脳幹部にのみ画像所見を呈したRPLS（reversible posterior leukoencephalopathy syndrome）脳幹型variantの1例

A Case of Brainstem Variant of Reversible Posterior Leukoencephalopathy Syndrome

Ⅰ．はじめに

　Reversible posterior leukoencephalopathy syndrome（RPLS）は高血圧・子癇・腎不全・抗がん剤投与などが原因で，頭痛・嘔吐・意識障害・痙攣・視覚障害などの神経症状を来し，画像上，後頭葉領域を中心とした可逆性の皮質および皮質下の浮腫を呈する病態である．今回，われわれは画像上，脳幹部に限局した浮腫性変化を認めたRPLSの亜型（variant）と考えられる1例を経験したので，文献的考察を含めて報告する．

　A rare case of a brainstem variant of reversible posterior leukoencephalopathy syndrome (RPLS) is reported. A 34-year-old man with a past history of untreated chronic renal failure and hypertension was admitted to our hospital complaining of severe nuchal headache lasting for about four days. His neurological examination was normal, however physical examination revealed his blood pressure was 216/120mmHg. Computed tomography imaging (CT) showed his brain stem with a low attenuation. Magnetic resonance imaging (MRI) revealed extensive hyperintensity and enlargement of the midbrain and pons on T2 weighted and fluid attenuated inversion-recovery (FLAIR) image. However, there was no abnormal lesion seen in either bilateral occipital lobe. Diffusion-weighted image (DWI) was normal at the brainstem, but apparent diffusion coefficient (ADC) values were slightly elevated at the left midbrain. There was no contrast enhancement. His symptom and radiological finding improved soon after his blood pressure was controlled. A repeated MRI taken two weeks later showed complete resolution of the lesion.

　RPLS associated with predominant involvement of the brainstem and sparing of the supratentorial region is rare,but it should be differentiated from brain stem infarction,pontine glioma,central pontine myelinolysis and infective encephalitis,since the neulological consequences are potentially fully reversible after adequate and prompt treatment.