'Choroid bar': easy-to-seek marker of normal posterior fossa at 12-14 weeks' gestation.

OBJECTIVES: Our objectives were: (1) to assess the visualization rate of the choroid bar in a consecutive series of 306 first-trimester scans; (2) to verify, in this cohort of fetuses, the normality of the posterior fossa later in pregnancy; and (3) to confirm the non-visualization of the choroid bar in a retrospective series of fetuses with posterior fossa malformations. METHODS: This study included a prospective and a retrospective series. The former comprised 306 fetuses undergoing routine obstetric ultrasound at our unit in both the first and second trimesters over a 6-month period, while the latter comprised 12 cases of posterior fossa malformations. In the prospective study, the presence of the choroid bar, which is defined as a visually continuous, homogeneously hyperechogenic, thick structure bridging the cisterna magna from side to side, was evaluated at the end of the first-trimester nuchal translucency scan. In the retrospective study, previously acquired three-dimensional volume datasets were processed in order to assess whether the choroid bar could be visualized in cases of open spinal dysraphisms and vermian cystic anomalies. In the prospective study, confirmation of a normal posterior fossa was based on the sonographic features of this anatomical region at the time of the second-trimester anomaly scan at 19-21 weeks' gestation, while, in the retrospective study, it was based on autopsy results, when available, or further direct imaging of the defect later in pregnancy. RESULTS: In the prospective study, the choroid bar could be visualized in all 306 fetuses, on transabdominal ultrasound in 287 (93.8%) cases and on transvaginal ultrasound in 19 (6.2%) cases. The choroid bar was displayed with a ventral/dorsal approach in 67 (21.9%) cases, with a lateral approach in 56 (18.3%) cases and with both in 183 (59.8%) cases. All 306 cases were confirmed to have a sonographically normal posterior fossa at 19-21 weeks. On the other hand, in the retrospective study, it was not possible to visualize the choroid bar in any of the fetuses with posterior fossa malformations. CONCLUSIONS: We have described a new sign, the choroid bar, consistent with a normal posterior fossa at 12-14 weeks' gestation. The choroid bar provides the option of screening for major abnormalities of the posterior fossa, since its absence raises suspicion of both open spinal dysraphisms and posterior fossa cystic malformations. At the same time, it is easy to visualize, as it can be seen with all lines of insonation. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal diagnosis of vermian cyst: a new type of posterior fossa cyst.

BACKGROUND: Prenatal diagnoses of cystic malformations of the posterior fossa mainly encompass arachnoid cysts, Blake's pouch cysts and Dandy-Walker syndrome. To date, vermian cysts have not been reported prenatally. OBJECTIVES: To report a series of fetuses with a vermian cyst. MATERIALS AND METHODS: This was a single-center retrospective study conducted from 2012 to 2021. We included all fetuses presenting with a vermian cyst and excluded all other types of posterior fossa cyst. The cyst was visible at prenatal ultrasound (US) and/or magnetic resonance imaging (MRI). Postnatal imaging and/or clinical outcome data were available. RESULTS: Sixteen fetuses fulfilled the inclusion criteria with a strong female predominance (n=13). US and MRI were performed at a mean gestational age of 29+5 and 33+1 weeks, respectively. In all patients, the cyst was in the vermian horizontal fissure. The mean longest dimension was about 10 mm. The vermis and other posterior fossa structures were otherwise normal. At postnatal imaging, 13 children underwent brain imaging including 11 MRIs with complete regression (n=9), stability (n=1) and increase in size (n=3) of the cyst. Psychomotor development was normal in 14 children. One child (with an inner ear malformation) showed a slight delay in walking and language acquisition. Slight walking ataxia was present in another child. CONCLUSION: We report 16 fetuses with posterior fossa cysts located within the vermis at the level of the horizontal fissure, diagnosed at US and/or MRI and carrying an overall excellent neurological prognosis.

Refining the Neuroimaging Definition of the Dandy-Walker Phenotype.

BACKGROUND AND PURPOSE: The traditionally described Dandy-Walker malformation comprises a range of cerebellar and posterior fossa abnormalities with variable clinical severity. We aimed to establish updated imaging criteria for Dandy-Walker malformation on the basis of cerebellar development. MATERIALS AND METHODS: In this multicenter study, retrospective MR imaging examinations from fetuses and children previously diagnosed with Dandy-Walker malformation or vermian hypoplasia were re-evaluated, using the choroid plexus/tela choroidea location and the fastigial recess shape to differentiate Dandy-Walker malformation from vermian hypoplasia. Multiple additional measures of the posterior fossa and cerebellum were also obtained and compared between Dandy-Walker malformation and other diagnoses. RESULTS: Four hundred forty-six examinations were analyzed (174 fetal and 272 postnatal). The most common diagnoses were Dandy-Walker malformation (78%), vermian hypoplasia (14%), vermian hypoplasia with Blake pouch cyst (9%), and Blake pouch cyst (4%). Most measures were significant differentiators of Dandy-Walker malformation from non-Dandy-Walker malformation both pre- and postnatally (P < .01); the tegmentovermian and fastigial recess angles were the most significant quantitative measures. Posterior fossa perimeter and vascular injury evidence were not significant differentiators pre- or postnatally (P > .3). The superior posterior fossa angle, torcular location, and vermian height differentiated groups postnatally (P < .01), but not prenatally (P > .07). CONCLUSIONS: As confirmed by objective measures, the modern Dandy-Walker malformation phenotype is best defined by inferior predominant vermian hypoplasia, an enlarged tegmentovermian angle, inferolateral displacement of the tela choroidea/choroid plexus, an obtuse fastigial recess, and an unpaired caudal lobule. Posterior fossa size and torcular location should be eliminated from the diagnostic criteria. This refined phenotype may help guide future study of the numerous etiologies and varied clinical outcomes.

Fossa navicularis magna: detección por tomografía computarizada de haz cónico / Fossa navicularis magna: detection by cone-beam computed tomography

Introducción: La identificación, interpretación y manejo de hallazgos incidentales en imagenología dental es imprescindible. Algunos de ellos requieren técnicas de imagen adicionales y remisión a profesionales de experiencia, otros únicamente su descripción. Una de estas variantes anatómicas se halla en el clivus, la fossa navicularis magna, asociada en pocos casos a repercusiones sistémicas. Objetivo: Describir las características de la fossa navicularis magna para su identificación mediante tomografía computarizada de haz cónico. Presentación de los casos: Tres pacientes de sexo femenino, con un rango de edad entre 35-71 años que acuden al Centro Odontológico de la Universidad San Martín de Porres para tratamientos de ortodoncia y rehabilitación oral. En estas áreas, como parte del protocolo se solicita tomografía computarizada de haz cónico por pieza retenida y elaboración de guías quirúrgicas respectivamente. El escaneo permite la identificación de un defecto tipo muesca en el clivus, de límites bien definidos y bordes corticalizados, lo que sugiere fossa navicularis magna. La historia clínica de los pacientes no sugirió implicaciones clínicas. Principales comentarios: Se informa y discute esta variante anatómica cuya presencia no requiere tratamiento y generalmente no tiene repercusiones sistémicas. En contados casos ha estado asociado con cuadros clínicos que amenazan la vida del paciente, precisamente porque puede servir como un trayecto para infecciones intracraneales. De ahí la necesidad de conocer y describir esta variante anatómica(AU)

Introduction: The identification, interpretation and management of incidental findings in dental imaging is essential. Some of them require additional imaging techniques and referral to experienced professionals, others only their description. One of these anatomical variants is found in the clivus, fossa navicularis magna, associated in few cases with systemic repercussions. Objective: Describe the characteristics of fossa navicularismagna for its identification by cone-beam computed tomography. Presentation of cases: Three female patients, with an age range between 35-71 years who come to the Dental Center of San Martín de Porres University for orthodontic treatments and oral rehabilitation. In these areas, as part of the protocol, cone-beam computed tomography per retained piece and development of surgical guides are requested, respectively. The scan allows the identification of a notch-like defect in the clivus, of well-defined boundaries and corticalized edges, suggesting fossa navicularis magna. The patients' medical history did not suggest clinical implications. Main comments: This anatomical variant is reported and discussed and its presence does not require treatment and generally has no systemic repercussions. In rare cases it has been associated with clinical pictures that threaten the patient's life, precisely because it can serve as a path for intracranial infections. Hence the need to know and describe this anatomical variant(AU)

A myriad of posterior fossa cysts: A single center experience.

Antenatal posterior fossa cystic lesions are intimidating due to overlapping imaging features of benign and severe malformations. Sonographic assessment of the posterior fossa with good resolution median sagittal and axial views, either primary or secondarily reconstructed, plays the lead role in antenatal evaluation, further enhanced when sequential assessments are added. We present 10 cases of fetal posterior fossa cystic lesions diagnosed in the first and second trimesters that were sequentially analyzed and followed up till delivery or termination. The ultrasound imaging appearance, evolution, and morphometry have been presented in this article.

Anatomical variations of clivus: a descriptive anatomical study.

PURPOSE: The clivus is a part of the sphenoid bone. It may show some anatomical variations such as fossa navicularis magna (FNM), canalis basilaris medianus (CBM) and craniopharyngeal canal (CPC). These variations have been associated with conditions like meningitis and tumors of skull base. Inadequate information about these structures may pose a risk of inaccurate diagnosis resulting in unwarranted interventional procedures. Hence, the knowledge about the prevalence of these variations is important. Thus, the objective of this study was to determine the prevalence of fossa navicularis magna, craniopharyngeal canal and canalis basilaris medianus and its types utilizing cone-beam computed tomography (CBCT) images. METHODS: Retrospectively, a total of 350 CBCT scans were evaluated for the presence of FNM, CBM, its types and CPC. The analysis was done by two observers independently. Cohen's kappa statistics was used to determine the interobserver agreement. RESULTS: FNM was noted in 19.4% cases, CBM in 9.7% cases, whereas CPC was not identified in any case. Type 5 was the most common type of CBM. There was no significant difference (p > 0.05) between genders and age groups for the prevalence and a highly significant (p < 0.01) substantial agreement between observers for the prevalence of FNM and highly significant (p < 0.01) moderate agreement for the prevalence of CBM and its types was obtained. CONCLUSION: FNM, CBM, CPC, albeit rare anatomical variations of clivus, knowledge of these structures is important for radiologists, anatomists and surgeons to avoid misdiagnosis and provide awareness to the individual of a higher possibility of meningitis or tumors of the skull base.

Comprehensive review of the mastoid foramen.

Anatomical variations of the mastoid foramen have been observed to vary in a number of qualities including size, number, and location. These variants have the potential to become problematic during surgical approaches to the posterior cranial fossa and mastoid part of the temporal bone, and should thus be appreciated by the surgeon. Herein, we discuss the mastoid foramen in detail including issues with such foramina that should be known to the neurosurgeon.

Biometric assessments of the posterior fossa by fetal MRI: A systematic review.

BACKGROUND: Posterior fossa abnormalities (PFAs) are commonly identified within routine screening and are a frequent indication for fetal magnetic resonance imaging (MRI). Although biometric measurements of the posterior fossa (PF) are established on fetal ultrasound and MRI, qualitative visual assessments are predominantly used to differentiate PFAs. OBJECTIVES: This systematic review aimed to assess 2-dimensional (2D) biometric measurements currently in use for assessing the PF on fetal MRI to delineate different PFAs. METHODS: The protocol was registered (PROSPERO ID CRD42019142162). Eligible studies included T2-weighted MRI PF measurements in fetuses with and without PFAs, including measurements of the PF, or other brain areas relevant to PFAs. RESULTS: 59 studies were included - 6859 fetuses had 62 2D PF and related measurements. These included linear, area and angular measurements, representing measures of PF size, cerebellum/vermis, brainstem, and supratentorial measurements. 11 measurements were used in 10 or more studies and at least 1200 fetuses. These dimensions were used to characterise normal for gestational age, diagnose a range of pathologies, and predict outcome. CONCLUSION: A selection of validated 2D biometric measurements of the PF on fetal MRI may be useful for identification of PFA in different clinical settings. Consistent use of these measures, both clinically and for research, is recommended.

Intoxicación por cianuro y accidente cerebrovascular en fosa posterior: reporte de un caso y revisión de la literatura / Cyanide poisoning and cerebrovascular accident in the posterior fossa: a case report and review of the literature

La intoxicación por cianuro y el accidente cerebrovascular (ACV) en fosa posterior es una asociación que genera un paradigma trascendental y desafiante en el escenario clínico actual, presentando un trasfondo fisiopatológico intrincado aún sin establecer. La muerte fatal por cianuro está suscrita a infarto de miocardio, embolismo pulmonar o disritmia ventricular, entre otras. Cuando existe injuria del sistema nervioso central (SNC) podemos encontrar compromiso a nivel de núcleos de la base de cráneo; sin embargo, es inusual el ACV en fosa posterior, más aún en paciente joven y sin secuelas neurológicas importantes posteriores a la intoxicación. Es menester, intentar proporcionar los elementos necesarios para fomentar la sospecha clínica, alcanzar un diagnóstico oportuno y un óptimo tratamiento; ya que, es excepcionalmente raro y complejo este tipo de presentación clínica. (AU)

Cyanide poisoning and stroke in posterior fossa is an association that generates a transcendental and challenging paradigm in the current clinical setting, presenting an intricate pathophysiological background that has yet to be established. Fatal death from cyanide is subscribed to myocardial infarction, pulmonary embolism or ventricular dysrhythmia, among others. When there is injury to the central nervous system (CNS) we can find compromise at the level of the nuclei of the skull base; however, stroke in the posterior fossa is unusual, even more so in young patients and without significant neurological sequelae after intoxication. It is necessary to try to provide the necessary elements to promote clinical suspicion, achieve a timely diagnosis and optimal treatment; since this type of clinical presentation is exceptionally rare and complex. (AU)

Tortícolis como forma de presentación de quiste de la bolsa de Blake. Diagnóstico ecográfico en atención primaria / Torticolis as a form of presentation of Blake's pouch cyst. Ultrasound diagnosis in primary care

La tortícolis es un signo clínico definido por la inclinación lateral del cuello y rotación de la cabeza, que puede ser fija o flexible y acompañarse o no de dolor cervical. Aparece en trastornos de diferente complejidad. Ante un caso de tortícolis, es preciso realizar una historia clínica cuidadosa y un examen físico completo, y, en caso de ser persistente, solicitar pruebas de imagen.Se hace referencia a una causa de tortícolis no descrita en la literatura. Se trata de una tumoración quística compresiva en la fosa craneal posterior, quiste de la bolsa de Blake, en una lactante pequeña diagnosticada mediante ecografía en la consulta de Pediatría de Atención Primaria. Tras el diagnóstico, se remitió al centro hospitalario de referencia, donde se intervino de urgencia por Neurocirugía Pediátrica, mediante fenestración de la tumoración por ventriculostomía endoscópica y derivación ventrículo-peritoneal. Actualmente, se encuentra asintomática y sin secuelas.

Torticollis is a clinical sign defined by the lateral inclination of the neck and rotation of the head, which can be fixed or flexible and accompanied or not by cervical pain. It appears in disorders of different complexity. In a case of torticollis it is necessary to carry out a careful medical history and a complete physical examination and, if persistent, request imaging tests.Reference is made to a cause of torticollis not described in the literature. This is a compressive cystic tumor in the posterior cranial fossa, Blake's pouch cyst, in a small infant diagnosed by ultrasound in the Primary Care Pediatrics office. After diagnosis, she was referred to the referral hospital, where emergency intervention was performed by pediatric neurosurgery, by fenestration of the tumor by endoscopic ventriculostomy and ventriculo-peritoneal shunt. She is currently asymptomatic and without sequelae.

[Torticolis as a form of presentation of Blake's pouch cyst. Ultrasound diagnosis in primary care]. / Tortícolis como forma de presentación de quiste de la bolsa de Blake. Diagnóstico ecográfico en atención primaria.

Torticollis is a clinical sign defined by the lateral inclination of the neck and rotation of the head, which can be fixed or flexible and accompanied or not by cervical pain. It appears in disorders of different complexity. In a case of torticollis it is necessary to carry out a careful medical history and a complete physical examination and, if persistent, request imaging tests. Reference is made to a cause of torticollis not described in the literature. This is a compressive cystic tumor in the posterior cranial fossa, Blake's pouch cyst, in a small infant diagnosed by ultrasound in the Primary Care Pediatrics office. After diagnosis, she was referred to the referral hospital, where emergency intervention was performed by pediatric neurosurgery, by fenestration of the tumor by endoscopic ventriculostomy and ventriculo-peritoneal shunt. She is currently asymptomatic and without sequelae.

La tortícolis es un signo clínico definido por la inclinación lateral del cuello y rotación de la cabeza, que puede ser fija o flexible y acompañarse o no de dolor cervical. Aparece en trastornos de diferente complejidad. Ante un caso de tortícolis, es preciso realizar una historia clínica cuidadosa y un examen físico completo, y, en caso de ser persistente, solicitar pruebas de imagen. Se hace referencia a una causa de tortícolis no descrita en la literatura. Se trata de una tumoración quística compresiva en la fosa craneal posterior, quiste de la bolsa de Blake, en una lactante pequeña diagnosticada mediante ecografía en la consulta de Pediatría de Atención Primaria. Tras el diagnóstico, se remitió al centro hospitalario de referencia, donde se intervino de urgencia por Neurocirugía Pediátrica, mediante fenestración de la tumoración por ventriculostomía endoscópica y derivación ventrículo-peritoneal. Actualmente, se encuentra asintomática y sin secuelas.

Arteriovenous malformations of the posterior fossa: a systematic review.

BACKGROUND: Posterior fossa arteriovenous malformations (pfAVMs) can be challenging lesions to manage. AVMs in this location may have distinct features compared with supratentorial AVMs. Our aim was to systematically review the literature on the presenting characteristics of pfAVMs and compare clinical and angiographic outcomes after the various types of treatment employed. METHODS: The review was conducted according to the Cochrane Collaboration guidelines. Electronic databases from 1900 to March 2018 were searched and complemented by hand-searching and cross-referencing. Articles were categorized into (i) AVM studies that included those in the posterior fossa, (ii) those that focused exclusively on pfAVM, and (iii) those that further specified a cerebellar or brainstem location of the AVM. RESULTS: Seventy-seven articles with 4512 pfAVM patients were retained for analyses. Compared with historical supratentorial controls, pfAVMs were reported to more frequently present with rupture, to more commonly have associated arterial aneurysms, and to more frequently lead to poor clinical and angiographic outcomes. The quality of the literature and lack of standardization of outcome reporting precluded performing a meta-analysis on the results of the various different treatment modalities. CONCLUSIONS: Posterior fossa AVMs may have some distinct features compared with supratentorial AVMs. The available reports on pfAVMs are not sufficiently standardized to provide reliable guidance for patient management decisions. This goal will require future studies to be multicentric and to focus on standardized, repeatable clinical and angiographic outcomes.

Blake's Pouch Cysts and Differential Diagnoses in Prenatal and Postnatal MRI : A Pictorial Review.

PURPOSE: The clinical variability of Blake's pouch cysts (BPC) may range from asymptomatic via ataxia to sequelae of decompensated hydrocephalus. On the other hand, Dandy-Walker malformation (DWM) and cerebellar vermis hypoplasia generally correlate with less favorable neurologic development. The aim was to illustrate the potential of prenatal and postnatal neuroimaging to distinguish a BPC or persistent BP from other posterior fossa malformations. METHODS: This pictorial review addresses the inconsistent nomenclature, clinical features, and magnetic resonance imaging (MRI) patterns of BPC and five differential diagnoses. The MRI findings of 11 patients, acquired at up to 3 T in 3 institutions, are demonstrated. Furthermore, the literature was searched for recent improvements in genetic and embryological background knowledge. RESULTS: Posterior fossa malformations often resemble each other and may even be imitated by sequelae of hemorrhagic, ischemic or infectious disruptions, i.e. congenital anomalies of morphology despite normal developmental potential. Hydrocephalus is a typical, albeit not always congenital finding in BPC. It is frequently associated with cerebellar disruptions and DWM; however, it is also a rare complication of posterior fossa arachnoid cysts. A moderately elevated vermis needs follow-up to confirm persistent BP versus vermian hypoplasia or DWM. The fetal cerebellar tail, previously assumed to be specific for DWM, may be imitated in cases of persistent BP. CONCLUSION: The accurate diagnosis of isolated BPC is not always straightforward, which is especially critical in the context of fetomaternal medicine. A detailed description of posterior fossa malformations is to be preferred over unspecific terminology.

Quantitative fetal magnetic resonance imaging assessment of cystic posterior fossa malformations.

OBJECTIVE: Normal cognitive development usually requires a structurally intact and complete cerebellar vermis. The aim of this study was to evaluate whether quantification by fetal magnetic resonance imaging (MRI) of vermis- and brainstem-specific imaging markers improves the definition of cystic posterior fossa malformations (cPFM). METHODS: Fetuses diagnosed with cPFM that had an available midsagittal plane on T2-weighted MRI were identified retrospectively and compared with gestational-age (GA) matched brain-normal controls. Fetuses with cPFM were assigned to three groups, according to standard criteria (vermian size and brainstem-vermis (BV) angle): normal vermian area and BV angle < 25° (Group 1); reduced vermian area and/or BV angle of 25-45° (Group 2); and reduced vermian area and BV angle > 45° (Group 3; Dandy-Walker malformation (DWM) group). The number of differentiable vermian lobules and the areas of the vermis, mesencephalon, pons and medulla oblongata were quantified, correlated with and controlled for GA, and compared between the study groups. RESULTS: In total, 142 cases of cPFM were included, with a mean GA of 25.20 ± 5.11 weeks. Cases comprised Blake's pouch cyst (n = 46), arachnoid cyst (n = 12), inferior vermian hypoplasia (n = 5), megacisterna magna (n = 35) and classic DWM (n = 44). In the control group, 148 fetuses were included, with a mean GA of 25.26 ± 4.12 weeks. All quantified areas and the number of differentiable vermian lobules had a significant positive correlation with GA. The number of vermian lobules and the areas of all quantified regions, except for that of the medulla oblongata, differed significantly between the study groups (P ≤ 0.015 for all). The control group had the highest number of differentiable vermian lobules and the DWM group had the lowest (P < 0.01). CONCLUSIONS: Prenatal MRI assessment of vermian lobules is a useful addition to standard neuroradiological and neurosonographic techniques. The quantification of vermian lobules using fetal MRI allows further differentiation of cPFM into subgroups and thereby improves the classification of hindbrain malformations. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Quantitative diagnostic advantages of three-dimensional ultrasound volume imaging for fetal posterior fossa anomalies: Preliminary establishment of a prediction model.

OBJECTIVES: To quantitatively assess prenatal diagnostic performance of three-dimensional ultrasound (3D-US) for posterior fossa anomalies (PFA) and establish a preliminarily 3D-US prediction model. METHODS: Sixty singleton fetuses suspected of PFA by 2D-US presented their detailed 3D-US evaluation. The surface area of vermis (SAV), brainstem-vermis, and brainstem-tentorium angles were measured by 3D-US. The good prognosis was defined as normal neurodevelopmental outcome. MRI and autopsy were the diagnostic reference standard. RESULTS: There was a significant difference between 2D-US (60.0%, 36/60) and 3D-US (94.8%, 55/58) for the diagnostic accuracy (P < .01). Prenatal 3D-US prediction model was established with observed/expected SAV as the main predictor (area under the curve [AUC]: 0.901; 95% CI, 0.810-0.992, P < .001). When it was more than 107.5%, the prognosis seemed to be good (sensitivity: 96.4%, specificity: 26.7%), which led to consideration of mega cisterna magna, Blake pouch cyst, or small arachnoid cyst. The prognosis appeared to be poor when it was less than 73% (sensitivity: 71.4%, specificity: 100%), and the diagnosis tended to be a Dandy-Walker malformation, vermian hypoplasia, and cerebellar hypoplasia. Brainstem-vermis and brainstem-tentorium angles were the secondary indicators (AUC: 0.689 vs 0.761; 95% CI, 0.541-0.836 vs 0.624-0.897, P = .014 vs.001). CONCLUSIONS: It seems that the exact types of PFA can be effectively diagnosed by quantitative indicators of 3D-US.

Utilization of neurosonography for evaluation of the corpus callosum malformations in the era of fetal magnetic resonance imaging.

AIM: We evaluated the ability of fetal neurosonography and magnetic resonance imaging (MRI) to asses callosal anomalies (CA) and associated cranial malformations. We also aimed to determine the long-term prognosis of the cases. METHODS: Thirty-six cases of CA diagnosed combined with neurosonography and MRI between January 2012 and October 2017 were retrospectively reviewed. RESULTS: Seventeen of 36 fetuses were diagnosed complete agenesis of corpus callosum (CACC) (47.2%), 9 had partial agenesis of corpus callosum (PACC) (25%) and 10 was dysgenesis of the corpus callosum (DCC) (27.2%) at ultrasonography (US) examination. Fetal MRI reported 16 of cases as CACC (44.4%), 11 PACC (30.5%) and nine (25%) DCC. The overall consistency between neurosonography and MRI in the definition of CA were 91% of cases. Sulcation anomalies were present in 9 cases in the US (25%) and 11 cases in MRI (30.4%). Seven of cases showed posterior fossa abnormalities in the US (19.4%) and eight cases in MRI (22.1%). Neonatal MRI added new findings to fetal MRI and neurosonography including grade-1 intraventricular hemorrhage and periventricular leukomalacia in two cases (12.5%). Eighteen cases were terminated (50%), 17 cases were followed up and mean follow up interval was 39 ± 5.1 months. The neurologic outcome was abnormal in seven (41.7%) patients. Presence of associated brain anomalies worsened the prognosis. CONCLUSION: Fetal neurosonography has a comparable performance with MRI in the diagnosis of CA and associated anomalies. It should be used in collaboration with MRI to achieve accurate diagnosis which is crucial for counseling.

Small posterior fossa in Chiari I malformation affected families is significantly linked to 1q43-44 and 12q23-24.11 using whole exome sequencing.

The posterior fossa of the cranium contains the cerebellum and brainstem. Processes that reduce the volume of the posterior fossa squeeze the cerebellum and brainstem caudally, resulting in Chiari I malformation (CM1). CM1 causes neck pain, balance issues, decreased motor skills and headaches in those affected. We have posterior fossa measurements and whole exome sequence data on individuals from 7 extended families from Russia that have a family history of CM1. We performed parametric linkage analyses using an autosomal dominant inheritance model with a disease allele frequency of 0.01 and a penetrance of 0.8 for carriers and 0.0 for non-carriers. Variant-based two-point linkage analysis and gene-based linkage analysis was performed. Our results found a genome-wide significant signal on chromosome 1q43-44 (max HLOD = 3.3) in the variant-based analysis and 12q23 (max HLOD = 4.2) in the gene-based analysis. In both cases, the signal was driven by a single (different) family that contained a long, linked haplotype across the region in question. Using functional annotation, we were able to identify several rare nonsynonymous variants that were enriched in each family. The best candidate genes were rs765865412:G>A in MYBPC1 for the 12q haplotype and rs61749963:A>G in COX20 for the 1q haplotype. Good candidate variants in the 1q haplotype were also identified in CEP170 and AKT. Further laboratory work is planned to verify the causality of these genes.

Dermoid cyst with cerebellar meningoencephalocele at different locations accompanied by posterior fossa abnormalities: case report

ABSTRACT CONTEXT: Dermoid cysts are well-defined cysts containing sebaceous glands and dermal structures. In the literature, dermoid cysts and associated closure defects have been described in the same locations. CASE REPORT: In this case, a dermoid cyst was found at the base of the mouth with a coexisting closure defect in the occipital calvarium. Additional abnormalities were also observed, including posterior myeloschisis, right cerebellar dysgenesis, vermian hypogenesis and posterior fusion of the second and third vertebrae. The finding of a dermoid cyst located at the base of the mouth is discussed here, with additional imaging findings. CONCLUSION: Dermoid cysts in the head and neck region may be accompanied by posterior fossa abnormalities.