Diencephalic syndrome

Summary

Diencephalic syndrome (DS) is an uncommon cause of failure to thrive in infants and young children. It is characterized by a complex series of signs and symptoms related to hypothalamic dysfunction. Its main features are emaciation, despite a normal or slightly diminished calorie intake, and an alert appearance. DS has been almost exclusively described in association with space-occupying lesions of the hypothalamic-optic chiasma region, mainly juvenile pilocytic astrocytoma. Hyperkinesia and euphoria may lead to delayed diagnosis of a tumor. The astrocytomas associated with DS are larger, occur at a younger age, and are often more aggressive than other astrocytomas arising in this region. Other features include hydrocephalus, nystagmus, visual field defects, optic pallor, emesis, and headache. A systematic diagnostic approach must be adopted, including contrast-enhanced magnetic resonance imaging (MRI) of the child's head, which often shows evidence of tumor dissemination. Treatment with aggressive surgery and/or radiotherapy is variably successful in controlling disease and may result in severe neurologic sequelae. Chemotherapy has recently been shown to be effective in patients with low grade gliomas of childhood, but it is used infrequently in those with DS. Treatment with a carboplatin and vincristine regimen may result in tumor shrinkage, allow demonstrable weight gain, and in some cases, significantly delay the need for alternative therapies.