I. Structure and function of the hypothalamus The hypothalamus is located at the bottom of the brain and is a structure with integrated functions in the brain. The hypothalamus extends from the front from the optic cross backward to the papillae. In adults, the hypothalamus weighs less than 2.5 grams. In the median sagittal position, its anterior border is the end plate, the posterior border is the flat plate between the posterior commissure and the caudal part of the papillae, the superior border is the hypothalamic sulcus, and the hypothalamus forms the bottom wall of the three ventricles, below which is the gray node, the boundaries of which are not well defined on both sides and can be roughly bounded by the internal capsule, the cerebral peduncle and the basal thalamus. The hypothalamus can be divided longitudinally into two bands, the dense medial band of cells and the relatively less cellular lateral band, which is delimited by the anterior column of the fornix. Most of the hypothalamic nuclei are in the medial band. In addition, the hypothalamus can be divided into four zones from the anterior-posterior direction. The preoptic area runs from the optic cross on the mouth side to the anterior union on the dorsal side, the supraoptic area is above the optic cross, the nodal area is located in and above the gray nodes, and the papillary area includes the papillary bodies and the posterior hypothalamic nuclei. Through a large number of connections of efferent and afferent fibers, the hypothalamus combines autonomic, somatic, endocrine, and behavioral activities. It receives afferent fibers and projects these fibers to a wide range of the forebrain, brainstem and spinal cord. In addition, the hypothalamus is involved in the regulation of emotions. Clinical manifestations The clinical symptoms of hypothalamic malformations are related to the physiological functions of the hypothalamus and its surrounding structures themselves. In addition to the typical demented laughter episodes, patients may develop other forms of episodes as they age. Other concomitant symptoms include central precocious puberty, behavioral disturbances, and progressive cognitive decline. Demented laughter seizures are a typical form of seizures in hypothalamic malformation tumors that begin in childhood, or in some cases in the neonatal period, and progress to become “catastrophic” epilepsy that is difficult to control with medication. The typical presentation of demented laughter seizures is repetitive and explosive laughter, often unrelated to emotion. In addition to seizure laughter, other forms of seizures are often present and are often more disabling. Multiple seizure forms are present in most patients, such as generalized tonic clonic seizures, complex partial seizures, drop seizures and atypical disorientation. In addition, pediatric patients are more likely to have cognitive and behavioral impairments than adult patients. 2. Behavioral and cognitive dysfunction Persistent demented laughter seizures in patients with hypothalamic malformations can lead to severe epileptic encephalopathy and childhood catastrophic epilepsy, and are often combined with behavioral disturbances such as reported ADHD, anger and aggressive behaviors are often present. In addition to aggressive behavior, slowly progressive cognitive decompensation is often seen in patients with hypothalamic malformation tumors with demented laughter seizures. Exacerbation of behavioral and cognitive dysfunction often parallels the exacerbation of epilepsy. 3. Psychiatric symptoms A high percentage of patients with hypothalamic malformation tumors have combined psychiatric disorders. Pediatric patients presenting with demented seizures have a higher prevalence of psychiatric disorders, such as obsessive-compulsive disorder (83.3%), ADHD (75%), conduct disorder (33.3%), and affective disorder (16.7%). 4. Central precocious puberty and other endocrine abnormalities The relationship between hypothalamic malformation tumors and central precocious puberty is well established. Hypothalamic malformation tumors with a tibial connection below the three ventricles often do not manifest as epilepsy, especially in girls before 8 years of age and in boys before 9 years of age who often show precocious puberty. Central precocious puberty occurs significantly earlier than primary precocious puberty. Central precocious puberty was reported in 82% of the earliest reported group of patients with hypothalamic malformation tumors younger than 2 years of age.