Vertebral Arter V3 Segmenti ve Atlas (C1) Varyasyonlarının Kraniyovertebral Bölge Yaklaşımlarındaki Öneminin Araştırılması
Özet
Objective: The complex anatomy of the craniovertebral junction (CVJ), the relationship
between bone and vascular structures, and the frequent occurrence of variations in both
make this region complex in terms of safe surgery. In addition, the existence of differences
in the prevalence of variation between populations necessitates the determination of
frequencies specific to each population. Our aim in this study is to determine the
prevalence of vertebral artery V3 segment and atlas (C1) variations in Turkish population,
analyze their relationship with each other, make morphometric measurements according
to certain landmarks, compare the results with the literature, offer appropriate suggestions
and contribute to the literature.
Methods: From October 1, 2018, to October 1, 2023, computed tomography angiography
(CTA) scans of a cohort comprising two hundred individuals (one hundred women and
one hundred men, aged 18-65, who had not undergone CVJ surgery) from the Department
of Neurosurgery at Hacettepe University Faculty of Medicine were analyzed through 3-D
reconstruction and modeling. The identified atlas and VA-V3 segment were scanned for
variations, and their morphometric relationships were evaluated. In addition, atlas and V3
segment variation examination was performed in the dissection of ten cadavers. The
detected variations were used to support positive radiological results with real anatomy.
Results: The prevalence of posterior arch defect of atlas (PAAD) was 3% (n = 5 Type A,
n = 1 Type B) in 200 individuals. There was no significant relationship between it and any
V3 segment variation (p=0.57). Type A PAAD was in only one cadaver. The prevalence
of ponticulus posticus (PP) – ponticulus lateralis (PL) was 16.7% (n=67/400) out of four
hundred. The presence of V3 segment variation was found to increase the prevalence of
PP-PL (p = 0.01). Considering three variations of the V3 segment (persistent first
intersegmental artery (PIFA), fenestration of vertebral artery (VAF), extradural origin of
posterior inferior cerebellar artery (ed-PICA)), the prevalence is 3.3% (n=13/400), and considering seven variations (additional vertebral artery atresia (continuation of V3 as
PICA (V3-PICA)), dominancy of vertebral artert (VAD), hypoplastic vertebral artery
(VAH), suboccipital artery of Salmon (SAS)), it is 14.8% (n=59). /400) was determined.
The most common was VAD (9%) and the least was PIFA (0.3%). PIFA variation was
detected in 1 cadaver, and an important contribution was made since anatomical PIFA
dissection could not be detected in the literature. While the prevalence of VAF was
observed to be (1%), it was not detected in cadavers. The frequency of ed-PICA was found
to be 2% (n=8/400). ed-PICA was detected in 1 cadaver. It was noticed that, unlike atlas
bone variations, the prevalence of vascular variations increased from West to East. The
prevalence of VA atresia (V3-PICA) was found to be 0.5% (n=2/400). The frequency of
VAD was 9.5% (n=36/400), and VAH was 3.5% (n=14/400). Although left dominance
was observed, this difference was not statistically significant (p=0.08). The prevalence of
SAS was 7.3% (n=29/400), and it was detected in 25% of cadaveric sides. Parameter A
(𝑥�̅= 12.86 ± 1.62 mm); Parameter B was found as (𝑥�̅ = 20.17 ± 2.34 mm). It was concluded
that a bilateral distance of 12 mm on the superior surface of the arch and 18 mm on the
posterior surface would be a safe area. As parameter C (𝑥�̅ = 32.56 ± 2.66 mm) and
parameter D (𝑥�̅ = 6.65 ± 2.16 mm), these values were found to be lower in VAHs and higher
in VADs (p<0.001). The parameter was found to be F (𝑥�̅ = 4.34 ± 2.26 mm), and it was
concluded that this distance increased significantly when PP-PL, that is, it could protect
VA.
Conclusion: With the results obtained, atlas and VA V3 variation prevalence analysis
specific to the Turkish population, mutual morphometric measurements of these two
structures were made, and their importance in CVJ surgery was examined. Anatomical
variations obtained with cadaver dissection have strengthened the connection between
virtual 3-D radiological results and reality, and a rare example of PIFA dissection has been
introduced to the literature. Preoperative CTA examination has been found to be useful in
detecting significant variations and is an important method for safe surgery. Artificial
intelligence and machine learning, which have become an important part of today's world,
leave no doubt that these modalities will also play a role in future healthcare delivery. The data we obtained from our study will provide an important database for the
implementation of safe interventions in humans in the future.
