Case Reports / Journal of Clinical Neuroscience 22 (2015) 771–773
References [1] Merlini G, Bellotti V. Molecular mechanisms of amyloidosis. N Engl J Med 2003;349:583–96. [2] Goren H, Steinberg MC, Farboody GH. Familial oculoleptomeningeal amyloidosis. Brain 1980;103:473–95. [3] Uitti RJ, Donat JR, Rozdilsky B, et al. Familial oculoleptomeningeal amyloidosis. Report of a new family with unusual features. Arch Neurol 1988;45:1118–22. [4] Nakamura M, Yamashita T, Ueda M, et al. Neuroradiologic and clinicopathologic features of oculoleptomeningeal type amyloidosis. Neurology 2005;65:1051–6. [5] Urban PP, Hertkorn C, Schattenberg JM, et al. Leptomeningeal familial amyloidosis: a rare differential diagnosis of leptomeningeal enhancement in MRI. J Neurol 2006;253:1238–40.
771
[6] Honig S, Murali R. Spinal cord claudication from amyloid deposition. J Rheumatol 1992;19:1988–90. [7] Davidson GS, Montanera WJ, Fleming JF, et al. Amyloid destructive spondyloarthropathy causing cord compression: related to chronic renal failure and dialysis. Neurosurgery 1993;33:519–22. [8] Vignes JR, Eimer S, Dupuy R, et al. Beta(2)-microglobulin amyloidosis caused spinal cord compression in a long-term haemodialysis patient. Spinal Cord 2007;45:322–6. [9] Cloft HJ, Quint DJ, Markert JM, et al. Primary osseous amyloidoma causing spinal cord compression. AJNR Am J Neuroradiol 1995;16:1152–4. [10] Sekijima Y, Yoshida K, Tokuda T, et al. Familial transthyretin amyloidosis. In: Pagon RA, Adam MP, Ardinger HH, Bird TD, Dolan CR, Fong CT, et al., editors. GeneReviews(R). Seattle: University of Washington; 1993–2014.
http://dx.doi.org/10.1016/j.jocn.2014.09.023
Intracardiac migration and knotting of a ventriculoperitoneal shunt Gert Frahm-Jensen a,1, Peter R. Newton b,⇑,1, Katharine J. Drummond b, Tim P. Wagner a, Barend M.E. Mees a a b
Department of Vascular Surgery, Royal Melbourne Hospital, Parkville, Melbourne, VIC, Australia Department of Neurosurgery, Royal Melbourne Hospital, Grattan Street, Parkville, Melbourne, VIC 3050, Australia
a r t i c l e
i n f o
Article history: Received 9 September 2014 Accepted 25 October 2014
a b s t r a c t We report a patient with delayed migration of the distal ventriculoperitoneal shunt catheter from the peritoneum to the right atrium with associated knotting of the catheter complicating removal. We also review the literature on this topic. Crown Copyright Ó 2014 Published by Elsevier Ltd. All rights reserved.
Keywords: Complications Foreign-body migration Jugular vein injury Knot Ventriculoperitoneal shunt
1. Introduction Cerebrospinal fluid shunts are commonly used for the management of hydrocephalus, with ventriculoperitoneal (VP) shunts most often employed. Complications of VP shunts, usually as a result of obstruction, mechanical failure or infection, are unfortunately common. We report a patient with migration of the distal VP shunt catheter from the peritoneum to the right atrium with associated knotting of the catheter complicating removal. We also review the literature on this topic. 2. Case report A 77-year-old woman underwent an unremarkable VP shunt insertion (Codman Hakim Programmable Valve with Codman Bactiseal Ventricular and Distal Catheter; Codman & Shurtleff, Raynham, MA, USA) for normal pressure hydrocephalus (NPH) in early February 2013 with initial improvement in her symptoms. Postoperative imaging, including a radiograph shunt series, confirmed correct shunt placement. Two months later she returned with unrelated poorly controlled hypertension and a return of gait
⇑ Corresponding author. Tel.: +61 431 231 501; fax: +61 3 9342 8951. 1
E-mail address: [email protected] (P.R. Newton). These authors have contributed equally to the manuscript.
unsteadiness suggesting shunt malfunction with recurrence of symptoms of NPH. A chest radiograph indicated that the shunt had migrated from the abdomen into the chest and was overlying the cardiac shadow (Fig. 1). A CT scan demonstrated that the shunt entered the right internal jugular vein (IJV) above the right clavicle with multiple coils in the right atrium (Fig. 2). There was no shunt identified in the abdomen. Revision of the VP shunt was planned between the Neurosurgery and Vascular Surgery Units. The IJV was exposed via a transverse skin incision 1 inch cranial from the right clavicle and the shunt entry identified. A purse string suture of 5–0 prolene was placed around the entry site in the vein and the distal catheter was slowly pulled. Significant resistance was felt after 30 cm of catheter had been removed. Using image intensifier radiography a large knot in the catheter below the right clavicle was displayed. A longitudinal venotomy was extended to the origin of the brachiocephalic vein, which was controlled using a Satinsky clamp. On loosening the clamp, the knot was successfully pulled out with primary closure of the venotomy (Fig. 3). The shunt was seen to be draining cerebrospinal fluid. The post-auricular cranial and subcostal laparotomy wounds were reopened and a shunt tunneler passed between them allowing passage of a new distal catheter (Codman Bactiseal) which was connected to the shunt valve and placed into the peritoneal cavity. A radiograph shunt series 1 week post-operatively confirmed correct placement of the shunt.
772
Case Reports / Journal of Clinical Neuroscience 22 (2015) 771–773
Fig. 3. Removal of the knotted ventriculoperitoneal shunt catheter via the right internal jugular vein.
Fig. 1. Anteroposterior chest radiograph demonstrating intrathoracic migration of the ventriculoperitoneal shunt.
initial subcutaneous tunnelling of the catheter or gradual erosion of the IJV over time [2,6]. In our patient, the short duration between insertion of the VP shunt and discovery of the intracardiac migration would suggest a direct injury. The proximal migration of the distal catheter is aided by negative intrathoracic pressure and venous flow [5]. Complications of intracardiac migration include shunt malfunction, pulmonary emboli, sepsis, pulmonary infarction, local thrombus formation, valve insufficiency and arrhythmias [2,4,6,7]. The other two reports describing this rare combination of intracardiac migration and knotting of the distal end of a VP shunt are by Chong et al. in 2008 [1] and Nguyen et al. in 2010 [2]. Both cases were similar; VP shunt insertion occurred without apparent complication, retrieval via a cervical incision failed due to knotting of the distal catheter that was not previously identified and removal required the assistance of Interventional Radiology using either a snare catheter or loop snare and pigtail catheter, respectively. As in these cases we did not initially appreciate that there was a knot formed in the distal catheter. The CT scan of the chest indicated several loops of catheter in the right atrium and in hindsight it was apparent that the turbulent motion due to the cardiac cycle had caused the spontaneous knot formation. The successful removal in our patient was facilitated by the teamwork of the Vascular Surgery and Neurosurgery teams allowing for vascular access and repair. This case highlights the importance of a multidisciplinary approach as a ‘‘push-and-pull” approach could have had disastrous consequences if the knot had not been appreciated during surgery.
Conflicts of Interest/Disclosures Fig. 2. Coronal reconstruction of the CT scan of the chest demonstrating the ventriculoperitoneal shunt within the right atrium.
The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
3. Discussion This case highlights a rare but important complication of VP shunts. There are fewer than 20 reports of intracardiac migration of a VP shunt in the literature and only two where this is further complicated by knotting of the distal catheter [1–7]. Most cases involved entry into the venous system via the IJV. This is suggested to occur due to either direct but unrecognised trauma during the
References [1] Chong JY, Kim JM, Cho DC, et al. Upward migration of distal ventriculoperitoneal shunt catheter into the heart: case report. J Korean Neurosurg Soc 2008;44:170–3. [2] Nguyen HS, Turner M, Butty SD, et al. Migration of a distal shunt catheter into the heart and pulmonary artery: report of a case and review of the literature. Childs Nerv Syst 2010;26:1113–6.
Case Reports / Journal of Clinical Neuroscience 22 (2015) 773–774 [3] Kano T, Kurosaki S, Iwasa S, et al. Migration of a distal ventriculoperitoneal shunt catheter into the internal jugular vein and heart through the external jugular vein: case report. Neurol Med Chir 2010;50:945–8. [4] Morell RC, Bell WO, Hertz GE, et al. Migration of a ventriculoperitoneal shunt into the pulmonary artery. J Neurosurg Anesthesiol 1994;6:132–4. [5] Zairi F, du Moulinet d’Hardemaere V, Assaker R. Early cardiac migration of distal shunt catheter. Br J Neurosurg 2012;26:545–6.
773
[6] Wei Q, Qi S, Peng Y, et al. Unusual complications and mechanism: migration of the distal catheter into the heart–report of two cases and review of the literature. Childs Nerv Syst 2012;28:1959–64. [7] Nordbeck P, Beer M, Wirbelauer J, et al. Intracardial dislocation of a cranioperitoneal shunt in a 6-year-old boy. Clin Res Cardiol 2010;99:677–8.
http://dx.doi.org/10.1016/j.jocn.2014.10.020
A rare marginal tentorial artery to ophthalmic artery anastomosis Daniel A. Tonetti a, Ashutosh P. Jadhav b, Andrew F. Ducruet a,⇑ a Department of Neurological Surgery, University of Pittsburgh Medical Center, University of Pittsburgh Medical Center Presbyterian, Suite B-400, 200 Lothrop Street, Pittsburgh, PA 15213, USA b Department of Neurology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
a r t i c l e
i n f o
Article history: Received 6 October 2014 Accepted 4 November 2014
Keywords: Anastomosis Marginal tentorial artery Neuroanatomy Ophthalmic artery
a b s t r a c t We report a patient with a marginal tentorial artery to ophthalmic artery anastomosis. A middle-aged man presented with subarachnoid hemorrhage and underwent angiography, where selective microcatheter injection of the meningohypophyseal trunk and marginal tentorial artery revealed a collateral to the distal ophthalmic artery. The radiological findings, embryology behind ophthalmic artery anastomoses and the neurosurgical and neurovascular relevance are discussed. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction The ophthalmic artery (OA) is one of the major branches of the internal carotid artery (ICA). The origin point is variable on the ICA; in 53.6% of patients, the OA arises from the anteromedial aspect of the ICA, the superomedial aspect in 37.5%, medial aspect in 7.1% and anterosuperior aspect in 1.8% [1]. Several reports have been published on the variation of the origin of the OA as occasionally it does not arise from the supraclinoid ICA. It may uncommonly originate from the intracavernous part of the ICA or from the middle meningeal artery [1,2]. Other rare origins have been reported, including basilar artery [3], anterior cerebral artery [4], and posterior communicating artery [5]. We report a man with a marginal tentorial artery variant with anastomotic connection to the OA and discuss its neurosurgical and neurovascular relevance. To our knowledge, it is the first such case described in the literature. 2. Case report A 60-year-old man underwent cerebral angiography for evaluation of posterior fossa subarachnoid hemorrhage at an outside facility, where a right-sided medial tentorial dural arteriovenous fistula (dAVF) was incidentally discovered. At our institution, diagnostic cerebral angiography was performed to definitively establish the presence of a dAVF. Careful review of the images demonstrated the dAVF arising from the right marginal tentorial artery with drainage through the straight sinus (Fig. 1). Right ICA injection revealed a supercav⇑ Corresponding author. Tel.: +1 412 864 1839; fax: +1 412 864 3441. E-mail address: [email protected] (A.F. Ducruet).
ernous OA supplying the retina (Fig. 2), and right external carotid artery injection revealed no supply to the OA. Selective microcatheter injection of the meningohypophyseal trunk (MHT) and marginal tentorial artery during this procedure revealed a collateral to the distal OA (Fig. 3). In light of this potentially dangerous collateral, the procedure was terminated and no further consideration was given to therapeutic embolization.
3. Discussion The embryology of the definitive adult OA is a complex phenomenon. In the developing embryo, two arteries supply the orbital region: the ventral ophthalmic artery (VOA) arising from the future anterior cerebral artery and the dorsal ophthalmic artery (DOA) arising from the horizontal carotid siphon. The VOA reaches the orbit via the optic canal and the DOA through the superior orbital fissure [6]. Soon thereafter, an anastomosis is formed between the ICA and the VOA followed by regression of the proximal part of the VOA, resulting in the VOA persisting as the primitive OA arising from the supracavernous segment of the ICA. Simultaneously, the DOA and VOA anastomose inside the orbit around the optic nerve, and from this anastomosis the distal OA (the temporal ciliary artery, the nasal ciliary artery, and the central retinal artery) will arise. In the normal scenario, the DOA then regresses at the level of the superior orbital fissure, leaving as its remnants the anteromedial branch of the inferolateral trunk and the recurrent tentorial branch of the OA [6,7]. We postulate that our patient represents a variant of this anatomy, where there is an anastomosis between the marginal tentorial artery of the MHT and the recurrent tentorial branch of the
References [1] Merlini G, Bellotti V. Molecular mechanisms of amyloidosis. N Engl J Med 2003;349:583–96. [2] Goren H, Steinberg MC, Farboody GH. Familial oculoleptomeningeal amyloidosis. Brain 1980;103:473–95. [3] Uitti RJ, Donat JR, Rozdilsky B, et al. Familial oculoleptomeningeal amyloidosis. Report of a new family with unusual features. Arch Neurol 1988;45:1118–22. [4] Nakamura M, Yamashita T, Ueda M, et al. Neuroradiologic and clinicopathologic features of oculoleptomeningeal type amyloidosis. Neurology 2005;65:1051–6. [5] Urban PP, Hertkorn C, Schattenberg JM, et al. Leptomeningeal familial amyloidosis: a rare differential diagnosis of leptomeningeal enhancement in MRI. J Neurol 2006;253:1238–40.
771
[6] Honig S, Murali R. Spinal cord claudication from amyloid deposition. J Rheumatol 1992;19:1988–90. [7] Davidson GS, Montanera WJ, Fleming JF, et al. Amyloid destructive spondyloarthropathy causing cord compression: related to chronic renal failure and dialysis. Neurosurgery 1993;33:519–22. [8] Vignes JR, Eimer S, Dupuy R, et al. Beta(2)-microglobulin amyloidosis caused spinal cord compression in a long-term haemodialysis patient. Spinal Cord 2007;45:322–6. [9] Cloft HJ, Quint DJ, Markert JM, et al. Primary osseous amyloidoma causing spinal cord compression. AJNR Am J Neuroradiol 1995;16:1152–4. [10] Sekijima Y, Yoshida K, Tokuda T, et al. Familial transthyretin amyloidosis. In: Pagon RA, Adam MP, Ardinger HH, Bird TD, Dolan CR, Fong CT, et al., editors. GeneReviews(R). Seattle: University of Washington; 1993–2014.
http://dx.doi.org/10.1016/j.jocn.2014.09.023
Intracardiac migration and knotting of a ventriculoperitoneal shunt Gert Frahm-Jensen a,1, Peter R. Newton b,⇑,1, Katharine J. Drummond b, Tim P. Wagner a, Barend M.E. Mees a a b
Department of Vascular Surgery, Royal Melbourne Hospital, Parkville, Melbourne, VIC, Australia Department of Neurosurgery, Royal Melbourne Hospital, Grattan Street, Parkville, Melbourne, VIC 3050, Australia
a r t i c l e
i n f o
Article history: Received 9 September 2014 Accepted 25 October 2014
a b s t r a c t We report a patient with delayed migration of the distal ventriculoperitoneal shunt catheter from the peritoneum to the right atrium with associated knotting of the catheter complicating removal. We also review the literature on this topic. Crown Copyright Ó 2014 Published by Elsevier Ltd. All rights reserved.
Keywords: Complications Foreign-body migration Jugular vein injury Knot Ventriculoperitoneal shunt
1. Introduction Cerebrospinal fluid shunts are commonly used for the management of hydrocephalus, with ventriculoperitoneal (VP) shunts most often employed. Complications of VP shunts, usually as a result of obstruction, mechanical failure or infection, are unfortunately common. We report a patient with migration of the distal VP shunt catheter from the peritoneum to the right atrium with associated knotting of the catheter complicating removal. We also review the literature on this topic. 2. Case report A 77-year-old woman underwent an unremarkable VP shunt insertion (Codman Hakim Programmable Valve with Codman Bactiseal Ventricular and Distal Catheter; Codman & Shurtleff, Raynham, MA, USA) for normal pressure hydrocephalus (NPH) in early February 2013 with initial improvement in her symptoms. Postoperative imaging, including a radiograph shunt series, confirmed correct shunt placement. Two months later she returned with unrelated poorly controlled hypertension and a return of gait
⇑ Corresponding author. Tel.: +61 431 231 501; fax: +61 3 9342 8951. 1
E-mail address: [email protected] (P.R. Newton). These authors have contributed equally to the manuscript.
unsteadiness suggesting shunt malfunction with recurrence of symptoms of NPH. A chest radiograph indicated that the shunt had migrated from the abdomen into the chest and was overlying the cardiac shadow (Fig. 1). A CT scan demonstrated that the shunt entered the right internal jugular vein (IJV) above the right clavicle with multiple coils in the right atrium (Fig. 2). There was no shunt identified in the abdomen. Revision of the VP shunt was planned between the Neurosurgery and Vascular Surgery Units. The IJV was exposed via a transverse skin incision 1 inch cranial from the right clavicle and the shunt entry identified. A purse string suture of 5–0 prolene was placed around the entry site in the vein and the distal catheter was slowly pulled. Significant resistance was felt after 30 cm of catheter had been removed. Using image intensifier radiography a large knot in the catheter below the right clavicle was displayed. A longitudinal venotomy was extended to the origin of the brachiocephalic vein, which was controlled using a Satinsky clamp. On loosening the clamp, the knot was successfully pulled out with primary closure of the venotomy (Fig. 3). The shunt was seen to be draining cerebrospinal fluid. The post-auricular cranial and subcostal laparotomy wounds were reopened and a shunt tunneler passed between them allowing passage of a new distal catheter (Codman Bactiseal) which was connected to the shunt valve and placed into the peritoneal cavity. A radiograph shunt series 1 week post-operatively confirmed correct placement of the shunt.
772
Case Reports / Journal of Clinical Neuroscience 22 (2015) 771–773
Fig. 3. Removal of the knotted ventriculoperitoneal shunt catheter via the right internal jugular vein.
Fig. 1. Anteroposterior chest radiograph demonstrating intrathoracic migration of the ventriculoperitoneal shunt.
initial subcutaneous tunnelling of the catheter or gradual erosion of the IJV over time [2,6]. In our patient, the short duration between insertion of the VP shunt and discovery of the intracardiac migration would suggest a direct injury. The proximal migration of the distal catheter is aided by negative intrathoracic pressure and venous flow [5]. Complications of intracardiac migration include shunt malfunction, pulmonary emboli, sepsis, pulmonary infarction, local thrombus formation, valve insufficiency and arrhythmias [2,4,6,7]. The other two reports describing this rare combination of intracardiac migration and knotting of the distal end of a VP shunt are by Chong et al. in 2008 [1] and Nguyen et al. in 2010 [2]. Both cases were similar; VP shunt insertion occurred without apparent complication, retrieval via a cervical incision failed due to knotting of the distal catheter that was not previously identified and removal required the assistance of Interventional Radiology using either a snare catheter or loop snare and pigtail catheter, respectively. As in these cases we did not initially appreciate that there was a knot formed in the distal catheter. The CT scan of the chest indicated several loops of catheter in the right atrium and in hindsight it was apparent that the turbulent motion due to the cardiac cycle had caused the spontaneous knot formation. The successful removal in our patient was facilitated by the teamwork of the Vascular Surgery and Neurosurgery teams allowing for vascular access and repair. This case highlights the importance of a multidisciplinary approach as a ‘‘push-and-pull” approach could have had disastrous consequences if the knot had not been appreciated during surgery.
Conflicts of Interest/Disclosures Fig. 2. Coronal reconstruction of the CT scan of the chest demonstrating the ventriculoperitoneal shunt within the right atrium.
The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
3. Discussion This case highlights a rare but important complication of VP shunts. There are fewer than 20 reports of intracardiac migration of a VP shunt in the literature and only two where this is further complicated by knotting of the distal catheter [1–7]. Most cases involved entry into the venous system via the IJV. This is suggested to occur due to either direct but unrecognised trauma during the
References [1] Chong JY, Kim JM, Cho DC, et al. Upward migration of distal ventriculoperitoneal shunt catheter into the heart: case report. J Korean Neurosurg Soc 2008;44:170–3. [2] Nguyen HS, Turner M, Butty SD, et al. Migration of a distal shunt catheter into the heart and pulmonary artery: report of a case and review of the literature. Childs Nerv Syst 2010;26:1113–6.
Case Reports / Journal of Clinical Neuroscience 22 (2015) 773–774 [3] Kano T, Kurosaki S, Iwasa S, et al. Migration of a distal ventriculoperitoneal shunt catheter into the internal jugular vein and heart through the external jugular vein: case report. Neurol Med Chir 2010;50:945–8. [4] Morell RC, Bell WO, Hertz GE, et al. Migration of a ventriculoperitoneal shunt into the pulmonary artery. J Neurosurg Anesthesiol 1994;6:132–4. [5] Zairi F, du Moulinet d’Hardemaere V, Assaker R. Early cardiac migration of distal shunt catheter. Br J Neurosurg 2012;26:545–6.
773
[6] Wei Q, Qi S, Peng Y, et al. Unusual complications and mechanism: migration of the distal catheter into the heart–report of two cases and review of the literature. Childs Nerv Syst 2012;28:1959–64. [7] Nordbeck P, Beer M, Wirbelauer J, et al. Intracardial dislocation of a cranioperitoneal shunt in a 6-year-old boy. Clin Res Cardiol 2010;99:677–8.
http://dx.doi.org/10.1016/j.jocn.2014.10.020
A rare marginal tentorial artery to ophthalmic artery anastomosis Daniel A. Tonetti a, Ashutosh P. Jadhav b, Andrew F. Ducruet a,⇑ a Department of Neurological Surgery, University of Pittsburgh Medical Center, University of Pittsburgh Medical Center Presbyterian, Suite B-400, 200 Lothrop Street, Pittsburgh, PA 15213, USA b Department of Neurology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
a r t i c l e
i n f o
Article history: Received 6 October 2014 Accepted 4 November 2014
Keywords: Anastomosis Marginal tentorial artery Neuroanatomy Ophthalmic artery
a b s t r a c t We report a patient with a marginal tentorial artery to ophthalmic artery anastomosis. A middle-aged man presented with subarachnoid hemorrhage and underwent angiography, where selective microcatheter injection of the meningohypophyseal trunk and marginal tentorial artery revealed a collateral to the distal ophthalmic artery. The radiological findings, embryology behind ophthalmic artery anastomoses and the neurosurgical and neurovascular relevance are discussed. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction The ophthalmic artery (OA) is one of the major branches of the internal carotid artery (ICA). The origin point is variable on the ICA; in 53.6% of patients, the OA arises from the anteromedial aspect of the ICA, the superomedial aspect in 37.5%, medial aspect in 7.1% and anterosuperior aspect in 1.8% [1]. Several reports have been published on the variation of the origin of the OA as occasionally it does not arise from the supraclinoid ICA. It may uncommonly originate from the intracavernous part of the ICA or from the middle meningeal artery [1,2]. Other rare origins have been reported, including basilar artery [3], anterior cerebral artery [4], and posterior communicating artery [5]. We report a man with a marginal tentorial artery variant with anastomotic connection to the OA and discuss its neurosurgical and neurovascular relevance. To our knowledge, it is the first such case described in the literature. 2. Case report A 60-year-old man underwent cerebral angiography for evaluation of posterior fossa subarachnoid hemorrhage at an outside facility, where a right-sided medial tentorial dural arteriovenous fistula (dAVF) was incidentally discovered. At our institution, diagnostic cerebral angiography was performed to definitively establish the presence of a dAVF. Careful review of the images demonstrated the dAVF arising from the right marginal tentorial artery with drainage through the straight sinus (Fig. 1). Right ICA injection revealed a supercav⇑ Corresponding author. Tel.: +1 412 864 1839; fax: +1 412 864 3441. E-mail address: [email protected] (A.F. Ducruet).
ernous OA supplying the retina (Fig. 2), and right external carotid artery injection revealed no supply to the OA. Selective microcatheter injection of the meningohypophyseal trunk (MHT) and marginal tentorial artery during this procedure revealed a collateral to the distal OA (Fig. 3). In light of this potentially dangerous collateral, the procedure was terminated and no further consideration was given to therapeutic embolization.
3. Discussion The embryology of the definitive adult OA is a complex phenomenon. In the developing embryo, two arteries supply the orbital region: the ventral ophthalmic artery (VOA) arising from the future anterior cerebral artery and the dorsal ophthalmic artery (DOA) arising from the horizontal carotid siphon. The VOA reaches the orbit via the optic canal and the DOA through the superior orbital fissure [6]. Soon thereafter, an anastomosis is formed between the ICA and the VOA followed by regression of the proximal part of the VOA, resulting in the VOA persisting as the primitive OA arising from the supracavernous segment of the ICA. Simultaneously, the DOA and VOA anastomose inside the orbit around the optic nerve, and from this anastomosis the distal OA (the temporal ciliary artery, the nasal ciliary artery, and the central retinal artery) will arise. In the normal scenario, the DOA then regresses at the level of the superior orbital fissure, leaving as its remnants the anteromedial branch of the inferolateral trunk and the recurrent tentorial branch of the OA [6,7]. We postulate that our patient represents a variant of this anatomy, where there is an anastomosis between the marginal tentorial artery of the MHT and the recurrent tentorial branch of the
