British Journal of Radiology (2005) 78, 569-572
© 2005 British Institute of Radiology
doi: 10.1259/bjr/22072424
Bilateral absence of the internal carotid artery: MR angiography and ultrasound findings
D W Anderson, MBBS(hons), FRANZCR
Monash Medical Centre, 246 Clayton Road, Clayton, Victoria, Australia 3168
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Abstract
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Presented is a case of congenital absence of the internal carotid arteries (ICAs) in a 13-year-old boy. This condition has been rarely reported in the literature and presented are our imaging findings, including descriptions of findings with MRI, MR angiography and ultrasound.
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Introduction
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A case of our imaging findings is presented demonstrating bilateral agenesis of the internal carotid arteries (ICAs) in a 13-year-old male. Bilateral absence of the ICA (congenital) is a very rare abnormality [1, 2]. Most cases have been demonstrated by catheter angiography or dissection studies [1]. This case describes the appearances on MRI and MR angiography (MRA) of the intracranial circulation together with the appearances of the cervical arterial vasculature on ultrasound.
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Case report
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A 13-year-old Caucasian male presented to a local emergency department with severe generalized headache. This followed a minor head injury sustained 6 h earlier whilst playing cricket. Onset of headache was while straining at toilet. On examination the patient appeared neurologically intact and had a Glasgow coma score of 15. There was no neck stiffness. Headache resolved over 90 min and he was subsequently discharged. Further similar headache, onset again with straining at toilet occurred 5 days later, prompting representation with subsequent CT examination performed to exclude subarachnoid haemorrhage. This revealed a large calibre basilar artery without evidence of recent subarachnoid haemorrhage. Lumbar puncture was not performed.
Given the clinical suspicion of subarachnoid haemorrhage and the appearance of the basilar artery, MRI was performed after transfer to our hospital. Routine aneurysm imaging (axial T1, T2, fluid attenuated inversion recovery (FLAIR), sagittal T1, diffusion weighted imaging (DWI) and 3D time of flight (TOF) MRA) was performed which demonstrated absence of the bilateral internal carotid arteries (Figures 1–4
). Both anterior circulations were supplied by large posterior communicating arteries via an intact circle of Willis. No further vascular abnormality was seen and in particular there was no evidence of aneurysm or focal stenosis. There was no identifiable intracranial bleeding or infarction. A cavum septum pellucidum et vergae was seen as a normal variant. Review of the prior CT examination demonstrated bilateral absence of the bony canal for the ICA within the skull base. Presented for comparison are the same projections of normal MRA images from a 14-year-old patient (Figures 5 and 6) as well as axial T2 weighted images from the same normal patient (Figures 8 and 9).
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Figure 1. Lateral MR angiography projection showing absent anterior circulation below the circle of Willis.
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Figure 2. Anteroposterior MR angiography projection showing absent anterior circulation below the circle of Willis.
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Figure 4. Axial MR angiography at level of cavernous sinuses showing absent internal carotid artery flow voids.
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Figure 7. Axial T2 weighted image showing large calibre basilar artery and absent internal carotid artery flow voids.
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Figure 8. Axial T2 weighted image in a normal patient demonstrating normal calibre basilar artery and internal carotid artery flow voids.
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Subsequent ultrasound examination of the neck arteries revealed large calibre vertebral arteries (R=4.0 mm L=4.3 mm; Figure 9
), with bilateral small calibre common carotid arteries (R=2.9 mm L= 3.3 mm; Figure 10). There was no identifiable ICA, either at its expected origin or elsewhere within the neck. Vertebral flow velocities were 90/40 cm s–1 bilaterally. This is within the reported normal range of vertebral artery velocities for a patient of this age [3]. The patient was uneventfully discharged and remains well at 1 year post discharge.
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Discussion
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Absence of the ICA may be the result of acquired disease (common), congenital hypoplasia (uncommon) or congenital aplasia (very rare). This is more commonly seen unilaterally [4–8]. Most reported cases of bilateral absence have been recorded prior to 1980 [1]. There is most experience with catheter angiography, the first case report in 1965, where review of 1407 angiograms revealed a single case of bilateral ICA absence with supply to the anterior circulation via multiple ophthalmic and petrous collaterals [9]. Earlier case reports rely on dissection studies (4 cases) [10, 11]. This case reports the findings demonstrable with MRI, MRA and ultrasound. The developmental nature of our patient's bilateral ICA absence was confirmed by CT examination showing absence of the bony ICA canal within the skull base [12]. Several case reports have discussed the MRI and MRA findings in unilateral aplasia or hypoplasia of the ICA, including children [4–8]. Several authors have commented on the utility of MRA in providing a non invasive assessment of both the absence of vessel as well as the associated collateral circulation [4–8]. Kidooka et al believed the MRA assessment in their case was equivalent to that provided by the catheter angiography [5].
The MRA in this case demonstrated supply to the anterior circulation via enlarged posterior communicating arteries, the most commonly seen collateral arrangement (12 of 18 cases) [1]. Other recognized collateral arrangements include persistent trigeminal arteries (2 cases), ophthalmic artery (2 cases) and maxillary derived collaterals (2 cases) [1]. Petrous anastomoses and accessory meningeal supply have also been described [12, 13].
An aneurysm was not demonstrated in our patient on MRA. Correlative catheter angiography was not performed. MRA is recognized to have a limited sensitivity for the detection of small aneurysms [14–18]. This is variably stated to be as low as 54% for aneurysms <5 mm [15] and 55% for aneurysms <3 mm [17]. Whilst much ongoing debate exists regarding screening for aneurysms with MRA [13, 14] it does seem that absence of the ICA is associated with a greatly increased incidence of aneurysm. This has been variably stated as 25% (9 of 36 patients) [19] and 24–36% for patients with unilateral agenesis of the ICA [18]. This is presumed the result of altered/abnormal haemodynamic stressors. Other authors have argued that unilateral ICA agenesis may be regarded as an incidental or non clinically significant finding [7]. The current available case reports of bilateral ICA absence suggest that it is unlikely to represent an incidental finding of no diagnostic or prognostic value [1].
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Conclusion
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Bilateral absence of the ICA is a very rarely reported abnormality. Our case report suggests that MRA is able to successfully demonstrate ICA absence and common collateralisation in a non invasive fashion, in agreement with others who have described its use in unilateral ICA agenesis. There also exists the potential for aneurysm screening, of which it is likely these patients have a significantly increased incidence. We have also provided description of the ultrasound findings in the vertebral and common carotid arteries, with our case demonstrating a significantly larger calibre vertebral system in comparison with the common carotid artery.
Received for publication October 13, 2004.
Revision received December 23, 2004.
Accepted for publication January 31, 2005.
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References
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- Cali RL, Berg R, Rama K. Bilateral internal carotid artery agenesis: a case study and review of the literature. Surgery 1993;113:227–33.[Medline]
- Owada Y, Sakuta Y. Bilateral carotid artery agenesis with corpus callosum hypogenesis - a case report. No-To-Shinkei 1995;47:589–94.
- Schoning M, Niemann G, Hartig B. Transcranial color duplex sonography of basal cerebral arteries: reference data of flow velocities from childhood to adulthood. Neuropediatrics 1996;27:249–55.[Medline]
- Mellado JM, Merino X, Ramos A, Salvado E, Sauri A. Agenesis of the internal carotid artery with a trans-sellar anastomosis: CT and MRI findings in late onset congenital hypopituitarism. Neuroradiology 2001;43:237–41.[CrossRef][Medline]
- Kidooka M, Okada T, Handa J. Agenesis of the internal carotid artery – report of a case combined with arachnoid cyst in a child. No To Shinkei 1992;44:371–5.[Medline]
- Slaba SG, Zafatayeff SN, Chelala AS. Complete imaging study of internal carotid artery agenesis with intercavernous anastomosis. Neurochirurgie 2002;48:35–8.[Medline]
- Lee JH, Oh CW, Lee SH, Han DH. Aplasia of the internal carotid artery. Acta Neurochirurgica 2003;145:117–25.[CrossRef][Medline]
- Inaml Y, Harada K. Agenesis of the internal carotid artery and congenital pituitary hypoplasia: proposal of a cause of congenital hypopituitarism. Eur J Pediatr 2003;162:610–2.[CrossRef][Medline]
- Fields WS. Collateral circulation to the brain. Baltimore: Williams and Wilkins, 1965:211–2.
- Dilenge D. Bilateral agenesis of the internal carotid artery. J Can Assoc Radiol 1975;26:91–4.[Medline]
- Hills J. Bilateral agenesis of the internal carotid artery associated with cardiac and other anomalies. Neurology 1968;18:142–6.[Medline]
- Given CA, Huang-Hellinger F, Chepuri NB, Morris PP. Congenital absence of the internal carotid artery: case reports and review of the collateral circulation. AJNR Am J Neuroradiol 2001;22:1953–9.[Abstract/Free Full Text]
- Smith R. Agenesis of the internal carotid artery with an unusual primitive collateral. J Neurosurg 1972;37:460–2.[Medline]
- International study of unruptured aneurysms (ISUIA) Investigators. Hemorrhage rates in patients with unruptured intracranial aneurysms. Stroke 1998;29:273.
- White PM, Lindsay KW, Teasdale E, Teasdale GM. Should we screen for familial intracranial aneurysm? Stroke 1999;30:2238–48.[Free Full Text]
- Korogi Y, Takahashi M, Mabuchi N, Nakagawa T, Fujiwara S, Horikawa Y. Intracranial aneurysms: diagnostic accuracy of MR angiography with evaluation of maximum intensity projection and source images. Radiology 1996;199:199–207.[Abstract/Free Full Text]
- White PM, Wardlaw JM. How reliable is the non invasive imaging of intracranial aneurysms? An objective assessment of the quality of the published literature. Cerebrovasc Dis 1999;9(Suppl. 1):51.
- Okahara M, Kiyosue H, Yamashita M, Nagatomi H, Hata H, Saginoya Y, et al. Diagnostic accuracy of magnetic resonance angiography for cerebral aneurysms in correlation with 3D digital subtraction angiographic images. Stroke 2002;33:1803–8.[Abstract/Free Full Text]
- Servo A. Agenesis of the left internal carotid artery associated with an aneurysm on the right carotid siphon. J Neurosurg 1977;46:677–80.[Medline]
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Abstract
Introduction
