Internal carotid agenesis

Title

Other Names:

Agenesis of the internal carotid artery; Internal carotid artery agenesis

Categories:

Blood Diseases; Congenital and Genetic Diseases; Nervous System Diseases

Summary Summary

Internal carotid agenesis occurs when one or both of the blood vessels that supply blood to the brain (internal carotid arteries) do not develop (agenesis). In most people, there is a pair of internal carotid arteries, with one on the left side and one on the right side. Internal carotid agenesis can occur on either side of the body, but it occurs on the left side three times more frequently than the right side.^[1] People missing one or both of the internal carotid arteries may not have any symptoms, because there are several blood vessels that can transport blood to the brain instead. Some people do have symptoms including headaches, blurred vision, paralysis of some of the nerves in the head (palsy), recurrent seizures (epilepsy), or muscle weakness on one side of the body (hemiparesis).^[2] People who have internal carotid agenesis have an increased risk for enlargement of the other blood vessels (aneurysm) in the brain.^[1]

The exact cause of internal carotid agenesis is not known. There are no reports of more than one family member having this malformation.^[3] Diagnosis of internal carotid agenesis often occurs accidentally when a person is having a brain MRI or CT scan. The diagnosis can be confirmed with magnetic resonance angiography (MRA). People with internal carotid agenesis should be watched for the development of brain aneurysms. In some cases, surgery may be necessary to treat symptoms caused by internal carotid agenesis.^[1]

Last updated: 10/1/2017

Symptoms Symptoms

Internal carotid agenesis occurs when one or both of the blood vessels that supply blood to the brain (internal carotid artery) do not form (agenesis). Internal carotid agenesis does not always cause symptoms because there are several blood vessels that transport blood to the brain. However, some people may have symptoms such as headaches, blurred vision, paralysis of some of the nerves in the head (palsy), recurrent seizures (epilepsy), or muscle weakness on one side of the body (hemiparesis).^[2]

Some people with internal carotid agenesis may have other malformations involving the blood vessels, face, or ears. This typically occurs on the same side of the body as the internal carotid agenesis.^[4] People who have internal carotid agenesis are at an increased risk to develop an enlargement of other blood vessels in the brain (aneurysm). The risk for people with internal carotid agenesis to develop a brain aneurysm is estimated at 24-34%.^[1]

Last updated: 10/1/2017

The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.

Signs and Symptoms	Approximate number of patients (when available)
Cerebral ischemia	Frequent (present in 30%-79% of cases)
Dilatation of the cerebral artery	Frequent (present in 30%-79% of cases)
Subarachnoid hemorrhage	Frequent (present in 30%-79% of cases)
Arachnoid cyst	Occasional (present in 5%-29% of cases)
Headache	Occasional (present in 5%-29% of cases)

Last updated: 10/1/2017

Cause Cause

The cause of internal carotid agenesis is currently unknown. The malformation is present from birth and is believed to be caused when something happens early during the development of the baby that stops the carotid artery from forming correctly. Most of the time, the malformation is thought to occur by chance. However, less commonly, a person with internal carotid agenesis may also have other diseases or syndromes. People with internal carotid agenesis caused by other syndromes typically have other symptoms or medical problems.^[4]

Last updated: 10/1/2017

Inheritance Inheritance

Mutations (changes) in a specific gene have not been associated with internal carotid agenesis, and the malformation is not known to run in families.^[3] Therefore, other family members are not known to be at risk to have the malformation as well. If a person with internal carotid agenesis has an aneurysm, other family members may be recommended to have screening to check for aneurysms as well.

Internal carotid agenesis is known to be associated with a few other diseases or syndromes.^[1] If an individual has internal carotid agenesis as a sign of another disease or syndrome, then it is possible that the malformation was inherited and that it could be passed on to future generations.

Last updated: 10/1/2017

Diagnosis Diagnosis

Internal carotid agenesis is diagnosed when one or both of the internal carotid arteries are found to be missing by specific imaging tests. These imaging tests may include angiography, computed tomography scanning (CT scan), and magnetic resonance imaging (MRI).^[2] These tests are used to visualize the blood vessels and the surrounding bones. The diagnosis may be confirmed with another imaging test called magnetic resonance angiogram (MRA) that looks specifically at the blood vessels.^[2] If people who have internal carotid agenesis do not have symptoms of the malformation, it is typically diagnosed by accident (or incidentally) when evaluating for other health concerns.

Last updated: 10/1/2017

Treatment Treatment

The treatment of internal carotid agenesis may depend on the signs and symptoms present in each individual. Other blood vessels that supply blood to the brain may be affected in people who have internal carotid agenesis because the blood vessels need to make up for the loss of blood flow from the missing artery. However, exactly how the blood vessels make up for the missing blood flow may differ from person to person. In some cases, surgical treatment may be required to alleviate any symptoms resulting from internal carotid agenesis. However, affected people may have complications related to surgery, so it is important that pre-surgical studies be completed first.^[1]

People with internal carotid agenesis should receive periodic imaging by MRA or other imaging of the blood vessels. This imaging is important to check for the development of aneurysms. If a brain aneurysm is observed, further monitoring or surgical treatment may be necessary.^[1]

Last updated: 10/1/2017

Prognosis Prognosis

The long-term outlook for people affected by internal carotid agenesis is typically good. Although the malformation may be associated with complications such as brain aneurysm, there are imaging techniques and surgical procedures that can be used to identify and treat people with aneurysms.^[5] People with this malformation may be more likely to experience complications during certain types of surgery, so it is important to tell all of your doctors or other trusted medical professionals about the diagnosis.^[6] In some cases, internal carotid agenesis may be associated with other diseases or syndromes.^[1]^[7] In these cases, the long-term outlook depends on the underlying cause of the malformation.

Last updated: 10/1/2017

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Organizations Organizations

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Providing General Support

American Stroke Association
National Center
7272 Greenville Avenue
Dallas, TX 75231
Telephone: 888-478-7653
Website: http://www.strokeassociation.org/
Brain Aneurysm Foundation
269 Hanover Street
Hanover, MA 02339
Telephone: 888-272-4602
E-mail: office@bafound.org
Website: https://www.bafound.org/

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Learn More Learn More

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

In-Depth Information

The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
PubMed is a searchable database of medical literature and lists journal articles that discuss Internal carotid agenesis. Click on the link to view a sample search on this topic.

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References References

Claros P, Bandos R, GIlea I, Claros Jr A, Capdevila A, Gardia Rodrigues J, and Claros A. Major congenital anomalies of the internal carotid artery: agenesis, aplasia and hypoplasia. Int J Pediatr Otorhinolaryngol. June 15, 1999; 49(1):69-76. http://www.ncbi.nlm.nih.gov/pubmed?term=10428407.
Florio F, Balzano S, Nardella M, Strizzi V, Cammisa M, Bozzini V, Catapano G, and D'Angelo V. Congenital Absence of the Internal Carotid Artery. Vardiovasc Intervent Radiol. January 1999; 22(1):74-78. https://www.ncbi.nlm.nih.gov/pubmed/9929551.
Internal carotid agenesis. Orphanet. http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=981. Accessed 9/23/2017.
Lee JH, Oh CW, Lee SH, and Han DH. Aplasia of the internal carotid artery. Acta Neruochir. February 2003; 145(2):117-125. http://www.ncbi.nlm.nih.gov/pubmed/12601459.
Ohtani T, Iijima K, Aishima K, Wada H, Sasaguchi N, and Kurihara H. Segmental Aplasia of Bilateral Internal Carotid Arteries Accompanied by Intracranial Aneurysms: A Case Report. NMC Case Report Journal. July 2017; 4(3):67-69. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5566686/.
Kumaresh A, Kumar Vasanthraj P, and Chandrasekharan A. Unilateral Agenesis of Internal Carotid Artery with Intercavernous Anastamosis: A Rare Case Report. Journal of Clinical Imaging Science. 2015; 5:7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4322372/.
Dinc H, Alioglu Z, Erdol H, and Ahmetoglu A. Agenesis of the internal carotid artery associated with aortic arch anomaly in a patient with congenital Horner’s syndrome. American Journal of Neuroradiology. June 2002; 23(6):929-931. http://www.ajnr.org/content/23/6/929.long.