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

• Familial Hemiplegic Migraine 1 with Progressive Cerebellar Ataxia
• FHM1 (Familial Hemiplegic Migraine Type 1)

What is Familial Hemiplegic Migraine Type 1? (Definition/Background Information)

• Familial Hemiplegic Migraine Type 1 (FHM1) is a subtype of familial hemiplegic migraine that is characterized by migraine with aura observed along-with motor weaknesses during the episodic attacks. The signs and symptoms may also include headaches, nausea and vomiting, and visual disturbances
• There are four forms of familial hemiplegic migraine based on the involved gene. Familial Hemiplegic Migraine Type 1 is caused by mutation(s) in the CACNA1A gene. The condition is transmitted in an autosomal dominant manner. FHM1 is the most common type and accounts for over 50% of familial hemiplegic migraine cases
• The signs and symptoms of Familial Hemiplegic Migraine Type 1may 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 Familial Hemiplegic Migraine Type 1? (Age and Sex Distribution)

• Familial Hemiplegic Migraine Type 1 is a rare congenital disorder. The exact prevalence of this condition is not known
• The presentation of symptoms may occur between the ages of 5-30 years, with most cases being reported in teens and young adults
• Although both genders may get affected, females are more prone to familial hemiplegic migraine
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Familial Hemiplegic Migraine Type 1? (Predisposing Factors)

• A positive family history may be an important risk factor, since Familial Hemiplegic Migraine Type 1 (FHM1) can be inherited
• The episodes of FHM1 may be triggered by minor head trauma/injury

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 Familial Hemiplegic Migraine Type 1? (Etiology)

• Familial Hemiplegic Migraine Type 1 is caused by mutation(s) on the CACNA1A gene
• The condition is inherited in an autosomal dominant manner

Autosomal dominant: 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 Familial Hemiplegic Migraine Type 1?

The signs and symptoms of Familial Hemiplegic Migraine Type 1 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
• 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
• Dizziness
• Confusion and drowsiness
• Loss of memory
• Balance issues - vertigo

How is Familial Hemiplegic Migraine Type 1 Diagnosed?

Familial Hemiplegic Migraine Type 1 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) - a mutation on the CACNA1A gene is necessary to establish the diagnosis
• Differential diagnosis to rule out conditions which may present with similar signs and symptoms

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 Familial Hemiplegic Migraine Type 1?

The complications of Familial Hemiplegic Migraine Type 1 may include:

• Anxiety and depression
• Prolonged episodes of migraine
• Memory lapses
• Panic attacks
• Permanent neurological damage; cerebellar degeneration
• 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 Familial Hemiplegic Migraine Type 1 Treated?

The treatment of Familial Hemiplegic Migraine Type 1 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 Familial Hemiplegic Migraine Type 1 be Prevented?

Currently, Familial Hemiplegic Migraine Type 1 may not be preventable, since it is a genetic disorder.

• 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 Familial Hemiplegic Migraine Type 1? (Outcomes/Resolutions)

The prognosis of Familial Hemiplegic Migraine Type 1 is reported to be good.

Additional and Relevant Useful Information for Familial Hemiplegic Migraine Type 1:

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

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