Imaging of the septum pellucidum: normal, variants and pathology.

The septum pellucidum is a largely neglected anatomical midline structure during post-natal neuroimaging interpretation. Conversely, it is one of the anatomical landmarks used on pre-natal ultrasound to access normal midline formation. Because of its importance during the pre-natal period, the awareness of its primary malformative abnormalities is much higher than its disruptive acquired pathologies, often leading the misinterpretation. In this article, we will review the normal septum pellucidum formation, anatomy, and anatomical variants and will describe the imaging findings in primary malformative and secondary disruptive abnormalities affecting the septum pellucidum.

Ultrasound Measurements of Frontal Horns and the Cavum Septi Pellucidi in Healthy Fetuses in the Second and Third Trimesters of Pregnancy.

OBJECTIVES: To assess the visualization rate and size of the frontal horns (FHs) and cavum septi pellucidi (CSP) in healthy fetuses throughout pregnancy. METHODS: After Institutional Review Board approval, 522 consecutive uncomplicated singleton pregnancies between 15 and 39 gestational weeks were enrolled in the study. Ultrasound measurements of the anterior horn width (AHW), center from the horn distance (CFHD), distance from the FHs to the CSP, and CSP width were retrospectively performed using axial transventricular or transcerebellar planes. Available maternal body mass indices were recorded. RESULTS: At least 1 FH was seen in 78% of the cases. The mean AHW decreased over the second trimester and plateaued in the third trimester. The CFHD plateaued in the second trimester and increased in the third trimester. Downside FHs were generally larger than upside FHs. More FHs were measured in transventricular (69%) than transcerebellar (31%) planes. Frontal horns were seen with high, low, and no confidence in 57%, 21%, and 22% of cases, respectively. No-confidence rates were 17% in the second trimester and 42% in the third trimester. The CSP was not visualized in 4% of cases; 15 of 19 cases of a nonvisualized CSP were scanned between 18 and 37 weeks. Mean body mass indices ± SDs were 27.6 ± 6.7 kg/m2 for the patients in cases of a visualized CSP and 32.4 ± 9.1 kg/m2 for the patients in cases of a nonvisualized CSP. CONCLUSIONS: Normative data for the fetal FH and CSP width were established. Frontal horns are more frequently seen on transventricular views and are difficult to confidently assess in the late third trimester. This study challenges previously reported data that the CSP is seen in 100% of cases from 18 to 37 weeks.

The Prevalence of Cavum Septum Pellucidum in Mental Disorders Revealed by MRI: A Meta-Analysis.

OBJECTIVE: The prevalence of cavum septum pellucidum (CSP) in mental disorders, particularly schizophrenia spectrum disorders and mood disorders, remains uncertain. The authors used a meta-analytical approach to determine the prevalence of CSP in mental disorders and to compare these with the prevalence of CSP in psychiatrically healthy comparison subjects. METHODS: PubMed and Embase were systematically searched for relevant articles published as of January 9, 2018. After a quality assessment of individual studies using the Newcastle-Ottawa Scale, a random-effects model within Stata statistical software was used to synthesize 25 eligible studies that included 2,392 patients with mental disorders and 1,445 psychiatrically healthy comparison subjects. RESULTS: The prevalence of CSP of any size and large CSP was found to be significantly higher in individuals with mental disorders compared with healthy comparison subjects, and the prevalence of CSP in schizophrenia spectrum and mood disorders did not differ between the groups. CONCLUSIONS: The meta-regression with predefined covariance indicated that imaging parameters were not associated with the heterogeneity among original studies; however, the mean age of enrolled subjects was identified as a possible source of heterogeneity. No publication bias was found.

An investigation of the standardization of fetal cavum septi pellucidi measurements using three-dimensional volumes of the fetal head.

PURPOSE: The purpose of this study was to measure the maximal width, middle width, and length of the cavum septi pellucidi (CSP) in normal fetuses, and compare these measurements obtained in the transthalamic (TT) plane with those obtained in the transventricular (TV) plane. METHOD: A prospective study was conducted of normal singleton fetuses, ranging from 18 to 36 weeks in gestational age. In each case, a three-dimensional volume of the fetal head was obtained in the TT plane for further offline measurements, then the maximal width, middle width, and length of the CSP in both the TT and TV planes were measured. Intraobserver and interobserver reproducibility was assessed, and curve estimation was used to assess the possible relationship between these measurements of CSP and gestational age (GA). RESULTS: A total of 267 normal fetuses were studied. The CSP width and length in TT and TV planes as a function of GA were analyzed using a quadratic regression model. Intraobserver and interobserver agreement of the CSP measurements was excellent overall (ICCs >0.9), with intraobserver and interobserver differences of less than 4%. CONCLUSION: Measurements of CSP in the TT and TV planes are equally reproducible.

Visualization of the cavum septi pellucidi, cavum Vergae, and cavum veli interpositi using magnetic resonance imaging.

PURPOSE: The morphology of the cavum septi pellucidi (CSP), cavum Vergae (CV), and cavum veli interpositi (CVI) has been infrequently explored with neuroimaging. The aim of the present study was to delineate these cavities using magnetic resonance (MR) imaging. METHODS: A total of 71 patients were enrolled in the present study. Following initial examinations with conventional MR sequences, constructive interference in steady-state (CISS) sequence was performed in the coronal and sagittal sections for 60 and 11 patients, respectively. RESULTS: The coronal CISS images at the level of the aqueduct showed two distinct morphologies of the CV roof, one formed by the fornices with varying degrees of conjugation and the other formed by the corpus callosum with completely separated fornices. Appearance of the CSP was classified into four distinct types. Furthermore, the CVI presented two distinct appearances. CONCLUSIONS: Typically, the CSP, CV, and CVI present with asymptomatic conditions with morphological variabilities. Visualization of the CSP, CV, and CVI using the CISS sequences may be useful when managing lesions affecting these cavities.

Cavum septum pellucidum and first-episode psychosis: A meta-analysis.

OBJECTIVES: To investigate the prevalence and changes of cavum septum pellucidum (CSP) in first-episode psychosis (FEP) patients. METHODS: Medline, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched to identify eligible studies comparing FEP patients and healthy controls from inception to Feb 29, 2016. RESULTS: Ten cross-sectional studies and three longitudinal studies reported in ten articles met our criteria. Our meta-analysis found no significant differences in the prevalence of either "any CSP" (OR = 1.41; 95% CI 0.90-2.20; p = 0.13; I2 = 52.7%) or "large CSP" (OR = 1.10; 95% CI 0.77-1.58; p = 0.59; I2 = 24.1%) between FEP patients and healthy controls. However, the heterogeneity analysis of the prevalence of "any CSP" suggested bias in outcome reporting. CONCLUSIONS: The results based on current evidence suggest it is unclear whether "any CSP" is a risk factor for FEP due to the heterogeneity of the studies. There is insufficient evidence to support that "large CSP" is a possible risk factor for FEP.

[Septal Activation and Control of Limbic Structures].

Coherent activation of limbic system structures as the main function of theta-rhythm is widely discussed in the literature. However until now does not exist the common view on its generation in these brain structures. The model of septal theta-rhythmic activation and control of limbic structures is suggested basing on the literature and own experimental data.

Cerebrospinal fluid reconstitution via a perfusion-based cadaveric model: feasibility study demonstrating surgical simulation of neuroendoscopic procedures.

Cadaveric surgical simulation carries the advantage of realistic anatomy and haptic feedback but has been historically difficult to model for intraventricular approaches given the need for active flow of CSF. This feasibility study was designed to simulate intraventricular neuroendoscopic approaches and techniques by reconstituting natural CSF flow in a cadaveric model. In 10 fresh human cadavers, a simple cervical laminectomy and dural opening were made, and a 12-gauge arterial catheter was introduced. Saline was continuously perfused at physiological CSF pressures to reconstitute the subarachnoid space and ventricles. A neuroendoscope was subsequently inserted via a standard right frontal bur hole. In 8 of the 10 cadavers, adequate reconstitution and endoscopic access of the lateral and third ventricles were achieved. In 2 cadavers, ventricular access was not feasible, perhaps because of a small ventricle size and/or deteriorated tissue quality. In all 8 cadavers with successful CSF flow reconstitution and endoscopic access, identifying the foramen of Monro was possible, as was performing septum pellucidotomy and endoscopic third ventriculostomy. Furthermore, navigation of the cerebral aqueduct, fourth ventricle, prepontine cistern, and suprasellar cistern via the lamina terminalis was possible, providing a complementary educational paradigm for resident education that cannot typically be performed in live surgery. Surgical simulation plays a critical and increasingly prominent role in surgical education, particularly for techniques with steep learning curves including intraventricular neuroendoscopic procedures. This novel model provides feasible and realistic surgical simulation of neuroendoscopic intraventricular procedures and approaches.

An anatomic review of thalamolimbic fiber tractography: ultra-high resolution direct visualization of thalamolimbic fibers anterior thalamic radiation, superolateral and inferomedial medial forebrain bundles, and newly identified septum pellucidum tract.

BACKGROUND: Images obtained through ultra-high-field 7.0-tesla magnetic resonance imaging with track-density imaging provide clear, high-resolution tractograms that have been hitherto unavailable, especially in deep brain areas such as the limbic and thalamic regions. This study is a largely pictorial description of the deep fiber tracts in the brain using track-density images obtained with 7.0-T diffusion-weighted imaging. METHODS: To identify the fiber tracts, we selected 3 sets of tractograms and performed interaxis correlation between them. These tractograms offered an opportunity to extract new information in areas that have previously been difficult to examine using either in vivo or in vitro human brain tractography. RESULTS: With this new technique, we identified 4 fiber tracts that have not previously been directly visualized in vivo: septum pellucidum tract, anterior thalamic radiation, superolateral medial forebrain bundle, and inferomedial forebrain bundle. CONCLUSIONS: We present the high-resolution images as a tool for researchers and clinicians working with neurodegenerative and psychiatric diseases, such as Parkinson disease, Alzheimer disease, and depression, in which the accurate positioning of deep brain stimulation is essential for precise targeting of nuclei and fiber tracts.

Automated interhemispheric surface extraction in T1-weighted MRI using intensity and symmetry information.

BACKGROUND: Localizing the human interhemispheric region is of interest in image analysis mainly because it can be used for hemisphere separation and as a preprocessing step for interhemispheric structure localization. Many existing methods focus on only one of these applications. NEW METHOD: Here a new Intensity and Symmetry based Interhemispheric Surface extraction method (ISIS) that enables both applications is presented. A combination of voxel intensity and local symmetry is used to optimize a surface from T1-weighted MRI. RESULTS: ISIS was evaluated in regard to cerebral hemisphere separation using manual segmentations. It was also evaluated in regard to being a preprocessing step for interhemispheric structure localization using manually placed landmarks. COMPARISON WITH EXISTING METHODS: Results were compared to cerebral hemisphere separations by BrainVisa and Freesurfer as well as to a midsagittal plane (MSP) extraction method. ISIS had less misclassified voxels than BrainVisa (ISIS: 0.119±0.114%, BrainVisa: 0.138±0.084%, p=0.020). Freesurfer had less misclassified voxels than ISIS for one dataset (ISIS: 0.063±0.056%, Freesurfer: 0.049±0.044%, p=0.019), but failed to produce usable results for another. Total voxel distance from all manual landmarks did not differ significantly between ISIS and the MSP method (ISIS: 4.00±1.88, MSP: 4.47±4.97). CONCLUSIONS: ISIS was found successful in both cerebral hemisphere separation and as a preprocessing step for interhemispheric structure localization. It needs no time consuming preprocessing and extracts the interhemispheric surface in less than 30 s.

Profiling differences in chemical composition of brain structures using Raman spectroscopy.

Raman spectroscopy enables non-invasive investigation of chemical composition of biological tissues. Due to similar chemical composition, the analysis of Raman spectra of brain structures and assignment of their spectral features to chemical constituents presents a particular challenge. In this study we demonstrate that standard and independent component analysis of Raman spectra is capable of assessment of differences in chemical composition between functionally related gray and white matter structures. Our results show the ability of Raman spectroscopy to successfully depict variation in chemical composition between structurally similar and/or functionally connected brain structures. The observed differences were attributed to variations in content of proteins and lipids in these structures. Independent component analysis enabled separation of contributions of major constituents in spectra and revealed spectral signatures of low-concentration metabolites. This provided finding of discrepancies between structures of striatum as well as between white matter structures. Raman spectroscopy can provide information about variations in contents of major chemical constituents in brain structures, while the application of independent component analysis performed on obtained spectra can help in revealing minute differences between closely related brain structures.

Cavum Septum Pellucidum: Hallazgo Mediante Disección Neuroanatómica / Cavum Septum Pellucidum: Finding from Neuroanatomical Dissection

Se reporta una marcada cavitación a nivel del septum pellucidum, un gran cavum septum pellucidum de una persona adulta, en el espacio reconocido generalmente como cerrado del sistema nervioso central, que se hace evidente como tal, en ciertas fases de la vida intrauterina. Esta cavitación está ausente en el adulto sano, pero en algunas personas esquizofrénicas y con demencia pugilística, dicha cavidad, puede considerarse como un hallazgo de relativa frecuencia. Este hallazgo se encontró aleatoriamente en uno de cuarenta y dos encéfalos de adultos, valorados superficialmente desde la anatomía macroscópica como normales. Dicho hallazgo posiblemente se asocie con desórdenes conductuales, en vista que dicho encéfalo correspondía a un individuo proveniente de un hospital psiquiátrico.

A marked cavitation in the septum pellucidum level is reported, a great cavum septum pellucidum of an adult in the closed space generally recognized as the central nervous system, which is evident in itself, at certain stages of intrauterine life. This cavitation is usually absent in the healthy adult, but in some people with schizophrenia and pugilistic dementia, the cavity can be regarded and found relatively frequently. This finding was found randomly in one of forty-two adult brains, superficially valued from the gross anatomy as normal. This finding may be associated with behavioral disorders, taking in to account that the brain corresponded to a person from a psychiatric hospital.

Transseptumpellucidumrostrostomy: anatomical considerations and neuroendoscopic approach.

PURPOSE: Verify the presence of the rostral lamina of the corpus callosum, and set parameters for neuroendoscopy. METHODS: Relationship of the floor of the frontal horn of lateral ventricle and the hypothalamic-septal region were studied after sagittal and axial sections of the brains. Measurements were compared using F and Student t tests. The correlations between anterior-posterior diameter of the interventricular foramen / anterior-posterior diameter of the fornix column, and between anterior-posterior diameter of the interventricular foramen / length of the rostral lamina were performed by Pearson index test. RESULTS: There was no statistically significant difference in measurements performed in both hemispheres (p<0.05). Positive correlations were observed between the anterior-posterior diameter of the interventricular foramen / anterior-posterior diameter of the fornix column (R = 0.35), and between the anterior-posterior diameter of the interventricular foramen / length of the rostral lamina (R = 0.23). CONCLUSION: Rostral lamina was observed in all brains. It was possible to perform an endoscopic fenestration in the rostral lamina, communicating safely the lateral ventricle with a polygonal subcallosal cistern.

Automatic measurement of midline shift on deformed brains using multiresolution binary level set method and Hough transform.

Midline shift (MLS) is an important quantitative feature clinicians use to evaluate the severity of brain compression by various pathologies. The midline consists of many anatomical structures including the septum pellucidum (SP), a thin membrane between the frontal horns (FH) of the lateral ventricles. We proposed a procedure that can measure MLS by recognizing the SP within the given CT study. The FH region is selected from all ventricular regions by expert rules and the multiresolution binary level set method. The SP is recognized using Hough transform, weighted by repeated morphological erosion. Our system is tested on images from 80 patients admitted to the neurosurgical intensive care unit. The results are evaluated by human experts. The mean difference between automatic and manual MLS measurements is 0.23 ± 0.52 mm. Our method is robust and can be applied in emergency and routine settings.

Transseptumpellucidumrostrostomy: anatomical considerations and neuroendoscopic approach / Transseptopelucidorostrostomia: considerações anatômicas e abordagem neuroendoscópica

PURPOSE: Verify the presence of the rostral lamina of the corpus callosum, and set parameters for neuroendoscopy. METHODS: Relationship of the floor of the frontal horn of lateral ventricle and the hypothalamic-septal region were studied after sagittal and axial sections of the brains. Measurements were compared using F and Student t tests. The correlations between anterior-posterior diameter of the interventricular foramen / anterior-posterior diameter of the fornix column, and between anterior-posterior diameter of the interventricular foramen / length of the rostral lamina were performed by Pearson index test. RESULTS: There was no statistically significant difference in measurements performed in both hemispheres (p<0.05). Positive correlations were observed between the anterior-posterior diameter of the interventricular foramen / anterior-posterior diameter of the fornix column (R = 0.35), and between the anterior-posterior diameter of the interventricular foramen / length of the rostral lamina (R = 0.23). CONCLUSION: Rostral lamina was observed in all brains. It was possible to perform an endoscopic fenestration in the rostral lamina, communicating safely the lateral ventricle with a polygonal subcallosal cistern.

OBJETIVO: Verificar a presença da lâmina rostral do corpo caloso e padronizar parâmetros para a realização de neuroendoscopia. MÉTODOS: A relação do assoalho do corno frontal do ventrículo lateral e a região hipotálamo-septal lateral foi estudada através de secções sagitais e axiais dos cérebros. As medidas foram comparadas utilizando os testes F e t-Student. As correlações entre diâmetro ântero-posterior do forame interventricular / diâmetro ântero-posterior da coluna do fornix, e entre o diâmetro ântero-posterior do forame interventricular / comprimento da lâmina rostral foram estudadas pelo teste de Pearson. RESULTADOS: Não houve diferença estatisticamente significante nas medidas realizadas em ambos hemisférios (p <0.05). Correlações positivas foram observadas entre diâmetros ântero-posteriores do forame interventricular / coluna do fornix (R = 0.35), os diâmetros ântero-posteriores do forame interventricular / comprimento da lâmina rostral (R = 0.23). CONCLUSÃO: A lâmina rostral foi observada em todos espécimes. Foi possível realizar uma fenestração endoscópica na lâmina rostral, comunicando com segurança o ventrículo lateral a uma cisterna poligonal subcalosa.

Septal vein symmetry: implications for endoscopic septum pellucidotomy.

BACKGROUND: Endosopic septum pellucidotomy is used for treating patients with unilateral and specific types of bilateral hydrocephalus. The ideal location for septostomy is controversial; however, an avascular region is preferred. OBJECTIVE: As the septal veins (SVs) are viewed only from one side, we studied the symmetry of the SVs in an attempt to define a safe area for septostomy. METHODS: Sixteen cadaver brains were dissected. The septum pellucidum was exposed bilaterally and divided into 3 regions. SVs of both sides were evaluated according to number, size, distribution, and location relative to common markers on both sides. RESULTS: Each side included 1 to 7 large veins (mean ± standard deviation, 2.3 ± 1.4), 0 to 3 small veins (2.05 ± 1.73), and a total of 2 to 7 veins (4.35 ± 1.53). Of the large veins, 88% were located in the anterior septal region (anterior to the foramen of Monro). Among the 10 brains that were extensively dissected, 90% had asymmetric SVs (either in the number of large veins or in the existence of any veins) in at least 1 of the septal regions, and 50% of brains had asymmetric SVs in the anterior region. CONCLUSION: Distribution of the SVs is asymmetric in most cases. We recommend septostomy be performed at the anterior area of the middle septal region, at the level of the foramen of Monro, mid-height between the corpus callosum and fornix. Careful evaluation of preoperative images and thorough coagulation at the septostomy site are essential to avoid injury to a contralateral large SV.

Technical considerations of endoscopic septostomy using a biportal approach in a case of hydrocephalus associated with tuberous sclerosis.

INTRODUCTION: We report herein the technical considerations for endoscopic septostomy in a case of hydrocephalus associated with tuberous sclerosis. CASE REPORT: A 17-year-old boy presented with visual and gait disturbances. Computed tomography revealed an intraventricular mass obstructing the foramen of Monro bilaterally and marked hydrocephalus. First, we planned a ventriculo-peritoneal shunt with endoscopic septostomy using a biportal approach to resolve the hydrocephalus. Guidance by a rigid endoscope inserted into the anterior horn of the left lateral ventricle allowed us to easily and safely perform septostomy using the fiberscope inserted into the anterior horn of the right lateral ventricle. CONCLUSION: A biportal approach such as the dual endoscopic technique is useful in the treatment of complicated intraventricular lesions with loss of midline structures.

Genomic anatomy of the hippocampus.

Availability of genome-scale in situ hybridization data allows systematic analysis of genetic neuroanatomical architecture. Within the hippocampus, electrophysiology and lesion and imaging studies demonstrate functional heterogeneity along the septotemporal axis, although precise underlying circuitry and molecular substrates remain uncharacterized. Application of unbiased statistical component analyses to genome-scale hippocampal gene expression data revealed robust septotemporal molecular heterogeneity, leading to the identification of a large cohort of genes with robust regionalized hippocampal expression. Manual mapping of heterogeneous CA3 pyramidal neuron expression patterns demonstrates an unexpectedly complex molecular parcellation into a relatively coherent set of nine expression domains in the septal/temporal and proximal/distal axes with reciprocal, nonoverlapping boundaries. Unique combinatorial profiles of adhesion molecules within these domains suggest corresponding differential connectivity, which is demonstrated for CA3 projections to the lateral septum using retrograde labeling. This complex, discrete molecular architecture provides a novel paradigm for predicting functional differentiation across the full septotemporal extent of the hippocampus.