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Anatomy of the head and neck
Published in Helen Whitwell, Christopher Milroy, Daniel du Plessis, Forensic Neuropathology, 2021
Inferiorly, the diencephalon is related to the midline optic chiasma, caudal to which is a small midline elevation called the tuber cinereum. From its apex extends the infundibulum or pituitary stalk, which attaches to the pituitary gland. Further caudal to the tuber cinereum, a pair of rounded eminences, the mamillary bodies, is located on either side of the midline. These contain the mamillary nuclei of the hypothalamus.
Distribution and Characteristics of Brain Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
The hypothalamus is located below the thalamus and above the pituitary gland (Figure 3.8). It is situated in the ventral diencephalon and is composed of many fiber tracts and discrete nuclei that are positioned symmetrically around the third ventricle. In midsagittal section, the human hypothalamus is bound anteriorly by the lamina terminalis, posteriorly by the posterior commissure at the caudal limit of the mammillary body, and superiorly by the hypothalamic sulcus. The lateral boundaries on each side of the hypothalamus include the internal capsule, cerebral peduncle, and subthalamus. Ventrally, the hypothalamus forms the floor of the third ventricle. Its inferior surface, called the tuber cinereum, contains the median eminence, one of seven circumventricular areas of the brain that have permeable capillaries and are not protected by the BBB.
The Pituitary Gland Eva Nagy
Published in Istvan Berczi, Pituitary Function and Immunity, 2019
Several decades ago, transplantation studies indicated that hypophyseal function is dependent on hypothalamic influences.12–13 The pituitary removed from direct contact with median eminence loses the capacity to synthesize and release most of its hormones. Based on this evidence, Green and Harris14 postulated that neurohormonal substances might originate in the median eminence of the tuber cinereum and thus, regulate secretion of anterior pituitary hormones. Subsequent work by Schally and coworkers15,16 and by Guillemin and Peterson17,18 and by others led to the detection of a number of hypothalamic factors controlling the release of pituitary hormones (Table 3). Thyrotropin-releasing hormone (TRH) was identified and biochemically analyzed in 1969,19,20 gonadotropin-releasing hormone (LH-RH) in 1971,21 growth hormone release-inhibiting hormone (GH-RIH) in 1973,22 corticotropin-releasing hormone (CRH) in 1981–82,23–25 and growth hormone-releasing factor (GH-RF) identified in 196526 and characterized in 1980–83.27–30
Emerging indications for stereotactic laser interstitial thermal therapy in pediatric neurosurgery
Published in International Journal of Hyperthermia, 2020
Madison Remick, Michael M. McDowell, Kanupriya Gupta, James Felker, Taylor J. Abel
Since early reports of success in 2012 [17], HH has rapidly gained precedence as one of the optimal treatment targets for LITT due a combination of factors: deep seated location, high-risk eloquent adjacent tissues, little growth potential, and symptom responsiveness to ablative treatment. Hypothalamic hamartomas are concentrations of normal neuronal cells with abnormal architecture arising often within the tuber cinereum or other areas of the ventral hypothalamus [4]. The hallmark of HH symptomology is gelastic seizures, defined as short bursts of unprovoked, uncontrollable laughter in the absence of changes in consciousness and with the presence of epileptic discharges (often undetectable on surface electoencephalography) [4]. However, these lesions can cause other symptoms including non-gelastic epilepsy, precocious puberty, and severe neurocognitive issues including developmental regression secondary to epileptic encephalopathy. Symptom development appears to be correlated to the location of the lesion within the hypothalamus. Parahypothalamic HH attached to the floor of the third ventricle appear to be more associated with precocious puberty but less frequently with seizures. In contrast, intrahypothalamic HH are often seen to result in a greater displacement of tissues within the hypothalamus as well as the third ventricle and are seen to have a greater tendency toward displaying multiple symptoms including both gelastic and non-gelastic epilepsies, behavioral dysfunction, and intellectual disability. These associations are not absolute, and it is unclear exactly how much of a role size and tissue displacement play in these differences [23,24].
Ablative brain surgery: an overview
Published in International Journal of Hyperthermia, 2019
Andrea Franzini, Shayan Moosa, Domenico Servello, Isabella Small, Francesco DiMeco, Zhiyuan Xu, William Jeffrey Elias, Angelo Franzini, Francesco Prada
HHs are developmental malformations centered around the tuber cinereum that are associated with medically refractory epilepsy, gelastic seizures, developmental delay and often precocious puberty [142]. The deep location of these lesions, which is close to several critical neural and vascular structures, has discouraged direct surgical resective approaches, while favoring the adoption of minimally invasive ablative stereotactic procedures or disconnecting surgery. Stereotactic RF coagulation is one of the alternatives to surgical resection; however, multiple probe passes are often necessary due to the irregular conformations of HHs, and the extension of the RF lesion cannot be accurately predicted or monitored. This entails a risk of damaging the hypothalamus, optic pathways and perforating arteries [142,148]. Despite this, Kaneyama et al. recently reported a 71% seizure-free rate with little morbidity in a large series of 100 patients who were treated with a novel disconnecting MRI-guided RF technique. These results suggest that modern imaging technologies could make the traditional RF technique safer [149]. SRS is another safe and effective alternative for HH ablation. Two prospective trials and several case series showed good results in terms of seizure freedom and morbidity [133,148,150]. SRS is particularly suitable to HHs as it allows the surgeon to accurately conform the radiation dose to the lesion shape [142,148]. More recently, LITT has emerged as a promising treatment modality for HHs. The largest case series published thus far included 71 patients. Freedom from gelastic seizures after single or multiple laser ablations was achieved in 93% of these patients [151]. Another case series of 18 patients reported rates of gelastic and nongelastic seizure freedom of 81% and 56%, respectively [75]. The postoperative complication rate for LITT is lower than that of ATL, but disabling complications may still happen [152]. However, MRI-guidance and thermal energy monitoring keep the risk of injuring nearby critical structures to a minimum [142].