Expanded Transsphenoidal Trans-Lamina Terminalis Approach to Tumors Extending Into the Third Ventricle: Technique Notes and a Single Institute Experience

ObjectThe trans lamina terminalis approach (TLTA) has been described as a way to remove third ventricular tumors. The aim of this paper was to analyze the feasible outcomes of TLTA applied to tumors extending into the third ventricle in our institute.MethodsSuprasellar tumors (n = 149) were treated by the extended endonasal approach from September 2019 to December 2020 in Beijing Tiantan Hospital. Eleven of the tumors were treated by TLTA or TLTA via the trans-chiasm-pituitary corridor (TCPC). The surgical technique notes of TLTA were described and indications and outcomes of the approach were analyzed.ResultsThere were 11 patients enrolled in the study, six with papillary craniopharyngiomas, two with adamantinomatous craniopharyngiomas, one with a germinal cell tumor (GCT), one with cavernous malformation and one with chordoid glioma. Four of the patients received a radical resection by TLTA alone, while seven of them received TLTA via the TCPC. Gross total resection was achieved in eight patients (72.7%), and partial resection in three patients (27.3%). Visual function was improved in four of the 11 patients (36.4%), was unchanged in five patients (45.5%), and deteriorated in two patients (18.2%). New-onset hypopituitarism occurred in seven patients (63.3%) and new-onset diabetes insipidus occurred in two patients (18.2%). Electrocyte imbalance were observed in six patients (54.5%) at post-operative week 2. There were no surgery-related deaths or cerebrospinal fluid leaks. Postoperative intracranial infection was observed in one patient (9.1%), and during the follow-up period, tumor recurrence occurred in one patient (9.1%).ConclusionThe expanded TLTA provides a feasible suprachiasm corridor to remove tumors extending into the third ventricle, especially for craniopharyngiomas. Sound understanding of the major strengths and limitations of this approach, as well as strategies for complication avoidance, is necessary for its safe and effective application.

Activation of the Organum Vasculosum of the Lamina Terminalis Produces a Sympathetically Mediated Hypertension

Neurons in the organum vasculosum of the lamina terminalis (OVLT) sense extracellular NaCl and angiotensin II concentrations to regulate body fluid homeostasis and arterial blood pressure. Lesion of the anteroventral third ventricular region or OVLT attenuates multiple forms of neurogenic hypertension. However, the extent by which OVLT neurons directly regulate sympathetic nerve activity to produce hypertension is not known. Therefore, the present study tested this hypothesis by using a multi-faceted approach including optogenetics, single-unit and multifiber nerve recordings, and chemogenetics. First, optogenetic activation of OVLT neurons in conscious Sprague-Dawley rats (250–400 g) produced frequency-dependent increases in arterial blood pressure and heart rate. These responses were not altered by the vasopressin receptor antagonist (β-mercapto-β,β-cyclopentamethylenepropionyl1,O-me-Tyr2,Arg8)–vasopressin but eliminated by the ganglionic blocker chlorisondamine. Second, optogenetic activation of OVLT neurons significantly elevated renal, splanchnic, and lumbar sympathetic nerve activity. Third, single-unit recordings revealed optogenetic activation of the OVLT significantly increased the discharge of bulbospinal, sympathetic neurons in the rostral ventrolateral medulla. Lastly, chronic chemogenetic activation of OVLT neurons for 7 days significantly increased 24-hour fluid intake and mean arterial blood pressure. When the 24-hour fluid intake was clamped at baseline intakes, chemogenetic activation of OVLT neurons still produced a similar increase in arterial blood pressure. Neurogenic pressor activity assessed by the ganglionic blocker chlorisondamine was greater at 7 days of OVLT activation versus baseline. Collectively, these findings indicate that acute or chronic activation of OVLT neurons produces a sympathetically mediated hypertension.

Identification of the suprachiasmatic nucleus venous portal system in the mammalian brain

There is only one known portal system in the mammalian brain - that of the pituitary gland, first identified in 1933 by Popa and Fielding. Here we describe a second portal pathway in the mouse linking the capillary vessels of the brain’s clock suprachiasmatic nucleus (SCN) to those of the organum vasculosum of the lamina terminalis (OVLT), a circumventricular organ. The localized blood vessels of portal pathways enable small amounts of important secretions to reach their specialized targets in high concentrations without dilution in the general circulatory system. These brain clock portal vessels point to an entirely new route and targets for secreted SCN signals, and potentially restructures our understanding of brain communication pathways.

Glioblastoma de la región pineal: reporte de un caso y revisión de la literatura

Los tumores de la región pineal representan el 0,1-0,4% de los tumores cerebrales primarios 1) Los más frecuentes son los de células germinales, seguidos por los originados de células del parénquima pineal. Menos frecuente, tumores de estirpe glial y misceláneos; 2) De los gliomas, el más frecuente es el astrocitoma bien diferenciado; 3) Los glioblastomas son un hallazgo infrecuente. Reportamos el caso de un paciente de 62 años, cuya clínica se caracteriza por diplopía altitudinal y cefalea. En estudio de imágenes a su ingreso destacan hidrocefalia supratentorial; lesión pineal de aspecto infiltrativo; y aspectos sugerentes de diseminación leptomeningea. En la región espinal se encuentran lesiones metastásicas. Los biomarcadores resultaron negativos. El tratamiento inicial consiste en realizar fenestración de lámina terminalis para manejo de hidrocefalia. Se practica una biopsia de lesión intradural extramedular T10-T11 que es informada como Glioma de alto grado IDH 1 no mutado, con microproliferacion vascular y numerosas figuras mitóticas. Su historia natural permite una sobrevida solo de 5 meses. Las lesiones pineales de estirpe glial son poco frecuentes. Los casos con características de Gliomas Malignos pueden corresponder a Astrocitomas grado 3 OMS y menos frecuentemente a Glioblastomas. Su diagnóstico requiere estudios histológicos y inmunohistologicos detallados, la presencia de diseminación leptomeningea es de mayor frecuencia en los Glioblastomas. Pese a todas las opciones terapéuticas disponibles, este tipo de tumores tienen baja sobrevida.

The subfornical organ drives hypertension in polycystic kidney disease via the hypothalamic paraventricular nucleus

AimsHypertension is a prevalent yet poorly understood feature of polycystic kidney disease. Previously, we demonstrated that increased glutamatergic neurotransmission within the hypothalamic paraventricular nucleus produces hypertension in the Lewis Polycystic Kidney (LPK) rat model of polycystic kidney disease. Here, we tested the hypothesis that augmented glutamatergic drive to the paraventricular nucleus in Lewis polycystic kidney rats originates from the forebrain lamina terminalis, a sensory structure that relays blood-borne information throughout the brain.Methods and resultsAnatomical experiments revealed that 38% of paraventricular nucleus-projecting neurons in the subfornical organ of the lamina terminalis expressed Fos/Fra, an activation marker, in LPK rats while <1% of neurons were Fos/Fra+ in Lewis control rats (P = 0.01, n = 8). In anaesthetized rats, subfornical organ neuronal inhibition using isoguvacine produced a greater reduction in systolic blood pressure in LPK vs. Lewis rats (−21±4 vs. −7±2 mmHg, P < 0.01; n = 10), which could be prevented by prior blockade of paraventricular nucleus ionotropic glutamate receptors using kynurenic acid. Blockade of ionotropic glutamate receptors in the paraventricular nucleus produced an exaggerated depressor response in LPK relative to Lewis rats (−23±4 vs. −2±3 mmHg, P < 0.001; n = 13), which was corrected by prior inhibition of the subfornical organ with muscimol but unaffected by chronic systemic angiotensin II type I receptor antagonism or lowering of plasma hyperosmolality through high-water intake (P > 0.05); treatments that both nevertheless lowered blood pressure in LPK rats (P < 0.0001).ConclusionOur data reveal multiple independent mechanisms contribute to hypertension in polycystic kidney disease, and identify high plasma osmolality, angiotensin II type I receptor activation and, importantly, a hyperactive subfornical organ to paraventricular nucleus glutamatergic pathway as potential therapeutic targets.

When is it Worth Working for Water? A Utility Maximization Theory

In nature, amount of work an animal must do to obtain a resource like water depends on conditions in the environment. Conditions change, so it would behoove animals to allocate effort flexibly such that they work enough, but not more than necessary. To study this, we maintained rats in an environment where all water was earned in a task. We varied the reward magnitude and measured voluntary effort and water consumption. The rats did more trials per day when the reward per trial was smaller, yet worked for more water per day when rewards were larger. We propose an analytic model based on utility maximization which can account for these behavioral observations. The model is fit with per-day total work and consumption, but provides insight into the timing of trials and implicates lamina terminalis as a candidate neural substrate.