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| CASE REPORT |
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| Year : 2013 | Volume
: 2
| Issue : 3 | Page : 216-218 |
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Anomalous origin of left vertebral artery
Veena Vidya Shankar, PM Radhika, C Sheshgiri
Department of Anatomy, M.S. Ramaiah Medical College, Bangalore, Karnataka, India
| Date of Web Publication | 25-Oct-2013 |
Correspondence Address:
Veena Vidya Shankar
Department of Anatomy, M.S. Ramaiah Medical College, MSRIT Post, Mathikere, Bangalore 560 054, Karnataka
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/2278-344X.120597
Vertebral artery arises from the upper surface of the first part of subclavian artery on both sides. The morphological variations of the vertebral artery are of immense importance in surgery, angiography and all non-invasive procedures. During the routine dissection of a male cadaver aged about 65 years, we observed a variation in the branching of arch of aorta. The arch of aorta gave off four branches-brachiocephalic trunk, left common carotid artery (CCA), left vertebral artery (LVA) and left subclavian artery. LVA was arising between left CCA and left subclavian artery.The knowledge of variations in the vertebral artery is of great clinical interest to the neurosurgeon and radiologist for diagnostic investigation and surgical procedures of the neck. Keywords: Arch of aorta, foramen transversarium, subclavian artery, variations, vertebral artery
How to cite this article:
Shankar VV, Radhika P M, Sheshgiri C. Anomalous origin of left vertebral artery
. Int J Health Allied Sci 2013;2:216-8 |
| Introduction | |  |
The vertebral artery arises from the superior surface of the first part of subclavian artery medial to the thyrocervical trunk in the scaleno-vertebral triangle. It ascends vertically from the base to the apex of the scaleno-vertebral triangle along with its accompanying vein. The vertebral artery is essential for posterior cerebral circulation. It takes a vertical posterior course to enter into the foramen transversarium of the 6 th cervical vertebra (C 6 ), ascends through the transverse foramina of the cervical vertebrae. It turns posteromedially on the posterior arch of atlas, pierces the atlanto-occipital membrane and the dura mater and enters the foramen magnum. It is divided into 4 segments - The pre-vertebral (V 1 ) segment, Vertebral (V 2 ) segment, atlantooccipital (V 3 ) segment, intracranial (V 4 ) segment. [1],[2]
The segment of the vertebral artery from its origin at the subclavian artery to its entry into the respective transverse foramina is called the pre-transverse or pre-vertebral segment. [3]
The main cause for compromised blood supply to the brain is atherosclerosis of the vertebral and internal carotid artery giving rise to serious clinical consequences. The anomalies of the origin and distribution of vertebral can cause changes in cerebral hemodynamics that may lead to cerebral abnormalities. An anatomical knowledge of anomalous origin of vertebral artery is of utmost importance in surgery, angiography and all non-invasive procedures to prevent inadvertent complications. [4] These abnormalities are of diagnostic importance either prior to vascular surgery in the neck region or in cases of intra-vascular disease such as arteriovenous malformations or cerebral aneurysms. [5]
| Materials and Methods | | |
During the routine dissection of a male cadaver aged about 65 years, we observed a variation in the origin of vertebral artery from the arch of aorta. The region was neatly dissected, measurements of pre-vertebral segment of vertebral artery was taken with the measuring tape. The distance between the origin of left common carotid artery (CCA) and left vertebral artery (LVA) and distance between LVA and left subclavian artery was taken with the digital Vernier's caliper and photographed.
| Observation | | |
A variation in the origin of vertebral artery from the arch of the aorta was observed. Along with the vertebral artery, the other branches arising from the arch of aorta were brachiocephalic trunk, left CCA and left subclavian artery. The LVA was arising from the arch of the aorta, between the origins of left common carotid and left subclavian arteries. The distance between the origin of left CCA and LVA was 4.2 mm and between LVA and left subclavian artery was 3.4 mm [Figure 1]. After its origin the artery ascended vertically, posterior and to the left of left CCA. It traversed the scaleno-vertebral triangle from base to apex medial to the thyrocervical trunk and entered the foramen transversarium of the sixth cervical vertebra [Figure 2]. The length of the pre-vertebral segment of the LVA was 9.3 cm. However, the right vertebral artery arose normally from the posterosuperior aspect of the first part of the right subclavian artery.
| Discussion | | |
The prevalence of anomalous origin of vertebral artery from the aortic arch has been reported as 1.6-5.8%. [3],[6],[7],[8],[9],[10],[11] This variation in the origin of vertebral artery is asymptomatic. Nonetheless, diagnosis of these abnormalities in cases of vascular diseases such as arteriovenous malformations or aneurysms, before cerebral angiography, is important to avoid wrongly interpreting non-opacification of vertebral arteries as a blockage or stenosis that may prove dangerous during the endovascular surgeries in the head and neck region. [12]
The knowledge of development of the aortic arch and the brachiocephalic vessels is essential to understand the hypothetical development of the anomalous origin of the vertebral artery. The vertebral artery is formed between 32 nd and 40 th day of gestation. The first part develops from the proximal part of dorsal branch of 7 th cervical inter-segmental artery proximal to post-costal anastomosis while the second part develops from the longitudinal communications of post-costal anastomoses. Any abnormalities in the fusion process leads to abnormal origins. [2] An aortic origin LVA may be due to the persistence of the dorsal division of the left 6 th inter-segmental [Figure 3] instead of left 7 th dorsal inter-segmental artery as the first part of vertebral artery, [8],[10] or it may be due to the persistence of the 8 th inter-segmental artery. [12] | Figure 3: Schematic representation of the embryological basis of anomalous origin of left vertebral artery. The sixth inter-segmental artery persists instead of the seventh; hence, the left vertebral artery arises from the aortic arch, between the left common and left subclavian arteries
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In the present case, left sixth dorsal inter-segmental artery might have persisted as the first part of vertebral artery because the vertebral artery was arising between left common carotid and left subclavian artery. If the LVA was arising distal to the left subclavian, it would have been due to the persistence of left 8 th dorsal inter-segmental artery. [12]
The knowledge of anomalous variation of the vertebral artery is important to know the predilection for dissection because the LVA of the aortic arch origin has a predilection for dissection in comparison with left and right vertebral artery arising from left and right subclavian artery respectively. [9]
Variation in the origin of vertebral artery may lead to altered hemodynamics, predisposing to intracranial aneurysm formation. Therefore, a thorough search for coexisting aneurysms should be undertaken in patients with these anomalies. Endovascular therapy of intracranial aneurysms can be performed before they present clinically as subarachnoid hemorrhages or mass effect and thereby, decrease morbidity and mortality. [13]
A thorough knowledge of the anomalous origins of the great vessels is an essential prerequisite for angiographic procedures as they also represent a potential pitfall at diagnostic cerebrovascular imaging. The anomalous origin of unilateral or bilateral vertebral arteries may be misinterpreted as being congenitally absent or be wrongly assumed to be occluded or diseased, either by eluding catheterization during angiography or by lying outside the region of interest during non-invasive studies such as computed tomography (CT) angiography, magnetic resonance angiography, or Doppler sonography. [14] The awareness of variations is of clinical interest in vascular or cardiothoracic surgical planningand during the endovascular treatment of the aortic arch injuries and during angioplasty and stent procedures in conditions such as aortic coarctation. Stent coverage of the left subclavian origin in such procedures results in perfusion of the left subclavian artery by way of the subclavian steal phenomenon from anormally positioned LVA.
However, when a patient who has an anomalous LVA requires endovascular treatment, stent coverage can occlude the LVA origin. This will preclude the subclavian steal phenomenon from occurring so as to perfuse the left subclavian artery; consequently, surgical re-implantation of the left subclavian artery to the left carotid artery would be mandatory. [15]
| Conclusion | | |
The awareness of the variation in the origin and distribution of the vertebral artery is clinically important in diagnostic investigation and interpretation of the pathology of the vertebral artery by computed tomography CT, magnetic resonance angiographic and ultrasound procedures. It is also an essential prerequisite for planning endovascular interventions and vascular surgery in the neck region.
| References | | |
| 1. | Williams PL, Bannister LH, Berry MM, Collins P, Dyson M, Dussek JE, et al. Cardiovascular system-subclavian system of arteries. In: Gabela G, editor. Gray's Anatomy. 38 th ed. New York, London: Churchill Livingstone; 1995. p. 1529-36. 
|
| 2. | Moore KL. The Developing Human: Clinically Oriented Embryology. 3 rd ed. WB Saunders: Philadelphia; 1982. p. 291-318.
|
| 3. | Imre N, Yalcin B, Ozan H. Unusual origin of the left vertebral artery. Int J Anat Var 2010;3:80-2.
|
| 4. | Singla RK, Sharma T, Sachdeva K. Variant origin of left vertebral artery. Int J Anat Var 2010;3:97-9.
|
| 5. | Jayanthi V, Prakash, Devi MN, Geethanjali BS, Rajini T. Anomalous origin of the left vertebral artery from the arch of the aorta: Review of the literature and a case report. Folia Morphol (Warsz) 2010;69:258-60.
|
| 6. | Vorster W, du Plooy PT, Meiring JH. Abnormal origin of internal thoracic and vertebral arteries. Clin Anat 1998;11:33-7.
|
| 7. | Komiyama M, Morikawa T, Nakajima H, Nishikawa M, Yasui T. High incidence of arterial dissection associated with left vertebral artery of aortic origin. Neurol Med Chir (Tokyo) 2001;41:8-11.
|
| 8. | Panicker HK, Tarnekar A, Dhawane V, Ghosh SK. Anomalous origin of left vertebral arteryembryological basis and applied aspects a case report. J Anat Soc India 2002;51:234-5.
|
| 9. | Yamaki K, Saga T, Hirata T, Sakaino M, Nohno M, Kobayashi S, et al. Anatomical study of the vertebral artery in Japanese adults. Anat Sci Int 2006;81:100-6.
|
| 10. | Nayak SR, Pai MM, Prabhu LV, D'Costa S, Shetty S. Anatomical organization of aortic arch variations in the India: Embryological basis and review. J Vasc Bras 2006;5:95-100.
|
| 11. | Himabindu A, Narasinga Rao B. A study on variant origins of vertebral artery. Int J Basic Appl Med Sci 2012;2:34-7.
|
| 12. | Goraya VB, Joshi AR.,Garga A, Merchanta S, Yadava B, Maheshwaria P. Aortic arch variation: A unique case with anomalous origin of both vertebral arteries as additional branches of the aortic arch distal to left subclavian artery. AJNR Am J Neuroradiol 2005;26:93-5.
|
| 13. | Poonam SRK, Sharma T. Incidence of anamolous origins of vertebral artery-anatomical study and clinical significance. J Clin Diagn Res 2010;4:2626-31.
|
| 14. | Satti SR, Cerniglia CA, Koenigsberg RA. Cervical vertebral artery variations: Ananatomic study. AJNR Am J Neuroradiol 2007;28:976-80.
|
| 15. | Vander Merwe B, Ackermann C, Scheepers S, Moosa S. Is anomalous origin of the left vertebral artery indeed a rare finding? SAJR 2012;16:144-46.
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[Figure 1], [Figure 2], [Figure 3]
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