| [ Summary ] |
Pancreatic insulinoma is a rare functional islet cell tumor which induces autonomically excessive secretion of active insulin. The clinical symptoms of insulinoma are characterized by disturbance of both the central nervous system and the autonomic nervous system due to hypoglycemia. Manifestations include headache, restlessness, anxiety, tremor, nausea, tachycardia, disturbance of conciousness and other central nervous system symptoms. To make the earliest possible diagnosis of insulinoma, it is clinically important to detect the presence of both hyperinsulinism, by measuring immunoreactive insulin (IRI), and hypoglycemia. The ratio of IRI/blood glucose is recommended as a useful means for diagnosis of insulinoma. Previously, several stimulatory and inhibitory tests of insulin secretion have been employed. Recently, however, these tests have become unpopular clinically, because of severe hypoglycemic attacks during the tests. In addition, for biochemical analysis of the localization of insulinoma, the anatomical distribution of the blood insulin level can be determined by transhepatic portal venous sampling. For surgical management, it is of paramount importance to localize the insulinoma by using several new imaging techniques, including transcutaneous ultrasonography, computed tomography, magnetic resonance imaging and angiography. Furthermore, intraoperative ultrasound is helpful for detecting nonpalpable insulinomas. Surgical resection is the most effective treatment for insulinoma. Prompt diagnosis coupled with advances in preoperative and intraoperative localization techniques have resulted in an increased number of curative resections. |