Persistent proatlantal artery with carotid-vertebral anastomosis Case report T. SURYA RAO, SURGEON-COMMANDER, M.S., M. CH. (NEURO),
AND PRAHLAD K. SETHI, MAJOR, M.D.
Departments of Neurosurgery and Neurology, Command Hospital, Lucknow, India ~" The authors describe the occurrence of proatlantal artery as an incidental angiographic observation in a young Indian soldier. This primitive anastomotic channel is seen extending from near the origin of the external carotid artery to the suboccipital region, traversing the foramen magnum and coursing beyond like a vertebral artery. The developmental and roentgenological aspects of carotid-basilar and carotid-vertebral anastomosis are discussed, along with a review of four similar cases reported previously. KEY WORDS persistent proatlantal artery carotid-vertebral anastomosis "
T an early 4-mm embryonic stage, the entire developing brain is supplied by the primitive carotid arterial system. Later, at the 7- to 12-mm stage, the vertebral arteries develop to take over the supply to the vertebrobasilar territory?~ In this transitional period, a supplementary blood supply is carried by some transient anastomotic arteries? ,H These channels in cranio-to-caudal sequence are the cranial extension of the internal carotid artery (ICA), and primitive trigeminal, otic, hypoglossal, and proatlantal arteries. 7 The cranial extension of the ICA becomes the posterior communicating artery and the rest are obliterated, first the otic, followed by the hypoglossal and finally the trigeminal artery. Until the vertebral system fully takes over, the caudal part of the developing basilar
A
J. Neurosurg. / Volume 43 / October, 1975
9 external carotid origin
9
artery is supplied by the proatlantal artery for a few critical days. 7 Of these five temporary vessels, a persistent origin of the posterior cerebral artery direct from the ICA and the persistent trigeminal artery are two abnormalities which may be frequently observed. The latter vessel is seen coursing between the ICA as it enters the cavernous sinus and the rostral part of the basilar artery. The primitive otic artery passes through the internal acoustic meatus and connects the intrapetrous part of the ICA and caudal portion of the basilar artery. 7 The persistent hypoglossal artery arises as a robust branch from the cervical part of the ICA at the C2-3 level, follows a tortuous course through the anterior condyloid foramen (not the foramen magnum) to join the caudal part of the basilar artery, and 499
T. S. Rao and P. K. Sethi
FIo. 1. Frontal (left) and lateral (right) angiographic projections, showing the intracranial branches of the anomalous vessel corresponding to those of normal vertebral and basilar arteries, and an extensive vascularized sellar mass.
TABLE 1 Nomenclature used in reported cases' of proatlantal artery
Author, Year Gottschau, 1885
Origin*
Nomenclature Used
ICA
anatomical description of an "abnormal vessel" anomalous carotidvertebral anastomosis; primitive cervical segmental artery "proatlantal artery" anomalous origin of lt. vertebral a. from ECA external carotid origin of dominant vertebral a. congenital external carotid vertebral anastomosis persistent primitive hypoglossal artery "proatlantal artery"
Conforti, et al., 1966 ICA
Lie, 1972 Lucca ReUi & De Farrari, 1960
ICA ECA
Flynn, 1968
ECA
Hackett & Wilson, 1968
ECA
Samra, et al., 1969
ECA
Surya Rao & Sethi, 1975
ECA
* ICA=internal carotid artery; ECA=external carotid artery. 500
might be associated with an absent posterior communicating artery. The persistent proatlantal artery arises similarly from the ICA, and ascends obliquely in the upper lateral part of the neck to reach the suboccipital region. There it connects with the horizontal portion of the vertebral artery as it lies over the posterior arch of the atlas, traverses the foramen magnum and behaves beyond it as a normal vertebral artery. This transient shunt vessel starts regressing at the 7- to 12-mm stage of the embryonic development and disappears when the embryo reaches 12 to 14 mm? This vessel may originate either from the cervical ICA or the external carotid artery. ~ Case
Report
T h i s 2 3 - y e a r - o l d m a n p r e s e n t e d with deterioration o f vision in his left eye. O n left carotid a n g i o g r a p h y , a large, rapidly growing sellar m a s s was found. A sizable vessel was seen b r a n c h i n g obliquely from near the origin of the external carotid artery. This a b n o r m a l vessel ascended the upper lateral part o f the neck to the suboccipital region, and entered the cranial cavity by the f o r a m e n m a g n u m (Fig. 1). J. Neurosurg. / Volume 43 / October, 1975
Proatlantal artery with carotid-vertebral anastomosis 2. Conforti P, Armenise B, Galligioni F: Anomalous carotid-vertebral anastomosis: primiIn 1954, Padget, 9 while discussing the tive cervical segmental artery. Neurochirurgia nomenclature of the embryonic intersegmen(Stuttg) 9:99-106, 1966 3. Flynn RE: External carotid origin of the domital vessels, specifically gave the name nant vertebral artery. Case report. J "proatlantal artery" to the suboccipital inNeurosurg 29:300-301, 1968 tersegmental vessel, in order to distinguish it from the hypoglossal artery above it, and all 4. Gottschau M: Zwei seltene Variet[iten der Stamme des Aortenbogen. Anat Entwickother vessels caudal to it that pass between lungsgeseh: 245-252, 1885 two developing cervical segments. This vessel, 5. Hackett ER, Wilson CB: Congenital external passing over the atlas along with the first cercarotid-vertebral anastomosis. A case report. vical nerve, lies above all cervical somites, Am J Roentgenol Rad Ther Nucl Med hence the name. 9 Although this artery and the 104:86-90, 1968 6. Kaplan AH: Anatomy and embryology of the posterior communicating artery at one stage arterial system of the fore brain, in Vinken P J, do play a critical part in irrigating the Bruyn GW (eds): Handbook of Clinical posterior circulatory bed, it is surprising that Neurology, Vol 2. New York, American its persistence has been reported only three Elsevier, 1972, pp 1-23 times with its origin from the ICA and four 7. Lie TA: Congenital malformations of the times originatfllg from the external carotid carotid and vertebral arterial systems, inartery (Table 1). 7 Only L i d referred to it by cluding persistent anastomosis, in Vinken P J, the correct nomenclature; the rest used Bruyn GW (eds): Handbook of Clinical descriptive terms of the vessel as it existed or Neurology, Vol 2. New York, American functioned. Samra, et al., 12 described what Elsevier, 1972, pp 289-339 8. Lucca Relli S, De Farrari U: Studio actually was a p r o a t l a n t a l vessel as a clinicoradiologico di un caso di origine hypoglossal artery and this designation was anomala (dalla carotide esterna) dell' arteria rightly objected to by Lie. 7 vertebrale sinistra. Radiol Med (Torino) The clinical significance of such primitive 46:963-974, 1960 vessels, which originate from near the com9. Padget DH: Designation of embryonic inmon carotid stem and supply vital hindbrain tersegmental arteries in reference to vertebral areas, has already been stressed by Flynn, s artery and subclavian stem. Anat Rec Samra, et al.? 2 and Wise and Palubinskas ~3 119:349-356, 1954 with particular r e f e r e n c e to associated 10. Padget DH: The development of cranial anomalies and catastrophic sequelae of their arteries in human embryo. Contrib Embryoi natural or surgical occlusion. 32:205-261, 1948 11. Patten BM: Human Embryology, ed 2. New York, McGraw-Hill, 1953 Acknowledgments 12. Samra K, Scoville WB, Yaghmai M: We are most grateful to Major-General A. C. Anastomosis of carotid vertebral arteries: perBose, AMC, Senior Consultant in Surgery, for his sistent primitive trigeminal and hypoglossal guidance and encouragement in preparation of this artery. Report of two cases. J Neurosurg paper. We are also thankful to the Director30:622-623, 1969 General, Armed Forces Medical Services, New 13. Wise BL, Palubinskas A J: Persistent Delhi-11, for permission to publish this report. trigeminal artery (carotid-basilar anastomosis). J Neurosurg 21:199-206, 1964 Discussion
References
1. Arey LB: Developmental Anatomy. A Textbook and Laboratory Manual of Embryology, ed 6. Philadelphia, WB Saunders, 1958, p 369
J. Neurosurg. / Volume 43 / October, 1975
Address reprint requests to: Surgeon Commander T. Surya Rao, M.S., M.Ch., Neurosurgical Centre, Command Hospital, Lucknow-2, India 226002.
50l
AND PRAHLAD K. SETHI, MAJOR, M.D.
Departments of Neurosurgery and Neurology, Command Hospital, Lucknow, India ~" The authors describe the occurrence of proatlantal artery as an incidental angiographic observation in a young Indian soldier. This primitive anastomotic channel is seen extending from near the origin of the external carotid artery to the suboccipital region, traversing the foramen magnum and coursing beyond like a vertebral artery. The developmental and roentgenological aspects of carotid-basilar and carotid-vertebral anastomosis are discussed, along with a review of four similar cases reported previously. KEY WORDS persistent proatlantal artery carotid-vertebral anastomosis "
T an early 4-mm embryonic stage, the entire developing brain is supplied by the primitive carotid arterial system. Later, at the 7- to 12-mm stage, the vertebral arteries develop to take over the supply to the vertebrobasilar territory?~ In this transitional period, a supplementary blood supply is carried by some transient anastomotic arteries? ,H These channels in cranio-to-caudal sequence are the cranial extension of the internal carotid artery (ICA), and primitive trigeminal, otic, hypoglossal, and proatlantal arteries. 7 The cranial extension of the ICA becomes the posterior communicating artery and the rest are obliterated, first the otic, followed by the hypoglossal and finally the trigeminal artery. Until the vertebral system fully takes over, the caudal part of the developing basilar
A
J. Neurosurg. / Volume 43 / October, 1975
9 external carotid origin
9
artery is supplied by the proatlantal artery for a few critical days. 7 Of these five temporary vessels, a persistent origin of the posterior cerebral artery direct from the ICA and the persistent trigeminal artery are two abnormalities which may be frequently observed. The latter vessel is seen coursing between the ICA as it enters the cavernous sinus and the rostral part of the basilar artery. The primitive otic artery passes through the internal acoustic meatus and connects the intrapetrous part of the ICA and caudal portion of the basilar artery. 7 The persistent hypoglossal artery arises as a robust branch from the cervical part of the ICA at the C2-3 level, follows a tortuous course through the anterior condyloid foramen (not the foramen magnum) to join the caudal part of the basilar artery, and 499
T. S. Rao and P. K. Sethi
FIo. 1. Frontal (left) and lateral (right) angiographic projections, showing the intracranial branches of the anomalous vessel corresponding to those of normal vertebral and basilar arteries, and an extensive vascularized sellar mass.
TABLE 1 Nomenclature used in reported cases' of proatlantal artery
Author, Year Gottschau, 1885
Origin*
Nomenclature Used
ICA
anatomical description of an "abnormal vessel" anomalous carotidvertebral anastomosis; primitive cervical segmental artery "proatlantal artery" anomalous origin of lt. vertebral a. from ECA external carotid origin of dominant vertebral a. congenital external carotid vertebral anastomosis persistent primitive hypoglossal artery "proatlantal artery"
Conforti, et al., 1966 ICA
Lie, 1972 Lucca ReUi & De Farrari, 1960
ICA ECA
Flynn, 1968
ECA
Hackett & Wilson, 1968
ECA
Samra, et al., 1969
ECA
Surya Rao & Sethi, 1975
ECA
* ICA=internal carotid artery; ECA=external carotid artery. 500
might be associated with an absent posterior communicating artery. The persistent proatlantal artery arises similarly from the ICA, and ascends obliquely in the upper lateral part of the neck to reach the suboccipital region. There it connects with the horizontal portion of the vertebral artery as it lies over the posterior arch of the atlas, traverses the foramen magnum and behaves beyond it as a normal vertebral artery. This transient shunt vessel starts regressing at the 7- to 12-mm stage of the embryonic development and disappears when the embryo reaches 12 to 14 mm? This vessel may originate either from the cervical ICA or the external carotid artery. ~ Case
Report
T h i s 2 3 - y e a r - o l d m a n p r e s e n t e d with deterioration o f vision in his left eye. O n left carotid a n g i o g r a p h y , a large, rapidly growing sellar m a s s was found. A sizable vessel was seen b r a n c h i n g obliquely from near the origin of the external carotid artery. This a b n o r m a l vessel ascended the upper lateral part o f the neck to the suboccipital region, and entered the cranial cavity by the f o r a m e n m a g n u m (Fig. 1). J. Neurosurg. / Volume 43 / October, 1975
Proatlantal artery with carotid-vertebral anastomosis 2. Conforti P, Armenise B, Galligioni F: Anomalous carotid-vertebral anastomosis: primiIn 1954, Padget, 9 while discussing the tive cervical segmental artery. Neurochirurgia nomenclature of the embryonic intersegmen(Stuttg) 9:99-106, 1966 3. Flynn RE: External carotid origin of the domital vessels, specifically gave the name nant vertebral artery. Case report. J "proatlantal artery" to the suboccipital inNeurosurg 29:300-301, 1968 tersegmental vessel, in order to distinguish it from the hypoglossal artery above it, and all 4. Gottschau M: Zwei seltene Variet[iten der Stamme des Aortenbogen. Anat Entwickother vessels caudal to it that pass between lungsgeseh: 245-252, 1885 two developing cervical segments. This vessel, 5. Hackett ER, Wilson CB: Congenital external passing over the atlas along with the first cercarotid-vertebral anastomosis. A case report. vical nerve, lies above all cervical somites, Am J Roentgenol Rad Ther Nucl Med hence the name. 9 Although this artery and the 104:86-90, 1968 6. Kaplan AH: Anatomy and embryology of the posterior communicating artery at one stage arterial system of the fore brain, in Vinken P J, do play a critical part in irrigating the Bruyn GW (eds): Handbook of Clinical posterior circulatory bed, it is surprising that Neurology, Vol 2. New York, American its persistence has been reported only three Elsevier, 1972, pp 1-23 times with its origin from the ICA and four 7. Lie TA: Congenital malformations of the times originatfllg from the external carotid carotid and vertebral arterial systems, inartery (Table 1). 7 Only L i d referred to it by cluding persistent anastomosis, in Vinken P J, the correct nomenclature; the rest used Bruyn GW (eds): Handbook of Clinical descriptive terms of the vessel as it existed or Neurology, Vol 2. New York, American functioned. Samra, et al., 12 described what Elsevier, 1972, pp 289-339 8. Lucca Relli S, De Farrari U: Studio actually was a p r o a t l a n t a l vessel as a clinicoradiologico di un caso di origine hypoglossal artery and this designation was anomala (dalla carotide esterna) dell' arteria rightly objected to by Lie. 7 vertebrale sinistra. Radiol Med (Torino) The clinical significance of such primitive 46:963-974, 1960 vessels, which originate from near the com9. Padget DH: Designation of embryonic inmon carotid stem and supply vital hindbrain tersegmental arteries in reference to vertebral areas, has already been stressed by Flynn, s artery and subclavian stem. Anat Rec Samra, et al.? 2 and Wise and Palubinskas ~3 119:349-356, 1954 with particular r e f e r e n c e to associated 10. Padget DH: The development of cranial anomalies and catastrophic sequelae of their arteries in human embryo. Contrib Embryoi natural or surgical occlusion. 32:205-261, 1948 11. Patten BM: Human Embryology, ed 2. New York, McGraw-Hill, 1953 Acknowledgments 12. Samra K, Scoville WB, Yaghmai M: We are most grateful to Major-General A. C. Anastomosis of carotid vertebral arteries: perBose, AMC, Senior Consultant in Surgery, for his sistent primitive trigeminal and hypoglossal guidance and encouragement in preparation of this artery. Report of two cases. J Neurosurg paper. We are also thankful to the Director30:622-623, 1969 General, Armed Forces Medical Services, New 13. Wise BL, Palubinskas A J: Persistent Delhi-11, for permission to publish this report. trigeminal artery (carotid-basilar anastomosis). J Neurosurg 21:199-206, 1964 Discussion
References
1. Arey LB: Developmental Anatomy. A Textbook and Laboratory Manual of Embryology, ed 6. Philadelphia, WB Saunders, 1958, p 369
J. Neurosurg. / Volume 43 / October, 1975
Address reprint requests to: Surgeon Commander T. Surya Rao, M.S., M.Ch., Neurosurgical Centre, Command Hospital, Lucknow-2, India 226002.
50l
