Familial or sporadic hemiplegic migraine

Hemiplegic migraine (HM) is a rare and severe subtype of migraine with aura characterized by episodes of temporary motor weakness or paralysis (hemiplegia) affecting one side of the body, accompanied by other aura symptoms such as visual disturbances, sensory changes, and speech difficulties. These episodes are followed by a typically severe, throbbing headache. The condition primarily affects the nervous system, specifically involving cortical spreading depression — a wave of neuronal and glial depolarization that spreads across the cerebral cortex. Episodes can be frightening, as symptoms may mimic a stroke, and in some cases can be accompanied by confusion, fever, prolonged weakness, seizures, or even coma. Hemiplegic migraine is classified into two main forms: familial hemiplegic migraine (FHM) and sporadic hemiplegic migraine (SHM). FHM is inherited in an autosomal dominant pattern and is associated with mutations in several genes, including CACNA1A (FHM1), ATP1A2 (FHM2), SCN1A (FHM3), and PRRT2 (FHM4). These genes encode ion channels or transporters critical for normal neuronal signaling. FHM1 caused by CACNA1A mutations is the most well-characterized form and may be associated with progressive cerebellar ataxia in some families. SHM presents with identical clinical features but occurs in individuals without a family history, potentially due to de novo mutations or multifactorial causes. Age of onset is typically in childhood or adolescence, though it can vary. There is currently no cure for hemiplegic migraine. Treatment focuses on managing acute attacks and preventing future episodes. Acute treatment may include analgesics, anti-nausea medications, and in some cases intranasal ketamine. Triptans and ergotamines are generally avoided due to theoretical concerns about vasoconstriction, though this remains debated. Preventive therapies may include verapamil, flunarizine, lamotrigine, valproate, or acetazolamide, particularly in FHM1 with cerebellar features. Management should be individualized and guided by a neurologist experienced in headache disorders.

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