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Sporadic hemiplegic migraine
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Reviewed February 2014
What is sporadic hemiplegic migraine?
Sporadic hemiplegic migraine is a rare form of migraine headache. Migraines typically cause intense, throbbing pain in one area of the head. Some people with migraines also experience nausea, vomiting, and sensitivity to light and sound. These recurrent headaches typically begin in childhood or adolescence and can be triggered by certain foods, emotional stress, and minor head trauma. Each headache may last from a few hours to a few days.
In sporadic hemiplegic migraine and some other types of migraine, a pattern of neurological symptoms called an aura occurs before onset of the headache. An aura commonly includes temporary visual changes such as blind spots (scotomas), flashing lights, zig-zagging lines, and double vision. In people with sporadic hemiplegic migraine, auras are also characterized by temporary numbness or weakness, often affecting one side of the body (hemiparesis). Additional features of an aura can include difficulty with speech, confusion, and drowsiness. An aura typically develops gradually over a few minutes and lasts about an hour.
Some people with sporadic hemiplegic migraine experience unusually severe migraine episodes. These episodes can include fever, prolonged weakness, seizures, and coma. Although most people with sporadic hemiplegic migraine recover completely between episodes, neurological symptoms such as memory loss and problems with attention can last for weeks or months. Some affected individuals develop mild but permanent difficulty coordinating movements (ataxia), which may worsen with time, and rapid, involuntary eye movements called nystagmus. Mild to severe intellectual disability has been reported in some people with sporadic hemiplegic migraine.
How common is sporadic hemiplegic migraine?
The worldwide prevalence of sporadic hemiplegic migraine is unknown. Studies suggest that in Denmark about 1 in 10,000 people have hemiplegic migraine and that the condition occurs equally in families with multiple affected individuals (familial hemiplegic migraine) and in individuals with no family history of the condition (sporadic hemiplegic migraine).
Read more about familial hemiplegic migraine.
What genes are related to sporadic hemiplegic migraine?
Mutations in the ATP1A2 and CACNA1A genes have been found to cause sporadic hemiplegic migraine. The proteins produced from these genes transport charged atoms (ions) across cell membranes. The movement of these ions is critical for normal signaling between nerve cells (neurons) in the brain and other parts of the nervous system. Signaling between neurons relies on chemicals called neurotransmitters, which are released from one neuron and taken up by neighboring neurons. Mutations in the ATP1A2 and CACNA1A genes disrupt the transport of ions in neurons, which is thought to impair the normal release and uptake of certain neurotransmitters in the brain. The resulting abnormal signaling may lead to the severe headaches and auras characteristic of sporadic hemiplegic migraine.
Many people with sporadic hemiplegic migraine do not have a mutation in one of the known genes. Researchers believe that mutations in other genes are also involved in the condition, although these genes have not been identified.
There is little evidence that mutations in the CACNA1A and ATP1A2 genes play a role in common migraines, which affect millions of people each year. Researchers are searching for additional genetic changes that may underlie rare types of migraine, such as sporadic hemiplegic migraine, as well as the more common forms of migraine.
How do people inherit sporadic hemiplegic migraine?
Sporadic means that the condition occurs in individuals with no history of the disorder in their family. While most cases result from new (de novo) mutations that likely occur during early embryonic development, some affected individuals inherit the genetic change that causes the condition from an unaffected parent. (When some people with the mutation have no signs and symptoms of the disorder, the condition is said to have reduced penetrance.) Although family members of an affected individual do not have sporadic hemiplegic migraine, some experience migraine headaches without hemiparesis. A related condition, familial hemiplegic migraine, has signs and symptoms identical to those in sporadic hemiplegic migraine but occurs in multiple members of a family.
Where can I find information about diagnosis or management of sporadic hemiplegic migraine?
These resources address the diagnosis or management of sporadic hemiplegic migraine and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about sporadic hemiplegic migraine?
You may find the following resources about sporadic hemiplegic migraine helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for sporadic hemiplegic migraine?
What if I still have specific questions about sporadic hemiplegic migraine?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding sporadic hemiplegic migraine?
ataxia ; aura ; cell ; coma ; disability ; double vision ; embryonic ; familial ; family history ; fever ; hemiparesis ; hemiplegic ; inherit ; involuntary ; ions ; migraine ; mutation ; nervous system ; neurological ; neuron ; neurotransmitters ; nystagmus ; penetrance ; prevalence ; sensitivity ; sporadic ; stress ; trauma
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (7 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.