Massa intermedia in adults: incidence, dimension, location and clinical importance.

PURPOSE: This retrospective magnetic resonance imaging investigation aimed to obtain information related to the anatomy of the massa intermedia (MI) in an adult population. METHODS: The work conducted on MRI views of 1058 (539 males and 519 females) healthy adult samples aged with 48.93 ± 17.63 years. Initially, the presence or absence of MI was noted, and then if present, its numbers and location in the third ventricle were recorded. Its horizontal (HDMI) and vertical (VDMI) diameters were measured on MRI views, while the cross-sectional area (CSAMI) was calculated using its diameters. RESULTS: MI was missing in 2.6% (27 cases) of 1058 adult samples. Six subjects (0.6%) had a double MI. HDMI, VDMI and CSAMI were measured as 4.83 ± 1.01 mm, 4.86 ± 0.98 mm, and 19.11 ± 7.23 mm2, respectively. MI size did not show a significant alteration from 19 up to 49 years, but then its size distinctly decreased between 50 and 60 years. After age 60, MI dimension did not display an important change. MI was settled in the antero-superior quadrant in 929 cases (90.63% of 1025 subjects), in the postero-superior quadrant in 22 cases (2.15%), in the antero-inferior quadrant in 32 cases (3.12%), in the postero-inferior quadrant in 8 cases (0.78%), and in the central part in 34 cases (3.32%). CONCLUSIONS: The size, position and incidence of MI were not affected by sex, and its position and incidence were not affected by adult age periods. In adults, MI size demonstrated a significant decrease in the middle age.

Transcallosal-Transchoroidal Fissure Approach for Midbrain and Thalamic Cavernous Malformations: 2-Dimensional Operative Video.

INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE: Cavernous malformations of the third ventricle arise from the medial thalamus and/or periaqueductal midbrain. Microsurgical resection is indicated when the lifetime risk of hemorrhage outweighs the surgical risks. ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: superior sagittal sinus, callosomarginal and pericallosal arteries, corpus callosum, foramen of Monro, choroidal fissure, fornix, thalamostriate veins, internal cerebral veins (ICVs), velum interpositum, and thalamus. ESSENTIAL STEPS OF THE PROCEDURE: The patient consents to the procedure. With the patient supine, the head is turned 90° and laterally flexed 45°. A bifrontal craniotomy positioned two-thirds anterior and one-third posterior to the coronal suture is performed. The interhemispheric fissure is opened, and a 2-cm corpus callosotomy is performed. Choroid plexus cauterization exposes the choroidal fissure. Sharp division of the taenia fornicea opens the velum interpositum, where the thalamostriate vein can be followed around the venous angle to the ICV. The anterior septal vein may be divided to communicate between the foramen of Monro and choroidal fissure. Dissection between the ICVs opens the velum interpositum into the third ventricle. PITFALLS/AVOIDANCE OF COMPLICATIONS: Frontal or deep vein occlusion causes venous infarction, and dissection on the nondominant hemisphere is preferred. Other complications include arterial infarction, fornix injury from choroidal fissure dissection or forniceal retraction, and thalamic or midbrain injury during lesion resection. VARIANTS AND INDICATIONS FOR THEIR USE: The contralateral choroidal fissure is used for low-lying medial thalamic and midbrain lesions. The ipsilateral choroidal fissure is used for high-lying or large lesions extending laterally. Transchoroidal approaches are not needed for superior (transcallosal only) or anterior (contralateral transcallosal-contralateral transforaminal) thalamic lesions. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Anatomic Features of the Interthalamic Adhesion in the Pediatric Population.

OBJECTIVE: The main goal of this retrospective study was to examine the morphology of the interthalamic adhesion (ITA) in normal children aged between 1 and 18 years. METHODS: The study universe consisted of magnetic resonance images of 180 healthy pediatric subjects (age, 9.50 ± 5.20 years, sex, 90 girls and 90 boys). The cross-sectional area (CSA), vertical diameter (VD), and horizontal diameter (HD) of the ITA were measured and in addition, its location was noted. RESULTS: HD, VD, and CSA of the ITA were measured as 8.47 ± 1.64 mm, 7.59 ± 1.57 mm, and 52.06 ± 18.51 mm2, respectively. HD did not change from infancy until postpubescence, but then significantly decreased (P < 0.001). VD increased up to early childhood but then did not alter until the end of prepubescence. After that period, it decreased in postpubescence (P < 0.001). CSA tended to decrease in an irregular pattern according to pediatric age periods (P < 0.001). The ITA was located at the anterosuperior quadrant in 138 individuals (76.70%), at the anteroinferior quadrant in 7 individuals (3.90%), and the center of the lateral wall of the third ventricle in 35 individuals (19.40%). Linear functions were calculated as y = 9.490-0.107 × age (years) for HD, y = 8.453-0.091 × age (years) for VD, and y = 63.559-1.211 × age (years) for CSA. CONCLUSIONS: ITA size irregularly decreases with advancing age from 1 to 18 years. Our calculated linear functions, showing the growth dynamics of the ITA by pediatric ages, may be helpful in estimating its dimension.

Extra-Axial Third Ventriculostomy Through Lamina Terminalis with Multiple Cisternostomies - Rescue Surgery for Patients with Failed Shunt Surgeries and Hydrocephalus.

Background and Aim: Contemporary management of hydrocephalus involves various modes of cerebrospinal fluid (CSF) diversion, including shunt surgery and endoscopic ventriculostomy. However, there are times when either of these procedures have either failed or are not feasible. Highly invasive procedures aimed at internal CSF have been described previously, which, with the aid of modern microsurgical techniques, can be attempted in cases with very limited options. Our aim was to study the utility of extra-axial third ventriculostomy via lamina terminalis fenestration with multiple cisternostomies in the treatment of failed hydrocephalus. Materials and Methods: Forty-five patients with hydrocephalus were operated for extra-axial trans-lamina terminalis third ventriculostomy with multiple cisternostomies from January 2017 to January 2019. A minimally invasive supraorbital craniotomy was performed with subfrontal fenestration of the lamina terminalis and trans-lamina terminalis fenestration of the floor of the third ventricle with multiple cisternostomies including the optico-carotid cistern and opening of the Liliequist membrane. Results: Tuberculous meningitis was the most common etiology in the series, and multiple shunt procedures and incompatible CSF profiles were the most common reasons that necessitated this alternate rescue procedure. At a mean follow-up of 6 months, no patient required a revision shunt surgery. There was one death due to cardiac failure with anasarca, unrelated to the procedure. Conclusions: Extra-axial trans-lamina terminalis ventriculostomy with cisternostomies can safely be performed using minimally invasive micro-neurosurgical techniques, adding to the armamentarium of neurosurgeons in the management of complex cases of hydrocephalus.

Cell proliferation and glial cell marker expression in the wall of the third ventricle in the tuberal region of the male mouse hypothalamus during postnatal development.

The third ventricle (3 V) wall of the tuberal hypothalamus is composed of two types of cells; specialized ependymoglial cells called tanycytes located ventrally and ependymocytes dorsally, which control the exchanges between the cerebrospinal fluid and the hypothalamic parenchyma. By regulating the dialogue between the brain and the periphery, tanycytes are now recognized as central players in the control of major hypothalamic functions such as energy metabolism and reproduction. While our knowledge of the biology of adult tanycytes is progressing rapidly, our understanding of their development remains very incomplete. To gain insight into the postnatal maturation of the 3 V ependymal lining, we conducted a comprehensive immunofluorescent study of the mouse tuberal region at four postnatal ages (postnatal day (P) 0, P4, P10, and P20). We analyzed the expression profile of a panel of tanycyte and ependymocyte markers (vimentin, S100, connexin-43 [Cx43], and glial fibrillary acidic protein [GFAP]) and characterized cell proliferation in the 3 V wall using the thymidine analog bromodeoxyuridine. Our results show that most changes in marker expression occur between P4 and P10, with a switch from a 3 V mostly lined by radial cells to the emergence of a tanycytic domain ventrally and an ependymocytic domain dorsally, a drop in cell proliferation and increased expression of S100, Cx43, and GFAP that acquire a mature profile at P20. Our study thus identifies the transition between the first and the second postnatal week as a critical time window for the postnatal maturation of the 3 V wall ependymal lining.

Trans-lamina Terminalis Approach for Resection of Third Ventricular Tumor.

Granular cell tumors are rare vascular neoplastic lesions of the sellar and suprasellar region that usually arise from the pituitary stalk but can originate as low as the posterior pituitary or as high as the tuber cinereum.1 Complete resection, although ideal, can yield high rates of endocrine or visual morbidity.1,2 On headache workup, a 66-year-old woman was found to have a 1.2 × 1.1 × 1.3-cm contrast-enhancing lesion in the anterior-inferior third ventricle, posterior to the infundibulum. Endocrine testing was unremarkable, and a lumbar puncture was nondiagnostic. An open biopsy and possible resection were selected by the patient over short-interval imaging. A translamina terminalis approach was selected over a transsphenoidal approach to preserve the third ventricular floor (Video 1). A right frontotemporal craniotomy was performed, including flattening of the lesser sphenoid wing. The optic chiasm was exposed via subfrontal microsurgical dissection, and the lamina terminalis was opened sharply. A firm, vascular tumor was identified extending into the anterior-inferior aspect of the third ventricle. Frozen pathologic analysis was nondiagnostic. Given the proximity of the optic chiasm, a complete piecemeal microsurgical resection was performed, preserving the floor and lateral walls of the third ventricle and optic apparatus. Final pathology was a granular cell tumor. Postoperatively, the patient had transient diabetes insipidus, with preserved vision and normal endocrine function on follow-up. The trans-lamina terminalis approach can be used for safe resection of anterior third ventricular tumors. Preservation of the floor and walls of the third ventricle is critical to avoid morbidity.

Strictly third ventricle craniopharyngiomas: pathological verification, anatomo-clinical characterization and surgical results from a comprehensive overview of 245 cases.

The strictly third ventricle craniopharyngioma topography (strictly 3V CP) defines the subgroup of lesions developed above an anatomically intact third ventricle floor (3VF). The true existence of this exceedingly rare topographical category is highly controversial owing to the presumed embryological CP origin from Rathke's pouch, a structure developmentally situated outside the neural tube. This study thoroughly analyzes the largest series of strictly 3V CPs ever collected. From 5346 CP reports published between 1887 and 2021, we selected 245 cases with reliable pathological, surgical, and/or neuroradiological verification of an intact 3VF beneath the tumor. This specific topography occurs predominantly in adult (92.6%), male (64.4%) patients presenting with headache (69.2%), and psychiatric disturbances (59.2%). Neuroradiological features defining strictly 3V CPs are a tumor-free chiasmatic cistern (95.9%), an entirely visible pituitary stalk (86.4%), and the hypothalamus positioned around the tumor's lower pole (92.6%). Most are squamous papillary (82%), showing low-risk severity adhesions to the hypothalamus (74.2%). The adamantinomatous variant, however, associates a higher risk of severe hypothalamic adhesion (p < .001). High-risk attachments are also associated with psychiatric symptoms (p = .013), which represented the major predictor for unfavorable prognoses (83.3% correctly predicted) among cases operated from 2006 onwards. CP recurrence is associated with infundibulo-tuberal symptoms (p = .036) and incomplete surgical removal (p = .02). The exclusive demographic, clinico-pathological and neuroradiological characteristics of strictly 3V CPs make them a separate, unique topographical category. Accurately distinguishing strictly 3V CPs preoperatively from those tumors replacing the infundibulum and/or tuber cinereum (infundibulo-tuberal or not strictly 3V CPs) is critical for proper, judicious surgical planning.

Pineal region tumours in the sitting position: how I do it.

BACKGROUND: Pineal region tumours remain challenging neurosurgical pathologies. METHODS: Detailed anatomical knowledge of the posterior incisural space and its variations is critical. An opaque arachnoidal membrane seals the internal cerebral and basal veins, leading to thalamic, basal ganglia, mesencephalic/pontine infarctions if injured. Medium-size tumours can be removed en-bloc with all traction/manipulation applied on the tumour side, virtually without contact of ependymal surfaces of the pulvinars or third ventricle. Sacrifice of the cerebello-mesencephalic fissure vein may be required. CONCLUSIONS: The sitting position offers superior anatomical orientation and remains safe with experienced teams. Meticulous microsurgical techniques and detailed anatomical knowledge are likely to secure safe outcomes.

Exploiting lamina terminalis appearance and motion in prediction of hydrocephalus using convolutional LSTM network.

BACKGROUND: Evaluation of the lamina terminalis (LT) is crucial for non-invasive evaluation of the CSF diversion for the treatment of hydrocephalus. Together with deep learning algorithms, morphological and physiological analyses of the LT may play an important role in the management of hydrocephalus. AIM: We aim to show that exploiting the motion of LT can contribute to the evaluation of hydrocephalus using deep learning algorithms. METHODS: The dataset contains 61 True-fisp data with routine sequences 37 of which are labeled as 'hydrocephalus' and the others as 'normal condition'. A fifteen-year experienced neuroradiologist divided data into two groups. The first group, 'hydrocephalus', consists of patients with typical MRI findings (ventriculomegaly, enlargement of the third ventricular recesses and lateral ventricular horns, decreased mamillo-pontine distance, reduced frontal horn angle, thinning/elevation of the corpus callosum, and non-dilated convexity sulci), and the second group contains samples that did not show any symptoms or neurologic abnormality and labeled as 'normal condition'. The region of interest was determined by the radiologist supervisor to cover the LT. To achieve our purpose, we used both spatial and spatio-temporal analysis with two different deep learning architectures. We utilized Convolutional Neural Networks (CNN) for spatial and Convolutional Long Short-Term Memory (ConvLSTM) models for spatio-temporal analysis using an ROI around LT on sagittal True-fisp images. RESULTS: Our results show that 80.7% classification accuracy was achieved with the ConvLSTM model exploiting LT motion, whereas 76.5% and 71.6% accuracies were obtained by the 2D CNN model using all frames, and only the first frame from only spatial information, respectively. CONCLUSION: We suggest that the motion of the LT can be used as an additional attribute to the spatial information to evaluate the hydrocephalus.

Developmental genes controlling neural circuit formation are expressed in the early postnatal hypothalamus and cellular lining of the third ventricle.

The arcuate nucleus of the hypothalamus is central in the regulation of body weight homeostasis through its ability to sense peripheral metabolic signals and relay them, through neural circuits, to other brain areas, ultimately affecting physiological and behavioural changes. The early postnatal development of these neural circuits is critical for normal body weight homeostasis, such that perturbations during this critical period can lead to obesity. The role for peripheral regulators of body weight homeostasis, including leptin, insulin and ghrelin, in this postnatal development is well described, yet some of the fundamental processes underpinning axonal and dendritic growth remain unclear. Here, we hypothesised that molecules known to regulate axonal and dendritic growth processes in other areas of the developing brain would be expressed in the postnatal arcuate nucleus and/or target nuclei where they would function to mediate the development of this circuitry. Using state-of-the-art RNAscope® technology, we have revealed the expression patterns of genes encoding Dcc/Netrin-1, Robo1/Slit1 and Fzd5/Wnt5a receptor/ligand pairs in the early postnatal mouse hypothalamus. We found that individual genes had unique expression patterns across developmental time in the arcuate nucleus, paraventricular nucleus of the hypothalamus, ventromedial nucleus of the hypothalamus, dorsomedial nucleus of the hypothalamus, median eminence and, somewhat unexpectedly, the third ventricle epithelium. These observations indicate a number of new molecular players in the development of neural circuits regulating body weight homeostasis, as well as novel molecular markers of tanycyte heterogeneity.

Lamina terminalis fenestration: An important neurosurgical corridor.

Cerebrospinal fluid (CSF) disorders are challenging conditions in neurosurgical practice. The majority of CSF is contained in the basal cisterns of the brain, which are subarachnoid compartments that communicate with each other, and contribute to the circulation of CSF. Yasargil et al. (1976) was the first to provide the systematic classification and naming of the basal cisterns. The lamina terminalis (LT) starts from the gyrus rectus and descends to the lateral aspect of the optic chiasm. It is a thick arachnoidal membrane delineating the anterior wall of the third ventricle that borders the LT cistern. With the introduction of the operating microscope and the progressive development of modern neurosurgery, the arachnoid and basal cisterns have been used as surgical corridors in order to reach deep areas of the brain and to release CSF for brain relaxation. In this way, the LT is used as a surgical corridor for the treatment of several conditions such as obstructive hydrocephalus and diencephalic tumors. In this chapter, we will describe the anatomy of the LT, possible conditions treated by opening the LT, the different surgical approaches to opening the LT, along with their advantages and disadvantages.

Massa intermedia of the thalamus: an anatomical study using magnetic resonance imaging.

PURPOSE: Few studies have explored the morphology of massa intermedia (MI). The aim of the present study was to characterize it using magnetic resonance imaging (MRI). METHODS: A total of 205 patients were enrolled in this study. Following initial examinations with conventional MRI sequences, thin-slice coronal and sagittal T2-weighted imaging was performed. For MI localization, the third ventricle was arbitrarily divided into nine areas on the midsagittal image. RESULTS: MI was identified in 93% of the total patients-89% in male and 91% in female patients. Among them, 68% showed a single, styloid-shaped MI with variable thickness and cross sectional configuration, followed by broad and double MIs that were found in 18% and 10% patients, respectively. In the anteroposterior dimension, 99% of the MIs were identified in the middle third area, followed by the posterior third area. In the supero-inferior dimension, 95% of the MIs were identified in the middle third area, followed by the upper third area. With a significant difference, a broad MI was more frequently found in women than in men. CONCLUSIONS: MIs are commonly located in the middle third of the third ventricle as a single commissure with high morphological variability. Compared to men, women may have a well-developed, broader MI.

Prevalence and anatomical characteristics of the human massa intermedia.

Massa intermedia (MI), also known as interthalamic adhesion is an inconsistent bridge connecting the two thalami. Recent studies suggest MI contains functional neuronal tissue and is responsible for interhemispheric communication. Absence of MI has been linked to cognitive differences and psychiatric disorders. However, MI is naturally absent in up to 35 percent of cases but its true prevalence during life in humans is unknown. High resolution anatomical MR studies of 1410 subjects aged 2 months to 93 years were reviewed and those with MI were identified. Prevalence and characteristics of MI were identified and grouped by gender and decade of life. MI was present in 87.3% of the studied subjects. Absence of MI was noted in as early as first decade of life as well as all decades of life, but its absence increased with age, suggesting additional factors during life as mediators. Females had 2.75 times higher likelihood of MI presence than males. Size of MI decreased with increasing age up to age 70. Size of MI was best predicted by third ventricular width and age mediating a larger MI with smaller third ventricular size and younger age. MI is present in 87.3% of the population as determined in this MRI study. Absence of MI is identifiable in very early years of life, suggesting a congenital cause. MI's prevalence, however, was also found to decrease with advancing age, suggesting a dynamic process of MI disappearance during life.

Trans-lamina terminalis suprategmental approach for ventral midbrain lesions: Technical note.

Surgical resection of lesions located in the ventral midbrain is challenging. Few approaches and safe entry zones (SEZs) have been proposed and used to remove this type of lesion, and each has its limitations. Using two illustrating cases, the authors describe a trans-lamina terminalis suprategmental approach for removing ventral midbrain lesions. This approach provides a straight surgical trajectory with sparse neurovascular structures and can be performed with a standard pterional or subfrontal craniotomy. It may be the ideal approach for ventromedial midbrain lesions extending towards the third ventricle.

Transcallosal, transchoroidal clipping of a hypothalamic collateral vessel aneurysm in Moyamoya disease.

Peripheral collateral vessel aneurysms in Moyamoya disease (MMD) remain difficult to treat due to their deep location, small size, and vascular fragility. We report the case of an aneurysm localized in the hypothalamus, which was rapidly increasing in size with repeated hemorrhage despite revascularization surgery. Aneurysm clipping was performed to prevent further progress and rerupture with favorable outcome. To our best knowledge, this is the first description of a hypothalamic aneurysm in MMD being clipped via a transcallosal, transchoroidal approach through the third ventricle.