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Bilateral Persistent Trigeminal Arteries Associated with Bilateral Carotid Aneurysms
692
•
May 2007
Letters to the Editor
tem would likely be unsuccessful. Exchange was made for a long 12-F vascular sheath (Cook, Bloomington, Ind). A 25mm-diameter Amplatz Goose Neck snare (ev3, Plymouth, Minn) was inserted and its curved 6-F snare catheter used to select the left renal vein. The snare loop was opened in the left renal vein and the filter tip was captured upon withdrawal of the snare system (Figure, parts b and c). Moderately rapid upward force was successful in freeing the arms and legs of the filter from their caval wall sleeves, and then the filter was removed via the jugular sheath (Figure, part d). Gross inspection after removal revealed that the filter was intact with no thrombus. Completion vena cavography showed no abnormality. Removal of an optional vena cava filter from a left-sided IVC was first described in 2004 (1). A Günther Tulip filter (Cook) was retrieved without difficulty 17 days after insertion via the right internal jugular vein by using a 25-mmdiameter Amplatz Goose Neck snare. In 2005, Richard and colleagues (2) described retrieval of a Recovery filter from a left-sided IVC without difficulty 53 days after insertion by using the Recovery Cone Removal System via a jugular vein. The images from that report show that the Recovery filter had been deployed in the mid-lower aspect of the left-sided infrarenal IVC, more than one filter length below the left renal vein. In our patient, the Recovery filter had been deployed with its tip at the level of the inferior aspect of the left renal vein, resulting in an acute misalignment between the right-sided suprarenal IVC and the superior aspect of the left-sided infrarenal IVC in which our filter was deployed. Instructions for use for the Recovery filter state that the filter tip should be positioned 1 cm below the lowest renal vein. Placement of the Recovery filter too cephalad in our case may have contributed to subsequent filter tip tilting and contralateral hooking of an arm into the renal vein, thereby further exacerbating the acute misalignment. In future cases where an optional filter is used in a left-sided IVC with a plan for subsequent filter removal by means of a jugular approach, we recommend that the filter be positioned lower in the infrarenal cava to avoid an acute misalignment or step-off; in this manner, the standard retrieval cone may be used successfully to remove a Recovery filter, and selection of the left renal vein may not be required when using a loop snare to remove a Günther Tulip filter, for example. Alternatively, as suggested by Brountzos and colleagues (1), suprarenal placement of an optional filter may be considered in the presence of a left-sided infrarenal IVC. To our knowledge, the use of a loop snare to remove a Recovery filter has not been described. In fact, the Information for Use booklet packaged with the Recovery filter includes the warning, “Only use the Recovery Cone Removal System to remove the Recovery Filter.” A recent report by Stavropoulos et al (3), however, describes the safe and successful removal of Recovery filters with their tips tilted and embedded within caval walls in four patients by using rigid bronchoscopy forceps. We surmise that removal of the Recovery filter with a loop snare instead of the retrieval cone may be safe and effective in other circumstances, and perhaps even in uncomplicated cases. We note at our institution that an Amplatz Goose Neck snare is substantially less expensive than a Recovery Cone Removal System. Several studies, however, describe a high success rate for Recovery filter retrieval with the Recovery Cone Removal System. There have been several adjunctive techniques described to aid in removing a Recovery filter with the retrieval cone. Asch (4) described the “guide wire-assisted technique,” in
JVIR
which a wire placed via the central lumen of the cone is directed near the filter tip, preferably toward the side of the filter with the shortest distance between the filter tip and the caval wall. Centering a tilted Recovery filter tip with a tip-deflecting wire has also been described (5). In our patient, such adjunctive techniques would be unlikely to correct the large degree of acute misalignment between a retrieval cone and the filter tip because of several factors: the acute step-off between the axes of the right-sided suprarenal IVC and the left-sided infrarenal IVC, the cephalad location of the filter tip within the left renal vein inflow, hooking of a right-sided filter arm into the left renal vein outflow, and tilting of the filter tip leftward. We believe that, in our case, the use of a loop snare was the simplest and safest effective technique for Recovery filter removal and that snare retrieval of Recovery filters may be potentially useful in other situations. References 1. Brountzos EN, Kaufman JA, Lakin PL. Guenther Tulip filter retrieval from a left-sided inferior vena cava. Cardiovasc Intervent Radiol 2004; 27:58 – 60. 2. Richard HM III, Lowe SR, Malloy PC. Retrieval of Bard Recovery filter from left-sided inferior vena cava [letter]. J Vasc Interv Radiol 2005; 16:1039 –1041. 3. Stavropoulos SW, Solomon JA, Trerotola SO. Wall-embedded Recovery inferior vena cava filters: imaging features and technique for removal. J Vasc Interv Radiol 2006; 17:379 –382. 4. Asch MR. Initial experience in humans with a new retrievable inferior vena cava filter. Radiology 2002; 225:835– 844. 5. Hagspiel KD, Leung DA, Aladdin M, Spinosa DJ, Matsumoto AH, Angle JF. Difficult retrieval of a Recovery IVC filter [letter]. J Vasc Interv Radiol 2004; 15:645– 647.
Bilateral Persistent Trigeminal Arteries Associated with Bilateral Carotid Aneurysms From: Saad Ali, MD Matthew T. Walker, MD Department of Radiology, Section of Neuroradiology The Feinberg School of Medicine of Northwestern University 676 N St Clair St, Ste 1400 Chicago, IL 60611 Editor: During the embryonic development of the intracranial vasculature, several anastomoses exist between the carotid and vertebrobasilar systems. The most common of these to persist into adulthood is the trigeminal artery, which extends from the internal carotid artery to the basilar artery at the level of the cavernous sinus. The prevalence of the trigeminal artery has been reported to be 0.1%– 0.6% in large angiographic series (1). The coexistence of more than one anastomosis in an adult, however, is rare. Herein, we present a case of a patient with bilateral persistent trigeminal arteries (PTAs) with associated aneurysms at their origins.
DOI: 10.1016/j.jvir.2007.01.027
Volume 18
Number 5
Letters to the Editor
•
693
Figure. (a) Axial source image from CT angiography demonstrates bilateral PTAs, each arising from petrocavernous junction aneurysms (arrowheads). The right artery (large arrow) is larger than the left artery (small arrow). (b, c) Sagittal curved reformatted images show the right PTA (arrow in b) and left PTA (arrow in c) arising from their respective internal carotid artery aneurysms (arrowheads).
A 55-year-old woman underwent magnetic resonance imaging at an outside institution; an incidental right cavernous internal carotid artery aneurysm was found. The patient was referred to our institution for further evaluation and possible endovascular therapy. Computed tomographic (CT) angiography of the head revealed a 13-mm aneurysm of the right internal carotid artery at its petrocavernous junction. The aneurysm gave rise to a PTA that supplied the posterior circulation (Fig 1a, 1b). An 8-mm aneurysm was seen at the left petrocavernous junction, and that aneurysm gave rise to a left PTA (Fig 1a, 1c). The bilateral PTAs inserted into the mid-basilar artery. The basilar artery proximal to their insertion was hypoplastic. This vascular anatomy precluded further discussion of endovascular therapy. Quain was the first to describe the PTA while studying an autopsy specimen in 1844, and Sutton was the first to demonstrate the anomaly at angiography in 1950 (2). Since then, the finding has been reported frequently in the
literature and is estimated to be present in 0.1%– 0.6% of individuals (1). The embryologic development and involution of these vestigial carotid-basilar anastomoses has been described by Padget (3). The fetal carotid-basilar anastomoses form on approximately the 24th day of fetal embryogenesis, when the embryo is 3 mm in size. The trigeminal artery arises as the second of two branches of the first aortic arch (the first branch representing the primitive internal carotid). Progressing caudally, the otic, hypoglossal, and proatlantal intersegmental arteries arise similarly, communicating anteriorly with the internal carotid artery and posteriorly with the longitudinal neural arteries. In general, the fetal arteries exist for 7–10 days and transiently serve as the primary blood supply to the longitudinal neural arteries. These fetal arteries disappear by the time the embryo is 14 –15-mm in size, at which time the paired longitudinal neural arteries have fused into the basilar artery and the posterior circulation has fully developed
694
•
Letters to the Editor
(1). If any of these arteries fail to regress, they become developmental persistent fetal carotid-basilar anastomoses. Except for the proatlantal intersegmental artery, the rate at which these arteries persist is inversely correlated with their order of regression. Consequently, the primitive trigeminal artery, the last to regress, is the most common to persist of the fetal carotid-basilar anastomoses. Bilateral PTAs are rare. Although there are many explanations for the failure of regression of the trigeminal artery, the precise reason is unknown. One explanation is that the cervical portions of the internal carotid artery may become occluded in the fetus, and the forebrain thereby receives blood supply in a retrograde fashion from the basilar artery via these vessels (4). Another possibility, and this was observed in our case, is that the posterior circulation may not develop completely and, to maintain supply to the hindbrain, the PTAs cannot regress and persist after birth. PTAs are associated with a variety of vascular malformations and anomalies. These include unilateral or bilateral vertebral artery hypoplasia, absence of the posterior communicating artery, hypoplasia or absence of the proximal portion of the basilar artery, arteriovenous malformations, brain tumors, carotid-cavernous fistulas, moyamoya disease, and aortic arch anomalies (1,5). The most important relationship—and the one that is most relevant to our case—is the one between the PTA and aneurysms. There are numerous reports in the literature of aneurysms arising from the PTA or its junction with the internal carotid artery. This occurrence is seen in an estimated 2% of PTA cases (1). In our case, both anomalous vessels demonstrated aneurysms at their origin with the cavernous internal carotid artery. More commonly, aneurysms arise elsewhere in the cerebral vasculature, occurring in up to 14%–32% of PTA cases (5). These high estimates, however, have resulted from studies based on collections of case reports (eg,
May 2007
JVIR
incidental aneurysm or arteriovenous malformation associated with PTA), which biases the likelihood of finding an aneurysm. Cloft et al (5) tried to eliminate this selection bias by retrospectively evaluating a series of 31 patients with PTA and excluding those with symptomatic aneurysms. In that study, incidental asymptomatic aneurysms were seen in 3% of patients with PTA—a value very close to the prevalence of 3.7% in the general population found with retrospective angiographic studies (6). The presence of structural defects in the walls of the cerebral arteries has been suggested as the underlying cause of a cerebral aneurysm coexisting with a PTA (1). Following the reasoning presented by Cloft et al (5), however, the PTA may be a potential site of aneurysm formation simply because it is a bifurcation and has no greater predisposition for aneurysm formation than do other bifurcations. Conversely, a fetal artery that persists into adult life—whether it is a trigeminal artery, sciatic artery, or an aberrant right subclavian artery— often becomes aneurysmal. References 1. Silver J, Wilkins, RH. Persistent embryonic intracranial and extracranial vessels. In: Wilkins R, Rengachary SS, eds. Neurosurgery. 2nd ed. New York, NY: McGraw-Hill, 1996; 1990 –1991. 2. Sutton D. Anomalous carotid-basilar anastomosis. Br J Radiol 1950; 23:617– 619. 3. Padget D. The development of the intracranial arteries in the human embryo. Contrib Embryol 1948; 32:205–262. 4. Okuno T, Nishiguchi T, Hayashi S, et al. A case of carotid superior cerebellar artery anastomosis associated with bilateral hypoplasia of the internal carotid artery represented as the rupture of posterior cerebral artery-posterior communicating artery aneurysm [in Japanese]. No Shinkei Geka 1988; 16:1211–1217. 5. Cloft HJ, Razack N, Kallmes DF. Prevalence of cerebral aneurysms in patients with persistent primitive trigeminal artery. J Neurosurg 1999; 90:865– 867. 6. Rinkel GJE, Djibuti M, Algra A, et al. Prevalence and risk of rupture of intracranial aneurysms: a systematic review. Stroke 1998; 29:251–256.
•
May 2007
Letters to the Editor
tem would likely be unsuccessful. Exchange was made for a long 12-F vascular sheath (Cook, Bloomington, Ind). A 25mm-diameter Amplatz Goose Neck snare (ev3, Plymouth, Minn) was inserted and its curved 6-F snare catheter used to select the left renal vein. The snare loop was opened in the left renal vein and the filter tip was captured upon withdrawal of the snare system (Figure, parts b and c). Moderately rapid upward force was successful in freeing the arms and legs of the filter from their caval wall sleeves, and then the filter was removed via the jugular sheath (Figure, part d). Gross inspection after removal revealed that the filter was intact with no thrombus. Completion vena cavography showed no abnormality. Removal of an optional vena cava filter from a left-sided IVC was first described in 2004 (1). A Günther Tulip filter (Cook) was retrieved without difficulty 17 days after insertion via the right internal jugular vein by using a 25-mmdiameter Amplatz Goose Neck snare. In 2005, Richard and colleagues (2) described retrieval of a Recovery filter from a left-sided IVC without difficulty 53 days after insertion by using the Recovery Cone Removal System via a jugular vein. The images from that report show that the Recovery filter had been deployed in the mid-lower aspect of the left-sided infrarenal IVC, more than one filter length below the left renal vein. In our patient, the Recovery filter had been deployed with its tip at the level of the inferior aspect of the left renal vein, resulting in an acute misalignment between the right-sided suprarenal IVC and the superior aspect of the left-sided infrarenal IVC in which our filter was deployed. Instructions for use for the Recovery filter state that the filter tip should be positioned 1 cm below the lowest renal vein. Placement of the Recovery filter too cephalad in our case may have contributed to subsequent filter tip tilting and contralateral hooking of an arm into the renal vein, thereby further exacerbating the acute misalignment. In future cases where an optional filter is used in a left-sided IVC with a plan for subsequent filter removal by means of a jugular approach, we recommend that the filter be positioned lower in the infrarenal cava to avoid an acute misalignment or step-off; in this manner, the standard retrieval cone may be used successfully to remove a Recovery filter, and selection of the left renal vein may not be required when using a loop snare to remove a Günther Tulip filter, for example. Alternatively, as suggested by Brountzos and colleagues (1), suprarenal placement of an optional filter may be considered in the presence of a left-sided infrarenal IVC. To our knowledge, the use of a loop snare to remove a Recovery filter has not been described. In fact, the Information for Use booklet packaged with the Recovery filter includes the warning, “Only use the Recovery Cone Removal System to remove the Recovery Filter.” A recent report by Stavropoulos et al (3), however, describes the safe and successful removal of Recovery filters with their tips tilted and embedded within caval walls in four patients by using rigid bronchoscopy forceps. We surmise that removal of the Recovery filter with a loop snare instead of the retrieval cone may be safe and effective in other circumstances, and perhaps even in uncomplicated cases. We note at our institution that an Amplatz Goose Neck snare is substantially less expensive than a Recovery Cone Removal System. Several studies, however, describe a high success rate for Recovery filter retrieval with the Recovery Cone Removal System. There have been several adjunctive techniques described to aid in removing a Recovery filter with the retrieval cone. Asch (4) described the “guide wire-assisted technique,” in
JVIR
which a wire placed via the central lumen of the cone is directed near the filter tip, preferably toward the side of the filter with the shortest distance between the filter tip and the caval wall. Centering a tilted Recovery filter tip with a tip-deflecting wire has also been described (5). In our patient, such adjunctive techniques would be unlikely to correct the large degree of acute misalignment between a retrieval cone and the filter tip because of several factors: the acute step-off between the axes of the right-sided suprarenal IVC and the left-sided infrarenal IVC, the cephalad location of the filter tip within the left renal vein inflow, hooking of a right-sided filter arm into the left renal vein outflow, and tilting of the filter tip leftward. We believe that, in our case, the use of a loop snare was the simplest and safest effective technique for Recovery filter removal and that snare retrieval of Recovery filters may be potentially useful in other situations. References 1. Brountzos EN, Kaufman JA, Lakin PL. Guenther Tulip filter retrieval from a left-sided inferior vena cava. Cardiovasc Intervent Radiol 2004; 27:58 – 60. 2. Richard HM III, Lowe SR, Malloy PC. Retrieval of Bard Recovery filter from left-sided inferior vena cava [letter]. J Vasc Interv Radiol 2005; 16:1039 –1041. 3. Stavropoulos SW, Solomon JA, Trerotola SO. Wall-embedded Recovery inferior vena cava filters: imaging features and technique for removal. J Vasc Interv Radiol 2006; 17:379 –382. 4. Asch MR. Initial experience in humans with a new retrievable inferior vena cava filter. Radiology 2002; 225:835– 844. 5. Hagspiel KD, Leung DA, Aladdin M, Spinosa DJ, Matsumoto AH, Angle JF. Difficult retrieval of a Recovery IVC filter [letter]. J Vasc Interv Radiol 2004; 15:645– 647.
Bilateral Persistent Trigeminal Arteries Associated with Bilateral Carotid Aneurysms From: Saad Ali, MD Matthew T. Walker, MD Department of Radiology, Section of Neuroradiology The Feinberg School of Medicine of Northwestern University 676 N St Clair St, Ste 1400 Chicago, IL 60611 Editor: During the embryonic development of the intracranial vasculature, several anastomoses exist between the carotid and vertebrobasilar systems. The most common of these to persist into adulthood is the trigeminal artery, which extends from the internal carotid artery to the basilar artery at the level of the cavernous sinus. The prevalence of the trigeminal artery has been reported to be 0.1%– 0.6% in large angiographic series (1). The coexistence of more than one anastomosis in an adult, however, is rare. Herein, we present a case of a patient with bilateral persistent trigeminal arteries (PTAs) with associated aneurysms at their origins.
DOI: 10.1016/j.jvir.2007.01.027
Volume 18
Number 5
Letters to the Editor
•
693
Figure. (a) Axial source image from CT angiography demonstrates bilateral PTAs, each arising from petrocavernous junction aneurysms (arrowheads). The right artery (large arrow) is larger than the left artery (small arrow). (b, c) Sagittal curved reformatted images show the right PTA (arrow in b) and left PTA (arrow in c) arising from their respective internal carotid artery aneurysms (arrowheads).
A 55-year-old woman underwent magnetic resonance imaging at an outside institution; an incidental right cavernous internal carotid artery aneurysm was found. The patient was referred to our institution for further evaluation and possible endovascular therapy. Computed tomographic (CT) angiography of the head revealed a 13-mm aneurysm of the right internal carotid artery at its petrocavernous junction. The aneurysm gave rise to a PTA that supplied the posterior circulation (Fig 1a, 1b). An 8-mm aneurysm was seen at the left petrocavernous junction, and that aneurysm gave rise to a left PTA (Fig 1a, 1c). The bilateral PTAs inserted into the mid-basilar artery. The basilar artery proximal to their insertion was hypoplastic. This vascular anatomy precluded further discussion of endovascular therapy. Quain was the first to describe the PTA while studying an autopsy specimen in 1844, and Sutton was the first to demonstrate the anomaly at angiography in 1950 (2). Since then, the finding has been reported frequently in the
literature and is estimated to be present in 0.1%– 0.6% of individuals (1). The embryologic development and involution of these vestigial carotid-basilar anastomoses has been described by Padget (3). The fetal carotid-basilar anastomoses form on approximately the 24th day of fetal embryogenesis, when the embryo is 3 mm in size. The trigeminal artery arises as the second of two branches of the first aortic arch (the first branch representing the primitive internal carotid). Progressing caudally, the otic, hypoglossal, and proatlantal intersegmental arteries arise similarly, communicating anteriorly with the internal carotid artery and posteriorly with the longitudinal neural arteries. In general, the fetal arteries exist for 7–10 days and transiently serve as the primary blood supply to the longitudinal neural arteries. These fetal arteries disappear by the time the embryo is 14 –15-mm in size, at which time the paired longitudinal neural arteries have fused into the basilar artery and the posterior circulation has fully developed
694
•
Letters to the Editor
(1). If any of these arteries fail to regress, they become developmental persistent fetal carotid-basilar anastomoses. Except for the proatlantal intersegmental artery, the rate at which these arteries persist is inversely correlated with their order of regression. Consequently, the primitive trigeminal artery, the last to regress, is the most common to persist of the fetal carotid-basilar anastomoses. Bilateral PTAs are rare. Although there are many explanations for the failure of regression of the trigeminal artery, the precise reason is unknown. One explanation is that the cervical portions of the internal carotid artery may become occluded in the fetus, and the forebrain thereby receives blood supply in a retrograde fashion from the basilar artery via these vessels (4). Another possibility, and this was observed in our case, is that the posterior circulation may not develop completely and, to maintain supply to the hindbrain, the PTAs cannot regress and persist after birth. PTAs are associated with a variety of vascular malformations and anomalies. These include unilateral or bilateral vertebral artery hypoplasia, absence of the posterior communicating artery, hypoplasia or absence of the proximal portion of the basilar artery, arteriovenous malformations, brain tumors, carotid-cavernous fistulas, moyamoya disease, and aortic arch anomalies (1,5). The most important relationship—and the one that is most relevant to our case—is the one between the PTA and aneurysms. There are numerous reports in the literature of aneurysms arising from the PTA or its junction with the internal carotid artery. This occurrence is seen in an estimated 2% of PTA cases (1). In our case, both anomalous vessels demonstrated aneurysms at their origin with the cavernous internal carotid artery. More commonly, aneurysms arise elsewhere in the cerebral vasculature, occurring in up to 14%–32% of PTA cases (5). These high estimates, however, have resulted from studies based on collections of case reports (eg,
May 2007
JVIR
incidental aneurysm or arteriovenous malformation associated with PTA), which biases the likelihood of finding an aneurysm. Cloft et al (5) tried to eliminate this selection bias by retrospectively evaluating a series of 31 patients with PTA and excluding those with symptomatic aneurysms. In that study, incidental asymptomatic aneurysms were seen in 3% of patients with PTA—a value very close to the prevalence of 3.7% in the general population found with retrospective angiographic studies (6). The presence of structural defects in the walls of the cerebral arteries has been suggested as the underlying cause of a cerebral aneurysm coexisting with a PTA (1). Following the reasoning presented by Cloft et al (5), however, the PTA may be a potential site of aneurysm formation simply because it is a bifurcation and has no greater predisposition for aneurysm formation than do other bifurcations. Conversely, a fetal artery that persists into adult life—whether it is a trigeminal artery, sciatic artery, or an aberrant right subclavian artery— often becomes aneurysmal. References 1. Silver J, Wilkins, RH. Persistent embryonic intracranial and extracranial vessels. In: Wilkins R, Rengachary SS, eds. Neurosurgery. 2nd ed. New York, NY: McGraw-Hill, 1996; 1990 –1991. 2. Sutton D. Anomalous carotid-basilar anastomosis. Br J Radiol 1950; 23:617– 619. 3. Padget D. The development of the intracranial arteries in the human embryo. Contrib Embryol 1948; 32:205–262. 4. Okuno T, Nishiguchi T, Hayashi S, et al. A case of carotid superior cerebellar artery anastomosis associated with bilateral hypoplasia of the internal carotid artery represented as the rupture of posterior cerebral artery-posterior communicating artery aneurysm [in Japanese]. No Shinkei Geka 1988; 16:1211–1217. 5. Cloft HJ, Razack N, Kallmes DF. Prevalence of cerebral aneurysms in patients with persistent primitive trigeminal artery. J Neurosurg 1999; 90:865– 867. 6. Rinkel GJE, Djibuti M, Algra A, et al. Prevalence and risk of rupture of intracranial aneurysms: a systematic review. Stroke 1998; 29:251–256.