可逆性脳血管攣縮症候群（RCVS），可逆性後頭葉白質脳症（PRES）

Reversible Cerebral Vasoconstriction Syndrome（RCVS）and Posterior Reversible Encephalopathy Syndrome（PRES）

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・可逆性脳血管攣縮症候群（RCVS）と可逆性後頭葉白質脳症（PRES）は，若年性脳卒中の鑑別および原因として考慮すべき症候群である．

・両者は，顕著な高血圧，子癇，薬剤使用，自己免疫疾患などに関連して発症し，しばしば同一患者に合併することから，共通・類似の病態が推測されている．

・適切な早期診断のためには，両者の臨床像，画像所見およびその経時的変化の特徴を理解しておくことが肝要である．

　Reversible cerebral vasoconstriction syndrome（RCVS）is a clinical and radiological syndrome that is characterized by recurrent severe thunderclap headaches with or without other neurological symptoms and diffuse segmental constriction of cerebral arteries that usually resolves spontaneously within three months. Posterior reversible encephalopathy syndrome（PRES）is also a clinical and radiological syndrome characterized by headache, seizures, altered consciousness, cortical blindness, other focal neurological signs, and a diagnostic imaging picture of brain vasogenic edema. Both syndromes can occur in similar clinical contexts such as hypertension, pre-eclampsia/eclampsia, drug neurotoxicity, uremia, and some autoimmune diseases, and are frequently associated. Although the syndromes are usually fully reversible with early diagnosis and prompt treatment, some cases can develop hemorrhagic or ischemic brain lesions, often resulting in permanent disability. We need to be aware of the typical and atypical imaging manifestations of the syndromes to make an accurate diagnosis.