Familial hemiplegic migraine (FHM)

Familial Hemiplegic Migraine (FHM) is a rare and severe form of migraine that runs in families. It is characterized by weakness, often affecting one side of the body. However, the severity of this weakness can differ greatly, for instance only one hand or the whole side of the body can be affected.

Many patients also have other transient neurological complaints, called auras that gradually develop over time preceding headache such as:

  • temporary visual changes: blind spots, flashing lights and zig-zagging lines
  • temporary numbness or tingling in an arm, leg or the face
  • difficulty with speech; slurred speech, trouble remembering words
  • decreased consciousness  

FHM symptoms Familiaire Hemiplegische Migraine

Most often an aura starts with visual changes followed by the other aura symptoms. The duration of an aura differs greatly and it can be anything from several minutes to several days. The auras experienced by FHM patients can be distinguished from a stroke because they develop gradually during several minutes and often occur sequentially. During or after the aura the migraine headache starts. A migraine headache is severe, most often pulsating and one-sided. 


The severe (and sometimes long lasting) auras cause the most problems for hemiplegic migraine patents. Most often the attacks start during childhood and the attack frequency is most often between 2 and 3 attacks a year. Most often, the attacks become less frequent during life. If only one person in the family has hemiplegic migraine, the condition is called Sporadic Hemiplegic Migraine (SHM). In patients with SHM there can also be a mutation in one of the known FHM genes.   

FHM/SHM treatment

Currently, there is no treatment to cure FHM/SHM. However, there is medication available to decrease the frequency of attacks and to treat the pain during a headache attack.