ANOMALOUS LEFT VERTEBRAL ARTERY FROM ARCH OF AORTA: A THOUGHT FOR SURGEONS?

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Int J Anat Res 2015, 3(1):861-64. ISSN 2321-4287 861

Case Report

ANOM ALOUS LEFT VERTEBRAL ARTERY FROM ARCH OF AORTA-A

THOUGHT FOR SURGEONS?

Deepa Somanath *

1

_{, Shivali Srivastava}

2

_.

ABSTRACT

Address for Correspondence: Dr. Deepa Som anat h, Assist ant Professor, Dept . of Anat omy, Sri M anakula Vinayagar M edical College, M adagadipet , Puducherry- 605 107, India.

E-M ail: deepa.somanat h@gmail.com

* 1 _{Assistant Professor, Dept . of Anatomy, Sri M anakula Vinayagar M edical College, Puducherry, India.} 2_{Post Graduate St udent , Dept . of Anat omy, Sri M anakula Vinayagar M edical College, Puducherry,}

India.

Art erial variat ions in t he branching pat t er n of arch of aort a ar e uncom m on and m ay occur as a result of developm ent al changes in t he fusion and absorpt ion of various phar yngeal ar ch ar t eries int o t he aor t ic sac. The present case repor t describes a finding in a m ale cadaver aged bet w een 60- 65 years about t he origin of left vert ebral art ery direct ly from the arch of aort a. Such variat ions should be kept in m ind during surgical procedures in t he super ior m ediast inum .

KEYW ORDS:Lef t ver t ebral ar t ery, Arch of aorta, Arch art ery, Anom aly.

INTRODUCTION

Int ernat ional Journal of Anatomy and Research, Int J Anat Res 2015, Vol 3(1):861-64. ISSN 2321- 4287 DOI: ht t p:/ / dx.doi.org/10.16965/ ijar.2015.102

The vertebral artery cont ributes t o t he blood supply of t he brain by helping in t he format ion of circle of W illis. It forms a major part of t he posterior cerebral circulat ion.

60- 85% of t he populat ion have t hree direct b r an ch es f ro m t h e ar ch of aor t a, n am el y brachiocephalic t runk, left common carot id and left subclavian artery. Somet imes, t he arch of aorta can give rise t o t he vertebral arteries of one or bot h sides, commonly t he left side. The vertebral artery on eit her side usually arises from t he f irst part of t he subclavian art er y, m edial t o t he scalenus ant er ior m uscle. It ascen d s v er t i cal l y t o ent er t h e f o r am en t ransversarium of sixt h cervical vertebra and

t raverses all cervical foramina t ransversaria up t o t he first cervical vertebra (at las). This part of t he artery from it s origin t o t he ent ry int o t he f or am en t ran sver sar i u m i s cal led t h e pr e vertebral segment . Then t he artery lies on t he posterior arch of t he at las in t he sub occipital t riangle, follow ing w hich it pierces t he at lant o-o cci p i t al m em b ran e an d d u r a m at er. Th e v er t ebr al ar t er y t h en en t ers t he fo ram en m agnum and unit es w it h t he corresponding artery of t he opposite side t o form t he basilar artery w hich in t urn terminates as t w o posterior cerebral arteries [1].

The present case report depict s t he anomalous origin of t he left vertebral artery from t he arch of aorta.

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Received: 08 Jan 2015 Accept ed: 04 Feb 2015 Peer Review : 08 Jan 2015 Published (O):28 Feb 2015 Revised: None Published (P):31 M ar 2015

Int ernat ional Journal of Anat omy and Research ISSN 2321-4287

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Deepa Somanat h , Shivali Srivast ava. ANOM ALOUS LEFT VERTEBRAL ARTERY FROM ARCH OF AORTA-A THOUGHT FOR SURGEONS?.

CASE REPORT

During routine dissect ion of a formalin fixed male cadaver aged 60- 65 years, for undergraduate st udent s of Sri M anakula Vinayagar M edical College and Hospit al, Pondicher r y, t he lef t vertebral artery was seen t o be originat ing from t he arch of aort a bet w een t he left com m on carotid and t he left subclavian arteries, w hereas, t he vert ebral art ery on t he right side had a normal origin from t he first part of t he right subclavian artery.

In t he superior mediast inum, t he left vertebral artery was seen ascending t o reach t he neck t o

Fig. 1: Show ing Anom alous Left vert ebral art ery.

AA-arch o f ao r t a,BCT-Br achi oceph al ic t r un k,LCCA-Lef t co m m on caro t id ar t er y,LVA-Lef t ver t eb ral ar t er y, LSA-lef t subclavian art ery,LVN-Left vagus nerve

enter scaleno vertebral t riangle. The artery t hen ran a ver t ical course t o ent er t he foram en t ransversarium of t he sixt h cervical vertebra. It t raversed t he cervical foramina t ransversaria up t o t he foramen t ransversarium of t he at las. The artery had a non t ort uous course and t he pre vertebral segment measured about 51 mm. The vertebral artery on t he right side originated from t he first part of right subclavian artery medial t o scalenus anterior muscle and follow ed a nor m al course of pre ver t ebr al segm ent entering t he foramen transversarium of t he sixt h cervical vertebra.

Fig. 2: Show ing Anom alous Left vert ebral art ery.

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Int J Anat Res 2015, 3(1):861-64. ISSN 2321-4287 863 DISCUSSION

The vertebral artery is divided int o four part s; t he first part is derived from t he proximal part o f d or sal d i vi sio n o f t he seven t h cer v i cal intersegmental artery. The second part is derived from t he longit udinal com municat ions of t he post cost al anast om oses bet w een t he first t o sixt h cervical intersegmental arteries. The t hird part develops from t he spinal branch of t he first cervical intersegm ent al art ery and t he fourt h part develops from it s pre neural division [1, 2]. Albayram et al. have stated t hat an aberrant left vertebral artery from arch of aorta is due t o t he persistence of eight h intersegmental artery [3]. Aort ic arch anomalies are seen in chromosomal abnormalit ies such as 22q11 delet ion [4]. In a st udy by Shin et al. it was noted t hat t he left vert ebral artery arose from t he arch of aorta bet w een t he lef t com m on carot id and lef t subclavian art eries in 5.8% of cases [5] . In anot her st udy by Lemke et al. it was observed t h at 2.4- 5.8% cases h ad t h e ab ov e sai d variat ion[6].

Rekha et al. st at ed t he o ccu r ren ce o f lef t vertebral artery branching from the arch of aorta in 4.5% of cases in a sample size of 110 formalin fixed cadavers [7].

The incidence of t he left vertebral artery arising from t he arch of aorta was found t o be 3.33% in a st udy on 30 cadavers by Oza Sunil et al [8]. An unusual observat ion by Goray et al. depicted five direct branches arising from t he arch of aorta w hich included bot h vertebral arteries [9]. 1.6% of 62 cadavers w ere found to have an anomalous left vertebral artery from t he arch of aorta in a st udy by Nayak et al. [10]

Hassan et al. reported a case of a 40 year old fem ale w it h sym pt om s of cer vicom edullary st en o sis d ue t o co m p r essi o n o f t h e cervicomedullary junct ion by an anomalous left vertebral artery from t he arch of aorta [11]. An anomalous vertebral artery may or may not cause clinical sympt oms. How ever it is necessary t o b e vi gi lan t d u r in g p ro cedu r es o f t h e mediast inum and the neck to avoid misdiagnosis and iatrogenic complications. Since the vertebral artery forms an important part of t he posterior cerebral circulat ion, aberrat ions in it s origin,

course, diam et er and lengt h can af fect t he cerebral hemodynamics. This may cont ribute t o t he development of int racerebral malformations and dissect ion aneurysms [12]. As aforement io-ned, an anom alous vert ebral art ery w it h or w it hout aneurysm can cause compression of various st ruct ures on it s course.

Vertebral artery anomalies may also indicate t he presence of many ot her congenital malformat-ions of t he cardiovascular system, eg. Absence of inferior t hyroid artery, cardiac malformations, facial hemangiomas etc. [12]

Since the proximal part of direct branches of arch of aorta are more prone for at herosclerosis, any t hromboembolic disorder in t he vertebral artery can be hazardous as it cont ributes t he blood supply t o t he brain.

Know ledge of such variat ions is essent ial for surgeons and diagnost ic radiologist s in various procedures w hich require t he exposure of t he arch of aorta and its branches, such as aortic arch reconst ruct ion, graft technique for t ot al arch replacement , aneurysm repair and endarterec-t o m y. Oendarterec-t h er p r oced ur es w h i ch r eq u i re a t horough know ledge of vertebral artery and it s variat ions include angiography, low er cervical spine surgeries, t ranspedicular fixat ion, excision of cranio- cervical junct ion masses, endovascular procedures etc.

CONCLUSION

It is obvious from t he review of literat ure t hat left sided variat ions of t he vertebral artery are much more common than t hose of the right side. Certain chromosomal aberrat ions may give rise t o changes in t he developmental pat hway of t he art eries leading t o such anomalies. Variat ions such as the present case should be borne in mind dur ing t he above m ent ioned surgeries and procedures.

Acknow ledgem ent:

We w ould like t o t hank M aster Pranavan S, for helping us w it h t he phot ographs.

Conflicts of Interests: None

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ANOMALOUS LEFT VERTEBRAL ARTERY FROM ARCH OF AORTA: A THOUGHT FOR SURGEONS?