Congenital Absence of the Internal Carotid Artery

Transcription

1 Journal of Soonchunhyang Medical Science 16(1) p.09~15 June Congenital bsence of the Internal Carotid rtery Sun Hye Jeong, Hyun Sook Hong, Sung-Il Park, Dae Ho Kim, Hae Kyung Lee Department of Radiology, College of Medicine, Soonchunhyang University, Bucheon, Korea bstract bsence of the internal carotid artery is thought to result from developmental failure, which occurs before the complete development of the circle of Willis. Even though most patients are asymptomatic, this anomaly may be associated with other potentially severe malformations and disorders. n absent or hypoplastic carotid canal found on Computed Tomography(CT) scanning, suggests the presence of a congenital vascular anomaly with or without a potentially life-threatening intracranial aneurysms; further evaluation with CT angiography, or Magnetic Resonance(MR) angiography should be considered in such cases. We present the clinical features and radiological findings of five cases of congenital absence of the internal carotid artery. Key words : Congenital, Internal carotid artery Introduction 1) Congenital absence of one or both internal carotid arteries (IC) is a rare abnormality, which occurs in less than 0.01% of the population. Unilateral agenesis is more common than bilateral IC agenesis. 1,2) There are three types of developmental anomalies of the IC. genesis is defined as the total failure of the development of an organ, aplasia as a lack of development in spite of precursors and hypoplasia as incomplete development of an organ. 3) bsence of the carotid canal is associated with agenesis of the IC. However, if there is a carotid canal, aplasia or hypoplasia might be present. Intrasellar intercarotid Correspondence : Hyun Sook Hong Mailing address : Department of Radiology, College of Medicine, Soonchunhyang University Bucheon Hospital, 1174 Jung dong, Wonmi-gu, Bucheon, Gyeonggi-do, , South Korea Tel : ~2 / Fax hshong@schbc.ac.kr Received : 26 January 2010 / ccepted : 31 May 2010 communicating arteries are common if one of the ICsis absent. 3) In cases with bilateral IC agenesis, the anterior circulations are usually supplied by enlarged posterior communicating arteries and the basilar artery through the circle of Willis. 2) There is also a high incidence of intracranial aneurysmsassociated with IC agenesis due to the development of collateral vessels incidence of intracranial hemorrhaging. this increases the However, there have been some cases reported of intracranial hemorrhage without evidence of an aneurysm. 4) Here we report five cases of aplasia or hypoplasia of unilateral or bilateral ICs in two males and three females the age ranged from 30 to 58 years. The diagnosis of hypoplasia or agenesis of the IC was based on a hypoplastic or absent bony carotid canal by CT scan of the skull base and conventional angiography, CT or MR angiographic findings.

2 10 Journal of Soonchunhyang Medical Science Vol.16 No.1 June 2010 Methods and Results Case 1 35-year-old woman presented with generalized tonic seizures with sudden onset four hours prior to presenting to the hospital, and lasting for two to three minutes. The patient felt a tingling sensation in the left arm for several months. The brain MRI showed focal small infarcts in the left basal ganglia. The transfemoral cerebral angiography revealed bilateral hypoplastic ICs (Fig. 1, B). The branches of the IC distal to the ophthalmic artery were not visualized (Fig. 1C). Both vertebral arteries were prominent and the posterior communicating arteries were enlarged and supplied the anterior circulation (Fig. 1D, E). This patient was diagnosed with bilateral hypoplasia of the ICs. C D B Fig. 1. thirty-five year-old woman presented with ge- neralized tonic seizures. () Right IC angiogram shows hypoplastic right IC (arrows). (B) Left IC angiogram shows a hypoplastic left IC (arrows). (C) The branches distal to the ophthalmic artery of the IC are not visualized. (D, E) Both vertebral arteries are prominent and the posterior communicating arteries that supply the anterior circulation are enlarged. There was no evidence of a vascular anomaly such as an aneurysm. Case 2 58-year-old man presented with a history of intermittent headaches for several months. The brain MRI and CT angiography of the neck revealed almost a completely non visualized right IC and a partially visualized right supraclinoid IC. The supraclinoid IC was supplied from the right posterior communicating artery (Fig 2, B). Conventional angiography was not performed. On the CT angiography, the lumen of the right

3 Sun Hye Jeong : Congenital absence of the internal carotid artery 11 carotid canal was not well delineated in contrast to the left carotid canal the left IC was normally visualized (Fig. 2C). t that time, the patient was diagnosed with cancer of the right tonsil with metastasis to the tongue and salivary glands. Wide excision of the right tonsil with a modified radical neck dissection was performed. visualization of the right IC and a partially visualized right supraclinoid IC. The supraclinoid IC was supplied from the right posterior communicating artery. (C) On CT angiography, the lumen of the right carotid canal (arrowheads) is not well delineated in contrast to left carotid canal (arrows) where the left IC is normally visualized. Case 3 B 51-year-old woman who was diagnosed with stable angina due to significant stenosis of the proximal left anterior descending artery had a PCI stent inserted. The patient complained of paresthesias of both feet and hands at night for 1 year. Nonvisualization of the left IC with a small left CC was identified, and the left carotid canal was absent on the CT angiography of the neck. The left C and MC were visualized through the anterior communicating and posterior communicating arteries. Case 4 C Fig. 2. fifty-eight year-old man presented with a history of intermittent headaches for several months. (, B) The brain MR revealed almost total non 30-year-old man complained of a headache. The brain MRI showed no abnormal signal intensities in the brain parenchyma. The right IC was not seen after the bifurcation and the left vertebral artery was prominent on the MR. Conventional angiography revealed that the right CC could be visualized from the aortic arch directly; however, the IC was not seen (Fig. 3). The right MC originated from the basilar artery through the right PC (Fig. 3B, C). On the left internal carotid arteriogram, the right C was visualized through the anterior communicating artery from the left C; the right MC was visualized through a small connecting artery (Fig. 3D). There was no evidence of an aneurysm or VM. The right subclavian artery originated from the descending aorta; the right vertebral artery was the first branch of the subclavian artery (Fig. 3E).

4 12 Journal of Soonchunhyang Medical Science Vol.16 No.1 June 2010 E B C Fig. 3. thirty year-old man complained of headaches. () Conventional angiography revealed a right CC directly from the aortic arch, but the IC was not seen. (B,C) The MC originated from the basilar artery through the right PC. (D) On the left internal carotid arteriogram, the right C was visualized through the anterior communicating artery from the left C, and the right MC was visualized through a small connecting artery. (E) The right subclavian artery originated from the descending aorta, and the right vertebral artery was the first branch of the subclavian artery. Case 5 D 58-year-old woman was transferred to our hospital due to a subarachnoid hemorrhage. The patient had a severe headache for two days. There was a history of mitral valve stenosis that was treated by surgery 35 years ago. The brain CT scan revealed a subarachnoid hemorrhage mainly in the right Sylvian fissure. The left carotid canal was significantly narrowed compared to the right side (Fig. 4). The CT angiography showed a markedly narrowed left IC. On the cerebral angiography, the left IC was diffusely and markedly narrowed from the proximal portion, and the right MC was obstructed at the M1 portion with delayed visualization of the MC branches through irregular collaterals from the

5 Sun Hye Jeong : Congenital absence of the internal carotid artery 13 Table 1. Clinical and imaging findings of cases case ge/sex Chief complaints bnormality side Carotid canal nomaly of IC Collateral flow ssociated abnormalities 1 35/F Seizure Bilateral Narrowed Hypoplasia 2 58/M Headache Rt. bsent genesis 3 51/F Parethesia Lt. bsent genesis Basilar a. P-com Basilar a. P-com -com P-com Lt. basal ganglia infarction Right tonsilar cancer Stable angina 4 30/M Headache Rt. bsent genesis -com berrant Rt. Subclavian a. 5 58/F Headache Lt. Narrowed Hypoplasia C Prox.MC Subarachnoid hemorrhage noted on the brain CT, the brain CT and angiography did not show evidence of an intracranial aneurysm. The clinical and imaging findings of the reported cases are summarized in Table 1. Discussion B Fig. 4. fifty-eight years-old woman presented with a subarachnoid hemorrhage. () The brain CT revealed a left carotid canal (arrowheads) that was significantly narrowed compared to the right side (arrows). (B) On cerebral angiography, the left IC was diffusely and markedly narrowed from the proximal portion. C and proximal M1 branches (Fig. 4B). lthough there was a subarachnoid hemorrhage Patients with IC agenesis or hypoplasia are usually asymptomatic because cerebral perfusion is usually adequate due to the development of collaterals. Common symptoms and signs include headaches, blurred vision, hearing loss, hemiparesis with or without cranial nerve palsy, epilepsy, cerebrovascular insufficiency, and in the most severe cases, intracranial hemorrhaging due to a ruptured aneurysm. 4,5) The patients in this report presented with headache, seizure and paresthesias of both the feet and hands. The exact mechanisms leading to agenesis of the IC remain unknown, but some investigators have suggested the occurrence of various mechanical disturbances during early development, such as pressure effects and excessive bending of the cephalic portion of the embryo to one side or the other. 6) Lee et al reported six cases with an

6 14 Journal of Soonchunhyang Medical Science Vol.16 No.1 June 2010 aneurysm that had agenesis or aplasia of the ICs, and in all six cases, the aneurysms were detected ipsilateral to the aplastic IC, supporting a congenital developmental abnormality rather than hemodynamic factors. 5) ICs develop from portions of the first and third aortic arches and paired dorsal aorta, at the 3-mm embryo stage. The root and distal portions of the ICs each originate from the first and third aortic arches. The dorsal aorta, between the first and third arches, forms the intermediate segment. 7) The external carotid arteries arise from the aortic sacs and migrate up to the third arches. The CCs develop from the third arches proximal to the external carotid arteries in the 12- to 14-mm embryo. 8) Therefore, the developmental abnormalities of the first and third aortic arches result in agenesis or aplasia of the IC. The carotid canal develops in association with the IC. The primordial IC is well defined by the fourth embryonic week. However, the skull base does not begin to form until thefifth to sixth weeks of fetal life. If the embryonic primordium of the IC fails to develop before the third to fifth embryonic weeks or involutes early in embryonic life, the IC and carotid canal cannot develop. However, if an insult is either relatively mild or occurs relatively late during the course of development of the skull base portion of the IC, a hypoplastic IC within a hypoplastic carotid canal can result. 9) In three of the cases reported here, the carotid canal of the skull base was not delineated ipsilateral to the nonvisualized IC. Therefore, these cases illustrate agenesis of a unilateral IC. For the other two cases bilateral or unilateral hypoplastic bony carotid canals were identified, and hypoplasia was diagnosed. reduced diameter of the lumen of an IC on the affected side, on conventional angiograms, provides a clue to the correct diagnosis, because a reduced lumen is not visible in cases with IC occlusion of atherosclerotic origin or after a dissection. 10) neurysms and abnormal collateral channels around the circle of Willis are commonly associated vascular anomalies such as agenesis or aplasia of ICs. The incidence of intracranial aneurysms associated with agenesis or aplasia has been reported in about 25-67% of cases, which is much higher than that found in the general population, which is 2-4% without this anomaly presenting with an intracranial hemorrhage as the initial symptom. 1-2) However, none of our cases had an aneurysm. In one case, an aberrant subclavianartery developed from the descending aorta. This was the case of a 58 year old man diagnosed with right tonsillar cancer and metastasis to the right side of the tongue. In cases of unilateral absence of the IC, three types of collateral circulation were suggested by Lie: the fetal type is the most common of the three types of collateral circulation the ipsilateral anterior cerebral artery, to the side of the agenesis or aplasia of the IC, is supplied by the normal contralateral IC via the anterior communicating artery, whereas the middle cerebral artery is supplied by an enlarged posterior communicating artery. This type of collateral circulation develops during early embryonic stages. If both the anterior and middle cerebral arteries are fed by the anterior communication artery, this is referred to as the adult type, because it resembles what usually occurs in cases of thrombosis of the IC. Intercavernous, supraclinoid anastomosis was suggested by Lie to be a fusion of two primitive trigeminal arteries that develop from the contralateral IC in the absence of the cervical and petrous portion of the IC, this is the third type. 5) The lumen of the carotid canal was not de-

7 Sun Hye Jeong : Congenital absence of the internal carotid artery 15 lineated in all cases on the base. In this report, there are four CT scans of the skull cases with the fetal type of collateral circulation that the MC supplies through the posterior communicating artery. There is one case with an ipsilateral MC associated with IC hypoplasia that was supplied through the C. There were no cases with transsellar intercarotid or external carotid artery connections. We report five Conclusion cases of agenesis or hypoplasia of the IC. This anomaly might be associated with other intracranial aneurysms or the development of collateral vessels. Some patient present with clinical findings due to intracranial hemorrhaging or malformations of other vessels. n absent carotid canal on CT scanning and angiography should raise suspicion for agenesis or hypoplasia of the IC and further evaluation for the detection of collaterals and/or an associated aneurysm should follow. References 1. fifi K, Godersky JC, Menezes, Smoker WR, Bell WE, Jacoby CG: Cerebral hemiatrophy, hypoplasia of internal carotid artery, and intracranial aneurysm: a rare association occurring in an infant. rch Neurol 44: , Cali RL, Berg R, Rama K: Bilateral internal carotid artery agenesis: a case study and review of the literature. Surgery 113: , Lie T: Congenital anomalies of the carotid arteries. msterdam: Excerpta Medica 35 51, Takahashi S, Higano S, Kurihara N, Shirane R, sai R, Kadoyama S, et al: Congenital absence and aberrant course of the internal carotid artery. Eur Radiol 6: , Lee J-H, Oh CW, Lee SH, Han DH: plasia of the internal carotid artery. cta Neurochir 145: , Damry N, Hanquinet S, Christophe C, Janssen F, Delatte P, Perlmutter N: Pediatr Radiol 24: , Czarnecki EJ, Silbergleit R, Mehta B, Sanders WP: bsence of the supraclinoid internal carotid artery in association with intracranial aneurysms. Neuroradiology 40:11 14, Rosen IW, Mills DF, Nadel HI, Kaiserman DD: ngiographic demonstration of congenital absence of both internal carotid arteries. Case report. J Neurosurg 42: , Teal JS, Rumbaugh CL, Bergeron RT, Segall HD: Congenital absence of the internal carotid artery associated with cerebral hemiatrophy, absence of the external carotid artery and persistence of the stapedial artery. JR 118: , Sliwka U, Schmidt P, Reul J, Noth J: genesis of the internal carotid artery: colour Doppler, CT, and MR angiography findings. J Clin Ultrasound 26: , 1998.

8