Comparative Anatomical Study on Operability in Surgical Approaches to the Anterior Part of the Third Ventricle.

BACKGROUND: Surgery of the third ventricle still represents a challenge in modern neurosurgery. To optimize the surgical planning, some aspects, related to ventricular anatomy, have to be taken into consideration. An operability score could represent a preoperative tool to evaluate these variables to choose a tailored surgical approach. METHODS: We compared the transcallosal transforaminal approach and the combined interhemispheric subcommissural translamina terminalis approach (CISTA) to the anterior part of the third ventricle, applying the operability score. RESULTS: Compared with the transcallosal transforaminal approach, the CISTA provides a statistically significant improvement in terms of depth of surgical field, surgical angle of attack, and maneuverability arc considering as 4 approach-related critical structures: the optic chiasm (P value: <0.0001, <0.0001, <0.0001, respectively), the anterior commissure (P value: <0.0001, <0.0001, <0.0001 respectively), the tuber cinereum (P value: <0.0001, 0.0224, 0.0173), and the interthalamic adhesion (P value: 0.2917, <0.0001, <0.0001 respectively). CONCLUSIONS: Tumors originating from the anterosuperior part of the third ventricle can be easily approached through a transcallosal transforaminal route, whereas lesions arising from the anteroinferior portion of the third ventricle might be safely and effectively approached through the CISTA.

Anatomy of the pineal region applied to its surgical approach.

INTRODUCTION: The pineal region is situated in the posterior part of the incisural space. This region includes the pineal body inside the quadrigeminal arachnoidal cistern. This article reviews the anatomic features of this region, with particular emphasis on those aspects of importance for surgical access to the pineal region. MATERIAL & METHODS: Five cadaver heads fixed in 10% formalin and injected with colored latex were used for anatomic dissection (five other specimens were also prepared and dissected to illustrate the articles on surgical techniques and approaches presented elsewhere in this issue). RESULTS: The pineal body is surrounded by several important structures such as: posterior part of the third ventricle, tectum, the complex of the great cerebral vein of Galen, pulvinar nuclei of the thalamus and splenium of corpus callosum. CONCLUSION: The surgical approach of the pineal body, whatever the route or the technique used (microsurgical, endoscopic or stereotactic), creates a great challenge for the neurosurgeons due to its location in the deep part of the brain and its close relationships with complex surrounded vascular structures.

Premio Sixto Obrador 2013. Modelo topográfico de 3 ejes para el tratamiento quirúrgico de los craneofaringiomas. Parte II: Evidencias anatómicas y neurorradiológicas que definen el modelo de clasificación de 3 ejes y su utilidad para predecir el riesgo quirúrgico individual / The 2013 Sixto Obrador Award. A triple-axis topographical model for surgical planning of craniopharyngiomas. Part II: Anatomical and neuroradiological evidence to define triple-axis topography and its usefulness in predicting individual surgical risk

INTRODUCCIÓN Y OBJETIVOS: Este estudio analiza las evidencias patológicas y de imagen de resonancia magnética que definen la topografía de los craneofaringiomas y permiten una clasificación de las lesiones según el riesgo de daño hipotalámico que estas asocian. MATERIAL Y MÉTODOS: Se ha realizado un análisis sistemático de los métodos de clasificación topográfica empleados en las series quirúrgicas de craneofaringiomas descritas en la literatura (n = 145 series, 4.588 craneofaringiomas). También se analizaron las relaciones topográficas de casos individuales intervenidos y bien descritos de la literatura (n = 224 casos) y de casos estudiados en autopsias (n = 201 casos). Finalmente, se analizaron y compararon los estudios prequirúrgicos y posquirúrgicos de imagen de resonancia magnética de craneofaringiomas bien descritos (n = 130) para establecer un modelo diagnóstico topográfico en 3 ejes de la lesión, que permite anticipar cualitativamente el riesgo quirúrgico asociado de daño hipotalámico. RESULTADOS: Las 2 principales variables pronósticas que definen la topografía del craneofaringioma son su posición con respecto al diafragma selar y la afectación del suelo del tercer ventrículo. Un modelo diagnóstico de 5 variables, que son: edad del paciente, existencia de hidrocefalia o de alteraciones del comportamiento, posición relativa de los hipotálamos y el valor del ángulo mamilar, permiten diferenciar craneofaringiomas supraselares que comprimen el tercer ventrículo (craneofaringiomas seudointraventriculares) de lesiones estrictamente intraventriculares o aquellas con un crecimiento primario en el suelo del tercer ventrículo (craneofaringiomas infundibulotuberales o no estrictamente intraventriculares). CONCLUSIONES: Un modelo de clasificación topográfica de los craneofaringiomas en 3 ejes que incluya el grado de infiltración del hipotálamo es útil para la planificación del abordaje y el grado de resección. Los craneofaringiomas infundibulotuberales representan un 42% de los casos y muestran una adherencia fuerte y circunferencial al suelo del tercer ventrículo, asociando un riesgo de daño hipotalámico del 50%. El abordaje transesfenoidal endoscópico permite valorar la adherencia tumoral hipotalámica bajo visión directa

INTRODUCTION AND OBJECTIVES: This study evaluates the pathological and magnetic resonance imaging evidence to define the precise topographical relationships of craniopharyngiomas and to classify these lesions according to the risks of hypothalamic injury associated with their removal. MATERIAL AND METHODS: An extensive, systematic analysis of the topographical classification models used in the surgical series of craniopharyngiomas reported in the literature(n = 145 series, 4,588 craniopharyngiomas) was performed. Topographical relationships of well-described operated craniopharyngiomas (n = 224 cases) and of non-operated cases reported in autopsies (n = 201 cases) were also analysed. Finally, preoperative and postoperative magnetic resonance imaging studies displayed in craniopharyngiomas reports (n = 130) were compared to develop a triple-axis model for the topographical classification of the selesions with qualitative information regarding the associated risk of hypothalamic injury. RESULTS: The 2 major variables with prognostic value to define the topography of a craniopharyngioma are its position relative to the sellar diaphragm and its degree of invasion of the third ventricle floor. A multivariate diagnostic model including 5 variables -patient age, presence of hydrocephalus and/or psychiatric symptoms, the relative position of the hypothalamus and the mammillary body angle- makes it possible to differentiate suprasellar craniopharyngiomas displacing the third ventricle upwards (pseudointraventricular craniopharyngiomas) from either strictly intraventricular craniopharyngiomas or lesions developing primarily within the third ventricle floor (infundibulo-tuberal or not strictly intraventricular craniopharyngiomas). CONCLUSIONS: A triple-axis topographical model for craniopharyngiomas that includes the degree of hypothalamus invasion is useful in planning the surgical approach and degree of resection. Infundibulo-tuberal craniopharyngiomas represent 42% of all cases. These lesions typically show tight, circumferential adhesion to the third ventricle floor, with their removal being associated with a 50% risk of hypothalamic injury. The endoscopically-assisted extended transsphenoidal approach provides a proper view to assess the degree and extension of craniopharyngioma adherence to the hypothalamus

The microanatomical structure of the cistern of the lamina terminalis.

Microanatomical dissection was performed on 14 formalin-fixed human cadaveric head specimens to provide information relevant for surgical procedures involving the cistern of the lamina terminalis (LT). The cistern of the LT was located in the midline of the telencephalon and was tent-shaped. The superior wall was located between the septal areas bilaterally, the lateral walls leaned laterally downwards, the anterior wall was the integrated line of the bilateral leptomeninges, the posterior and the inferoposterior walls were composed of the LT, the inferior margin was the arachnoid membrane between the optic nerves, and the inferoanterior wall usually formed a recess in front of the optic chiasm. In summary, the shape of the cistern of the LT is relatively constant, which is helpful for predicting the direction of hemorrhage of an aneurysm of the anterior communicating artery; in distinguishing its neural, vascular, and fibrous contents; and guiding surgical procedures.

Changes in central sodium and not osmolarity or lactate induce panic-like responses in a model of panic disorder.

Panic disorder is a severe anxiety disorder characterized by recurrent panic attacks that can be consistently provoked with intravenous (i.v.) infusions of hypertonic (0.5 M) sodium lactate (NaLac), yet the mechanism/CNS site by which this stimulus triggers panic attacks is unclear. Chronic inhibition of GABAergic synthesis in the dorsomedial hypothalamus/perifornical region (DMH/PeF) of rats induces a vulnerability to panic-like responses after i.v. infusion of 0.5 M NaLac, providing an animal model of panic disorder. Using this panic model, we previously showed that inhibiting the anterior third ventricle region (A3Vr; containing the organum vasculosum lamina terminalis, the median preoptic nucleus, and anteroventral periventricular nucleus) attenuates cardiorespiratory and behavioral responses elicited by i.v. infusions of NaLac. In this study, we show that i.v. infusions of 0.5 M NaLac or sodium chloride, but not iso-osmolar D-mannitol, increased 'anxiety' (decreased social interaction) behaviors, heart rate, and blood pressure responses. Using whole-cell patch-clamp preparations, we also show that bath applications of NaLac (positive control), but not lactic acid (lactate stimulus) or D-mannitol (osmolar stimulus), increases the firing rates of neurons in the A3Vr, which are retrogradely labeled from the DMH/PeF and which are most likely glutamatergic based on a separate study using retrograde tracing from the DMH/PeF in combination with in situ hybridization for vesicular glutamate transporter 2. These data show that hypertonic sodium, but not hyper-osmolarity or changes in lactate, is the key stimulus that provokes panic attacks in panic disorder, and is consistent with human studies.

The circumventricular organs: an atlas of comparative anatomy and vascularization.

The circumventricular organs are small sized structures lining the cavity of the third ventricle (neurohypophysis, vascular organ of the lamina terminalis, subfornical organ, pineal gland and subcommissural organ) and of the fourth ventricle (area postrema). Their particular location in relation to the ventricular cavities is to be noted: the subfornical organ, the subcommissural organ and the area postrema are situated at the confluence between ventricles while the neurohypophysis, the vascular organ of the lamina terminalis and the pineal gland line ventricular recesses. The main object of this work is to study the specific characteristics of the vascular architecture of these organs: their capillaries have a wall devoid of blood-brain barrier, as opposed to central capillaries. This particular arrangement allows direct exchange between the blood and the nervous tissue of these organs. This work is based on a unique set of histological preparations from 12 species of mammals and 5 species of birds, and is taking the form of an atlas.

Improved outcome in high-grade aneurysmal subarachnoid hemorrhage by enhancement of endogenous clearance of cisternal blood clots: a prospective study that demonstrates the role of lamina terminalis fenestration combined with modern microsurgical cisternal blood evacuation.

INTRODUCTION: Cisternal and ventricular blood predisposes to hydrocephalus and cerebral ischemia after high-grade aneurysmal subarachnoid hemorrhage (HGSAH). We studied the role of lamina terminalis fenestration combined with cisternal blood evacuation in HGSAH. PATIENTS/MATERIALS AND METHODS: A clinical, prospective, non-randomized study of a series of HGSAH patients (Modified Fisher>or=3) treated in the acute phase was carried out. The microsurgical treatment included aneurysm clipping, cisternal blood evacuation, and fenestration of the lamina terminalis. A comparable, non-blood-cleansed, endovascular-treated group, was included as a control. Clinical results were evaluated by the Glasgow Outcome Scale (GOS). RESULTS: During a period of 30 months, 95 patients who met the selection criteria were treated by microsurgical procedures and 28 by endovascular procedures. The distribution of GOS scores was superior for the microsurgical group: good results (GOS 4-5) were obtained in 85.3%, with a mortality rate of 5.9%. By contrast, 60.3% of patients in the endovascular group achieved GOS 4-5 scores, and 15.8% died. Good results for the endovascular group correlated inversely with delay of treatment. A permanent ventriculo-peritoneal shunt was necessary in 3.2% and 7.1% of the microsurgical and endovascular groups, respectively. The incidence of cerebral infarct was 3.1% and 14.3% for the microsurgical and endovascular groups, respectively. DISCUSSION: Microsurgical management reduces the usually poor outcome of patients with HGSAH. Lamina terminalis fenestration diminishes the incidence of shunt-dependent hydrocephalus and, combined with extensive cisternal blood cleansing, can lower the incidence of stroke. A procedure for cleansing blood and clots from the cisterns in HGSAH, based on the pathophysiology of vasospasm, is proposed.

The cerebrum. Anatomy.

The cerebrum is the crown jewel of creation and evolution. It is a remarkably delicate, intricate, and beautiful structure. The goal of this chapter is to provide the information needed to permit the neurosurgeon to navigate accurately, gently, and safely around and through the cerebrum and intracranial space. The location of deep structures is frequently described in relation to cranial and superficial cerebral landmarks in order to develop the concept of see-through, x-ray type knowledge of the cerebrum. In numerous illustrations, stepwise dissections are used to clarify the relationship between structures in different layers. Important clinical and surgical concepts are intermixed with the description of the cerebrum and its arteries, veins, and ventricles.

Involvement of anteroventral third ventricular AMPA/kainate receptors in both hyperosmotic and hypovolemic AVP secretion in conscious rats.

The area of the brain called the anteroventral third ventricular region (AV3V) includes three different subtypes of glutamate receptor, as well as neural circuits controlling fluid balance and cardiovascular and neuroendocrine functions. Although our previous data indicate the ability of AV3V N-methyl-d-aspartate (NMDA) and metabotropic receptors to provoke vasopressin (AVP)-releasing, pressor and hyperglycemic responses, the roles of non-NMDA receptors selective for alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid and kainate have not been elucidated to date. To address this question, the effects of intracerebral infusion with FWD or NBQX (specific agonist and antagonist for non-NMDA receptors, respectively) on plasma AVP, glucose, osmolality, electrolytes and cardiovascular parameters were examined in conscious rats in the absence or presence of an osmotic or volemic stimulus. When applied topically to AV3V structures such as the median preoptic nucleus, FWD augmented plasma AVP, osmolality, glucose and arterial pressure in a dose-associated fashion. All responses of the variables were abolished by pre-administering NBQX, which exerted no conspicuous effect on any variable except arterial pressure. It was revealed that NBQX administration in AV3V structures such as the median preoptic nucleus and the periventricular nucleus inhibited the rise of plasma AVP in response to intravenous infusion with hypertonic saline or removal of systemic blood through the femoral artery. Elevation of plasma osmolality and sodium evoked by osmotic load, and elevation of plasma osmolality, glucose and angiotensin II and decrease of arterial pressure caused by bleeding, were not significantly affected by NBQX treatment. These results suggest that AV3V non-NMDA receptors, as well as NMDA receptors, may elicit AVP-releasing, pressor and hyperglycemic actions when stimulated in the basal state, and may facilitate AVP secretion under both hyperosmotic and hypovolemic conditions, without contributing to cardiovascular, blood glucose or other responses.

Lesion of the anteroventral third ventricle (AV3V) reduces hypothalamic activation and hypophyseal hormone secretion induced by lipopolysaccharide in rats.

This study examined whether electrolytic ablation of the periventricular anteroventral third ventricle (AV3V) region would affect the hypothalamic activation and the increase of hypophysial hormone secretion induced by systemic injection of lipopolysaccharide (LPS) in rats. LPS significantly increased the number of cells showing Fos immunoreactivity in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus (P<0.05) and also increased plasma levels of vasopressin, oxytocin, adrenocorticotropin and corticosterone (P<0.05). AV3V lesion significantly reduced LPS-induced Fos immunoreactivity (P<0.05) and vasopressin and oxytocin secretion (P<0.05). Elevations in adrenocorticotropin but not in plasma corticosterone after LPS were affected by prior AV3V lesions. These findings demonstrate that LPS-induced Fos expression in the PVN and SON, and hypophysial hormone secretion is dependent on the integrity of the AV3V region.

A novel stereotaxic approach to the hypothalamus for the use of push-pull perfusion cannula in Holstein calves.

To determine secretory patterns of growth hormone-releasing hormone (GHRH) and somatostatin (SS) and their roles in the regulation of growth hormone (GH) secretion, a method for collecting hypothalamic perfusates, a push-pull perfusion method was developed in calves. With the use of the stereotaxic apparatus for cattle, a cannula was implanted into the hypothalamus of four male calves based upon cerebral ventriculography. Push-pull perfusates were collected at 10 min intervals for 6h and GHRH and SS concentrations in perfusates and plasma GH concentration were determined by EIAs and RIA, respectively. A cannula was implanted into the hypothalamus based on the image of the third ventricle and maintained for 1 month. GHRH and SS showed pulsatile secretion and the pulses for GHRH and SS were irregular in conscious animals. Neither GHRH nor SS secretion had a clear relationship with GH secretion. In the present study, we thus (1) established a stereotaxic technique for approaching the hypothalamus using cerebral ventriculography for calves, and (2) demonstrated that GHRH and SS secretion were pulsatile but not closely related to GH profile in conscious calves. The technique is useful for the study of the functions of the hypothalamus in the control of pituitary hormones in cattle.

A technique for long-term implantation of a microcatheter into the third ventricle of post-pubertal Chinese Meishan pigs based on ventriculography.

The objectives of this study were to implant a microcatheter into the third ventricle of post-pubertal Chinese Meishan pigs, and to maintain the microcatheter for a long time without causing stress. Fourteen pigs (45-60 kg BW) were used. Each pig was anesthetized and the head was orientated on the stereotaxic apparatus. A radiopaque dye was placed into the ventricle via a guide cannula inserted 3.5 mm forward of the bregma. A microcatheter was inserted into the third ventricle using ventriculography, and fixed with dental cement to a metal-mesh protector and screw anchors embedded into the skull. The opposite end of the microcatheter was externalized from the dorsal neck so that corticotropin-releasing hormone (CRH) could be injected easily. Simultaneously, a catheter was fitted in the jugular vein, and the free end of the catheter was externalized from the dorsal neck. Microcatheter-implanted pigs showed a normal progesterone concentration profile, and a constant cortisol level during at least two estrous cycles. Furthermore, intracerebroventricular injections of CRH (25 microg/500 microl) resulted in an increased plasma cortisol concentration (P < 0.05). Thus, the technique developed in this study enables us to approach the third ventricle in post-pubertal freely-moving pigs effectively over a long time, without causing stress.

Morphometry of the anterior third ventricle region as a guide for the subfrontal (translaminaterminalis) approach.

The anterior third ventricle region acquires clinical significance in benign and malignant tumors and cyst formations, of which craniopharyngiomas and gliomas are the most common. The subfrontal approach is one of the most preferred approaches for removing these tumors. In this study, the microsurgical anatomy of 81 Turkish, adult cadaveric hemispheres was examined to provide morphometric data of the region. These measurements from the anterior third ventricle region serve as a guide for neurosurgeons during surgical approach for removing anterior third ventricle tumors.

The distribution and morphological characteristics of serotonergic cells in the brain of monotremes.

The distribution and cellular morphology of serotonergic neurons in the brain of two species of monotremes are described. Three clusters of serotonergic neurons were found: a hypothalamic cluster, a cluster in the rostral brainstem and a cluster in the caudal brainstem. Those in the hypothalamus consisted of two groups, the periventricular hypothalamic organ and the infundibular recess, that were intimately associated with the ependymal wall of the third ventricle. Within the rostral brainstem cluster, three distinct divisions were found: the dorsal raphe nucleus (with four subdivisions), the median raphe nucleus and the cells of the supralemniscal region. The dorsal raphe was within and adjacent to the periaqueductal gray matter, the median raphe was associated with the midline ventral to the dorsal raphe, and the cells of the supralemniscal region were in the tegmentum lateral to the median raphe and ventral to the dorsal raphe. The caudal cluster consisted of three divisions: the raphe obscurus nucleus, the raphe pallidus nucleus and the raphe magnus nucleus. The raphe obscurus nucleus was associated with the dorsal midline at the caudal-most part of the medulla oblongata. The raphe pallidus nucleus was found at the ventral midline of the medulla around the inferior olive. Raphe magnus was associated with the midline of the medulla and was found rostral to both the raphe obscurus and raphe pallidus. The results of our study are compared in an evolutionary context with those reported for other mammals and reptiles.