低血糖発作で発症した多発性内分泌腫瘍症候群Ⅰ型（MEN1）の1例

A Patient with Multiple Endocrine Neoplasia Type1（MEN1）Presenting with Hypoglycemic Attacks

Ⅰ．はじめに

　われわれ脳神経外科医は，救急の現場で意識障害を呈する患者を診療することが多い．ところが意識障害の原因が脳外科的なものではなく全身的な問題，たとえば低血糖発作，Adams-Stokes syndrome，低ナトリウム血症などであることも少なくない．今回，われわれは，食後に低血糖発作により意識障害を呈し，その後の精査にて膵インスリノーマが見つかった多発性内分泌腫瘍症候群Ⅰ型（multiple endocrine neoplasia type Ⅰ：MEN1）の1例を経験したので報告する．

　Here, we report the case of a woman with multiple endocrine neoplasia type 1（MEN1）who experienced hypoglycemic attacks. At the age of 59, she underwent parathyroid tumor resection for hyperparathyroidism. At the age of 65, she presented with dizziness at our hospital. Magnetic resonance imaging（MRI）revealed a left cerebellopontine（CP）angle tumor and a pituitary tumor. The CP angle tumor（acoustic neurionoma）was removed;the pituitary adenoma（prolactinoma）was managed by using bromocriptine. At the age of 77, she lost consciousness and was transferred to a local hospital. Her blood sugar level was 24mg/dL. Due to the frequent recurrence of hypoglycemic attacks, she was readmitted to our hospital. MRI revealed the almost complete removal of the acoustic tumor and that her pituitary gland was atrophied. Despite her baseline pituitary hormone levels being normal, we suspected panhypopituitarism and administered cortisol（15mg/day). As her hypoglycemia failed to improve, we performed a 75-g oral glucose tolerance test, and its result was not indicative of diabetes mellitus. Her pretest immunoreactive insulin（IRI）level was 6.8μU/mL;ΔIRI/ΔBS was 0.62, indicative of insulin hypersecretion. Contrast-enhanced abdominal computed tomography revealed multiple pancreatic tumors（insulinomas), and she underwent resection of the uncal tumor and pancreas body and tail. Her postoperative IRI level was normalized and she experienced no further hypoglycemic attacks. Based on her hyperparathyroidism, pancreatic tumor, and pituitary adenoma, we diagnosed her with MEN1.