[Diencephalic syndrome: An uncommon cause of malnutrition].
Diencephalic syndrome (DS) is a complex of signs and symptoms related to hypothalamic dysfunction. Its main features are emaciation despite normal energy intake and an alert appearance. This syndrome has been described in association with space-occupying lesions of the hypothalamic-optic chiasm region, mainly low-grade glioma, and less often with tumors in the proximity of the IV ventricle. Two patients with DS are reported. The first patient was an 8-month old boy with classical features of DS. Extensive investigation of malabsorption revealed no abnormalities and the first neurologic sign was a rotatory nystagmus. Magnetic resonance imaging (MRI) showed evidence of a hypothalamic tumor, which was identified after surgical resection as a pilocytic astrocytoma. The second patient was an adolescent boy who presented a 20-kg weight loss over a 6-month period and psychological disturbances. Gastrointestinal disease was ruled out as a cause of malnutrition. Because of a polydipsia-polyuria syndrome, manifest while the patient was hospitalized with a suspected diagnosis of anorexia nervosa, MRI of the brain was performed. Multiple intracranial lesions were revealed, mainly in the hypothalamus, and were identified as a disseminated disgerminoma. No neurologic signs or symptoms were present. The patients died 2 years and 1 year after diagnosis, respectively. Although DS is rare, it should be considered in severe failure to thrive or emaciation despite adequate food intake and normal absorptive function of the small bowel.