Internal carotid agenesis

Other Names: Agenesis of the internal carotid artery; Internal carotid artery agenesis 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).

People who have internal carotid agenesis have an increased risk for enlargement of the other blood vessels (aneurysm) in the brain.

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.

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. Therefore, other family members are not known to be at risk to have the malformation. However, 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. 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.

Signs and symptoms

Internal carotid agenesis does not always cause symptoms because the body uses other blood vessels (collateral pathways) to carry the 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). 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. 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%.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

30%-79% of people have these symptoms

• Cerebral ischemia(Disruption of blood oxygen supply to brain)
• Dilatation of the cerebral artery
• Subarachnoid hemorrhage

5%-29% of people have these symptoms

• Arachnoid cyst(Fluid-filled sac located in membrane surrounding brain or spinal cord)
• Headache(Headaches)

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). 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. 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.

Treatment

Internal carotid agenesis may not require any treatment if there are no symptoms. However, since the blood is rerouted through other smaller blood vessels to supply blood to the brain, these blood vessels may develop problems due to the extra blood flow. In some cases, surgery may be an option to relieve symptoms.

Due to the increased risk of aneurysms, many doctors recommend that a person with internal carotid agenesis be screened for the development of aneurysms. However, the condition is rare, it is not clear how often such screening should take place and if screening is actually helpful. If a brain aneurysm is observed, further monitoring or surgery may be necessary.

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. People with this malformation may be more likely to experience complications during certain types of surgery, so it is important for a person with internal carotid agenesis to tell all of their doctors, especially surgeons, about the diagnosis.In some cases, internal carotid agenesis may be associated with other diseases or syndromes.In these cases, the long-term outlook may depend on the associated syndrome or disease.

NIH genetic and rare disease info

• NIH info on Internal carotid agenesis

Internal carotid agenesis is a rare disease.

Internal carotid agenesis Resources
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