Cogan syndrome is a rare autoimmune disease that affects the eyes and inner ears. Symptoms of the syndrome include irritation and pain in the eyes, decreased vision, hearing loss, and vertigo. Other symptoms may include joint or muscle pain or inflammation of the blood vessels.

The exact cause of Cogan syndrome is not well-understood. It is thought that the syndrome is caused by an autoimmune response that causes the immune system to attack the tissues of the eyes and ears. Cogan syndrome is not known to run in families. Diagnosis of Cogan syndrome is based on observing symptoms associated with the syndrome and ruling out other possible causes of the symptoms. Treatment options generally include corticosteroids and immunosuppressive agents.

Cogan syndrome can also affect the blood vessels. This can cause symptoms in other parts of the body including pain or cramping in the muscles (myalgia), fever, headache, diarrhea, and stomach pain. In some cases, people with Cogan syndrome may have a heart murmur or other heart problems.

Cogan syndrome is an autoimmune disease, which means that it occurs when the immune system begins to attack the tissues of the body. This is called an autoimmune response. Specifically, the immune systems of people with Cogan syndrome begin to attack the tissues of the eyes and the inner ears. In some cases, the autoimmune response may also be directed against blood vessels. The exact reason that people with Cogan syndrome have an autoimmune response against the tissues of the eyes and the inner ears is not well-understood. For some people, it may be that symptoms of Cogan syndrome begin after an infection.

Changes (mutations) in a specific gene are not known to cause Cogan syndrome. This means that Cogan syndrome is not thought to be passed directly from parent to child, and the syndrome is not thought to run in families. In general, family members of an individual with an autoimmune disease are thought to be at an increased risk to develop an autoimmune disease themselves. Although there are not reports of Cogan syndrome running in families, it is possible that family members of people with Cogan syndrome are at an increased risk to develop other autoimmune diseases.

If a diagnosis of Cogan syndrome is suspected, it is suggested that the affected individual see an ophthalmologist and otolaryngologist to determine if there are other symptoms consistent with Cogan syndrome.

The long-term outlook for people with Cogan syndrome also depends on the involvement of the blood vessels. If the blood vessels are affected by the autoimmune response associated with Cogan syndrome and the treatment is not effective, symptoms such as stomach pain or headaches may persist. Life-threatening complications of Cogan syndrome are rare, but may include an aneurysm of the aorta.