Background: Magnetic resonance imaging (MRI) is the best technique for studying hypothalamic and hypophyseal structures.
Case reports: Four children aged 2 years 5 months to 8 years with idiopathic diabetes insipidus were studied. Their condition had been identified for 2-6 years. All the patients had undergone complete clinical, neurological and endocrinological investigations during the search for the cause of their diabetes insipidus. A CT scan was performed in one patient and MRI in all four; the investigations were repeated each 6 months for 4 years.
Results: The first examination showed complete lack of antidiuretic hormone (four patients) and growth hormone deficiency (two patients). An enlarged pituitary stalk was seen in three patients, one patient had a small anterior pituitary, and three patients gave no posterior pituitary hypersignal. Follow-up showed that three patients completely lacked of growth hormone. One was thyrotropin deficient, three had persistent enlarged pituitary stalks, three had sub-normal anterior pituitaries and all four patients produced no post-pituitary hypersignal. None of the patients developed signs of histiocytosis or germinoma.
Conclusion: The finding of abnormal pituitary stalks by MRI raises the possibility that the apparently idiopathic diabetes insipidus is due to some type of infiltrating disease of the hypothalamus and pituitary.