懸濁性ステロイド剤を用いた頸部神経根ブロックにより小脳・脳幹部梗塞をきたした1例 Brainstem and cerebellar infarction following cervical root block using a corticosteroid suspension Depo-Medrol^【○!R】

頸部神経根ブロックに使用した懸濁性メチルプレドニゾロンによると思われる小脳・脳幹部梗塞を経験した．症例，57歳女性．頸椎椎間板ヘルニアによるC6，C7の根性痛が増強したため，近医より神経根ブロック目的で当科に紹介された．X線透視下で神経根ブロックを試み，造影剤にて血管陰影を認めずC6神経根鞘が描出されたため，0.75％ロピバカイン1 mlと懸濁性メチルプレドニゾロン1 mlの混合液を1 ml注入したが異常なく，さらに0.5 ml注入した30秒後に意識が消失し，呼吸も停止した．7時間後のMRIで小脳・脳幹部梗塞と切迫ヘルニアがあったため，内・外減圧術および脳室ドレナージが施行された．術中所見と術後CTから解離性動脈瘤は否定された．本症例では，懸濁性メチルプレドニゾロンが神経根動脈を介して左椎骨動脈領域へ逆行性に流入した結果の合併症と考えられた．頸部神経根ブロックに懸濁性ステロイド剤を使用することは避けるべきであると考えられる．

We observed a case of brainstem and cerebellar infarction that was thought to have been caused by methylpredonisolone suspension (Depo-Medrol®) used for cervical nerve block. The patient was a 57-year-old women. She was referred from a local clinic to our department for nerve root block due to increased radicular pain at the C6/C7 level caused by cervical intervertebral disk hernia (C5/6, C6/7). We attempted nerve root block under X-ray visualization. Since no vascular shadow was shown by contrast medium and the C6 nerve root sheath was depicted, 1 ml of a mixed solution of 0.75% ropivacaine plus 1 ml of methylprednisolone suspension (40 mg/ml) was injected. No abnormality was noted, and a further 0.5 ml was injected. However, within 30 seconds the patient lost consciousness and stopped breathing. Since magnetic resonance imaging performed 7 hours later showed an infarct of the cerebellum and brainstem and impending herniation, external and internal decompression and ventricular drainage were performed. Intraoperative findings and postoperative CT findings ruled out the possibility of a dissecting aneurysm. The infarct was thought to have been caused by complications arising from retrograde flow of the methylprednisolone suspension from the radicular artery into the left vertebral artery area. Therefore we think that corticosteroid suspensions should not be used for cervical nerve root block.