Loss of pons-to-hypothalamic white matter tracks in brainstem obesity.

Hyperphagia and obesity have been reported following damage to the hypothalamus in humans. Other brain sites are also postulated to be involved in the control of food intake and body weight regulation, such as the amygdala and brainstem. The brainstem, however, is thought to primarily integrate short-term meal-related signals but not affect long-term alterations in body weight, which is controlled by higher centers. The objective of this study was to identify structural pathways damaged in a patient with a brainstem cavernoma who experienced sudden onset of hyperphagia and >50 kg weight gain in <1 year following surgical drainage via a midline suboccipital craniotomy. Diffusion tensor imaging revealed loss of nerve fiber connections between her brainstem, hypothalamus and higher brain centers with preservation of motor tracks. Imaging and endocrine testing confirmed normal hypothalamic structure and function. Gastric bypass surgery restored normal appetite and body weight to baseline. This is the first report of 'brainstem obesity' and adds to the brain regions that can determine the long-term body weight set point in humans.

Disseminated pilocytic astrocytoma involving brain stem and diencephalon: a history of atypical eating disorder and diagnostic delay.

The association of weight loss and pediatric brain tumors that affect the diencephalon or brain stem with weight loss is a recognized, but not fully understood phenomenon. Tumors located in the hypothalamic region may induce the diencephalic syndrome (DS), which is characterized by profound emaciation with almost complete loss of subcutaneous fatty tissue. Tumors that compress or infiltrate the brain stem rarely cause both psychological disturbance and emaciation. The clinical presentation may be different, depending on the location of the lesion and age of the patient. In this report we present an unusual case of severe emaciation in a 4(9)/(12)-year-old girl with a juvenile pilocytic astrocytoma of the hypothalamic region and brain stem with neuroaxis dissemination. This case illustrates the importance of considering intracranial mass-lesions in the differential diagnosis of weight loss, psychological disturbance and atypical eating disorder. We discuss the importance of tumor multifocality and the role of patient age in the clinical presentation with reference to the literature.