At 7 months, the patient was symptom-free on current pharmacotherapy. .... Ide C, De Coene B, Mailleux P, Baudrez V, Ossemann M, Trigaux JP. Hypoplasia of the ... Available at: http://www.sign.ac.uk/guidelines/fulltext/108/index.html. Ac-.
Hypoplastic internal carotid artery stenosis with a low-lying carotid bifurcation causing cerebral ischemia Alan G. Dawson, MBChB, BSc (Hons),a Alasdair Wilson, MSc, MD, FRCSEd,a Jana Maskova, MD, EBIR,b Alison D. Murray, FRCR,b John M. Reid, DPhil,c and Ganesh Kuhan, MD, FRCS,a Aberdeen, Scotland, United Kingdom Congenital abnormalities of the internal carotid artery (ICA) are infrequent and can be associated with aberrations of the Circle of Willis. A 47-year-old gentleman presented with transient neurological symptoms and cerebral infarction and carotid Doppler showed a stenotic right ICA. Subsequent computed tomographic angiography showed a hypoplastic ICA with a low-lying bifurcation at the C6 level and aplasia of the anterior communicating artery. This patient was commenced on aggressive medical therapy and at 7-month follow-up was symptom-free. This case report highlights the need for a centralized registry with long-term follow-up data in order to identify optimal management. ( J Vasc Surg 2012;56:1416-8.)
Congenital aberrations of the internal carotid artery (ICA) are an infrequent occurrence and have historically been classified as agenesis, aplasia, or hypoplasia.1 The development of a collateral circulation from the contralateral ICA and vertebrobasilar system normally renders this condition asymptomatic. Existing reports describe it as an incidental or post mortem finding.2,3 Where ICA hypoplasia, aplasia, or agenesis is present, it is not uncommon to have coincidental Circle of Willis abnormalities, particularly aneurysmal disease.4 This report illustrates a unique case with transient neurological symptoms and cerebral infarction in the appropriate territory of a diseased hypoplastic ICA with a low-lying bifurcation associated with aplasia of the A1 segment of the anterior communicating artery (ACA). CASE REPORT A 47-year-old gentleman presented to the acute stroke team with left arm weakness and dysarthria lasting for 15 minutes. The patient denied previous stroke-like symptoms. He had a history of migraine with visual aura and three previous middle ear operations, leaving a partial right lower motor neuron facial paralysis. He was a lifelong nonsmoker who consumed three bottles of wine per week. Neurological examination was otherwise normal. Blood pressure was 154/98 mm Hg. From the Department of Vascular Surgery,a Department of Radiology,b and Department of Neurology,c Aberdeen Royal Infirmary, Foresterhill. Author conflict of interest: none. Reprint requests: Dr Alan G. Dawson, Department of Vascular Surgery (Ward 36), Aberdeen Royal Infirmary, Foresterhill, Aberdeen, Scotland, United Kingdom, AB25 2ZN (e-mail: alan.g.dawson.04@aberdeen. ac.uk). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214/$36.00 Copyright © 2012 by the Society for Vascular Surgery. http://dx.doi.org/10.1016/j.jvs.2012.05.068
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Fig 1. Computed tomography (CT) carotid angiogram showing a hypoplastic artery entering the carotid canal confirming that it is a hypoplastic right internal carotid artery (ICA). The stenosed origin is also demonstrated. A, Hypoplastic ICA; B, carotid canal; C, external carotid artery; D, diseased origin of the hypoplastic ICA.
Routine blood tests and electrocardiogram were unremarkable. Nonfasting cholesterol was 4.3 mmol/L. Carotid duplex showed a 3-mm-diameter right ICA with a stenosis ⬎70% at its origin and low carotid bifurcation. Computed tomography (CT) of the brain revealed an acute small right temporal lobe infarct. CT angiography demonstrated a hypoplastic artery entering the carotid canal and thus was confirmed to be the ICA (Fig 1). The hypoplastic right ICA had a significant stenosis at the origin and a low-lying carotid bifurcation at the level of the C6 vertebra (Fig 2). The A1 segment of the right ACA was also found to be aplastic (Fig 3). Common carotid artery dissec-
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Fig 3. Three-dimensional computed tomography (CT) of Circle of Willis reconstruction showing aplasia of the A1 segment of the anterior communicating artery (ACA). A, Posterior cerebral artery; B, middle cerebral artery; C, agenesis of the ACA.
Fig 2. Three-dimensional computed tomography (CT) carotid angiogram reconstruction showing the hypoplastic right internal carotid artery (ICA) with a low-lying bifurcation. A, Vertebral artery; B, external carotid artery; C, hypoplastic ICA.
tion, stenosis, or ICA occlusion was not evident on cross-sectional CT imaging. This patient was started on daily atorvastatin 80 mg, ramipril 2.5 mg, and dual antiplatelet therapy (aspirin 75 mg and clopidogrel 75 mg following loading doses of 300 mg) for 3 months followed by clopidogrel 75 mg once daily monotherapy. At 7 months, the patient was symptom-free on current pharmacotherapy.
DISCUSSION This report illustrates a case of a patient presenting with a right hemispheric transient ischemic attack (TIA; by World Health Organization definition5) secondary to a stenosed hypoplastic right ICA with a low-lying bifurcation and an absent A1 segment of the ACA. The coexistence of ICA hypoplasia along with a low-lying bifurcation to our knowledge has not been previously reported. The ICA is considered to be one of the most stable arteries in terms of embryonic development. The reasons for developmental anomalies of the ICA remain controversial. Identification of ICA hypoplasia is associated with other anomalies, such as intracranial aneurysms and Circle of Willis abnormalities. It is imperative to look for these
abnormalities when hypoplastic ICAs are encountered. In the normal population, the incidence of intracerebral aneurysms is 2% to 4%; in the presence of ICA hypoplasia, this incidence increases to 25% to 34%.6 In this case, no intracranial aneurysms were identified, but absence of the A1 segment of the ACA was present. Hypoplasia of the A1 segment of the ACA will be present in 10% of the general population, while aplasia, as in this case, is a covariant of normal cerebral arterial circulation in only 2% of the general population.7 Management of patients with ICA hypoplasia is not clearly documented in previous reports. Two cases of TIA associated with ICA hypoplasia have been reported previously, and both patients were managed with antiplatelet agents (aspirin 325 mg daily) with no further ischemic events recorded at 28 months of follow up.8 Best medical therapy following TIA includes antiplatelet agents, statins, and blood pressure lowering medications.9 In this case, the choice of dual antiplatelet therapy for the first 3 months was based on supportive evidence from the effect of urgent treatment of transient ischemic attack and minor stroke on early recurrent stroke (EXPRESS) study.10 Due to the rarity of this condition, the evidence base for the optimal treatment of a symptomatic stenosed hypoplastic ICA is lacking. In this report, the patient opted for best medical therapy understanding the risk of a further TIA or stroke, which is a pragmatic conservative option. The presence of cerebral infarction in TIA is a risk factor for recurrent TIA/stroke in addition to clinical variables.11 The highest risk of recurrent TIA/stroke is within the first 14 days following the initial neurological event.12 This patient has
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remained symptom-free for 7 months and is therefore over the highest risk period; however, should further ischemic episodes be experienced, surgical intervention will be considered. The surgical options available for this patient were carotid endarterectomy with patch, ligation of ICA, ligation with external-to-ICA bypass, or carotid artery stenting. The low bifurcation would make controlling the common carotid artery difficult intraoperatively. The hypoplastic ICA seems to arise posteriorly from the common carotid artery, rendering patch repair difficult. Simple ligation of the ICA would have a higher risk of ischemic complication due to the incomplete Circle of Willis. One option would be to carry out awake testing under local anesthesia and to ligate if there were no neurological symptoms. A bypass from the external carotid artery to the ICA should be considered if the awake test was positive for neurological symptoms. Carotid artery stenting would not be ideal due to the small-diameter ICA and acute nature of the plaque. The adoption of best medical therapy as a first-line treatment has been met with success in this case thus far. This case report highlights the need for a centralized registry with long-term follow-up data in order to identify optimal management. REFERENCES 1. Lie TA. Congenital anomalies of the carotid arteries. Amsterdam, Netherlands: Excerpta Medica; 1968. p. 35-51. 2. Akfirat M, Cihangiroglu M, Ozdemir H, Topsakal C, Murat A, Yildirim H. Internal carotid artery hypoplasia in two cases. Clin Radiol 2002;57: 951-4. 3. Lhermitte F, Gautier JC, Poirier J, Tyrer JH. Hypoplasia of the internal carotid artery. Neurology 1968;18:439-46.
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4. Ide C, De Coene B, Mailleux P, Baudrez V, Ossemann M, Trigaux JP. Hypoplasia of the internal carotid artery: a noninvasive diagnosis. Eur Radiol 2000;10:1865-70. 5. WHO MONICA Project Principal Investigators. The World Health Organisation. MONICA Project (monitoring trends and determinanats in cardiovascular disease): a major international collaboration. J Clin Epidemiol 1988;41:105-14. 6. Afifi AK, Godersky JC, Menezes A, Smoker WR, Bell WE, Jacoby CG. Cerebral hemiatrophy, hypoplasia of internal carotid artery, and intracranial aneurysm. A rare association occurring in an infant. Arch Neurol 1987;44:232-5. 7. Mitchell DG, Merton DA, Mirsky PJ, Needleman L. Circle of Willis in newborns: color Doppler imaging of 53 healthy full-term infants. Radiology 1989;172:201-5. 8. Nardone R, Venturi A, Ausserer H, Buffone E, Covi M, Lochner P, et al. Transient ischaemic attacks in two cases of internal carotid artery hypoplasia. Neurol Sci 2005;26:282-4. 9. Scottish Intercollegiate Guidelines Network. Management of patients with stroke or TIA: assessment, investigation, immediate management and secondary prevention. A national clinical guideline; 2008. Available at: http://www.sign.ac.uk/guidelines/fulltext/108/index.html. Accessed February 28, 2012. 10. Rothwell PM, Giles MF, Chandratheva A, Marquardt L, Geraghty O, Redgrave JN, et al. Effect of urgent treatment of transient ischaemic attack and minor stroke on early recurrent stroke (EXPRESS study): a prospective population-based sequential comparison. Lancet 2007; 370:1432-42. 11. Giles MF, Albers GW, Amarenco P, Arsava MM, Asimos A, Ay H, et al. Addition of brain infarction to the ABCD2 Score (ABCD2I): a collaborative analysis of unpublished data on 4574 patients. Stroke 2010;41: 1907-13. 12. Rothwell PM, Giles MF, Flossmann E, Lovelock CE, Redgrave JN, Warlow CP, et al. A simple score (ABCD) to identify individuals at high early risk of stroke after transient ischaemic attack. Lancet 2005;366: 29-36.
Submitted Mar 19, 2012; accepted May 13, 2012.
