Surgical implications of the thickened pituitary stalk accompanied by central diabetes insipidus.

OBJECT: The authors discuss the indications for and timing of a diagnostic neurosurgical procedure in children with diabetes insipidus (DI) and a thickened pituitary stalk (TPS) on magnetic resonance (MR) imaging.

METHODS: Seven children with a TPS who presented with DI eventually underwent surgery for diagnostic purposes. The ages at onset of DI were 6 to 16 years, and the follow-up period until surgery was 26.9 +/- 11.9 months. In four of seven children, the stalk appeared normal on the first MR image, but it was thickened and variably enhancing on later images in all instances. The reason for eventual surgery was endocrinological deterioration in two of seven children, radiological progression in two children, and a combination of the two in three children. Three children experienced visual disturbances and four children had optic nerve, chiasma, or hypothalamus involvement. All children suffered additional endocrinological abnormalities pursuant to the initial DI. A definitive diagnosis was achieved in six of seven children: germinomas in five and Langerhans cell histiocytosis in one. One child had lymphocytic infiltrate. None of the children deteriorated neurologically or endocrinologically after the operation. On follow up, vision deficit was irreversible in all children who demonstrated visual abnormalities before treatment.

CONCLUSIONS: Surgery should be performed in children with a TPS and DI for early diagnosis and disease-oriented therapy when there is further endocrinological, radiological, or clinical deterioration. The complication rate is low in open biopsies, and histological diagnosis is achieved in most of the cases. All children who present with central DI must undergo head MR imaging, and even if results are normal, close radiological and clinical follow up is mandatory.