
The low frequency for fonticulus posterior might be peculiar to the population living in this area.

Full-text

Available from: Ahmet Kavakli, May 09, 2014
ABSTRACT
raniocervical junction is the area comprising
the inferior portion of the occipital bone that
surrounds the foramen magnum and the first 2
cervical vertebrae, atlas and axis. Due to its
complicated embryonic development, this area is
easily susceptible to skeletal and neural
developmental variants and anomalies, producing a
wide spectrum of symptom.
1
Clinical syndromes
develop as a result of mechanical disturbance of
movement or of deformities of the cervical cord
accompanying these developmental anomalies and
the variants of skeletal elements. The bone
deformity itself may be sufficient to cause pressure
on the upper cervical cord and the vertebral artery
during movements of the head and neck. In some
C
situations (such as, transient vertebra basilar
insufficiency, Barre-Lieou syndrome and chronic
upper cervical syndrome) a developmental variant
of the atlas is a significant factor.
2-5
Due to the
clinical significance, a variation of the first
vertebrae, retroarticular canal, was examined in
several populations.
3,5-9
Recently, a review by
Prescher
10
also reported the osseous variations in the
craniocervical junction.
The present study was undertaken to investigate
several varieties or deformities of the atlas vertebra
from skeletal specimens of the Eastern Anatolian
people. The purpose of the present study was to
determine the frequencies of the varieties of the first
From the Department of Anatomy (Kavakli, Kus), School of Medicine, Firat University, Elazig, Department of Anatomy (Aydinlioglu, Erdem),
Department of Neurology (Anlar), School of Medicine, Yuzuncu Yil University, Van, Department of Anatomy (Yesilyurt, Diyarbakırlı), School of
Medicine, Atatürk University, Erzurum, Turkey.
Received 11th August 2003. Accepted for publication in final form 29th October 2003.
Address correspondence and reprint request to: Dr. Ahmet Kavakli, Fırat University, Department of Anatomy, School of Medicine, 23119 Elazıg,
Turkey. Tel. +90 (424) 2370000. Fax . +90 (424) 2379138. E-mail: kavaklia@yahoo.com
Variants and deformities of atlas vertebrae in
Eastern Anatolian people
Ahmet Kavaklı, MD PhD, Atıf Aydınlıoglu, MD PhD, Hakkı Yesilyurt, MD PhD, Ilter Kus, PhD,
Semih Diyarbakırlı, PhD, Saadet Erdem, MSc, Ömer Anlar, MD.
322
Objective: At the craniocervical junction,
developmental anomalies of the atlas may produce
clinical symptoms by compressing on the vertebral
artery, particularly during extreme rotational movements
of the cervical spine. The aim of the present study was to
investigate several varieties and deformities of the atlas
vertebra from the skeletal specimens of Eastern Anatolian
people.
Methods: This study was carried out over a 3-year
period, 2000 through to 2002 in the Department of
Anatomy, Firat, Yuzuncu Yil and Ataturk University,
Turkey. Developmental anomalies and the variants of the
first vertebrae were investigated on 86 atlas.
Results: Ponticulus posterior was observed with a low
frequency on right as 2.3%. The bilateral localization was
10.5% and the left-side localization was 9.3%. Ponticulus
lateralis showed an equal localization as 1.2% on the
right, 1.2% on the left and 1.2% bilateral. In the present
study, a complete subdivision of the joint surface was
observed in 11 atlases (12.8%). Processus
infratransversarius atlantis with a frequency between
1.2-7%, arthrotic formation and corona atlantis
peridentals in 8 cases (9.3%) were also found.
Conclusion: The low frequency for fonticulus posterior
might be peculiar to the population living in this area.
Saudi Med J 2004; Vol. 25 (3): 322-325
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www.smj.org.sa Saudi Med J 2004; Vol. 25 (3) 323
localization of 3.5% on the right, 1.2% on the left
and 7% bilateral (
Table 1).
Arthritic deformities. (
Figures 3 & 4). In our
study, an arthritic formation at the arcus anterior
atlantis was found in 8 cases with a frequency of
9.3% (
Table 1).
Discussion. Bridge formations of the atlas
vertebrae: ponticulus posterior and ponticulus
lateralis. According to standard anatomical
description, a wide groove for vertebral artery and
suboccipital nerve on the superior aspect of the
posterior arch of the atlas vertebra crosses behind
each lateral mass. In some cases it is partly or
wholly made of a foramen by bone arching back
from the superior surface of the lateral mass.
11
This
bony bridge was first reported by MacAlister.
6
It
was variously described as ponticulus posterior or
posticus, Kimmerle’s variant, retroarticular canal,
foramen retro-articular superior, retro condylar
vertebral artery ring, posterior atlantoid foramen,
foramen arcual and atlas bridging.
2-5,8,10,12,13
The
ponticulus posterior was observed with a low
frequency on the right (2.3%) (
Table 1). The
percentage of the bilateral and left side localization
(Figure 1) showed no difference with those of the
American population, which was reported to be
between 9-15%.
3,5,6,9
Its incidence in the Indian
population was found as 11.4%
14
while in the South
African population, it was reported with complete
occurrence as 11.7% on the right and 24.6% on the
left.
4
Our study presented with partial posterior
bridge formation with 9.3% and complete formation
with 12.8% (
Table 1). Taitz and Nathan
5
found
partial formation as 25.9% and complete formation
as 7.9%.
Ponticulus lateralis. Represents the lateral
bridge, which extends from the upper edge of the
massa lateralis to fuse with the posterior root of the
transverse process.
5,10
The frequency of the lateral
cervical vertebra in the mentioned population,
which have not been documented in the literature.
The clinical symptoms and disturbances caused by
the anomalies of the atlas were also reviewed.
Methods. This study was carried out over a
3-year period from 2000 through to 2002, in the
Department of Anatomy, Firat, Yuzuncu Yil and
Ataturk University, Turkey. The present study is
based on the examination of 86 complete and
undamaged adult atlas vertebrae. Most of them were
the course materials obtained from cadavers for our
medical students. The others were from a collection
of vertebrae available in our departments. Our
materials were of undetermined age and gender.
Special attention was directed to the bridge
formation and arthritic changes of the atlas, which
are responsible for clinical symptoms.
Results. The results are summarized in
Table 1
as the shape variations and arthritic formations
(Figures 1-4).
Bony bridges. (Figure 1) In the present study,
ponticulus posterior was observed with a frequency
of 2.3% on the right. The percentage of bilateral
localization was 10.5% and the left-sided
localization was found with 9.3%. Partial posterior
bridge formation was found with 9.3% and
complete formation with 12%. The lateral bony
bridge, ponticulus lateralis represented an equal
localization with frequencies of 1.2% on the right,
1.2% on the left and 1.2% bilateral. One case
showed both posterior and lateral bridges (Table 1).
Facies articularis superior atlantis bipartite.
(Figure 2) Eleven atlases (12.8%) presented with a
complete subdivision of the joint surface was found
in our study (Table 1). No incomplete subdivision
was observed.
Processus infratransversarius atlantis. (Figure 3)
This variation was observed with a frequency and
Table 1 - Variations and arthrotic changes of atlas found in the present study (N=86).
Ponticulus posterior
Ponticulus lateralis
Ponticulus posterolateralis
Facies articularis superior atlantis bipartita
Processus infratransversarius atlantis
Localization Development
n
2
1
5
3
Right
(%)
(2.3)
(1.2)
(5.8)
(3.5)
n
8
1
4
1
Left
(%)
(9.3)
(1.2)
(4.7)
(1.2)
n
9
1
1
2
6
Bilateral
(%)
(10.5)
(1.2)
(1.2)
(2.3)
(7)
n
11
2
1
Complete
(%)
(12.8)
(2.3)
(1.2)
n
8
1
Incomplete
(%)
(9.3)
(1.2)
Arthrotic formation
Corona atlantis peridentalis
n(%)
8 (9.3)
Variations
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324 Saudi Med J 2004; Vol. 25 (3) www.smj.org.sa
materials of the dorsal arch and the lateral
extensions of the proatlas and to belong to the
manifestations of the occipital vertebra.
10
The clinical significance of bridge formation has
been discussed in reference to their possible effect
on normal vertebral artery function due to the
ponticulus formations that can be identified on the
conventional lateral and a.-p. radiographs.
3,10,18
This
formation can cause compression of the vertebral
artery, particularly during extreme rotational
movements of the cervical spine. This may play a
role in reduction of vertebral artery blood flow,
leading to symptoms of vertebrobasilar
insufficiency.
3,4,7
A correlation between migraine
cervicale and the presence of a ponticulus posterior
was reported. In such cases, resection of the
ponticulus may be indicated, which results in
decompression of the vertebral artery and the
accompanying nerves.
10,18
Facies articularis superior atlantis
bipartita. The superior articular surface of the
bridge in our study generally resembles to that of
the previous studies. In the literature, this variation
is reported with a percentage between 1.8-3.8,
5,10,15
which agrees with our findings. Our study also
presented an equal localization for this formation,
namely 1.2% on the right, 1.2% on the left and 1.2%
bilateral. Our observations showed a ratio of 2:1 for
complete and incomplete formation, similar to Taitz
and Nathan
5
finding. In our study, one atlas (1.2%)
showed both posterior and lateral bridges (
Table 1),
which accords with the literature.
5,10
The origin of
atlas bridging has been debated in the literature. The
opinion of ancient authors was that the posterior
bridge is a direct homologue of the superior oblique
process of other mammals.
6,16
Familial nature of
atlas bridging proposed by Selby et al
17
and an
acquired ossification of ligaments occurring with
aging
5,8
was not the same with the study of Lamberty
and Zivanovic,
3
that cartilaginous ponticuli
posteriores have been seen in fetuses and children.
Recently, atlas bridging is supposed to develop from
Figure 1 - A bony arch bridging the sulcus arteriae vertebralis
(arrows) behind the massa lateralis atlantis, namely,
ponticulus posterior. A complete bridge over the foramen
processus transversi of the atlas, ponticulus lateralis
(asterisk).
Figure 2 - Superior articular facet of atlas vertebra showing
subdivision into 2 parts, facies articularis superior atlantis
bipartite, with bilateral localisation (asterisk).
Figure 3 - A bony extension in the caudal direction, emerging from
the transverse process of the atlas (such as, processus
infratransversarius atlantis) (arrows) and arthrotic
formation of the atlas at the arcus anterior atlantis
(asterisk).
Figure 4 - A bony element at the arcus anterior atlantis, corona
atlantis peridentalis or "coulisse of the atlas" (asterisk).
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Variations of atlas ... Kavakli et al
www.smj.org.sa Saudi Med J 2004; Vol. 25 (3) 325
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12. Kendrick GS, Biggs NL. Incidence of the ponticulus
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seventeen. Anat Rec 1963; 145: 449-454.
13. Saunders SR, Popovich F. A family study of two skeletal
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retrotransverse groove (canal) in the Indian atlas vertebrae.
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1963; 55: 186-194.
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17. Selby S, Garn SM, Kanareff V. The incidence and familial
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Phys Anthropol 1955; 13: 129-141.
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20. Ganguly DN, Singh-Roy KK. A study on the
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atlas is concave and elongated, joint with the
corresponding occipital condyle. Sometimes the
articular surface is divided into 2-facet.
11
In the
present study, a complete subdivision of the joint
surface was observed in 11 atlases (12.8%) (
Table 1)
(
Figure 2). Prescher
10
found this variation in 28 out
of 200 atlases (14%): 7.5% on the right, 2% on the
left, 4.5% bilateral. In the literature, the frequency
of the bipartite superior joint surface was reported
between 5.5-33%.
10,19
That this variation develops
from 2 sources, namely, the proatlas and C1
segment, may explain its origin.
10,18,20
Clinical
symptoms and disturbances caused by facies
articularis superior bipartita atlantis have not been
reported. However, it may be mistaken for fractures
in tomography.
21
Processus infratransversarius atlantis. This is
a bony extension emerging from the transverse
process in caudal direction.
10
In the present study,
this structure was observed in different localization
with a frequency of 1.2-7% in variable lengths
(
Figure 3). Clinically, this variation may represent
symptomatic disturbances at the craniocervical
junction.
22
Patients with symptomatic variations of
the craniocervical junction often complain of pain in
the neck region or at the back of the head or they
suffer from vertigo or disturbances in balance.
Principal mechanisms of symptoms are mechanical
compression of nervous and vascular structures,
marked instability or in contrast, elevated rigidity.
23
Arthrotic formations simulating variants:
Corona atlantis peridentalis. In the present study,
arthritic formation, corona atlantis peridentalis or
"coulisse of the atlas" termed by Prescher,
10
at the
arcus anterior atlantis was found in 8 cases (9.3%),
corresponding to the "coulisse of the dens" (
Figure 3
& 4). Lombardi
24
reported that these formations
might be partly attributed to the occipital vertebra.
He also observed that the patients in his series were
free of any physical disturbances attributable to the
malformation.
In conclusion, the findings from our study
generally agree with those of the previous. The only
difference was that ponticulus posterior was
observed with a low frequency on the right, only
perhaps encountered by chance. It might even be
peculiar to the population living in the area. Our
results for processus infratransversarius atlantis,
arthrotic formation and corona atlantis peridentalis,
will also be compared with those of further works
for our literature survey failed to find any data
concerning them in other populations.
Acknowledgment. The authors would like to thank
Assoc. Prof. Hassan Boynukara who made the necessary
correction of the English grammar.
Page 4
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    • "Alterations in the morphometry of SAF will alter ergonomic of the atlantooccipital joint [11]. Various techniques have been used to evaluate the prevalence of PP in different populations, mostly performed by plain radiographs or dried atlas speci- mens [2,3,121314 . Radiographic analysis with lateral cervical spine or cephalometric radiographs can only evaluate the PP in two dimension. "
    [Show abstract] [Hide abstract] ABSTRACT: 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. 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). A retrospective study. Five hundred consecutive patients who had undergone dental CBCT scans. Age, sex, and radiologic measures. 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, χ2 test, and logistic regression model, as appropriate. 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, p<.001, respectively), and in the 11 unilateral partial PP patients (p=.001, p=.007, 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). 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. Copyright © 2015 Elsevier Inc. All rights reserved.
    Full-text · Article · Feb 2015 · The spine journal: official journal of the North American Spine Society
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  • [Show abstract] [Hide abstract] ABSTRACT: The groove for the vertebral artery (VA) may be bridged on C-1, forming a canal through which the artery passes. Because this variant may significantly affect the commonly performed C-1 posterior laminectomy, the authors studied the incidence and radiological appearance of this anatomical feature in surgical specimens. Anatomical measurements were performed using a Vernier caliper (accurate to 0.1 mm) on 166 dry C-1 vertebrae. In addition, a convenience sample of 172 cervical x-ray films was evaluated. Partial osseous bridging was detected in eight (4.8%), and a complete osseous bridge, forming the canalis arteriae vertebralis (canal for the VA), was seen unilaterally (eight on the left and two on the right) in 10 (6%) and bilaterally in eight (4.8%) of the dry vertebrae. On lateral radiography, a complete bone bridge was observed on nine (5.2%) and a partial bridge on 10 (5.8%) of the 172 studies. The discovery of a common variant may necessitate an immediate change in surgical management, and this anomaly could even increase the rate of surgery-related complications. The VA canal, present in the C-1 vertebra in approximately 5% of the specimens evaluated, was a variant that may be protective against VA injury. Knowledge of this variant may help the surgeon undertaking procedures in the C-1 region.
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