Hemiplegic migraine is an unusual variant of migraine. Persons with this form of migraine have headaches associated with the loss of motor strength on one side of the body. A migraine is a recurrent throbbing headache. Typically, the pain only affects one side of the head. While classic migraine is often accompanied by nausea and disturbed vision, with a hemiplegic migraine, the person may also have speech difficulties or confusion in addition to the unilateral weakness.
The diagnosis of familial hemiplegic migraine (FHM) requires the diagnosis of HM in two or more persons from the same family. Approximately half of the cases of hemiplegic migraine will have family members that have been identified as having the disorder. Those who present with symptoms of hemiplegic migraine but without a known familial connection are said to have sporadic hemiplegic migraine (SHM). Although the cause of SHM is unknown, it is probably the result of spontaneous gene mutations.
Because of the association with neurologic symptoms with either FHM or SHM, it is imperative to exclude other causes that may need treatment. Persons with a transient ischemic attack (TIA) present with stroke-like symptoms that last less than 24 hours. Like FHM or SHM, there is usually a unilateral weakness that may be associated with visual or speech disturbances.
TIAs may be secondary to carotid disease that can be excluded using carotid ultrasound to look for atherosclerotic disease. Electrocardiogram (EKG) and EKG rhythm monitoring may identify an irregular heart beating that may allow clots to form that can embolize to the brain causing neurologic symptoms. Echocardiography or ultrasonography of the heart can examine for prior cardiac muscle damage, as from a heart attack, that may allow clot to adhere to the muscle wall and be dislodged resulting in brain embolism. Sometimes, the neurologic findings can persist even up to or greater than 24 hours. In this setting, computerized tomography (CT scan) of the brain can exclude cerebral stroke or hemorrhage.
In the presence of symptoms directing at hemiplegic migraine, it is important to exclude other neurologic diseases. The SHM and FHM diagnoses are then based on an evaluation of the patients’ symptoms combined with a full family history. Genetic testing is now available for persons with hemiplegic migraine. If a person has a family member with hemiplegic migraine, or if testing is positive for the presence of genetic defects that have been linked to HM, the person is said to have the familial form of the disease. It would be imperative to pass that information on to family members.
The first goal of treatment is to confirm the diagnosis by excluding other causes of the neurologic symptoms. Although there is disagreement about the safety and effectiveness of the usual migraine medications, they are frequently used in the treatment of FHM and SHM.
Treatment for FHM and SHM is not standardized. Some doctors use triptans (serotonin receptor agonists) as the drug of choice to treat hemiplegic migraines. Other medications may be employed to treat and prevent migraine attacks. Medication using an anticonvulsant or a calcium channel blocker may reduce the frequency of migraine attacks. Calcium channel blockers improve blood flow. Two drugs from this category, Verapamil and Flunarizine, are used frequently in the treatment of hemiplegic migraine.
For many people, migraine headaches will go into remission and sometimes they will stop completely. However, the symptoms may be very severe. Up to 90% of persons are unable to function normally on the day of the migraine attack. More than 80% will have abnormal sensitivity to noise and light. Up to 30% will need bed rest for a period after the acute attack. Migraine is a chronic disorder, but with treatment the number and severity of attacks may be reduced. Many physicians use traditional therapies for migraines. For FHM and SHM, calcium channel blockers may be useful in particular.
The nervous system consists of the brain and the spinal cord (the central nervous system) and the nerves outside the spinal cord (the peripheral nervous system). Communication within the nervous system is carried out by the use of signals (electrical and chemical) that allow passage of these impulses from one nerve cell to the next. As the impulse arrives at the end of the nerve, it signals a gate to open releasing chemical messengers to tell the next nerve cell or muscle cell how to act. These chemicals that signal the next nerve cell are called neurotransmitters.
In the case of migraine, the neurotransmitters are released abnormally, signalling the next nerve cell or muscle in error. Researchers have identified three genes (CACNA1A, ATP1A2, and SCN1A) that when defective are associated with hemiplegic migraine. Mutations of these three genes result in the inability to make a specific protein needed for the communication between nerve cells. Thus, the neurons have trouble either releasing or binding up neurotransmitters causing the nerves to conduct in an abnormal manner. Typically, persons with familial hemiplegic migraine (FHM) have inherited the mutated gene from a single parent who was also symptomatic. The aberrant genes for FHM are found on chromosomes designated as 1 and 19. With the genetic mutations, the calcium channel doesn’t open or close properly. This inability to regulate calcium results in the neurons firing rapidly .
Effectiveness of calcium channel blockers has been found sometimes in preventing symptoms caused by FHM. A significant familial risk factor for migraine has long been apparent. This has been demonstrated in twin studies where the association for migraine in monozygotic twins is greater than that for dizygotic twins . Persons without any family history are said to have the sporadic form of the disease. Sporadic hemiplegic migraine is associated with mutations in some genes (ATP1A2 and CACNA1A). Protein products of these genes transport charged ions across cellular membranes. The transport of these ions has a critical role in the conduction of message between nerve cells in the brain and the rest of the nervous system.
The prevalence of sporadic hemiplegic migraine worldwide is not known. In Denmark, 1 in 10,000 people are estimated to have hemiplegic migraine. In case of FHM, the condition appears to be prevalent in about 50% of family members having a parent suffering from this disease. For sporadic hemiplegic migraine there is no family history for the condition.
Hemiplegic migraine typically progresses through the same stages of symptoms as in other migraine headaches. Persons initially have a prodrome phase with malaise occurring hours before the onset of migraine event. Immediately before the migraine, persons describe an aura. With the hemiplegic variant, persons still describe severe headaches that may last for up to 72 hours if left untreated. In addition, persons have a one-sided paralysis or paresis with sever weakness. After the acute phase, persons move into the resolution phase and may have symptoms that have been described as a migraine hangover.
It is now apparent that genetic disorders account for hemiplegic migraine. Four different missense mutations have been identified in the α1A subunit of the P/Q-type on chromosome 19 that are deemed responsible for familial hemiplegic migraine (FHM) in some families . This mutation results in a faulty calcium channel mediated transmission of the electrical signal from neuron to neuron or muscle cell. FHM has an autosomal dominant inheritance. In addition, defects in chromosome 19 have been identified in some families with typical migraine  .
De Fusco et al. have shown that the gene that codes for the alpha2 subunit of the Na+/K+ pump (ATP1A2), is associated with familial hemiplegic migraine type 2 (FHM2). It is linked to chromosome 1q23 . This gene mutation results in a loss of function of a single allele of ATP1.
There is disagreement regarding the treatment of hemiplegic migraines. Doctors use both triptans (serotonin receptor agonists), anticonvulsants, and calcium channel blockers to interrupt acute migraines and prevent future attacks. Verapamil and Flunarizine are both used to treat hemiplegic migraine.
Hemiplegic migraine is a migraine variant that includes neurologic symptoms (one-sided weakness or paralysis) that may mimic a transient ischemic attack (TIA) or stroke symptoms that completely resolve within 24 hours. It is a rare condition which is frequently linked to an underlying genetic abnormality. It has been diagnosed more frequently in the U.K. Symptoms are typical for migraine with the addition that temporary paralysis, hemiplegia, is associated with the debilitating headache. Two categories of the disease have been described. Familial hemiplegic migraine (FHM) is associated with a strong family history and involves defects in at least three different genes. About 50% of children born to a parent with FHM will develop this disorder. Sporadic hemiplegic migraine (SHM) is diagnosed when all symptoms of hemiplegic migraine are present without a family link to the disease. It is believed that this variant of the disease is caused by some ‘sporadic’ gene mutations.
Hemiplegic migraine is an important variant of migraine disorder. This migraine presents like other migraines with well-known stages.
Because of the association of neurologic symptoms with the headaches, it is important to seek medical attention to exclude other causes of the one-sided weakness, such as a stroke. Testing may include imaging studies of the brain, heart, and neck arteries. The diagnosis of familial hemiplegic migraine (FHM) depends on the observation of two or more people in the same family with one-sided weakness associated with migraine headache. Approximately one-half of the cases of hemiplegic migraine will have family members that have been diagnosed with the disorder.