[A 43-year-old patient with character changes, recurrent impaired consciousness and retrograde amnesia]

A 43-year-old male patient with recurring impaired consciousness and retrograde amnesia was admitted to the department of neurology. During the neurological evaluation no pathological findings could initially be revealed but one day the patient was confused again and presented with inadequate behavior: at this time a blood glucose value of 40 mg/dl was measured. For further evaluation the patient was transferred to our department. As the reason for the impaired consciousness was suspected to be of neuroglucopenic origin a rapid adrenocorticotropic hormone (ACTH) stimulation test was first performed to rule out adrenal insufficiency. For further evaluation a fasting test was conducted: after 48 h an episode with neuroglucopenic symptoms occurred again which disappeared after intravenous administration of glucose. The laboratory results of glucose, insulin and c-peptide determined at this point in time led to the diagnosis of an insulinoma. By ultrasound examination a hypoechogenic lesion 1.5 cm in size could be shown in the head of the pancreas and was confirmed by magnetic resonance imaging (MRI). After duodenum-preserving partial pancreatic head resection with enucleation of the insulinoma no further neuroglucopenic symptoms occurred.