Hemiplegic migraine
General Description
Hemiplegic migraine is characterized by a headache that includes preceding hemiplegia, typically beginning in teenagers to early 20s. As individuals age, the frequency and severity of attacks often decrease. Women are more commonly affected than men.
Familial Hemiplegic Migraine
Hemiplegic migraine is divided into familial hemiplegic migraine (FHM) and sporadic hemiplegic migraine. Familial hemiplegic migraine follows an autosomal dominant inheritance pattern and is linked to mutations in three specific genes: CACNA1A, ATP1A2, and SCN1A. Notably, the CACNA1A gene is also associated with Spinocerebellar ataxia 6 (SCA6), which can lead to cerebral ataxia in approximately 20% of patients.
Cortical swelling
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CerebrumCerebral cortex
The characteristic imaging finding of hemiplegic migraine includes diffuse unilateral cortical swelling of the cerebrum, contralateral to the symptomatic side. This swelling is typically evident on T2WI and FLAIR sequences, where hyperintensity is demonstrated.
Hypoperfusion in aura
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Cerebrum
When hemiplegia occurs as a migraine aura, imaging typically reveals diffuse hypoperfusion in the cerebrum on the side contralateral to the symptomatic side. This decreased perfusion is an important diagnostic indicator during such episodes.
Hyperperfusion during headache
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Cerebrum
When headache occurs, imaging typically reveals diffuse hyperperfusion in the cerebrum on the side contralateral to the symptomatic side.
Enhanced venous delineation in SWI
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Vein
The reduced blood flow due to migraine attacks increases deoxyhemoglobin, which causes an increase in the magnetic susceptibility of venous blood, and SWI has a low signal in the surrounding millimeters, depending on the strength of the magnetic susceptibility (blooming effect). This may give the appearance of dilated cortical veins in SWI.