Familial Hemiplegic Migraine

ICDH 3 Beta 1.2.3.1 Familial hemiplegic migraine (FHM)

Description:

Migraine with aura including motor weakness, and at least one first- or second-degree relative has migraine aura including motor weakness.

Diagnostic criteria:

A. Fulfils criteria for 1.2.3 Hemiplegic migraine
B. At least one first- or second-degree relative has had attacks fulfilling criteria for 1.2.3 Hemiplegic migraine.

Comments:

New genetic data have allowed a more precise definition of 1.2.3.1 Familial hemiplegic migraine (FHM) than was possible previously. Specific genetic subtypes have been identified: in FHM1 there are mutations in the CACNA1A gene (coding for a calcium channel) on chromosome 19; in FHM2 there are mutations in the ATP1A2 gene (coding for a K/Na-ATPase) on chromosome 1; and in FHM3 there are mutations in the SCN1A gene (coding for a sodium channel) on chromosome 2. There may be other loci not yet identified. If genetic testing is done, the genetic subtype (if discovered) should be specified at the fifth digit.

It has been shown that 1.2.3.1 Familial hemiplegic migraine (FHM) very often presents with brainstem symptoms in addition to the typical aura symptoms, and that headache almost always occurs. Rarely, during FHM attacks, disturbances of consciousness (sometimes including coma), confusion, fever and CSF pleocytosis can occur.

1.2.3.1 Familial hemiplegic migraine (FHM) may be mistaken for epilepsy and (unsuccessfully) treated as such. FHM attacks can be triggered by (mild) head trauma. In approximately 50% of FHM families, chronic progressive cerebellar ataxia occurs independently of the migraine attacks.

Article from Genetics Home Reference

Familial hemiplegic migraine is a form of migraine headache that runs in families. Migraines usually cause intense, throbbing pain in one area of the head, often accompanied by nausea, vomiting, and extreme 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 some types of migraine, including familial hemiplegic migraine, a pattern of neurological symptoms called an aura precedes the headache. The most common symptoms associated with an aura are temporary visual changes such as blind spots (scotomas), flashing lights, zig-zagging lines, and double vision. In people with familial 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.

Unusually severe migraine episodes have been reported in some people with familial hemiplegic migraine. These episodes have included fever, seizures, prolonged weakness, coma, and, rarely, death. Although most people with familial hemiplegic migraine recover completely between episodes, neurological symptoms such as memory loss and problems with attention can last for weeks or months. About 20 percent of people with this condition develop mild but permanent difficulty coordinating movements (ataxia), which may worsen with time, and rapid, involuntary eye movements called nystagmus.

Article from Up to date

The hallmark of hemiplegic migraine is unilateral weakness that accompanies a migraine headache attack. The weakness is a manifestation of motor aura and occurs with other forms of aura that impair vision, speech, or sensation. This form of migraine with aura may occur either in families or only in one individual (sporadic).

This topic will review the pathophysiology, clinical features, diagnosis, and management of familial and sporadic hemiplegic migraine. Other aspects of migraine are discussed elsewhere.

Classification

The primary feature that separates hemiplegic migraine from other types of migraine with aura is the presence of motor weakness as a manifestation of aura in at least some attacks. Migraine auras most often manifest as visual disturbances, but can also involve sensory, verbal, and rarely motor disturbances. Thus, hemiplegic migraine is an uncommon subtype of migraine with aura.  Hemiplegic migraine may be familial or sporadic, as discussed in the following section.

Pathophysiology

The weakness that characterizes hemiplegic migraine is a manifestation of motor aura. The aura of hemiplegic migraine is most probably caused by cortical spreading depression, a self-propagating wave of neuronal and glial depolarization that spreads across the cerebral cortex