The Diencephalon

The hypothalamus represents the ventral-most portion of the diencephalon that surrounds the anterior inferior portion of the third ventricle. It functions primarily as an integrative mechanism for various autonomic and neuroendocrine activities. The number of higher functions in which the hypothalamus appears to be involved is increasing, and so are the therapeutic applications and methods by which this structure is being used as a target. The hypothalamus is subject to many different types of lesions, including developmental abnormalities, primary tumors of the central nervous system, systemic tumors affecting the brain, inflammatory and granulomatous diseases, and lesions arising from the surrounding structures. The hypothalamus may be the site of pathology primarily involving its context and for which surgery is required. This is generally complex surgery being the hypothalamus located in one of the deepest regions of the skull, making then surgical approaches varied and with high risks for the patient. The understanding of such anatomic nuances' aids in the selection of the most appropriate surgical approach and in the prevention of potential complications. Functional stereotactic neurosurgery of the hypothalamus is currently used for the treatment of cluster headaches and has recently been shown to have beneficial effects in the treatment of paroxysmal ophthalmic pain in multiple sclerosis patients, sleep disorders, thermoregulation, epilepsy, disruptive behavior, and it has also been shown to activate neural activity in cognitive and memory circuits in patients with mild Alzheimer's disease.