What is Familial Hemiplegic Migraine? 2023
One of the worse things a Migraine headache can do to a person besides giving them a terrible one-sided headache along with nausea, vomiting, sensitivity to light and sound, and the need to be down, would be to cause paralysis on one side, to cause a hemiplegia.
Migraine can do that, but only in boys born with the Familial Hemiplegic Migraine gene. It is very rare.
This is an article by Britt Talley Daniel MD, member of the American Academy of Neurology, migraine textbook author, podcaster, YouTube video producer, and blogger.
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This is what the International Classification of Headache Disorder states for: 1.2.3.1 Familial hemiplegic migraine (FHM)
Description:
FHM is Migraine with aura including motor weakness, and at least one first- or second-degree relative who has migraine aura including motor weakness.
How is a diagnosis of FHM made?
Diagnosis of FHM is made according to these criteria:
Two attacks of each of:
Aura with motor weakness accompanied by either reversible visual symptoms (flickering lights, spots, lines, etc.), reversible sensory symptoms (pins and needles, numbness, etc.) or speech symptoms
At least two occurrences of:
One or more aura symptoms that develop over at least 5 minutes
These symptoms lasting more than 5 minutes and less than 24 hours
Headache beginning within 60 minutes of aura onset: These headaches can last 4–72 hours, occur on only one side of the head, pulsate, be of moderate to severe intensity, and may be aggravated by common physical activities such as walking. These headaches must also be accompanied by nausea and vomiting, photophobia, and or phonophobia.
At least one close (first- or second-degree) relative with FHM
No other likely cause
Sporadic forms follow the same diagnostic criteria, with the exception of family history.
Related Questions.
What are the genes that come with Familial Hemiplegic Migraine?
There are 3 kinds of Familial Hemiplegic Migraine, each with different genes involved.
FHM1 has mutations in the CACNA1A gene on chromosome 19.
FHM2 has mutations in the ATP1A2 gene on chromosome 1.
FHM3 has mutations in the SCN1A gene on chromosome 2.
There may be other loci which are not yet identified.
What type of inheritance is associated with FHM?
FHM is generally an autosomal dominant type of inheritance, although some cases have had a sporadic inheritance. Autosomal dominant inheritance means that one-half of children have a chance of getting the genetic make up for FHM.
What triggers an attack?
Mild head trauma sets of an attack in 50% of FHM families.
Is an attack of FHM associated with other neurologic problems?
An attack of FHM comes with brainstem involvement along with typical Migraine with aura symptoms.
An attack of FHM may be confused with epilepsy and treated as such, although anticonvulsant treatment doesn’t help.
Disturbed consciousness, coma, confusion, fever, and CSF pleocytosis may occur with FHM.
Problems with attention and memory may last months after an attack.
Some cases develop delayed cerebral edema, a serious neurologic problem, after minor head injury.
There may be an overlap of other neurologic conditions with FHM, including episodic ataxia type 2, spinocerebellar ataxia, benign familial infantile epilepsy, and alternating hemiplegia of childhood.
An attack of Migraine with aura and numbness on one side of the body is commonly confused with hemiplegic migraine. Often times persons affected with Migraine with aura can’t differentiate between numbness and weakness. With fear they go to the ER thinking they have had a stroke.
Read “Migraine with Aura” on my website, www.doctormigraine.com
Are there any long term results after attacks of FHM?
20% of patients may develop ataxia which involves trouble coordinating limbs or falling while walking.
Some patients with chronic attacks develop nystagmus, a rapid, vibrating, eye movement problem.
What in the brain causes the one-sided motor weakness? That is what is the Pathophysiology?
Like the typical aura of Migraine with aura which causes visual attacks, numbness, and trouble talking, the motor paralysis is thought to be due to cortical spreading depression.
This is an electric short out of the brain that moves slowly across the cortical surface, causing the symptoms mentioned. It cause depolarization and then it resets. Cortical spreading depression is a self-propagating wave of neuronal and glial depolarization that spreads across the cerebral cortex.
What is the result of Neurologic work up for FMH
EEG testing may show slowing in the brain on the side opposite the hemiplegia present during the attack which then clears later.
MRI scanning may be normal, depending on the timing of the scan in relation to the onset of symptoms. Some scans show cerebral edema with cortical enhancement and T1 gadolinium enhancement which goes away on rescanning.
Brain MRI
T2 fluid-attenuated inversion recovery (FLAIR) MRI sequence on coronal plane (A) shows cortical swelling involving the right temporoparietal occipital regions with subtle high signal intensity (arrow). The cortical swelling exhibits gyriform enhancement on T1 postgadolinium sequence (B). Follow-up MRI on T2 FLAIR sequence on coronal (C) and T1 postgadolinium sequence on axial plane (D) shows complete resolution of cortical swelling and enhancement.
What is the differential diagnosis of FHM?
Other neurologic considerations could be:
Migraine stroke or infarct
CADASIL-Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy
Cerebellar degeneration
Is it possible to genetically screen for FHM?
Prenatal screening is not done but it may be done for a younger child because penetrance is high.
What is management of FHM?
Persons with FHM should avoid minor head trauma and all contact sports.
Ergotamine or Triptans for acute Migraine treatment should be avoided.
Acetazolamide has some effect along with minor analgesics such as NSAIDS, caffeine, ibuprofen, and naproxen.
What is the epidemiology of FHM?
Migraine occurs in 15-20% of the population, while FHM occurs less often, at 0.01%.
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All the best.
Britt Talley Daniel MD