Case Report Anomalous Origin of Left Vertebral Artery from Carotid Bulb Seen as “Trifurcation” of Left Common Carotid Artery with Acute Infarct in Ipsilateral Thalamus: A Case Report Parag V. Patil, MD, DNB, FRCR, Abhijit M. Patil, MD, Abhang V. Apte, MD, DNB, Vinod Y. Attarde, MD, FRCR, FRANZCR From the Department of Radiology, Padmashree Dr. D. Y. Patil Medical College, Hospital & Research Center, Pimpri, Pune, India (PVP, AMP); Department of Radiology, MGM Medical College, Aurangabad, India (AVA); and Bolsover Radiology, Hillcrest Hospital, Rockhampton, QLD, Australia (VYA).
ABSTRACT Anomalous origin of vertebral arteries is not common and usually seen as an incidental finding on imaging. We report a case of anomalous origin of left vertebral artery from left carotid bulb (“trifurcation” of left common carotid artery) on magnetic resonance angiography in a 64-year old male who also had ipsilateral thalamic acute infarct.
Keywords: Anomalous origin, vertebral artery, trifurcation, MR angiography. Acceptance: Received April 8, 2014, and in revised form May 29, 2014. Accepted for publication July 13, 2014. Correspondence: Address correspondence to Parag Patil, 218, Bhawani Peth, Sat Kholya, Jalgaon Maharashtra State, India. Pin - 425001. E-mail: [email protected]. J Neuroimaging 2015;25:662-664. DOI: 10.1111/jon.12172
Introduction In normal anatomy, the vertebral artery originates as the first branch of the subclavian artery on either side; passes through the transverse foramina of sixth to first cervical vertebrae with eventual intracranial course. Anomalous origin of vertebral arteries is not a very common finding with reported incidence varying from 3% to 8%. Left vertebral artery is more frequently involved than the right. We describe the magnetic resonance (MR) angiographic findings in a case of anomalous origin of left vertebral artery from left carotid bulb.
artery in transverse foramina (Fig 2A). At the level of carotid bulb, apart from the origins of internal and external carotid arteries, origin of left vertebral artery was also noted immediately adjacent to the left external carotid artery (“trifurcation” of left common carotid artery) (Fig 2B) at C3 vertebral body level. Maximum intensity projection (MIP) images clearly depicted trifurcation of left common carotid artery (Fig 3). The artery entered left transverse foramen of C1 vertebra. Further course of left vertebral artery was similar to the contralateral vertebral artery. Both joined to form basilar artery.
Case
Discussion
A 64-year old male patient presented with acute onset weakness in right upper and lower limb associated with slurred speech since 1 day. He was a nonsmoker, nonalcoholic, normotensive, and nondiabetic. Vital parameters were stable. Three-fifth power was observed in right upper and right lower limb. No obvious sensory involvement was noted. Cranial nerve examination was unremarkable. He was subjected to magnetic resonance imaging (MRI) brain and MR angiography study. MRI brain revealed small acute nonhemorrhagic infarct in left thalamus (Fig 1). Also noted was gliotic area in head of right caudate nucleus with ex-vacuuo dilatation of frontal horn of right lateral ventricle. Three-dimensional (3D) Time of flight (TOF) MR angiography of cerebral vessels revealed absent A1 segment of right anterior cerebral artery. 3D TOF neck MR angiography below the level of carotid bulbs revealed absent left vertebral
Anomalous origin of left vertebral artery directly from arch of aorta is seen in approximately 7% of cases and represents the commonest variation in the origins of vertebral arteries and second commonest aortic arch anomaly.1 Anomalous origin of right vertebral artery is uncommon and is divided into three categories by Lemke et al: origin from aorta, origin from carotid or brachiocephalic artery, and duplicated origin.2 Various cases have been reported on the different kinds of anatomic variations in either or both of the vertebral arteries. These include variations in the origin (origin from aortic arch, origin as a second branch of subclavian artery, bifid origin, etc) with or without associated anomalies of aortic arch. Anomalous origin of vertebral arteries directly from carotid arteries is very rare. Vertebral artery originating from common carotid artery has been reported in literature.3–6 In
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Copyright
◦ 2014 by the American Society of Neuroimaging C
Fig 1. Diffusion-weighted image and corresponding ADC map at the level of thalami reveal small oval area of restricted diffusion in left thalamus suggesting acute infarct.
Fig 2. (A) 3D TOF MR angiography below the level of carotid bulbs: Left vertebral artery is not seen in the left transverse foramen (curved arrow). (B) 3D TOF MR angiography at the level of left carotid bulb: Left vertebral artery (thin arrow) is seen originating as the third branch of left carotid bulb posteromedial to the origin of external carotid artery (empty arrow). Origin of left internal carotid artery (thick solid arrow) is seen at expected location. all these cases, it originated from the lower cervical or upper thoracic level. Aberrant origin from external carotid artery is also reported.7 Trifurcation of common carotid artery has been reported with the occipital artery representing the third branch.8,9 However, vertebral artery representing the third branch of carotid bulb, as seen in our case, has not yet been reported. Embryologically, distal end of seventh dorsal intersegmental artery forms the origin of vertebral artery on either side. Plexiform longitudinal anastomoses between cervical intersegmental arteries coalesce to form definitive vertebral arteries on either side.10 Aberrant anastomosis during embryonic development leads to anomalous origin of vertebral arteries.2,11 Possible persistence of left proatlantal intersegmental artery continuing as left vertebral artery with obliteration of proximal longitudinal anastomoses appears to be the possible embryological basis of the anomalous origin of left vertebral artery from left carotid bulb in our case.
Fig 3. 3D TOF MR angiography MIP reconstruction images in three different angles: Left vertebral artery originating from left carotid bulb seen as “trifurcation” of left common carotid artery. (Thin arrow = Left vertebral artery, Thick solid arrow = Left internal carotid artery, Empty arrow = Left external carotid artery).
Patil et al: Anomalous Origin of Left Vertebral Artery
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Most of the anomalies of vertebral arteries are incidentally picked up on imaging. Information about the anomalous origin of vertebral arteries is very important for surgical planning; especially in cases where vertebral artery originates from one of the mediastinal vessels.11 Komiyama et al have found increased incidence of arterial dissection in left vertebral arteries originating from aorta compared to those arising from subclavian artery.12 Also, there is possible role of aortic arch anomalies in the disorders of cerebral circulation. Anomalous origins can cause altered cerebral hemodynamics and can be associated with cerebral vascular disorders.4,11 Our case has dual importance. First, vertebral artery representing the third branch of common carotid artery trifurcation is not reported in literature yet. Second, the presence of posterior circulation infarct and old gliotic area in anterior circulation without any predisposing factor (apart from age) supports possible alteration in cerebral hemodynamics.
References 1. Welch CS, Stark P. The five-vessel arch: independent origin of both vertebral arteries from the aortic arch. J Comput Assist Tomogr 2012;36(2):275-276. 2. Lemke AJ, Benndorf G, Liebig T, et al. Anomalous origin of the right vertebral artery: review of the literature and case report of right vertebral artery origin distal to the left subclavian artery. AJNR Am J Neuroradiol 1999;20(7):1318-1321.
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3. Park JK, Kim SH, Kim BS, et al. Two cases of aberrant right subclavian artery and right vertebral artery that originated from the right common carotid artery. Korean J Radiol 2008;9(Suppl):S39S42. 4. Bernardi L, Dettori P. Angiographic study of a rare anomalous origin of the vertebral artery. Neuroradiology 1975;9(1):43-47. 5. Ishihara H, San Millan Ruiz D, Abdo G, Asakura F, Yilmaz H, Lovblad KO, Rufenacht DA. Combination of rare right arterial variation with anomalous origins of the vertebral artery, aberrant subclavian artery and persistent trigeminal artery a case report. Interv Neuroradiol 2011;17(3):339-342. 6. Chen CJ, Wang LJ, Wong YC. Abnormal origin of the vertebral artery from the common carotid artery. AJNR Am J Neuroradiol 1998;19(8):1414-1416. 7. Nasir S, Hussain M, Khan SA, Mansoor MA, Sharif S. Anomalous origin of right vertebral artery from right external carotid artery. J Coll Physicians Surg Pak 2010;20(3):208-210. 8. Chitra R. Trifurcation of the right common carotid artery. Indian J Plast Surg 2008;41(1):85-88. 9. Gurbuz J, Cavdar S, Ozdogmus¸ O. Trifurcation of the left common carotid artery: a case report. Clin Anat 2001;14(1):58-61. 10. Osborn AG. The aortic arch and great vessels. In: Osborn AG, ed. Diagnostic Cerebral Angiography. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 1999:5-9. 11. Satti SR, Cerniglia CA, Koenigsberg RA. Cervical vertebral artery variations: an anatomic study. AJNR Am J Neuroradiol 2007;28(5):976-980. 12. Komiyama M, Morikawa T, Nakajima H, et al. High incidence of arterial dissection associated with left vertebral artery of aortic origin. Neurol Med Chir (Tokyo) 2001;41(1):8-11; discussion 11-2.
Journal of Neuroimaging Vol 25 No 4 July/August 2015
ABSTRACT Anomalous origin of vertebral arteries is not common and usually seen as an incidental finding on imaging. We report a case of anomalous origin of left vertebral artery from left carotid bulb (“trifurcation” of left common carotid artery) on magnetic resonance angiography in a 64-year old male who also had ipsilateral thalamic acute infarct.
Keywords: Anomalous origin, vertebral artery, trifurcation, MR angiography. Acceptance: Received April 8, 2014, and in revised form May 29, 2014. Accepted for publication July 13, 2014. Correspondence: Address correspondence to Parag Patil, 218, Bhawani Peth, Sat Kholya, Jalgaon Maharashtra State, India. Pin - 425001. E-mail: [email protected]. J Neuroimaging 2015;25:662-664. DOI: 10.1111/jon.12172
Introduction In normal anatomy, the vertebral artery originates as the first branch of the subclavian artery on either side; passes through the transverse foramina of sixth to first cervical vertebrae with eventual intracranial course. Anomalous origin of vertebral arteries is not a very common finding with reported incidence varying from 3% to 8%. Left vertebral artery is more frequently involved than the right. We describe the magnetic resonance (MR) angiographic findings in a case of anomalous origin of left vertebral artery from left carotid bulb.
artery in transverse foramina (Fig 2A). At the level of carotid bulb, apart from the origins of internal and external carotid arteries, origin of left vertebral artery was also noted immediately adjacent to the left external carotid artery (“trifurcation” of left common carotid artery) (Fig 2B) at C3 vertebral body level. Maximum intensity projection (MIP) images clearly depicted trifurcation of left common carotid artery (Fig 3). The artery entered left transverse foramen of C1 vertebra. Further course of left vertebral artery was similar to the contralateral vertebral artery. Both joined to form basilar artery.
Case
Discussion
A 64-year old male patient presented with acute onset weakness in right upper and lower limb associated with slurred speech since 1 day. He was a nonsmoker, nonalcoholic, normotensive, and nondiabetic. Vital parameters were stable. Three-fifth power was observed in right upper and right lower limb. No obvious sensory involvement was noted. Cranial nerve examination was unremarkable. He was subjected to magnetic resonance imaging (MRI) brain and MR angiography study. MRI brain revealed small acute nonhemorrhagic infarct in left thalamus (Fig 1). Also noted was gliotic area in head of right caudate nucleus with ex-vacuuo dilatation of frontal horn of right lateral ventricle. Three-dimensional (3D) Time of flight (TOF) MR angiography of cerebral vessels revealed absent A1 segment of right anterior cerebral artery. 3D TOF neck MR angiography below the level of carotid bulbs revealed absent left vertebral
Anomalous origin of left vertebral artery directly from arch of aorta is seen in approximately 7% of cases and represents the commonest variation in the origins of vertebral arteries and second commonest aortic arch anomaly.1 Anomalous origin of right vertebral artery is uncommon and is divided into three categories by Lemke et al: origin from aorta, origin from carotid or brachiocephalic artery, and duplicated origin.2 Various cases have been reported on the different kinds of anatomic variations in either or both of the vertebral arteries. These include variations in the origin (origin from aortic arch, origin as a second branch of subclavian artery, bifid origin, etc) with or without associated anomalies of aortic arch. Anomalous origin of vertebral arteries directly from carotid arteries is very rare. Vertebral artery originating from common carotid artery has been reported in literature.3–6 In
662
Copyright
◦ 2014 by the American Society of Neuroimaging C
Fig 1. Diffusion-weighted image and corresponding ADC map at the level of thalami reveal small oval area of restricted diffusion in left thalamus suggesting acute infarct.
Fig 2. (A) 3D TOF MR angiography below the level of carotid bulbs: Left vertebral artery is not seen in the left transverse foramen (curved arrow). (B) 3D TOF MR angiography at the level of left carotid bulb: Left vertebral artery (thin arrow) is seen originating as the third branch of left carotid bulb posteromedial to the origin of external carotid artery (empty arrow). Origin of left internal carotid artery (thick solid arrow) is seen at expected location. all these cases, it originated from the lower cervical or upper thoracic level. Aberrant origin from external carotid artery is also reported.7 Trifurcation of common carotid artery has been reported with the occipital artery representing the third branch.8,9 However, vertebral artery representing the third branch of carotid bulb, as seen in our case, has not yet been reported. Embryologically, distal end of seventh dorsal intersegmental artery forms the origin of vertebral artery on either side. Plexiform longitudinal anastomoses between cervical intersegmental arteries coalesce to form definitive vertebral arteries on either side.10 Aberrant anastomosis during embryonic development leads to anomalous origin of vertebral arteries.2,11 Possible persistence of left proatlantal intersegmental artery continuing as left vertebral artery with obliteration of proximal longitudinal anastomoses appears to be the possible embryological basis of the anomalous origin of left vertebral artery from left carotid bulb in our case.
Fig 3. 3D TOF MR angiography MIP reconstruction images in three different angles: Left vertebral artery originating from left carotid bulb seen as “trifurcation” of left common carotid artery. (Thin arrow = Left vertebral artery, Thick solid arrow = Left internal carotid artery, Empty arrow = Left external carotid artery).
Patil et al: Anomalous Origin of Left Vertebral Artery
663
Most of the anomalies of vertebral arteries are incidentally picked up on imaging. Information about the anomalous origin of vertebral arteries is very important for surgical planning; especially in cases where vertebral artery originates from one of the mediastinal vessels.11 Komiyama et al have found increased incidence of arterial dissection in left vertebral arteries originating from aorta compared to those arising from subclavian artery.12 Also, there is possible role of aortic arch anomalies in the disorders of cerebral circulation. Anomalous origins can cause altered cerebral hemodynamics and can be associated with cerebral vascular disorders.4,11 Our case has dual importance. First, vertebral artery representing the third branch of common carotid artery trifurcation is not reported in literature yet. Second, the presence of posterior circulation infarct and old gliotic area in anterior circulation without any predisposing factor (apart from age) supports possible alteration in cerebral hemodynamics.
References 1. Welch CS, Stark P. The five-vessel arch: independent origin of both vertebral arteries from the aortic arch. J Comput Assist Tomogr 2012;36(2):275-276. 2. Lemke AJ, Benndorf G, Liebig T, et al. Anomalous origin of the right vertebral artery: review of the literature and case report of right vertebral artery origin distal to the left subclavian artery. AJNR Am J Neuroradiol 1999;20(7):1318-1321.
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3. Park JK, Kim SH, Kim BS, et al. Two cases of aberrant right subclavian artery and right vertebral artery that originated from the right common carotid artery. Korean J Radiol 2008;9(Suppl):S39S42. 4. Bernardi L, Dettori P. Angiographic study of a rare anomalous origin of the vertebral artery. Neuroradiology 1975;9(1):43-47. 5. Ishihara H, San Millan Ruiz D, Abdo G, Asakura F, Yilmaz H, Lovblad KO, Rufenacht DA. Combination of rare right arterial variation with anomalous origins of the vertebral artery, aberrant subclavian artery and persistent trigeminal artery a case report. Interv Neuroradiol 2011;17(3):339-342. 6. Chen CJ, Wang LJ, Wong YC. Abnormal origin of the vertebral artery from the common carotid artery. AJNR Am J Neuroradiol 1998;19(8):1414-1416. 7. Nasir S, Hussain M, Khan SA, Mansoor MA, Sharif S. Anomalous origin of right vertebral artery from right external carotid artery. J Coll Physicians Surg Pak 2010;20(3):208-210. 8. Chitra R. Trifurcation of the right common carotid artery. Indian J Plast Surg 2008;41(1):85-88. 9. Gurbuz J, Cavdar S, Ozdogmus¸ O. Trifurcation of the left common carotid artery: a case report. Clin Anat 2001;14(1):58-61. 10. Osborn AG. The aortic arch and great vessels. In: Osborn AG, ed. Diagnostic Cerebral Angiography. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 1999:5-9. 11. Satti SR, Cerniglia CA, Koenigsberg RA. Cervical vertebral artery variations: an anatomic study. AJNR Am J Neuroradiol 2007;28(5):976-980. 12. Komiyama M, Morikawa T, Nakajima H, et al. High incidence of arterial dissection associated with left vertebral artery of aortic origin. Neurol Med Chir (Tokyo) 2001;41(1):8-11; discussion 11-2.
Journal of Neuroimaging Vol 25 No 4 July/August 2015
