Neuroradiology
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Anterior Inferior Cerebellar Artery Originating from the Cavernous Portion of the Internal Carotid Artery 1
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Giuseppe Scotti, M.D. An anomalous branch of the cavernous carotid artery, not reported previously, is described. Its appearance and distribution were unlike those of any known cavernous branch, originating at the level where the trigeminal artery is usually found but having no communication with the basilar artery. Its distribution approximated that of the anterior inferior cerebellar artery. The author believes that this is an unusual form of persistent embryonic communication between the carotid artery and the vessels of the posterior fossa. INDEX TERMS:
Arteries, cerebellar • Carotid Arteries, abnormalities
Radiology 116:93-94, July 1975
•
•
of the internal carotid artery which are usually seen at angiography arise from the supraclinoidal portion: in order of their origin, they are the ophthalmic, posterior communicating, anterior choroidal, terminal anterior, and middle cerebral arteries. The small branches originating from the intracavernous portion are rarely seen, becoming visible only when they are enlarged as the result of disease in the surrounding structures (1, 2, 15). Schnurer and Stattin subdivide these small vessels according to their origin from a "dorsal" and "lateral" mainstem (12), but other authors employ a slightly different terminology (5, 10). These vessels supply the dura at the base of the skull, the tentorium, the cavernous sinus, the sella turcica and its contents, the gasserian ganglion, and (in part) the third, fourth, and sixth cranial nerves. Anomalous branches of the internal carotid fall into two groups: branches of the cervical internal carotid (which are usually branches of the external carotid) and carotid-basilar anastomoses. Examples of the first group are anomalous occipital, ascending pharyngeal, internal maxillary, and vidian arteries (8, 14). Four types of embryonic carotid-basilar anastomoses have been described: in order of importance and frequency of persistence, they are the trigeminal, primitive hypoglossal, otic, and proatlantal arteries (3, 4, 6, 11, 16). Teal et et. (13, 14) described two very rare anomalies: _(a) an anastomosis between the internal carotid and superior cerebellar arteries without interposition of a segment of the basilar artery, which they interpreted as a variant of persistent trigeminal artery, and (b) origin of the posterior inferior cerebellar artery (PICA) from the distal cervical internal carotid artery, which they believed to be a variant of persistent hypoglossal artery rather than a previously unknown form of carotid-basilar anastomosis. I recently observed a patient in whom an anomalous vessel unlike any known cavernous branch in both appearance and distribution originated from the cavernous portion of the carotid artery at the level where the trigeminal artery is usually seen. This vessel had no communication with the basilar artery, nor did it have either the size or the appearance of the tentorial artery. Its distribution
T
HE
1
BRANCHES
Fig. 1. Left carotid angiogram, lateral projection, showing an anomalous branch resembling the anterior inferior cerebellar artery (arrows) originating from the cavernous portion of the carotid artery. Fig. 2. Left carotid angiogram, frontal projection, showing the anomalous branch (arrows).
approximated that of the anterior inferior cerebellar artery (AICA). CASE REPORT A 58-year-old woman with no significant previous pathology was admitted in January 1974 because of a transient episode of aphasia and right hemiparesis followed a few hours later by an acute episode. On admission she was alert, with a speech disturbance typical of mild Wernicke's aphasia. There was only minimal weakness of the right inferior facial nerve and no motor disturbances in the limbs. The aphasia cleared almost completely within three weeks. During the second week of hospitalization, paresis of the left arm lasting only a few minutes occurred one morning. Blood pressure was normal, and laboratory findings were within normal limits. The electroencephalogram showed slow-wave activity over the left anterior temporal region. A brain scan performed 9 days after the onset of symptoms showed a superficial area of hyperactivity in the left posterior frontal region. Chest and skull films were normal. Left carotid angiography demonstrated coiling of the internal carotid artery in the neck. An anoma-
From the Department of Radiology, Neurological Clinic, University of Milan, Milan, Italy. Accepted for publication in February 1975.
93
sjh
94
GIUSEPPE SCOTTI
lous intracranial branch was seen originating at the beginning of the cavernous portion, apparently on its lateral aspect (Figs. 1 and 2). Initially coursing anteriorly, it turned sharply backward after a few millimeters, following a very irregular course laterally and posteriorly to the clivus. After coiling a few times behind the petro us pyramid, it terminated in three branches over the surface of the cerebellar hemisphere. The remainder of the intracranial vascular circulation was normal, with the posterior cerebral artery having an infundibular origin from the carotid. Right brachial angiography was attempted unsuccessfully one week later and was not repeated. Right carotid angiography was normal except for coiling of the internal carotid in the neck; a normal thin posterior communicating artery was seen. At follow-up in the outpatient clinic nine months after admission, the patient was doing well and no neurological signs were present. DISCUSSION To my knowledge, origin of the AICA from the internal carotid artery has not been reported previously, nor is it described as a possible embryonic remnant in Lie's most recent review (7). I feel that this anomaly is analogous in many ways to the two cases reported by Teal et al., in which the superior cerebellar artery and PICA, respectively, were found to originate from the internal carotid (13, 14). These authors concluded that the cerebellar arteries were connected with the carotid via a persistent trigeminal trunk in the first case and a hypoglossal trunk in the second case, but neither patient demonstrated clear evidence of the two embryonic vessels. In my patient, there was no doubt that the anomalous branch did not communicate with the vertebrobasilar circulation. Moreover, although the first part originated at the usual site of the trigeminal artery, its course was quite different. Information about the vertebrobasilar circulation is lacking in this case, but the territory of distribution of the anomalous branch is undoubtedly that of the AICA. I can only speculate, as Teal et al. did in their similar cases (13, 14), that a primary communication between the internal carotid and part of the ipsilateral longitudinal neural artery remained patent. In Padget's drawings of the development of the cranial arteries of the human embryo, a component of the AICA is first shown originating from the basilar artery in a 12.5-mm embryo (9). The primitive trigeminal artery is still present, or at least some remnants of it; it disappears completely at the 14-mm stage. The potential stem of the future AICA is subsequently described in embryos approximately 16-18 mm, arising at the level of the eighth cranial nerve and terminating in the choroid plexus otthe fourth ventricle. In my patient, the AICA underwent normal differentiation in terms of both size and distribution, probably developing from the longitudinal neural artery as usual. However, the latter vessel, or at least
July 1975
the remnant which normally gives rise to the AICA, did not fuse with the contralateral channel and the cranial and caudal segments to form the basilar artery; instead, it remained connected to the carotid probably at the original site of communication, where the trigeminal artery is usually found. Department of Radiology Neurological Clinic University of Milan Via F. Sforza 35 Milan 20122 Italy REFERENCES 1. Bernasconi V, Cassinari V: Un segno carotidografico tipico di meningioma del tentorio. Chirurgia 11:58S-588, Dec 1956 2. Cortes 0, Chase NE, leeds N: Visualiiation of tentorial branches of the internal carotid artery in intracranial lesions other than meningiomas. Radiology 82:1024-1 028, Jun 1964 3. Harrison CR, luttrell C: Persistent carotid-basilar anastomosis. Three arteriographically demonstrated cases with one anatomical specimen. J Neurosurg 10:205-215, May 1953 4. Hutchinson NA, Miller JDR: Persistent proatlantal artery. J Neurol Neurosurg Psychiatry 3:524-527, Aug 1970 5. Krayenbuhl H, Ya~argil MG: Die zerebrale Angiographie. Stuttgart, Thieme, 2d Ed, 1965, pp 22-31 6. lecuire J, Buffard P, Goutelle A, et al: Considerations anatomiques, cliniques et radiologiques a propos d'une artere hypoglosse. J Radiol ElectroI46:217-222, May 1965 7. Lie TA: Congenital malformations of the carotid and vertebral arterial systems, including the persistent anastomoses. [In] Vinken PF, Bruyn GW, ed: Handbook of Clinical Neurology. Amsterdam, NorthHolland, 1972, Vol 12, Chapt 9, pp 289-339 8. Newton TH, Young DA: Anomalous origin of the occipital artery from the internal carotid artery. Radiology 90:550-552, Mar 1968 9. Padget DH: Development of the cranial arteries in the human embryo. Contrib Embryol (Nos. 207-212) 32:205-262, 1948 10. Parkinson D: Collateral circulation of cavernous carotid artery: anatomy. Can J Surg 7:251-268, Jul 1964 (quoted by Wallace et ai, ref. 13) 11. Samra K, Scoville WB, Yaghmai M: Anastomosis of carotid and basilar arteries. Persistent primitive trigeminal artery and hypoglossal artery: report of two cases. J Neurosurg 30:622-625, May 196~
12. Schnurer l-B, Stattin S: Vascular supply of intracranial dura from internal carotid artery with special reference to its angiographic significance. Acta Radiol [Diag] 1:441-450, Mar 1963 13. Teal JS, Rumbaugh Cl, Bergeron RT, et al: Persistent carotid-superior cerebellar artery anastomosis: a variant of persistent trigeminal artery. Radiology 103:335-341, May 1972 14. Teal JS, Rumbaugh Cl, Segall HD, et al: Anomalous branches of the internalcarotid artery. Radiology 106:567-573, Mar 1973 15. Wallace S, Goldberg HI, leeds NE, et al: The cavernous branches of the internalcarotid artery. Am J RoentgenoI101:34-46, Sep 1967 16. Wollschlaeger G, Wollschlaeger PB: The primitive trigeminal artery as seen angiographically and at postmortem examination. Am J RoentgenoI92:761-768, Oct 1964
•
Anterior Inferior Cerebellar Artery Originating from the Cavernous Portion of the Internal Carotid Artery 1
•
Giuseppe Scotti, M.D. An anomalous branch of the cavernous carotid artery, not reported previously, is described. Its appearance and distribution were unlike those of any known cavernous branch, originating at the level where the trigeminal artery is usually found but having no communication with the basilar artery. Its distribution approximated that of the anterior inferior cerebellar artery. The author believes that this is an unusual form of persistent embryonic communication between the carotid artery and the vessels of the posterior fossa. INDEX TERMS:
Arteries, cerebellar • Carotid Arteries, abnormalities
Radiology 116:93-94, July 1975
•
•
of the internal carotid artery which are usually seen at angiography arise from the supraclinoidal portion: in order of their origin, they are the ophthalmic, posterior communicating, anterior choroidal, terminal anterior, and middle cerebral arteries. The small branches originating from the intracavernous portion are rarely seen, becoming visible only when they are enlarged as the result of disease in the surrounding structures (1, 2, 15). Schnurer and Stattin subdivide these small vessels according to their origin from a "dorsal" and "lateral" mainstem (12), but other authors employ a slightly different terminology (5, 10). These vessels supply the dura at the base of the skull, the tentorium, the cavernous sinus, the sella turcica and its contents, the gasserian ganglion, and (in part) the third, fourth, and sixth cranial nerves. Anomalous branches of the internal carotid fall into two groups: branches of the cervical internal carotid (which are usually branches of the external carotid) and carotid-basilar anastomoses. Examples of the first group are anomalous occipital, ascending pharyngeal, internal maxillary, and vidian arteries (8, 14). Four types of embryonic carotid-basilar anastomoses have been described: in order of importance and frequency of persistence, they are the trigeminal, primitive hypoglossal, otic, and proatlantal arteries (3, 4, 6, 11, 16). Teal et et. (13, 14) described two very rare anomalies: _(a) an anastomosis between the internal carotid and superior cerebellar arteries without interposition of a segment of the basilar artery, which they interpreted as a variant of persistent trigeminal artery, and (b) origin of the posterior inferior cerebellar artery (PICA) from the distal cervical internal carotid artery, which they believed to be a variant of persistent hypoglossal artery rather than a previously unknown form of carotid-basilar anastomosis. I recently observed a patient in whom an anomalous vessel unlike any known cavernous branch in both appearance and distribution originated from the cavernous portion of the carotid artery at the level where the trigeminal artery is usually seen. This vessel had no communication with the basilar artery, nor did it have either the size or the appearance of the tentorial artery. Its distribution
T
HE
1
BRANCHES
Fig. 1. Left carotid angiogram, lateral projection, showing an anomalous branch resembling the anterior inferior cerebellar artery (arrows) originating from the cavernous portion of the carotid artery. Fig. 2. Left carotid angiogram, frontal projection, showing the anomalous branch (arrows).
approximated that of the anterior inferior cerebellar artery (AICA). CASE REPORT A 58-year-old woman with no significant previous pathology was admitted in January 1974 because of a transient episode of aphasia and right hemiparesis followed a few hours later by an acute episode. On admission she was alert, with a speech disturbance typical of mild Wernicke's aphasia. There was only minimal weakness of the right inferior facial nerve and no motor disturbances in the limbs. The aphasia cleared almost completely within three weeks. During the second week of hospitalization, paresis of the left arm lasting only a few minutes occurred one morning. Blood pressure was normal, and laboratory findings were within normal limits. The electroencephalogram showed slow-wave activity over the left anterior temporal region. A brain scan performed 9 days after the onset of symptoms showed a superficial area of hyperactivity in the left posterior frontal region. Chest and skull films were normal. Left carotid angiography demonstrated coiling of the internal carotid artery in the neck. An anoma-
From the Department of Radiology, Neurological Clinic, University of Milan, Milan, Italy. Accepted for publication in February 1975.
93
sjh
94
GIUSEPPE SCOTTI
lous intracranial branch was seen originating at the beginning of the cavernous portion, apparently on its lateral aspect (Figs. 1 and 2). Initially coursing anteriorly, it turned sharply backward after a few millimeters, following a very irregular course laterally and posteriorly to the clivus. After coiling a few times behind the petro us pyramid, it terminated in three branches over the surface of the cerebellar hemisphere. The remainder of the intracranial vascular circulation was normal, with the posterior cerebral artery having an infundibular origin from the carotid. Right brachial angiography was attempted unsuccessfully one week later and was not repeated. Right carotid angiography was normal except for coiling of the internal carotid in the neck; a normal thin posterior communicating artery was seen. At follow-up in the outpatient clinic nine months after admission, the patient was doing well and no neurological signs were present. DISCUSSION To my knowledge, origin of the AICA from the internal carotid artery has not been reported previously, nor is it described as a possible embryonic remnant in Lie's most recent review (7). I feel that this anomaly is analogous in many ways to the two cases reported by Teal et al., in which the superior cerebellar artery and PICA, respectively, were found to originate from the internal carotid (13, 14). These authors concluded that the cerebellar arteries were connected with the carotid via a persistent trigeminal trunk in the first case and a hypoglossal trunk in the second case, but neither patient demonstrated clear evidence of the two embryonic vessels. In my patient, there was no doubt that the anomalous branch did not communicate with the vertebrobasilar circulation. Moreover, although the first part originated at the usual site of the trigeminal artery, its course was quite different. Information about the vertebrobasilar circulation is lacking in this case, but the territory of distribution of the anomalous branch is undoubtedly that of the AICA. I can only speculate, as Teal et al. did in their similar cases (13, 14), that a primary communication between the internal carotid and part of the ipsilateral longitudinal neural artery remained patent. In Padget's drawings of the development of the cranial arteries of the human embryo, a component of the AICA is first shown originating from the basilar artery in a 12.5-mm embryo (9). The primitive trigeminal artery is still present, or at least some remnants of it; it disappears completely at the 14-mm stage. The potential stem of the future AICA is subsequently described in embryos approximately 16-18 mm, arising at the level of the eighth cranial nerve and terminating in the choroid plexus otthe fourth ventricle. In my patient, the AICA underwent normal differentiation in terms of both size and distribution, probably developing from the longitudinal neural artery as usual. However, the latter vessel, or at least
July 1975
the remnant which normally gives rise to the AICA, did not fuse with the contralateral channel and the cranial and caudal segments to form the basilar artery; instead, it remained connected to the carotid probably at the original site of communication, where the trigeminal artery is usually found. Department of Radiology Neurological Clinic University of Milan Via F. Sforza 35 Milan 20122 Italy REFERENCES 1. Bernasconi V, Cassinari V: Un segno carotidografico tipico di meningioma del tentorio. Chirurgia 11:58S-588, Dec 1956 2. Cortes 0, Chase NE, leeds N: Visualiiation of tentorial branches of the internal carotid artery in intracranial lesions other than meningiomas. Radiology 82:1024-1 028, Jun 1964 3. Harrison CR, luttrell C: Persistent carotid-basilar anastomosis. Three arteriographically demonstrated cases with one anatomical specimen. J Neurosurg 10:205-215, May 1953 4. Hutchinson NA, Miller JDR: Persistent proatlantal artery. J Neurol Neurosurg Psychiatry 3:524-527, Aug 1970 5. Krayenbuhl H, Ya~argil MG: Die zerebrale Angiographie. Stuttgart, Thieme, 2d Ed, 1965, pp 22-31 6. lecuire J, Buffard P, Goutelle A, et al: Considerations anatomiques, cliniques et radiologiques a propos d'une artere hypoglosse. J Radiol ElectroI46:217-222, May 1965 7. Lie TA: Congenital malformations of the carotid and vertebral arterial systems, including the persistent anastomoses. [In] Vinken PF, Bruyn GW, ed: Handbook of Clinical Neurology. Amsterdam, NorthHolland, 1972, Vol 12, Chapt 9, pp 289-339 8. Newton TH, Young DA: Anomalous origin of the occipital artery from the internal carotid artery. Radiology 90:550-552, Mar 1968 9. Padget DH: Development of the cranial arteries in the human embryo. Contrib Embryol (Nos. 207-212) 32:205-262, 1948 10. Parkinson D: Collateral circulation of cavernous carotid artery: anatomy. Can J Surg 7:251-268, Jul 1964 (quoted by Wallace et ai, ref. 13) 11. Samra K, Scoville WB, Yaghmai M: Anastomosis of carotid and basilar arteries. Persistent primitive trigeminal artery and hypoglossal artery: report of two cases. J Neurosurg 30:622-625, May 196~
12. Schnurer l-B, Stattin S: Vascular supply of intracranial dura from internal carotid artery with special reference to its angiographic significance. Acta Radiol [Diag] 1:441-450, Mar 1963 13. Teal JS, Rumbaugh Cl, Bergeron RT, et al: Persistent carotid-superior cerebellar artery anastomosis: a variant of persistent trigeminal artery. Radiology 103:335-341, May 1972 14. Teal JS, Rumbaugh Cl, Segall HD, et al: Anomalous branches of the internalcarotid artery. Radiology 106:567-573, Mar 1973 15. Wallace S, Goldberg HI, leeds NE, et al: The cavernous branches of the internalcarotid artery. Am J RoentgenoI101:34-46, Sep 1967 16. Wollschlaeger G, Wollschlaeger PB: The primitive trigeminal artery as seen angiographically and at postmortem examination. Am J RoentgenoI92:761-768, Oct 1964
