血液透析導入時に Wernicke 脳症を合併した1例 A case of Wernicke's encephalopathy associated with the introduction of hemodialysis

患者は74歳女性で，慢性腎不全にて保存的加療を行っていた．原疾患は腎硬化症が考えられていた．平成19年10月より吐気，食思不振を訴え，尿素窒素（BUN）64.1mg/dL，クレアチニン（Cr）5.14 mg/dL，重炭酸濃度（HCO3-）13.2 mmol/Lと腎不全の悪化を認めたため10月23日より入院となった．上部消化管内視鏡は慢性胃炎の所見であった．第3病日にはBUN 80.4mg/dL，Cr 6.38mg/dLと腎不全が進行し，尿毒症を考え第4病日より血液透析を開始した．しかし，その後も吐気が持続し，眼の焦点が合わない，頭がぼやけるなどの訴えが出現した．徐々に傾眠傾向となったため，第8病日に頭部MRIを撮影した．中脳水道周囲，乳頭体，視床内側に拡散強調像，T2強調像，fluid-attenuated inversion recovery（FLAIR）にて高信号域を認め，Wernicke脳症が疑われた．同日よりフルスルチアミンの投与を行ったところ意識レベルは速やかに改善した．後にビタミンB1は14（正常20〜50）ng/mLと低値であったことが分かった．維持血液透析，リハビリを続け，第57病日にリハビリ目的にて他病院に転院となった．食事療法，尿毒症による栄養摂取不良と血液透析による水溶性ビタミンの喪失がWernicke脳症の原因と考えられた．

The patient was a 74-year-old woman with chronic renal failure being treated conservatively. The cause of renal failure might be renal sclerosis. She had complained of nausea and anorexia since October 2007. She was admitted to Handa City Hospital due to the progression of renal failure on October 23, 2007. On admission, serum levels of blood urea nitorogen (BUN), creatinine (Cr), and bicarbonate (HCO3-) were 64.1mg/dL, 5.14mg/dL, and 13.2mmol/L, respectively. There was no abdominal pain and no signs of severe lesion on abdominal ultrasonograph. Only chronic gastritis was detected in the endoscopy. Her serum levels of BUN and Cr were elevated to 80.4mg/dL and 6.38mg/dL on the third day after admission. Hemodialysis was started for uremia on the fourth day. However, her complaint did not improve and poor sight and unclearness appeared. Consciousness gradually became somnolent, so magnetic resonance imaging (MRI) of the brain was performed on the 8th day. T2, FLAIR, and diffusion-weighted MRI showed high-signal-intensity areas in the periaqueduct, over the mamillary bodies, and inside the thalamus, which was a characteristic finding of Wernickes encephalopathy. Thiamine treatment was immediately initiated, and consciousness promptly improved. Later, a low plasma thiamine level of 14ng/mL (normal range 20-50 ng/mL) was demonstrated. She was treated with regular hemodialysis and rehabilitation, then transferred to another hospital for rehabilitation on the 57th day. The cause of Wernickes encephalopathy was considered to be in adequate nutrition due to diet therapy and uremia, coupled with the loss of water-soluble vitamins during the dialysis procedure.