Autosomal dominant compelling heliopthalmic outburst (ACHOO) syndrome is a genetic disorder that causes excessive sneezing. It is thought that this disorder is caused by sudden exposure to bright light. A patient with this condition generally experiences bouts of sneezing for a short period of time, but the number of sneezes can vary. Typically, a person who has this disorder sneezes 10 to 20 times in a row. There are several theories on why ACHOO occurs, but none have been proven.
In most cases, sneezing is caused by a mucus membrane irritation. Membranes can become agitated by things like pollution or pollens, which trigger a reaction. A sneeze is a reflex action that helps to remove the offending irritation. Occasionally, there is a need to sneeze more than once to remove it. The optic nerves can also trigger the same reaction.
It is thought that a patient suffering from ACHOO syndrome may have a hypersensitive reaction to direct, bright light. This does not have anything to do with irritated membranes, but it may be related to what occurs when a person sneezes. It is impossible to sneeze without closing the eyes, so this may be a way to protect them from the offending light. Sneezing may be an eye-protection mechanism.
Another theory suggests the brain may confuse bright light with a mucus membrane irritant. It is possible to have nasal allergies along with this syndrome, which might explain the connection. Many people who have ACHOO syndrome do not have problems with the nasal passages, however.
The ACHOO syndrome seems to be a genetic disorder, which means that it is hereditary. If a parent has this disorder, there is a 50-percent chance that one or more of the children will also eventually have it. Although this disorder is uncomfortable, it does not impact the quality of life and is not considered dangerous.
No medications are recommended for people suffering from ACHOO syndrome and no successful treatments are available. If a patient also suffers with nasal allergies, antihistamines can be taken, but they may not stop excessive sneezing brought on by bright light. Once a patient develops this disorder, it never goes completely away.