Ultrasound measurement of the fetal cavum septi pellucidi

Revisiting the Implications of a Wide or Narrow Fetal Cavum Septi Pellucidi

OBJECTIVES

To investigate short-term neonatal developmental outcomes in fetuses with an isolated wide or narrow cavum septi pellucidi (CSP) using new reference ranges.

METHODS

A cross-sectional study on fetuses at 16 + 0 to 36 + 6 weeks of gestation between December 2020 and January 2022. CSP width reference ranges were constructed from low-risk pregnancies. Wide and narrow CSPs were defined as measurements above the 95th percentile and below the 5th percentile, respectively. For the primary outcome fetuses with normal neurosonograms were included. Neonatal developmental outcomes were assessed using the Survey of Well-being of Young Children (SWYC).

RESULTS

A total of 352 fetuses were included in this study, of whom 138 were healthy and had uncomplicated neonatal outcomes. These fetuses constituted the control group and were used to construct the CSP width reference ranges. Of 185 fetuses in the neurosonography group, 9.7% had wide and 7.6% had narrow CSPs, of whom 33.3% and 22.2%, respectively, scored below the SWYC threshold for expected developmental milestones, a rate similar to that reported in the general population.

CONCLUSIONS

The presence of a prenatally isolated wide or narrow CSP does not appear to increase the risk of neonatal neurodevelopmental delay.

Obliterated cavum septi pellucidi: is it always a benign finding? A case report and narrative review of the literature

OBJECTIVE

The septum pellucidum is a virtual cavity located at the anterior part of the brain midline, which only in fetal life has a certain amount of fluid inside. The presence of an obliterated cavum septi pellucidi (oCSP) in the prenatal period is poorly described in the literature but, nevertheless, it constitutes an important clinical dilemma for the fetal medicine specialist in terms of significance and prognosis. Moreover, its occurrence is increasing maybe because of the widespread of high-resolution ultrasound machine. The aim of this work is to review the available literature regarding the oCSP along with the description of a case-report of oCSP with an unexpected outcome.

METHODS

A search of the literature through Pubmed was performed up to December 2022 with the aim to identify all cases of oCSP previously described, using as keywords "cavum septi pellucidi," "abnormal cavum septi pellucidi," "fetus," and "septum pellucidum." Along with the narrative review, we describe a case-report of oCSP.

RESULTS

A 39 years old woman was diagnosed with a nuchal translucency between the 95° and 99° centile in the first trimester and an oCSP and "hookshaped" gallbladder at 20 weeks. Left polymicrogyria was found at fetal magnetic resonance imaging (MRI). Standard karyotype and chromosomal microarray analysis (CMA) were normal. After birth, the newborn presented signs of severe acidosis, untreatable seizures and multiorgan failure leading to death. A targeted gene analysis of the epilepsy panel revealed the presence of a de novo pathogenic variant involving the PTEN gene. The literature review identified four articles reporting on the oCSP of which three were case report and one was a case-series. The reported rate of associated cerebral findings is around 20% and the rate of adverse neurological outcome is around 6%, which is higher than the background risk of the general population.

CONCLUSIONS

This case-report and review of the literature shows that oCSP is a clinical entity poorly described so far and that, despite the generally good prognosis, it requires caution in counseling. The diagnostic work-up should include neurosonography while fetal MRI may be always indicated for non-isolated cases only, depending on local facilities. Targeted gene analysis or whole exome sequencing may be indicated for non-isolated cases.

Modeling fetal cavum septum pellucidi width by quantile regression at 18-34 weeks of gestation: A prospective cross-sectional study

OBJECTIVE

Develop charts for cavum septum pellucidi (CSP) following a standardized methodology and using quantile regression. The secondary objective was to assess the influence of fetal gender on the generated reference curves.

METHODS

In a cross-sectional prospective study 453 low-risk singleton pregnancies were evaluated at a gestational age interval between 18 and 34 weeks. The width of CSP were measured on ultrasound images using a standardized technique and their changes were evaluated by quantile regression as a function of gestational age (GA) interval or head circumference (HC). Differences between sex were evaluated.

RESULTS

The measurement of CSP significantly increased with gestation and HC. Linear models better described the changes of CSP with GA and HC. The fits of CSP width with GA and HC were not significantly different. Male fetuses showed significantly higher CSP width when compared to female fetuses (u = 2.973; p = 0.005).

CONCLUSIONS

We generated prospective nomograms of fetal CSP development using quantile regression and following a strict standardized methodology. These new charts may be useful to better identify abnormal cases at higher risk of associated anomalies. Further our findings underline the potential effect of gender in developing fetal brain.

Comparison of Cavum Septum Pellucidum Size in Euploid and Aneuploid Fetuses

OBJECTIVE

 The aim of the present study is to compare the cavum septum pellucidi (CSP) z-score in euploid and aneuploid fetuses and to investigate the performance of the CSP width/length and CSP width/biparietal diameter (BPD) ratios as a diagnostic marker in aneuploidy.

METHODS

 A total of 54 patients, 20 aneuploid and 35 euploid fetuses, between 18 and 37 weeks of gestation, were included in this retrospective study. The CSP width z-score was compared between the two groups. Receiver operating characteristic (ROC) curves were calculated for the CSP width/length and CSP width/BPD ratios to predict aneuploidy.

RESULTS

 The median CSP width was 4.8 mm (range, 1.8 to 8.5 mm) in the euploid group, and 5.4 mm (range 3.1 to 8.4 mm) in the aneuploid group. Cavum septum pellucidi width z-score, CSP width/length ratio, and CSP width/BPD ratio were significantly higher in fetuses with aneuploidy than in fetuses with normal karyotype (p = 0.001; p = 0.013; p = 0.028). In the ROC analysis, the CSP width/length ratio had the optimal cutoff value of 0.59, with 72.0% sensitivity and 58.0% specificity, and for the CSP width/BPD ratio, the cutoff value was 0.081 with 83.0% sensitivity and 61.0% specificity for detection of aneuploidy.

CONCLUSION

 CSP width z-score was found to be increased in aneuploid fetuses. The CSP width /BPD ratio can be used as a new marker for predicting aneuploidy.

Obliterated cavum septi pellucidi: Clinical significance and role of fetal magnetic resonance

INTRODUCTION

The objective of this study was to describe a cohort of fetuses with an ultrasound prenatal diagnosis of obliterated cavum septi pellucidi (oCSP) with the aim to explore the rate of associated malformations, the progression during pregnancy and the role of fetal magnetic resonance imaging (MRI).

MATERIAL AND METHODS

This was a retrospective multicenter international study of fetuses diagnosed with oCSP in the second trimester with available fetal MRI and subsequent ultrasound and/or fetal MRI follow-up in the third trimester. Where available, postnatal data were collected to obtain information on neurodevelopment.

RESULTS

We identified 45 fetuses with oCSP at 20.5 weeks (interquartile range 20.1-21.1). oCSP was apparently isolated at ultrasound in 89% (40/45) and fetal MRI found additional findings in 5% (2/40) of cases, including polymicrogyria and microencephaly. In the remaining 38 fetuses, fetal MRI found a variable amount of fluid in CSP in 74% (28/38) and no fluid in 26% (10/38). Ultrasound follow-up at or after 30 weeks confirmed the diagnosis of oCSP in 32% (12/38) while fluid was visible in 68% (26/38). At follow-up MRI, performed in eight pregnancies, there were periventricular cysts and delayed sulcation with persistent oCSP in one case. Among the remaining cases with normal follow-up ultrasound and fetal MRI findings, the postnatal outcome was normal in 89% of cases (33/37) and abnormal in 11% (4/37): two with isolated speech delay, and two with neurodevelopmental delay secondary to postnatal diagnosis of Noonan syndrome at 5 years in one case and microcephaly with delayed cortical maturation at 5 months in the other.

CONCLUSIONS

Apparently isolated oCSP at mid-pregnancy is a transient finding with the visualization of the fluid later in pregnancy in up to 70% of cases. At referral, associated defects can be found in around 11% of cases at ultrasound and 8% at fetal MRI indicating the need for a detailed evaluation by expert physicians when oCSP is suspected.

Algorithmic approach to neuroradiological diagnosis with pre-natal MRI: non-visualization of the fetal cavum septi pellucidi on mid-trimester screening ultrasound

ADVANCES IN KNOWLEDGE

A systematic approach by the radiologist to analysis of imaging and other clinical data in the fetus with absent septal leaflets suspected on ultrasound will improve diagnostic efficiency, accuracy, and pre-natal counselling.

Fetal cavum septum pellucidum nomogram and its relationship with fetal Doppler: a prospective study of a Turkish population

Aim: Septum pellucidum is a thin membrane with right and left leaves, and cavum septum pellucidum (CSP) is formed in the intermembrane region. This study investigates CSP nomogram dimensions for all trimesters in the Turkish population. In addition, the relationship between fetal Doppler flow and CSP size was investigated in this study. Methods: This study was designed as a prospective cohort between 2019-2020. Pregnant women between 19-42 weeks who were followed up at XXX, Department of Obstetrics and Gynecology were included in the study. (blind review) Results: A total of 517 fetuses meeting our criteria were included in this prospective study. In the second trimester (19-28 weeks) CSP width (4.12±0.88 vs. 4.91±1.42, p < 0.001) and length (7.95±1.04 vs. 9.48±2.19, p < 0.001) were significantly higher than in the third trimester (28-42 weeks). While the mean CSP width increased up to 32th weeks, there was no clear increase-decrease pattern between 32th-38th weeks, and it was observed to decrease after 38th weeks. The mean CSP length increased up to 29th weeks, while there was no clear increase-decrease pattern between 29th-38th weeks, but decreased after 38th weeks. While a significant correlation was observed between gestational week and CSP width (r = 0.118, p = 0.010), there was no significant correlation between CSP length (r = 0.086, p =0.062). A significant correlation was observed between biparietal diameter (BPD) and CSP width (r = 0.180, p < 0.001) and length (r = 0.202, p < 0.001), but not with head circumference (HC). There was a significant correlation between middle cerebral artery (MCA) systolic/diastolic ratio (S/D) (r = 0.185, p < 0.001), pulsatility index (PI) (r = 0.210, p < 0.001) and resistive index (RI) (r = 0.233, p < 0.001) and CSP length, but not with CSP width. Conclusion: Turkish population fetal CSP nomogram is presented in this study. Fetal middle cerebral artery Doppler measurements (S/D, PI, and RI) showing cerebral blood flow correlate with CSP length, but not with CSP width. There was no correlation between fetal umbilical artery Doppler measurements and CSP sizes. The results pave the way for population-based studies with much larger samples.

Cavum septum pellucidum nomogram during the second trimester of pregnancy

This study aimed to determine cavum septum pellucidum (CSP) nomogram values between 15-28 weeks of gestation. Routine biometric measurements and CSP width were measured by transabdominal ultrasonography in 6042 structurally normal foetuses between 15-28 weeks of gestation. Distribution of CSP width by the week of pregnancy and percentile values were calculated. The mean week of gestation (GW) was 21 ± 1.7, and the mean biparietal diameter (BPD) was 50.2 ± 5.8 mm. The CSP width range was 1.6-7.7 mm at 15-28 weeks, and the mean CSP width was 4.1 ± 0.8 mm. CSP width was found to have a significant correlation between a gestational week (CSP = GW X 0.2705-1.6121; R = 0.62; p < .01) and BPD (CSP = BPD X 0.0859-0.273; R = 0.651; p 0.01). CSP width was found to differ significantly according to gestational weeks, and percentile distributions were calculated. Between 15 and 28 weeks of gestation, the 95th percentile values of CSP width were found to be 3.7-7 mm. Our study was determined that CSP width increased linearly between 15-28 weeks of gestation. For this reason, we think that it would be more appropriate to use CSP width percentile values in the examination of the foetus. Impact statementWhat is already known on this subject? The cavum septum pellucidum can be easily identified and evaluated by ultrasonography after 18 weeks of pregnancy. CSP can be associated with severe brain anomalies if it is not visualised or deformed. Moreover; large CSP may be associated with chromosomal abnormalities.What do the results of this study add? Our study showed that CSP width increased linearly between 15-28 weeks of gestation. CSP width was found to differ significantly according to gestational weeks, and between 15 and 28 weeks of gestation, the 95th percentile values of CSP width were found to be 3.7-7 mm.What are the implications of these findings for clinical practice and/or further research? We reported that it would be more appropriate to use CSP percentile values according to the gestational week in the definition of abnormal CSP.

Reference Ranges for Corpus Callosum and Cavum Septi Pellucidi Biometry on Prenatal Ultrasound: Systematic Review and Meta-Analysis

We conducted a systematic review and meta-analysis of published nomograms for fetal corpus callosum and cavum septi pellucid biometry. A structured literature search was conducted to identify studies that reported normal measurements of the fetal corpus callosum and cavum septi pellucidi. Random effects metaanalysis was used to calculate normal ranges, and reference curves are provided. The quality assessment demonstrated that there was generally poor reporting regarding maternal characteristics and neonatal outcomes. Our findings emphasize that standardization of research protocols and publishing criteria for normal biometric ranges is needed.

Fetal Brain Anatomy

"Fetal brain development has been well studied, allowing for an ample knowledge of the normal changes that occur during gestation. Imaging modalities used to evaluate the fetal central nervous system (CNS) include ultrasound and MRI. MRI is the most accurate imaging modality for parenchymal evaluation and depiction of developmental CNS anomalies. The depiction of CNS abnormalities in a fetus can only be accurately made when there is an understanding of its normal development. This article reviews the expected normal fetal brain anatomy and development during gestation. Additional anatomic structures seen on brain imaging sequences are also reviewed."

Methodological quality of fetal brain structure charts for screening examination and targeted neurosonography: a systematic review

Introduction: The methodological quality of fetal brain charts has not been critically appraised yet. Material and methods: MEDLINE, EMBASE, CINAHL and the Web of Science databases were searched electronically up to December 31, 2020. The primary outcome was to evaluate the methodology of the studies assessing the growth of fetal brain structures throughout gestation. A list of 28 methodological quality criteria divided into three domains according to “study design”, “statistical and reporting methods”, and “specific relevant neurosonography aspects” was developed in order to assess the methodological appropriateness of the included studies. The overall quality score was defined as the sum of low risk of bias marks, with the range of possible scores being 0–28. This quality assessment was applied to each individual study reporting reference ranges for fetal brain structures. Results: Sixty studies were included in the systematic review. The overall mean quality score of the studies included in this review was 51.3%. When focusing on each of the assessed domains, the mean quality score was 53.7% for “study design”, 54.2% for “statistical and reporting methods” and 38.6% for “specific relevant neurosonography aspects”. The sample size calculation, the correlation with a postnatal imaging evaluation and the whole fetal brain assessment were the items at the highest risk of bias for each domain assessed, respectively. The subgroup analysis according to different anatomical location showed the lowest quality score for ventricular and periventricular structures and the highest for cortical structures. Conclusions: Most previously published studies reporting fetal brain charts suffers from poor methodology and are at high risk of biases, mostly when focusing on neurosonography issues. Further prospective longitudinal studies aiming at constructing specific growth charts for fetal brain structures should follow rigorous methodology to minimize the risk of biases, guarantee higher levels of reproducibility and improve the standard of care.

Fetal intracranial structures: differences in size according to sex

OBJECTIVES

We aimed to compare gender difference on sizes of some structures in the brain of normal male and female fetuses between 20 and 22 week gestations.

METHODS

A total of 300 female and 300 male singleton pregnancies with low risk were included in the study. Biparietal diameter, head circumference, transcerebellar diameter, cisterna magna, nuchal fold thickness, anterior and posterior horn of lateral ventricles, length and width of cavum septum pellucidum were measured transabdominally. Mean±SD values were calculated and comparison of measurements were done between male and female fetuses. Kolmogorov-Smirnov and independent samples t-test were used for statistical analysis. A value of p<0.05 were accepted as statistically significant.

RESULTS

We determined statistically significant difference in sizes of some structures of the brain of male and female fetuses. Mean±SD value of cavum septi pellucidi width was 3.38±0.61 and 3.85±0.96 in female and males, respectively (p<0.05). Male fetuses were also found to have larger anterior (1.92±0.30 vs. 1.58±0.26, p<0.0001) and posterior horn of lateral ventricles (6.00±0.87 vs. 5.53±1.17, p<0.05).

CONCLUSIONS

Difference in sizes of some structures of the brain starts in fetal life. This finding may be important in evaluating the intracranial structures more precisely. These results may also give a contribution to the understanding physiological and pathologic differences between males and females.

Reference intervals and reliability of cavum septi pellucidi volume measurements by three-dimensional ultrasound between 19 and 24 weeks' gestation

OBJECTIVES

A small or a large cavum septi pellucidi (CSP) during routine second trimester sonography may suggest abnormal cerebral development. Therefore, determination of CSP volume with three-dimensional (3D) ultrasound can be valuable. For this purpose, we sought to evaluate the reference ranges and measurement reliability of CSP volume by Virtual Organ Computer-aided AnaLysis (VOCAL).

METHODS

VOCAL software was used to calculate the CSP volume from transabdominal multiplanar datasets of 99 structurally normal fetal ultrasound examinations between 19 and 24 weeks of gestation. Linear regression was utilized to determine reference intervals for CSP volumes as a function of gestational week (GW). Agreement among three evaluators with different proficiency levels (obstetrics and gynecology resident, perinatology fellow, and perinatologist) was assessed, using intraclass correlation coefficients (ICC) and 95% confidence intervals (CI).

RESULTS

CSP volume and gestational age was positively correlated (r2=0.383, p=0.0001), represented by the following equation: 0.058-(1.016 x GW). Interobserver agreement between perinatologist and fellow was relatively high (ICC, 0.78; 95% CI, 0.70-0.85), whereas limited ultrasound experience (resident) was associated with fair agreement with non-novice observers (ICC for resident and perinatologist, 0.50; 95% CI, 0.29-0.65 and ICC for resident and fellow, 0.57; 95% CI, 0.38-0.71).

CONCLUSIONS

Reference ranges of CSP volumes using VOCAL from 19 0/6 through 24 6/7 weeks of gestation were established. A first-degree model to estimate CSP volume as a function of gestational age was also constructed. CSP volumetry seems reliable when evaluated by an examiner with particular 3D sonography experience.

The normal fetal Cavum Septum Pellucidum in MR imaging - New biometric data

BACKGROUND AND PURPOSE

The cavum septum pellucidum (CSP) is an important landmark in the evaluation of the fetal neural axis. A deviation from the ultrasonic normal values may be associated with unfavorable outcomes, and a normal CSP provides reassurance of normal central forebrain development. Today, there is biometric data regarding the normal values for the width of the CSP in fetal ultrasound, but there is no such data for fetal MRI. The aim of this study was to determine the normal values for the measurements of the fetal CSP on MRI.

MATERIALS AND METHODS

We retrospectively examined 307 MRI scans of fetuses between 25 and 41 weeks gestation. Data was collected from the electronic charts of patients who underwent fetal MR imaging at a single tertiary Medical Center. The width and length of the CSP were measured in the axial plane, and the width and height were measured in the coronal plane.

RESULTS

The width and height of the CSP in fetuses tend to decrease starting from the 27th week of gestation onwards. High levels of intraobserver and interobserver agreements were calculated. The sex of the fetus does not appear to influence the biometry of the CSP.

CONCLUSION

This study provides MRI reference values for the dimensions of the CSP starting from the 25th week of gestation. Knowing the normal values for MRI could provide valuable information for researchers and in the decision-making process in patient's consultations.

Analysis of 270 fetuses with non-visualization of cavum septi pellucidi and vergae on in-utero magnetic resonance imaging

OBJECTIVE

To analyze a large retrospective cohort of fetuses in which the cavum septi pellucidi and vergae (CSPV) was not present or was not in its expected position on in-utero magnetic resonance imaging (iuMRI), in order to describe the possible causes of that finding and provide a diagnostic approach to assess such cases in clinical practice using iuMRI.

METHODS

This was a retrospective study of fetuses that underwent iuMRI at a single institution, over an 18-year period (2000-2017 inclusive), in which the CSPV was not visualized or was abnormal. All iuMRI studies were reviewed and classified as CSPV being not present, disrupted (visualization of remnants of an otherwise normally placed CSPV) or malpositioned (CSPV was present, but not in its expected position). We describe the neuropathology present in each of the groups.

RESULTS

Of the 270 fetuses that met the inclusion criteria, the CSPV was described as malpositioned in 150 (56%), disrupted in 71 (26%) and not present in 49 (18%). Malpositioned CSPV was present only in cases with agenesis of the corpus callosum and three specific patterns of malpositioning are described, depending on the location of the leaflets of the CSPV and fornix. Disrupted CSPV was present in fetuses with hydrocephalus or pathologies causing extensive brain parenchymal injury. Not present CSPV was found in cases with holoprosencephaly or when absence of the CSPV appeared to be an isolated finding.

CONCLUSION

We have described a large cohort of fetuses with non-visualization of a normal CSPV on iuMRI and present a categorical classification system based on the CSPV being not present, disrupted or malpositioned. This approach should help in the diagnosis of the underlying cause of a CSPV abnormality. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Enlarged cavum septi pellucidi Z-scores in fetuses with trisomy 18

Objective: We aim to establish a formula calculating the fetal cavum septi pellucidi (CSP) width Z-scores and compare CSP width between the normal fetus and 18-trisomy fetus.Methods: In this retrospective study, 608 normal fetuses and 71 fetuses with the 18-trisomy syndrome were included. Z-scores were calculated after the acquisition of CSP images. Normal CSP width Z-scores formulae were constructed based on gestational age (GA) by performing a standard regression analysis followed by weighted regression of absolute residual values. Subsequently, the Mann-Whitney U test was used to compare the CSP width Z-scores between normal and 18-trisomy groups.Results: Formulae calculating CSP width Z-scores were constructed. Normal fetal CSP width was significantly correlated with GA (R² = 0.50, p < .01). In 18-trisomy group, 69% (34/49) fetuses displayed enlarged fetal CSP width and CSP width Z-scores (p < .01).Conclusions: The CSP width Z-scores formulae established in the current study can provide a quantitative basis for the prenatal diagnosis of 18-trisomy syndrome. Enlarged CSP width Z-score may serve as a novel prenatal diagnostic marker for the 18-trisomy syndrome.

Normal appearances and dimensions of the foetal cavum septi pellucidi and vergae on in utero MR imaging

Purpose

The aim of this study is to provide normative data about the appearances and dimensions of the cavum septi pellucidi and vergae (CSPV) on in utero MR (iuMR) imaging in second and third trimester foetuses.

Methods

Two hundred normal foetuses (from a low-risk pregnancy, with normal ante-natal USS findings and no intracranial abnormality of iuMR) had iuMR imaging between 18 and 37 gestational weeks (gw). The anatomical features on those studies were compared with published atlases of post-mortem foetal brains. The length, width and volume of the CSPV were measured in all foetuses.

Results

The anatomy of the CSPV and its relationship with the corpus callosum and the fornices on iuMR imaging was comparable with post-mortem data at all gestational ages studied. The length of the CSPV increased throughout pregnancy, whereas the width and volume of CSPV reached a maximum between 29 and 31 gw and then showed a reduction later in pregnancy.

Conclusion

The iuMR imaging features of the CSPV and its close anatomical relations closely correspond to post-mortem data. The CSPV was patent in all cases but we have shown that closure commences in the midpart of the third trimester and advances in a posterior to anterior direction.

Electronic supplementary material

The online version of this article (10.1007/s00234-020-02364-5) contains supplementary material, which is available to authorized users.

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.

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.

Ultrasound and MR Imaging of the Normal Fetal Brain

Prenatal imaging of the central nervous system has proven to be essential in the detection of anomalies to guide counseling and intrauterine and postnatal therapies. However, understanding the appearance of normal is important because the fetal brain changes dramatically during the pregnancy. In this review, normal imaging of the brain with ultrasound and MR imaging is discussed. The initial section stresses techniques for both modalities. The second section describes ultrasound and MR landmarks in a normal fetal brain.

Dilated cavum septi pellucidi as sole prenatal ultrasound defect: Case-base analysis of fetal outcomes

OBJECTIVES

This retrospective study was undertaken to examine fetuses with dilated cavum septi pellucidi (CSP) as an isolated finding and to identify factors impacting postnatal outcomes.

STUDY DESIGN

Fully documented cases of dilated CSP as a sole prenatal defect were selected for study. Recorded data included serial sonographic examinations, fetal MRI studies, chromosomal testing, screening for infection, and postnatal follow-up. Fetal subjects were further stratified by gender, gestational age at diagnosis (<28 w or ≥28 w), CSP width at diagnosis (<10 mm or ≥10 mm), evolution at term (persistent vs non-persistent CSP), and postnatal MRI diagnosis (presence/absence of CSP cyst). Chi-square or Fisher's exact test (as appropriate) was used to compare categorical variables and patient groups.

RESULTS

A total of 48 fetuses met our inclusion criteria, none exhibiting chromosomal abnormalities. Six (12.5%) of these 48 were subsequently diagnosed with neurodevelopmental delays. However, such delays were unrelated to any categorical variable listed above (p > 0.05).

CONCLUSIONS

Dilated CSP as an isolated prenatal finding by ultrasound or MRI carries a low risk of chromosomal abnormalities but a high risk of neurodevelopmental delay. These perils should be adequately conveyed to the parents of such infants.

Fetal brain development in diabetic pregnancies and normal controls

Objective:

To compare the fetal brain structures assessed in routine sonographic scans during the second and third trimesters in diabetic and normal pregnancies.

Methods:

In this retrospective study, we measured the head circumference (HC), the transversal diameter of the cerebellum (TCD) and the sizes of the cisterna magna (CM), the cavum septi pellucidi (CSP) and the lateral ventricles (LV) in stored sonographic scans between 20 and 41 weeks of gestation. We compared 231 fetuses of diabetic mothers (diabetic group) to 231 fetuses of normal pregnancies (control group) matched by gestational age. The diabetic group was divided into three subgroups: pre-existing maternal diabetes, diet-controlled gestational diabetes and insulin-dependent gestational diabetes.

Results:

The mean widths of the CSP and LV were larger in fetuses of diabetic mothers in comparison with the controls (P<0.001, P<0.001; respectively). The sizes of HC, CM and TCD were similar in both groups. These results were consistent across the three subgroups.

Conclusions:

Diabetes is associated with altered fetal brain development. We would like to introduce the increased widths of CSP and LV as potential markers for gestational diabetes.

The relationship between cavum septum pellucidum and psychopathic traits in a large forensic sample

Cavum septum pellucidum (CSP) is a neuroanatomical variant of the septum pellucidum that is considered a marker for disrupted brain development. Several small sample studies have reported CSP to be related to disruptive behavior, persistent antisocial traits, and even psychopathy. However, no large-scale samples have comprehensively examined the relationship between CSP, psychopathic traits, and antisocial behavior in forensic samples. Here we test hypotheses about the presence of CSP and its relationship to psychopathic traits in incarcerated males (N = 1432). We also examined the incidence of CSP in two non-incarcerated male control samples for comparison (N = 208 and 125). Ethnic and racial composition was varied with a mean age of 33.1, and an average IQ of 96.96. CSP was evaluated via structural magnetic resonance imaging. CSP was measured by length (number of 1.0 mm slices) in continuous analyses, and classified as absent (0) or present (1+ mm), as well as by size (absent (0), small (1-3), medium (4-5), or large (6+ mm)) for comparison with prior work. The Wechsler Adult Intelligence Scale (WAIS-III), Structured Clinical Interview (SCID-I/P), and Hare Psychopathy Checklist-Revised (PCL-R) were used to assess IQ, substance dependence, and psychopathy, respectively. CSP length was positively associated with PCL-R total, Factor 1 (interpersonal/affective) and Facets 1 (interpersonal) and 2 (affective). CSP was no more prevalent among inmates than among non-incarcerated controls, with similar distributions of size. These results support the hypotheses that abnormal septal/limbic development may contribute to dimensional affective/interpersonal traits of psychopathy, but CSP is not closely associated with antisocial behavior, per se.

Cavum septi pellucidi (CSP) ratio: a marker for partial agenesis of the fetal corpus callosum

OBJECTIVE

While complete agenesis of the corpus callosum is often suspected on fetal ultrasound due to absence of the cavum septi pellucidi (CSP), suspicion of partial agenesis of the corpus callosum (pACC) is a challenge since the CSP is almost always present. The aim of this study was to measure the length and width of the CSP and calculate the length-to-width ratio (CSP ratio), and compare these between fetuses with pACC and normal fetuses.

METHODS

In this retrospective case-control study, the length and width of the CSP were measured in the axial plane of the fetal head, and the CSP length-to-width ratio calculated, in 323 normal fetuses and in 20 fetuses with pACC between 20 and 34 weeks' gestation. From the normal population we constructed reference ranges in relation to biparietal diameter (BPD). For all fetuses we calculated Z-scores for the CSP ratio.

RESULTS

In the normal population, the length and width of the CSP increased with increasing BPD, while the CSP ratio decreased. The CSP was short (< 5^th centile) in 85% (17/20) of fetuses with pACC and wide (> 95^th centile) in 65% (13/20). The CSP ratio was small (< 5^th centile) in 95% (19/20) of pACC fetuses, with 16/20 (80%) having a ratio below an empirical cut-off of 1.5. Analysis of Z-scores showed that fetuses with pACC had a significantly smaller CSP ratio (P < 0.0001) compared with the normal population.

CONCLUSIONS

Fetuses with a normal-sized corpus callosum have a rectangular-shaped CSP, with a CSP ratio > 1.5 in the second half of gestation. Most fetuses with pACC have an abnormally shaped, wide and short CSP, with a decreased CSP ratio. This simple ratio has the potential to identify fetuses at high risk for pACC. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Enlarged Cavum Septi Pellucidi and Vergae in the Fetus: A Cause for Concern

OBJECTIVES

To investigate fetal cases identified at our institution to determine whether an enlarged cavum septi pellucidi or cavum vergae is associated with other fetal abnormalities and whether its presence warrants more detailed investigation of the fetus.

METHODS

In a retrospective study, 15 high- and low-risk patients undergoing prenatal sonography who had an enlarged cavum septi pellucidi or cavum vergae identified were reviewed. Data were collected for the sonographic study indication, gestation age at diagnosis of a prominent cavum, and associated anomalies. Follow-up outcome data regarding further imaging, karyotype, diagnosis of brain anomaly, and associated congenital abnormalities were obtained.

RESULTS

Fifteen patients met the inclusion criteria. Nine patients were identified as having a prominent cavum septi pellucidi, and 6 were identified as having a prominent cavum vergae. The mean gestational age ± SD was 22.7 ± 5.9 weeks. Eleven patients made it to delivery. Of the 15 patients, 4 were thought to have trisomy 21, and 13 had congenital anomalies. Outcomes included 10 major adverse outcomes, 4 cases with normal development or minor abnormalities, and 1 lost to follow-up. An isolated dilated cavum on prenatal sonography was seen in 5 cases: 1 with lissencephaly on a neonatal examination, 3 premature deliveries (1 demise, 1 hospice, and 1 normal), and 1 unknown.

CONCLUSIONS

Our cohort had many associated clinical anomalies: 3 confirmed trisomy 21 and 1 probable trisomy 21, 2 genetic disorders, and 10 major adverse outcomes, 5 of which were grave. Although we studied a small cohort, we conclude that an enlarged cavum septi pellucidi or cavum vergae warrants consideration of genetic counseling, which may include noninvasive prenatal testing (cell-free DNA), amniocentesis with microarray testing, or both.

Absent cavum septum pellucidum: a review with emphasis on associated commissural abnormalities

The cavum septum pellucidum (CSP) is an important fetal midline forebrain landmark, and its absence often signifies additional underlying malformations. Frequently detected by prenatal sonography, absence of the CSP requires further imaging with pre- or postnatal MRI to characterize the accompanying abnormalities. This article reviews the developmental anatomy of the CSP and the pivotal role of commissurization in normal development. An understanding of the patterns of commissural abnormalities associated with absence of the CSP can lead to improved characterization of the underlying spectrum of pathology.

Sonographic appearance of the cavum septum pellucidum et vergae in normal fetuses in the second and third trimesters of pregnancy

BACKGROUND

To characterize the cavum septum pellucidum et vergae (CSPV) in normal fetuses in the second to third trimester.

METHODS

The cavum septum pellucidum (CSP) and CSPV were investigated in 322 uncomplicated singleton pregnancies from 25 to 39 weeks' gestation. Visualization rate, width, and morphology of both CSP and cavum vergae (CV) were assessed by ultrasound and MRI.

RESULTS

The CSP and CSPV visualization rates were 100% and 7.8% (25/322), respectively. The mean widths were 6.3 ± 1.2 mm (3.4-10 mm) and 6.7 ± 1.0 mm (5.1-9 mm), respectively, with no significant correlation between width and gestational age (r = -0.108, p > 0.05 and r = -0.182, p > 0.05, respectively). In CSPV fetuses, the CV to CSP ratio was 1.004 ± 0.018 (0.967-1.033). All CSPVs were rectangular in the transverse plane and extended posteriorly beyond the midpoint of the brain.

CONCLUSIONS

Common features of CSPVs include (1) a rectangular morphology, (2) communication between the two cavities, (3) a CV width within the normal range for CSP, and (4) a CV-CSP ratio of 1. These findings may help distinguish normal from abnormal CSPV.

The cavum septi pellucidi in euploid and aneuploid fetuses

OBJECTIVE

To examine whether the cavum septi pellucidi (CSP) is larger in second- and third-trimester fetuses with chromosomal abnormalities than in euploid fetuses.

METHODS

This was a retrospective study utilizing stored two-dimensional images of second- and third-trimester fetuses between 18 and 40 weeks' gestation from three centers in Germany. The width of the CSP was measured by placing the calipers on the inner portion of its lateral borders. Two operators, both of whom were blinded to the fetal karyotype and to the measurements obtained by the other, measured the CSP width. The normal range in euploid fetuses was computed based on the biparietal diameter (BPD) by applying univariate regression analysis. The CSP width in euploid and aneuploid fetuses was transformed into Z-scores and compared using Student's t-test. Univariate regression analysis was used to determine the dependency of Z-score on head biometry.

RESULTS

The study population consisted of 406 singleton pregnancies, 267 with euploid fetuses, 81 with trisomy 21, 50 with trisomy 18 and eight with trisomy 13. In the euploid group, the mean CSP width was 4.5 (range, 1.8-7.4) mm. Regression analysis showed a significant dependency of CSP width on BPD (CSP width = 0.658 + (0.064 × BPD), r = 0.781, P < 0.0001; both parameters in mm). The mean CSP width increased from 3.2 to 7.1 mm for BPD values of 40 to 100 mm, respectively. In the groups of fetuses with trisomy 21, 18 and 13, mean CSP width was 5.7 (range, 2.8-10.5), 7.9 (range, 3.5-12.8) and 5.8 (range, 4.0-9.0) mm, respectively. In 42.0% of the fetuses with trisomy 21, CSP width was above the 95(th) centile. In trisomy 18 and 13, CSP width was above the 95(th) centile in 92.0% and 37.5% of cases, respectively.

CONCLUSION

A large CSP width should prompt a detailed ultrasound examination to further assess the risk for chromosomal abnormalities.

Prenatal diagnosis of down syndrome associated with right aortic arch and dilated septum cavi pellucidi

A 30-year-old woman with a normal first trimester Down syndrome screening attended our ultrasound unit for a 20-week scan. The most remarkable anomalies were the presence of a right aortic arch along with a dilated cavum septi pellucidi. In addition, the scan showed an atrioventricular canal and bilateral choroid plexus cysts. Fetal karyotype showed the existence of trisomy 21. A novel association between Down syndrome and dilated cavum septi pellucidi is reported and the relationship between DS and vascular rings is discussed.

Non-visualization of the cavum septi pellucidi is not synonymous with agenesis of the corpus callosum

OBJECTIVES

To describe a cohort of fetuses with non-visualization of the cavum septi pellucidi (CSP) without callosal agenesis and to assess the significance of this finding with respect to postnatal development.

METHODS

We reviewed the files of all patients referred because of suspected fetal supratentorial midline anomalies, and identified those fetuses with a diagnosis of non-visualization or obliteration of the CSP.

RESULTS

From an initial cohort of 114 patients we identified 23 cases. Mean ( ± SD) gestational age at referral was 24.5 ± 1.3 weeks; referral diagnoses (with more than one in some cases) included: non-visualization or an echogenic CSP (n = 18), suspected callosal anomaly (n = 5), other findings (n = 5). The fetuses were examined for the first time at the Fetal Neurology Clinic at a mean gestational age of 26.6 ± 3.1 weeks (range, 22-34 weeks; median, 27 weeks). In all of the fetuses the zone where fluid should have been observed was echogenic. In 17 fetuses this was an apparently isolated finding and in six it was associated with other findings, but only one fetus had associated malformations. Follow-up was available for 16 children at a mean age of 17.4 months (range, 4-36 months; median, 19.5 months). Normal development was reported in 14 children. One child had infantile hypotonia but normal developmental milestones and another had mild motor delay and language delay. These two children did not have associated anomalies at the prenatal scan.

CONCLUSION

Non-visualization of the CSP is not always associated with agenesis of the corpus callosum. When isolated it may be considered a variation of normal development.

Cerebral measurements made using cranial ultrasound in term Ugandan newborns

BACKGROUND

Few cUS studies of cerebral measurements are available for normal term infants. Normative data is important for evaluating cerebral structure size in symptomatic term infants and assessing preterm brain growth by term age.

OBJECTIVES

To (i) make linear measurements using cranial ultrasound (cUS) for major cerebral structures and intracranial spaces in normal newborn term infants, (ii) correlate these measurements with gestational age (GA), birth weight (BW), head circumference (HC), gender and within one infant (iii) examine inter/intra-observer variation, and (iv) compare these data with those currently available.

DESIGN, SETTING AND PATIENTS

Linear cUS measurements of major cerebral structures were made in well term-born Ugandan infants at Mulago University Hospital, Kampala. Correlations between the measurements and gender, HC, BW and GA were calculated. Intra- and inter-observer agreements were assessed.

RESULTS

Data from 106 infants (mean GA 39.20±1.4SD weeks) were analysed. Intra/inter-observer agreement was substantial/excellent. Significant correlations were found between HC and pons anterior-posterior diameter (p<0.01), corpus callosal (CC) length (p=0.02) and transverse cerebellar diameter (TCD, p<0.01) and between BW and CC length (p=0.02), vermis height (<0.01) and thalamo-occipital distance (p=0.03); no significant correlation was found with GA. Within infants CC length and TCD correlated significantly (p=0.019). Males had larger left ventricular indices than females (p=0.04). The data was similar to those from other populations.

CONCLUSIONS

These data provide reliable reference values for linear measurements of many cerebral structures made using cUS. The data agree well with those from other populations suggesting that cerebral size is similar in different ethnic groups.

Can syndromic macrocephaly be diagnosed in utero?

OBJECTIVES

To compare the outcomes of fetuses with apparently isolated macrocephaly and those with associated findings, and to compare prenatal findings with postnatal diagnoses in children with syndromic macrocephaly.

METHODS

We reviewed the files of all patients referred for suspected fetal macrocephaly, during a 10-year period from 2000, to a large prenatal diagnosis unit with expertise in fetal neurology counseling. Macrocephaly was defined as head circumference (HC) > 2 SDs of the norm. Patients with confirmed HC > 2 SD were identified and contacted, and their development was evaluated.

RESULTS

Adequate data for analysis were available for 98 patients, in 82 of whom the fetal macrocephaly was considered isolated (Group A), and in 16 of whom associated fetal anomalies were identified (Group B). Macrocephaly was diagnosed earlier in Group B patients (28.4 vs. 32.3 weeks, P = 0.069), and the HC in Group B patients was larger (Z-score 2.95 vs. 2.3, P < 0.001). From Group A there were 81 liveborn; one of whom was diagnosed as having infantile autism. From Group B, there were nine liveborn. The associated central nervous system findings, as demonstrated by ultrasound and magnetic resonance imaging, included mild ventriculomegaly, malformations of cortical development, callosal abnormalities, overdeveloped sulcation, large cavum septi pellucidi, large subarachnoid spaces, mega cisterna magna, periventricular pseudocyst, open operculum and vermian dysgenesis. Syndromic diagnosis was made in utero in five fetuses and after birth in three. In eight patients, associated malformations were confirmed after birth but a specific diagnosis was not reached.

CONCLUSIONS

When fetal macrocephaly is associated with other brain or systemic anomalies, syndromic macrocephaly can be diagnosed in utero. Fetuses with syndromic macrocephaly have a significantly larger HC, usually > 2.5 SD above the mean. Isolated macrocephaly, particularly when the HC is < 2.5 SD above the norm, may be clinically benign.

The cavum septi pellucidi: why is it important?

OBJECTIVE

The cavum septi pellucidi (CSP) is routinely imaged in the fetal brain during obstetric sonography; in fact, for well over a decade, assessment of the CSP has been considered part of the required elements of a standard examination of fetal morphology in guidelines developed by multiple specialty societies. Our objective is to present the 4 reasons why all practicing sonologists and sonographers should be familiar with this anatomic structure.

METHODS

Prenatal sonograms and magnetic resonance imaging examinations are used to review the following topics: terminology, embryology, and anatomy of the CSP; pitfalls in its identification; and a wide variety of abnormalities (predominantly relating to nonvisualization) associated with the CSP.

RESULTS

Embryologic development of the CSP is intimately associated with the corpus callosum (CC); thus, correct identification of the CSP essentially excludes complete agenesis of the CC. Absence of the CSP is associated with an extremely wide spectrum of neuroanatomic malformations: these range from the lethal entities of hydranencephaly and alobar holoprosencephaly; to the potentially serious but nonlethal entities of schizencephaly, porencephaly, basilar encephaloceles, severe hydrocephalus, and the less severe prosencephalic cleavage disorders (including syntelencephaly); to the normal variant, the rare and somewhat controversial entity of isolated septal deficiency. The value of noting that the absent CSP allows diagnosis of very subtle and easily overlooked abnormalities such as septo-optic dysplasia is presented.

CONCLUSIONS

Correct recognition of the CSP provides welcome reassurance of proper development of the central forebrain.

Normal sonographic development of the central nervous system from the second trimester onwards using 2D, 3D and transvaginal sonography

The developmental changes of the fetal central nervous system (CNS) during the second and third trimesters, specifically the brain, relate mostly to changes in size. However, other changes do occur in the fetal brain during the second and third trimester such as: the union of the cerebellar hemispheres, development of the corpus callosum (CC), and increasing complexity of the cerebral cortex. These changes follow a well-defined developmental timeline recognizable by sonography. The fetal neuroscan can be divided into a 'basic scan' which is performed transabdominally and a 'targeted Exam or neurosonogram' which uses a multiplanar approach, which preferably should be performed transvaginally. During the 'basic scan', several brain structures are imaged in addition to obtaining important biometric measurements. The 'neurosonogram' is a more extensive or detailed fetal study during which the emphasis is on the addition of coronal and sagittal planes. The easiest way to obtain these planes, if the fetus is in a cephalic presentation, is the transvaginal route. Three-dimensional (3D) sonography should, if possible, be performed transvaginally using the multiplanar approach. An added benefit of 3D sonography is the ability to display and render the volume in a variety of ways which may enhance the detection of pathology.

Columns of the fornix, not to be mistaken for the cavum septi pellucidi on prenatal sonography

OBJECTIVE

Visualization of the cavum septi pellucidi (CSP) is considered an integral part of the prenatal second-and third-trimester sonographic evaluations of the fetal neural axis. We have noted that another anatomic structure, the columns of the fornix, can be mistaken for the CSP and result in the missed diagnosis of agenesis of the corpus callosum.

METHODS

We describe a case in which the columns of the fornix were misinterpreted as representing the CSP during a sonographic evaluation at 18 weeks' gestation. After a follow-up sonogram at 35 weeks, agenesis of the corpus callosum was detected. A retrospective evaluation of the prevalence of forniceal columns was then performed in 100 consecutive sonograms of pregnancies between 18 and 24 weeks' gestation. A prospective study was then performed in 20 patients to determine the prevalence of visualization of the columns of the fornix.

RESULTS

In 86 of 100 patients, the columns of the fornix were retrospectively identified as discrete and separate structures from the CSP. When additional views were obtained prospectively in the forebrain, the fornix could be identified in all 20 patients.

CONCLUSIONS

The columns of the fornix may simulate the appearance of the CSP on second- and third-trimester sonograms. The distinction between these structures can be made because the columns of the fornix will show a linear reflection (3 lines) at their interface, whereas the CSP will appear as a fluid-filled triangular or rectangular fluid-filled space without a central line.

Structural linear measurements in the newborn brain: accuracy of cranial ultrasound compared to MRI

BACKGROUND

Structural size in the neonatal brain is of clinical importance. Cranial ultrasonography (cUS) is the primary method used for evaluating the neonatal brain and it is important to know whether linear measurements made using this technique are accurate.

OBJECTIVE

To compare linear measurements of different cerebral structures made from neonatal cUS and contemporaneous MRI.

MATERIALS AND METHODS

Preterm and term infants studies with cUS and MRI on the same day were studied. Linear measurements made using both techniques from many cerebral structures were compared using a paired t-test.

RESULTS

A total of 44 sets of scans from 26 preterm and 8 term infants were assessed. Small but significant differences between the cUS and MRI measurements (P<0.05) were found for the ventricular index, the posterior horn depth of the lateral ventricle, the extracerebral space and interhemispheric fissure, and the cortex of the cingulate gyrus. No significant differences were found for any other measurements.

CONCLUSION

Linear measurements from cUS are accurate for most neonatal cerebral structures. Significant differences compared to MRI were found for a few structures, but only for the cortex were the absolute differences marked and possibly of clinical importance.

Large cava septi pellucidi in schizophrenic patients, alcoholics, head-traumatized, and normal individuals: morpholgical features and forensic implications. A postmortem study

BACKGROUND

The enlarged cava septi pellucidi (CSP = 6 mm in length) have been reported as a reliable marker of an underlying neuropsychiatric disease or disorder. Differences in the dimensions of cava longer than 6 mm associated with a neuropsychiatric impairment could be of possible clinical and forensic significance.

METHODS

We obtained 479 brains from autopsied persons (310 males and 169 females, aged 22-89 years) and observed that 110 brains (75 males and 35 females) had CSP, of which the length of CSP was equal to or longer than 6 mm on 69 (49 males and 20 females) of them. These cava were classified into four groups depending on the past medical histories of the autopsied person: five without neuropsychiatric history (asymptomatic CSP), 25 schizophrenic patients, 22 alcoholics, and 17 with a past head trauma (symptomatic CSP).

RESULTS

The linear parameters of CSP (i.e. length, width) of the symptomatic and asymptomatic groups were measured and were statistically analyzed. Analysis revealed that the cava in the group of schizophrenic patients were significantly longer and wider.

CONCLUSIONS

Discriminant function analysis was used to derive a mathematical formula to classify CSP into one of the groups obtained based on width measurements of the cavum.

Ultrasound Imaging of Fetal Brain Abnormalities

Prenatal ultrasound evaluation of the fetal brain requires documentation of specific structures according to guidelines set by the American College of Radiology and the American Institute of Ultrasound in Medicine. Among these required structures are: cerebellum, cisterna magna, lateral cerebral ventricles, choroid plexus, midline falx, and cavum septum pellucidum. All these structures can be visualized in three crucial planes of imaging that include cisterna magna/cerebellum, cavum septum pellucidum, and ventricular atria. A systematic approach can be achieved by instituting a protocol that includes these three basic levels of imaging of the fetal head. These anatomical levels should be incorporated in daily routine for complete obstetric ultrasound evaluation.

Linear parameters of normal and abnormal cava septi pellucidi: a post-mortem study

Anatomical variations in the dimensions of different brain structures have been correlated with clinical syndromes. This study on the parameters of normal and abnormal cavum septi pellucidi (CSP) can be of clinical significance. We obtained 479 brains from autopsied persons (310 males and 169 females, 377 normal or asymptomatic and 102 abnormal or symptomatic persons, aged 22-89 years) and observed that 110 brains (75 males and 35 females) had CSP. These cava were classified into two groups depending on the past medical histories of the autopsied person: 40 asymptomatic and 70 symptomatic cava. We have defined symptomatic cava as those in autopsied persons who had known past medical history of psychiatric or neurological disease. Asymptomatic cava were in autopsied persons who had no known past medical history of psychiatric or neurological disease. The CSP parameters (length, width, depth) of the symptomatic and asymptomatic groups were measured and were statistically analyzed. Analysis showed that the cava in the symptomatic group were significantly longer and wider. Discriminant function analysis was used to derive a mathematical formula to classify CSP into an asymptomatic or symptomatic group based on length and width measurements of the cavum.

Transabdominal sonography of the cavum septum pellucidum in normal fetuses in the second and third trimesters of pregnancy

OBJECTIVES

To assess the visualization rate and size of the cavum septum pellucidum (CSP) by transabdominal sonography in normal fetuses throughout pregnancy.

METHODS

The CSP was prospectively researched and measured using an axial transventricular plane in 286 consecutive uncomplicated singleton pregnancies between 15 and 41 weeks of gestation.

RESULTS

The CSP was seen in 40% of cases at 15 weeks, 82% at 16-17 weeks, 100% at 18-37 weeks and 79% at 38-41 weeks. Compared to biparietal diameter (BPD), the visualization rate was 33% between 31 and 32 mm, 45% between 33 and 34 mm, 84% between 35 and 43 mm, 100% between 44 and 88 mm and 86% between 89 and 99 mm. Mean CSP width was 5.3 +/- 1.7 mm (range 2-9 mm). The CSP width increased with gestational age and BPD but with a slight decrease around term.

CONCLUSIONS

In normal fetuses the CSP should always be visualized between 18 and 37 weeks, or with a BPD of 44-88 mm. Failure to observe the CSP in this interval, or possibly the presence of a large CSP, may indicate abnormal cerebral development and warrant further investigation. Conversely, absence of the CSP prior to 18 weeks, or later than 37 weeks, is a normal finding.