What are the other Names for this Condition? (Also known as/Synonyms)

• HM (Hemiplegic Migraine)

What is Hemiplegic Migraine? (Definition/Background Information)

• Hemiplegic Migraine (HM) is a rare type of “migraine with aura” observed with motor (muscle) weaknesses during the episodic attacks. The signs and symptoms may include visual changes, confusion, speaking difficulties, and loss of consciousness
• Hemiplegic Migraine develops from genetic mutations and are classified as:
  • Familial Hemiplegic Migraine (FHM) - the condition is inherited in an autosomal dominant manner and a positive family history of the condition is recognized
  • Sporadic Hemiplegic Migraine (SHM) - the condition develops spontaneously in the absence of any family history
• The signs and symptoms of Hemiplegic Migraine may be managed through suitable medications. Severe cases may result in complications including coma. The prognosis is generally assessed on a case-by-case manner, and can vary from one individual to another

Who gets Hemiplegic Migraine? (Age and Sex Distribution)

• Hemiplegic Migraine is a rare congenital disorder. The presentation of symptoms typically occurs in childhood
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Hemiplegic Migraine? (Predisposing Factors)

• A positive family history may be an important risk factor, since Hemiplegic Migraine can be an inherited condition
• Currently, no other risk factors have been clearly identified for this condition

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Hemiplegic Migraine? (Etiology)

Hemiplegic Migraine develop from gene mutations that are inherited from one’s parents or occurring sporadically (de novo).

• Familial Hemiplegic Migraine is transmitted in an autosomal dominant manner and may be caused by changes (mutations) in the CACNA1A, ATP1A2, SCN1A, and PRRT2 genes
  • The first three genes code for ion transporters, which are involved in moving charged atoms (ions) across cell membranes
  • The exact function of the PRRT2 gene is not yet understood but is also thought to play a part in controlling signals between neurons
• Sporadic Hemiplegic Migraine take place as a result of spontaneous mutation(s) in individuals with no known family history of the condition. In some cases, an involvement of the genes recognized for Familial Hemiplegic Migraine is noted
• Nevertheless, a family history of migraine with aura may or may not be present in the individual

It is believed that in addition to the four identified genes, there may be other as yet unidentified genes causing Hemiplegic Migraine.

Autosomal dominant inheritance: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition, or pass it on to their offspring.

What are the Signs and Symptoms of Hemiplegic Migraine?

The signs and symptoms of Hemiplegic Migraine may vary from one individual to another, and it may be mild or severe. In many, the presentations may last for a few hours to a few days (usually 72 hours or less) before a spontaneous resolution is noted. However, rarely, it may persist for several weeks.

In general, the following signs and symptoms may be observed:

• Headache
• Temporary focal motor deficit (muscle weakness) on one side of the body (hemiplegia) - this may result in movement disorder and clumsiness
• Episodic ataxia 
• Speech difficulties, especially when the right side of the body is affected
• Swallowing difficulties
• Nausea and vomiting
• Fever
• Visual changes or disturbances that may include flashing lights, sparkles, zigzag patterns, and blind spots
• Visual field defects
• Double vision; blurry vision
• Increased sensitivity to sound and light
• Numbness and loss of sensation that may involve a limb or the face
• Seizures
• Dizziness
• Confusion and drowsiness
• Loss of memory
• Balance issues - vertigo

How is Hemiplegic Migraine Diagnosed?

Hemiplegic Migraine is diagnosed on the basis of the following information:

• Complete physical examination and assessment of signs and symptoms
• Thorough analysis of personal and family medical history; identification of either a first degree or second degree relative with migraine attacks and meeting the diagnostic criteria for Hemiplegic Migraine is an important consideration
• Neurological examination by a qualified healthcare provider, if necessary
• Laboratory tests may be performed to rule out other causes of pain
• Computerized tomography (CT) scan of the head
• Magnetic resonance imaging (MRI) scan of the brain
• Molecular genetic testing to check for or confirm known causative gene mutation(s)
• Differential diagnosis to rule out conditions which may present with similar signs and symptoms

The criteria for diagnosis of Hemiplegic Migraine as outlined by the International Headache Society (IHS) is given below:

• Attacks fulfilling criteria for “migraine with aura” and the criterion below
• Aura consisting of both of the following:
  • Fully reversible motor weakness
  • Fully reversible visual, sensory and/or speech/language symptoms

(Source: International Headache Society Classification ICHD-3, London, United Kingdom)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Hemiplegic Migraine?

The complications of Hemiplegic Migraine may include:

• Risk of falls and injury due to seizures
• Anxiety and depression
• Attacks that are frequent and/or long lasting; prolonged weakness
• Permanent neurological damage; cerebellar atrophy
• Intellectual disability
• Paralysis of one side of the body
• Psychosis
• Impaired consciousness that may result in coma
• Reduced quality of life

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Hemiplegic Migraine Treated?

The treatment of Hemiplegic Migraine involves managing the signs and symptoms of the condition, which usually consists of the following measures:

• Administration of oral or intravenous medications such as acetazolamide, lamotrigine, verapamil, among others
• Nasal spray medications such as ketamine and triptans
• Symptomatic treatment with painkillers, antiemetics, and non-steroidal anti-inflammatory drugs (NSAIDs)
• Regular medical screening at periodic intervals with tests and physical examinations are recommended

It is important to check with the healthcare provider regarding the use and dosage of the medications (particularly triptans) prescribed.

How can Hemiplegic Migraine be Prevented?

Currently, Hemiplegic Migraine may not be preventable, since both the familial and sporadic forms develop from gene mutations. However, the following may be considered:

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• In individuals with long lasting and/or severe episodes of migraine, prophylactic treatment with amitriptyline, valproic acid, antiepileptic drugs, among others, to prevent a migraine from developing may be possible

Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders.

What is the Prognosis of Hemiplegic Migraine? (Outcomes/Resolutions)

In most cases, the prognosis of Hemiplegic Migraine is good with effective management of the signs and symptoms. The condition is generally known to improve with age.

• However, in rare cases, permanent neurological damage can result from frequent and prolonged episodes of Hemiplegic Migraine
• Typically, the prognosis may be specifically assessed on a case-by-case basis
• Severe and prolonged cases may have unfavorable prognoses

Additional and Relevant Useful Information for Hemiplegic Migraine:

It is important to note that witnessing a Hemiplegic Migraine attack can be difficult and a frightening experience in some cases. The caregiver should be educated about the condition and be made aware of the same.

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/