TIA様症状を契機に診断されたインスリノーマの１例

We report the case of a６７-year-old woman who had symptoms suggestive of a transient ischemic attack（TIA）, such as lightheadedness and transient visual changes before meals for ４ months. She experienced altered consciousness before lunch and was taken to the emergency room２weeks ago. She had repeated hypoglycemia with a blood glucose level of ３１ mg/dL. Insulin secretion was not suppressed, with an immunoreactive insulin level of １４．０ μU/mL and connecting peptide immunoreactivity of １．８３ ng/mL for occasional blood glucose levels of ４９ mg/dL. Dynamic CT revealed a １７‐mm mass enhanced during the arterial phase in the pancreatic uncinate process, suggestive of a pancreatic neuroendocrine tumor. A selective arterial secretagogue（calcium）injection test revealed the localization of insulinoma in the head of the pancreas. Therefore, pancreatoduodenectomy was performed. Hyperglycemia occurred after the surgery, and it was judged that the insulinoma was resected. This case showed TIA-like symptoms without signs of sympathetic overdrive associated with hypoglycemia. Thus, the diagnosis was delayed. Insulinoma may present with symptoms of neuroglycopenia but not autonomic activity due to hypoglycemia. Insulinoma should be distinguished in patients with unknown neurological symptoms since neuroglycopenia caused by insulinoma is diverse.