Hemiplegic migraine.

Area of Science:

• Neurology
• Genetics

Background:

• Hemiplegic migraine (HM) is a rare migraine subtype characterized by transient motor weakness during the aura phase.
• Diagnosis follows the International Classification of Headache Disorders criteria (ICHD-3), emphasizing clinical interviews and neurological exams.

Approach:

• Diagnostic tools include patient interviews, neurological examinations during attacks, and excluding conditions like epilepsy, stroke, and encephalitis.
• Genetic testing can confirm diagnosis by identifying mutations in CACNA1A, ATP1A2, or SCN1A genes, though absence of mutation doesn't exclude HM.
• Brain imaging, CSF analysis, and EEG are primarily used to rule out other causes of focal neurological symptoms.

Key Points:

• Mutations in identified genes (CACNA1A, ATP1A2, SCN1A) are linked to increased neurotransmitter and potassium levels, facilitating cortical spreading depolarization, the mechanism behind migraine aura.
• Familial and sporadic forms of HM exist, with extensive weakness and brainstem signs increasing the likelihood of a monogenic cause.
• Patients without identified gene mutations often present with milder phenotypes, similar to common migraine.

Conclusions:

• Current treatment guidelines for HM are based on limited evidence due to the disorder's rarity.
• Further research is needed to establish evidence-based treatment protocols for hemiplegic migraine.