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Aqueductal stenosis in RES. (A and B) Obstruction at the level of the superior colliculi (white arrow in A and black arrow in B), which are fused across the midline in Subject 29. Note the shunted hydrocephalus and severely dysgenetic corpus callosum with intact rostrum. (C and D) Obstruction at the level of the inferior colliculi (arrowheads), which are fused across the midline in Subject 8. Note the severe hydrocephalus with funnelling of the aqueduct, the retrocerebellar fluid collection and hypoplasia of the cerebellum and pons. (E and F) Obstruction at the junction of the aqueduct and fourth ventricle in Subject 2. The superior medullary velum is thickened (white arrow) and the superior cerebellar peduncles are angled medially. Note the mild inferior cerebellar ectopia in (E). Note the tiny focus of low signal within the superior aspect of the fourth ventricle (adjacent to the white arrow in F) and within the lateral ventricles in E is related to air from recent shunt manipulation. (G-I) Obstruction from the level of the thickened posterior commissure (bracket) to the level of the superior cerebellar peduncles with midline fusion of the superior colliculi (black arrow) in Subject 1. Note partial agenesis of the corpus callosum in (G) and the absence of hydrocephalus, despite complete obliteration of the cerebral aqueduct on imaging. Note also the severely hypoplastic mammillary bodies in Subjects 8, 2 and 1 (long white arrows in C, E and G). (A, C, E and G) sagittal T 1 ; (B, F and I) axial T 1 ; (D, H) axial T 2 .
Source publication
Rhombencephalosynapsis is a midline brain malformation characterized by missing cerebellar vermis with apparent fusion of the cerebellar hemispheres. Rhombencephalosynapsis can be seen in isolation or together with other central nervous system and extra-central nervous system malformations. Gómez-López-Hernández syndrome combines rhombencephalosyna...
Contexts in source publication
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... stenosis was present in 22/42 subjects and was strongly associated with the degree of cerebellar fusion (Table 2). Patency of the aqueduct was compromised at the level of the superior ( Fig. 3A and B) or inferior colliculus ( Fig. 3C and D), or more caudally at the level of the superior cerebellar peduncles (Fig. 4). All subjects with aqueductal stenosis had fusion of the overlying structures at the level of obstruction except Subject 28, in whom the superior colliculus did not appear to be fused, and in Subject 12 who had aqueductal stenosis at the most superior aspect of the aqueduct with a deformed tectum. In eight subjects (Subjects 1, 2, 15, 20, 21, 31, 19 and 42), the superior medullary velum also appeared thickened, with non-visualization or severe narrowing of the aqueduct at that level ( Fig. 3E and F). In four subjects (Subjects 1, 15, 20 and 35), the aqueductal stenosis was more diffuse, extending from the level of the superior cerebellar peduncle up to the posterior commissure ( Fig. 3G-I). In particular, Subject 15, and to a lesser extent Subject 35, had a mass-like fusion of all of the midbrain including the superior cerebellar peduncle, superior medullary velum, inferior colliculus, superior colliculus-as noted by other authors (Garfinkle, 1996;Pasquier et al., 2009)-and extending cranially with fusion of the thalami and hypothalami ( Fig. 5A and B). We did not observe deficiency of the superior medullary velum as described previously ( Gross, 1959;Barth, 2008). In 19 subjects, the superior cerebellar peduncles were closer to the midline than normal and angled more medially (Fig. 4). This abnormal superior cerebellar peduncle configuration was accom- panied by several different patterns of abnormalities of the ...
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... stenosis was present in 22/42 subjects and was strongly associated with the degree of cerebellar fusion (Table 2). Patency of the aqueduct was compromised at the level of the superior ( Fig. 3A and B) or inferior colliculus ( Fig. 3C and D), or more caudally at the level of the superior cerebellar peduncles (Fig. 4). All subjects with aqueductal stenosis had fusion of the overlying structures at the level of obstruction except Subject 28, in whom the superior colliculus did not appear to be fused, and in Subject 12 who had aqueductal stenosis at the most superior aspect of the aqueduct with a deformed tectum. In eight subjects (Subjects 1, 2, 15, 20, 21, 31, 19 and 42), the superior medullary velum also appeared thickened, with non-visualization or severe narrowing of the aqueduct at that level ( Fig. 3E and F). In four subjects (Subjects 1, 15, 20 and 35), the aqueductal stenosis was more diffuse, extending from the level of the superior cerebellar peduncle up to the posterior commissure ( Fig. 3G-I). In particular, Subject 15, and to a lesser extent Subject 35, had a mass-like fusion of all of the midbrain including the superior cerebellar peduncle, superior medullary velum, inferior colliculus, superior colliculus-as noted by other authors (Garfinkle, 1996;Pasquier et al., 2009)-and extending cranially with fusion of the thalami and hypothalami ( Fig. 5A and B). We did not observe deficiency of the superior medullary velum as described previously ( Gross, 1959;Barth, 2008). In 19 subjects, the superior cerebellar peduncles were closer to the midline than normal and angled more medially (Fig. 4). This abnormal superior cerebellar peduncle configuration was accom- panied by several different patterns of abnormalities of the ...
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... stenosis was present in 22/42 subjects and was strongly associated with the degree of cerebellar fusion (Table 2). Patency of the aqueduct was compromised at the level of the superior ( Fig. 3A and B) or inferior colliculus ( Fig. 3C and D), or more caudally at the level of the superior cerebellar peduncles (Fig. 4). All subjects with aqueductal stenosis had fusion of the overlying structures at the level of obstruction except Subject 28, in whom the superior colliculus did not appear to be fused, and in Subject 12 who had aqueductal stenosis at the most superior aspect of the aqueduct with a deformed tectum. In eight subjects (Subjects 1, 2, 15, 20, 21, 31, 19 and 42), the superior medullary velum also appeared thickened, with non-visualization or severe narrowing of the aqueduct at that level ( Fig. 3E and F). In four subjects (Subjects 1, 15, 20 and 35), the aqueductal stenosis was more diffuse, extending from the level of the superior cerebellar peduncle up to the posterior commissure ( Fig. 3G-I). In particular, Subject 15, and to a lesser extent Subject 35, had a mass-like fusion of all of the midbrain including the superior cerebellar peduncle, superior medullary velum, inferior colliculus, superior colliculus-as noted by other authors (Garfinkle, 1996;Pasquier et al., 2009)-and extending cranially with fusion of the thalami and hypothalami ( Fig. 5A and B). We did not observe deficiency of the superior medullary velum as described previously ( Gross, 1959;Barth, 2008). In 19 subjects, the superior cerebellar peduncles were closer to the midline than normal and angled more medially (Fig. 4). This abnormal superior cerebellar peduncle configuration was accom- panied by several different patterns of abnormalities of the ...
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... stenosis was present in 22/42 subjects and was strongly associated with the degree of cerebellar fusion (Table 2). Patency of the aqueduct was compromised at the level of the superior ( Fig. 3A and B) or inferior colliculus ( Fig. 3C and D), or more caudally at the level of the superior cerebellar peduncles (Fig. 4). All subjects with aqueductal stenosis had fusion of the overlying structures at the level of obstruction except Subject 28, in whom the superior colliculus did not appear to be fused, and in Subject 12 who had aqueductal stenosis at the most superior aspect of the aqueduct with a deformed tectum. In eight subjects (Subjects 1, 2, 15, 20, 21, 31, 19 and 42), the superior medullary velum also appeared thickened, with non-visualization or severe narrowing of the aqueduct at that level ( Fig. 3E and F). In four subjects (Subjects 1, 15, 20 and 35), the aqueductal stenosis was more diffuse, extending from the level of the superior cerebellar peduncle up to the posterior commissure ( Fig. 3G-I). In particular, Subject 15, and to a lesser extent Subject 35, had a mass-like fusion of all of the midbrain including the superior cerebellar peduncle, superior medullary velum, inferior colliculus, superior colliculus-as noted by other authors (Garfinkle, 1996;Pasquier et al., 2009)-and extending cranially with fusion of the thalami and hypothalami ( Fig. 5A and B). We did not observe deficiency of the superior medullary velum as described previously ( Gross, 1959;Barth, 2008). In 19 subjects, the superior cerebellar peduncles were closer to the midline than normal and angled more medially (Fig. 4). This abnormal superior cerebellar peduncle configuration was accom- panied by several different patterns of abnormalities of the ...
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... of the tectum across the midline, defined as the absence of the two prominences of the superior and/or inferior colliculi on axial images (Fig. 3B, D and I), was present in 16 subjects ( Subjects 1, 8, 10, 14, 15, 19-21, 26, 29, 31, 35, 38, 40, 41 and 42). Craniocaudal fusion of the colliculi was demonstrated on sagittal sections in at least four subjects (Subjects 1, 20, 21 and 40). This may under-represent the true frequency, as cranio- caudal fusion may be difficult to identify when the sagittal sections are not thin enough. In contrast, Subject 32 had ectopic tissue within the cerebral aqueduct seen on thin cuts at the level of the inferior colliculus, without collicular fusion, as noted by other authors ( Takano et al., 2010). The absence of ventriculomegaly and funnelling of the aqueduct excluded aqueductal stenosis in There is anterior vermis that extends beyond the confluence of the superior cerebellar peduncles into the most caudal aspect of the cerebral aqueduct, reflecting a more severe pattern of ectopic tissue. No associated aqueductal stenosis. The superior medullary velum is not seen in this case, which may relate to the extent of the ectopic cerebellar tissue, in addition to thick slices. (E and F) Subject 17, complete RES. The anterior vermis is not visualized in this case, however, small ectopic tissue is seen at-and obscuring-the confluence of the superior cerebellar peduncles, which appear fused at the midline. This is causing obstruction at the most caudal aspect of the cerebral aqueduct. The superior medullary velum is present superior to the arrow in (F). After shunting, the subject developed an intraventricular cyst ...
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... hydrocephalus can account for a number of the fore- brain imaging abnormalities, our data support a role for primary forebrain developmental defects as well, since a number the abnormalities were seen in subjects without hydrocephalus and some of the abnormalities are not typically caused by hydroceph- alus. The septum pellucidum was absent in 26 subjects, including all with obstructive hydrocephalus (Table 3). It was also absent in four subjects with ventriculomegaly (three with mild, one with mild/moderate) and three without ventriculomegaly. To determine whether the septum forms and later disappears, we evaluated prenatal imaging in two subjects with mild ventriculo- megaly (Subjects 18 and 23). Subject 18 had a normal septum pellucidum at 22 weeks gestation that was then partially deficient at 32 weeks. The ventricles were at worst moderately dilated (16 mm atrial measurement) in utero and only mildly dilated on post-natal imaging. Subject 23 had a partially absent septum posteriorly on foetal MRI at 18 weeks gestation with moderate ventriculomegaly (16 mm atrial measurement). A cranial ultra- sound at birth revealed a partially absent septum with mild prom- inence of the ventricles, but the septum was completely absent on MRI by 1 month of age. The corpus callosum was abnormal in 30/41 subjects with adequate imaging (Table 4). Most commonly, the corpus callosum was severely thinned and dysplastic in association with obstructive hydrocephalus; however, obstructive hydrocephalus does not ex- plain the absence of the rostrum in six of these subjects, and we hypothesize that they also have a primary defect in callosal devel- opment. Similarly, the corpus callosum was variably thin or par- tially/completely absent in a total of nine subjects without obstructive hydrocephalus, also supporting the role of a primary developmental defect. The mammillary bodies were not observed and considered to be hypoplastic or absent in 13/39 subjects with adequate imaging (Fig. 3C, E and G), as noted by other authors (Schachenmayr Table 4 Relationship between ventriculomegaly/hydrocephalus and callosal abnormalities in subjects with RES Friede, 1982). Subjects 15 and 35 had fusion of the hypo- thalamus including the mammillary bodies (Garfinkle, 1996). The fornices were fused in 18/37 subjects, all of whom also had absent septum (Fig. 2N). The fornices could not be visualized in five sub- jects ( Subjects 15, 19, 20, 27 and 35), while a single thinned out fornix was seen in two subjects (Subjects 12 and 29); these find- ings could be related to severe distortion due to hydroceph- alus destroying and/or limiting visualization of the fornices. Subjects 15 and 35 had the absence of the ventricles, septum and fornices. We noted that the anterior commissure was absent or hypo- plastic in 16/38 subjects: 14 with obstructive hydrocephalus and two without ventriculomegaly, indicating that most anterior com- missure abnormalities are secondary to hydrocephalus, rather being due to abnormal brain development. Assessment of the an- terior commissure was challenging in a number of subjects due to immature myelination and/or inadequate imaging quality. Similarly, the medial temporal lobes were thin and excessively folded in 25/39 subjects, including 19 with obstructive hydroceph- alus and six without hydrocephalus. The pituitary gland was un- remarkable in all ...
Citations
... Surgical management is done for associated anomalies. 6 Being a rare disorder, rhombencephalosynapsis is often missed on clinical diagnosis, which results in the birth of the affected child. Thus, prenatal counselling for this disorder should be encouraged to prevent future struggles for both the child and parents (11). ...
Rhombencephalosynapsis (RES) is a rare, congenital developmental disorder of the central nervous system. Even after many years of its identification, the etiology and pathogenesis of RES remain unclear. It occurs in combination with many syndromes and thus has overlapping symptoms. The clinical presentation of this disorder varies depending on the severity of the maldevelopment of vermis. Here, we present a case of a 60-year-old Indian female diagnosed with Rhombencephalosynapsis. Clinical and MRI characteristics of RES along with treatment options have been discussed.
... Rhombencephalosynapsis, a rare genetic disorder, is defined by the connection of the superior cerebellar peduncles, dentate nuclei, and cerebellar hemispheres and the lack of the cerebellar vermis, which results in a distinctive keyhole shape in the fourth ventricle [1]. On posterior coronal imaging, the cerebellar hemispheres appear to be connected in a horizontal foliate pattern. ...
... On posterior coronal imaging, the cerebellar hemispheres appear to be connected in a horizontal foliate pattern. A dorsoventral patterning deficiency in the rostral dorsal midline sections of the rhombomere [1], which are situated just beneath the isthmus and surround the upper fourth ventricle, is most likely the cause of rhombencephalosynapsis, despite the genetic etiology of the condition still being unclear [2,3]. Though the majority of patients lack a syndromic profile, they do exhibit evidence of delayed motor development, aberrant eye movements, and stereotypical head movements [4]. ...
... Magnetic resonance imaging has come a long way since its infancy, and the growing expertise of pediatric neurologists and neuroradiologists has led to an increase in the detection of rhombencephalosynapsis both during and after pregnancy [7,8]. There is a continuum of severity of rhombencephalosynapsis, from severe cases where the complete vermis is absent (including the nodulus) to mild cases where only the central portion of the vermis has fused, typically the posterior vermis, with portions of the anterior vermis visible beyond the fusion [1]. The loss of the posterior vermis and nodulus with the presence of some remnant anterior vermis characterizes an unusual partial rhombencephalosynapsis, which occurs in a limited number of cases [1]. ...
Rhombencephalosynapsis is an exceptionally uncommon cerebellar anomaly characterized by the absence or underdevelopment of vermal axons, the presence of dentate nuclei, and the fusion of cerebral hemispheres. Depending on the presence or absence of additional supratentorial anomalies, the prognosis and clinical appearance can vary widely. Here, we present the case of a consanguineous-parent newborn boy, aged four days, who was diagnosed with the use of an MRI. The child had spastic diplegia, bone anomalies, and facial dysmorphism. Slight hydrocephalus, hypogenesis of the corpus callosum, and agenesis of the septum pellucidum were some of the additional supratentorial abnormalities. This study details the clinical and MRI findings, as well as a possible etiology, of this illness.
... In view of the association hydrocephaly and RES, a multidisciplinary counseling with a pediatric neurologist informed the patient regarding a high risk of neurodevelopmental delay. The prognosis of RES diagnosed in prenatal, being often complete, could be worse than those diagnosed postnatally (including more often partial RES with better prognosis) [4]. In addition, the presence of a dysmorphic face and head was suggestive of a syndromic association such as GLHS. ...
... Overall, the exact genetic etiology remains unknown, and the diagnosis remains based on neuroimaging and clinical criteria. When considering prenatal imaging, RES is a hindbrain malformation evocative but not specific to GLHS, as it can also be consecutive to global brain division anomalies (holoprosencephaly and diencephalo/mesencephalosynapsis), neural tube defects or VACTERL association [4,15,16]. Thus, the absence of pro/mesenphalic division, vertebral, anal, cardiac, tracheal and limbs abnormalities is primordial to evoke GLHS. In addition, the diagnosis of RES can be difficult on prenatal imaging, especially if it is a partial form where the cerebellar diameter is often in the normal range without supra-tentorial anomalies [15]. ...
Introduction:
Gomez-Lopez-Hernandez Syndrome (GLHS), also known as cerebello-trigeminal-dermal dysplasia is an extremely rare neuro-cutaneous disease, classically described by the triad of rhombencephalosynapsis (RES), bilateral focal alopecia and trigeminal anesthesia. The clinical and radiographic spectrum of GLHS is now known to be broader, including craniofacial and supra-tentorial anomalies, as well as neurodevelopmental issues.
Case presentation:
Here, we present a case of antenatally diagnosed GLHS with RES, hydrocephaly and craniofacial anomalies identified on ultrasound (low-set ears with posterior rotation, hypertelorism, midface hypoplasia, micrognathia and anteverted nares) which were confirmed by autopsy after termination of pregnancy at 23 weeks gestation.
Discussion:
As no known genetic causes have been identified and the classical triad is not applicable to prenatal imaging, prenatal diagnosis of GLHS is based on neuro-imaging and the identification of supporting features. In presence of a RES associated with cranio-facial abnormalities in prenatal (brachycephaly, turricephaly, low-set ears, midface retrusion, micrognathia), GLHS should be considered as "possible" according to postnatal criteria.
... RES is a neurodevelopmental malformation that is characterized by midline fusion of the two cerebellar hemispheres, which is caused by failure of the midline structure development in the rhombencephalon. It is suggested that disruption of dorsoventral patterning of the rhombencephalon may cause RES [96]. RES is rare condition with unknown etiology, and the most specific and key MRI finding is agenesis or hypogenesis of the vermis, in which the cerebellar vermis is completely or partially absent with a fused cerebellar hemisphere and midline dentate nucleus [96]. ...
... It is suggested that disruption of dorsoventral patterning of the rhombencephalon may cause RES [96]. RES is rare condition with unknown etiology, and the most specific and key MRI finding is agenesis or hypogenesis of the vermis, in which the cerebellar vermis is completely or partially absent with a fused cerebellar hemisphere and midline dentate nucleus [96]. RES may be associated with other cerebellar abnormalities, such as Purkinje cell heterotopias [97]. ...
... (b) Coronal T 2 -weighted brain images. Cerebellar hemispheric hypoplasia with vermis relatively spared leading to classic dragonfly image midline brain structural defects including absent olfactory bulbs, dysgenesis of the corpus callosum, absent septum pellucidum, and in rare patients, atypical forms of holoprosencephaly [96]. RES has also been reported in vertebral anomalies, anal atresia, cardiovascular anomalies, trachea-esophageal fistula, renal anomalies, limb defects (VACTERL) association, and hydrocephalus [26,[97][98][99][100]. ...
Inherited cerebellar malformations cause lifelong disability and are not well studied in the newborns because there is a lack of appropriate clinical examination tools. Recently, inherited cerebellar malformations have been investigated using emerging advanced neuroimaging technologies such as magnetic resonance imaging (MRI), which has revealed many developmental disorders of the cerebellum. These malformations cause impairments that affect motor and nonmotor functions. Cerebellar hypoplasia (CH), cerebellar dysplasia (CD), Dandy–Walker malformation (DWM), Joubert syndrome and related disorders (JSRDs), pontocerebellar hypoplasia (PCH), rhombencephalosynapsis (RES), lissencephaly with cerebellar hypoplasia (LCH), and Lhermitte–Duclos disease (LDD) are examples of cerebellar malformations which this chapter will focus on using characteristic symptoms and signs. The current approaches for evaluation of the affected patients, differential diagnosis, and management of the malformations will be discussed.
... (A) Sagittal T2-weighted image at 20 GW shows predictive criteria for incomplete vermian rotation, including a brainstem-vermis angle ≥23 , width of the cisterna magna ≥9 mm and the presence of the "cerebellar tail sign"; (B) follow-up exam at 28 GW shows the persistence of an enlarged brainstem-vermis angle; (C) Sagittal T2-weighted image obtained postnatally confirms rotated vermis with inferior hypoplasia (arrow) RES is often part of complex malformation syndromes, including anomalies in the pons, midbrain, and forebrain associated with ventriculomegaly. 8 The accompanying hydrocephalus may be secondary to aqueductal stenosis, often resulting from median fusion of the midbrain, or mesencephalosynapsis. Enlarged ventricles are often the first noticeable sign of a brain abnormality, prompting the MR examination; thus, specific attention to cerebellar morphology should be given in all cases with ventriculomegaly. Partial RES poses a big diagnostic challenge due to the absence of clear clues and requires a high level of suspicion and a careful analysis of the cerebellar anatomy. ...
Fetal MRI is an important tool for the prenatal diagnosis of brain malformations and is often requested after second‐trimester ultrasonography reveals a possible abnormality. Despite the immature state of the fetal brain at this early stage, early suggestive signs of the presence of brain malformations can be recognized. To differentiate between the normal dynamics of the growing brain and the developing pathological conditions can be challenging and requires extensive knowledge of normal central nervous system developmental stages and their neuroradiological counterparts at those different stages. This article reviews the second‐trimester appearances of some commonly encountered brain malformations, focusing on helpful tricks and subtle signs to aid in the diagnosis of such conditions as rhombencephalosynapsis, various causes of vermian rotation, molar tooth spectrum anomalies, diencephalic‐mesencephalic junction dysplasia, ganglionic eminence anomalies, and the most common malformations of cortical development. Fetal MRI is an important tool for the prenatal diagnosis of brain malformations and is often requested after second‐trimester ultrasonography reveals a possible abnormality. Despite the immature state of the fetal brain at this early stage, early suggestive signs of the presence of brain malformations can be recognized.
... The added value of orthogonally oriented sections displayed in a single template is exemplary and was demonstrated in both fetuses with rhombencephalosynapsis (RES) and cerebellar hypoplasia (Fig. 3). The common features of abnormal rhombencephalic differentiation as described previously can be tracked in a step-by-step manner [44][45][46][47]. While summarizing the abnormal anatomic hints of the fetus in Fig. 3, a Goméz-López-Hernandéz syndrome might be likewise suggested. ...
Background
The aim of this study was to evaluate the accuracy and reliability of a semiautomated volumetric approach (5D CNS+™) when examining fetuses with an apparent abnormal anatomy of the central nervous system (CNS).
Methods
Stored 3D volumes extracted from a cohort of > 1.400 consecutive 2nd and 3rd trimester pregnancies (range 15–36 gestational weeks) were analyzed using the semiautomatic software tool 5D CNS+™, enabling detailed reconstruction of nine diagnostic planes of the fetal brain. All 3D data sets were examined and judged for plane accuracy, the need for manual adjustment, and fetal CNS anomalies affecting successful plane reconstruction.
Results
Based on our data of 91 fetuses with structural cerebral anomalies, we were able to reveal details of a wide range of CNS anomalies with application of the 5D CNS+™ technique. The corresponding anatomical features and consecutive changes of neighboring structures could be clearly demonstrated. Thus, a profound assessment of the entire altered CNS anatomy could be achieved in nearly all cases. The comparison with matched controls showed a significant difference in volume acquisition ( p < 0.001) and in need for manual adjustment ( p < 0.001) but not in the drop-out rates ( p = 0.677) of both groups.
Conclusion
5D CNS+™ is applicable in the majority of cases with brain lesions and constitutes a reliable tool even if the integrity of the fetal CNS is compromised by structural anomalies. Using volume data that were acquired in identical cutting sections needed for conventional biometry allows for detailed anatomic surveys grossly independent of the examiner’s experience.
... This condition is commonly associated with other midline malformations such as ventriculomegaly, commissural hypoplasia of the commissural system, absence of the olfactory tract agenesis of the posterior lobe of the pituitary and hypoplasia of the anterior visual pathway [4,5]. Association with VACTREL and Gomez-Lopez-Hernandez syndromes has also been reported [6]. Clinical presentation is extremely variable as it depends on the associated supratentorial anomalies [6]. ...
... Association with VACTREL and Gomez-Lopez-Hernandez syndromes has also been reported [6]. Clinical presentation is extremely variable as it depends on the associated supratentorial anomalies [6]. Prenatal diagnosis of this anomaly is currently possible. ...
... RES is a rare cerebellar malformation characterized by partial or complete absence of cerebellar vermis and fusion of cerebellar hemispheres and dentate nuclei [63] (Fig. 4b). Additional neuroradiological features variably reported include midline fusion of the tectum, absence of septum pellucidum, dysplastic corpus callosum, and holoprosencephaly. ...
... The cerebellum is often affected with variable severity, ranging from VH to PCH. Further CNS malformations may include corpus callosum anomalies and hydrocephalus [63,77]. Clinical findings include spastic tetraparesis, dystonia, hypothalamic dysfunction, epilepsy, and severe developmental delay. ...
Cerebellar hypoplasia (CH) refers to a cerebellum of reduced volume with preserved shape. CH is associated with a broad heterogeneity in neuroradiologic features, etiologies, clinical characteristics, and neurodevelopmental outcomes, challenging physicians evaluating children with CH. Traditionally, neuroimaging has been a key tool to categorize CH based on the pattern of cerebellar involvement (e.g., hypoplasia of cerebellar vermis only vs. hypoplasia of both the vermis and cerebellar hemispheres) and the presence of associated brainstem and cerebral anomalies. With the advances in genetic technologies of the recent decade, many novel CH genes have been identified, and consequently, a constant updating of the literature and revision of the classification of cerebellar malformations are needed. Here, we review the current literature on CH. We propose a systematic approach to recognize specific neuroimaging patterns associated with CH, based on whether the CH is isolated or associated with posterior cerebrospinal fluid anomalies, specific brainstem or cerebellar malformations, brainstem hypoplasia with or without cortical migration anomalies, or dysplasia. The CH radiologic pattern and clinical assessment will allow the clinician to guide his investigations and genetic testing, give a more precise diagnosis, screen for associated comorbidities, and improve prognostication of associated neurodevelopmental outcomes.
... [11][12][13] Other noteworthy neuroradiological findings include: 1) on sagittal images: absence of the primary fissure (Fig. 1C), abnormal (rounded) morphology of the fourth ventricle, and deficient indentation of the fourth ventricle by the nodulus; and 2) on axial and coronal images: continuity of the cerebellar folia and fissures across the midline ( Fig. 1A and B) and fusion/apposition of the superior cerebellar peduncles and the dentate nuclei (Fig. 1D). 3 Over 150 cases of RES have been reported in the literature. 14 RES frequently co-presents with a wide range of syndromes, including Gómez-López-Hernández syndrome 15 (the most frequent) and VACTERL association. 16,17 Although multiple cases suggest that RES has a genetic basis, the precise cause has not been identified. ...
... 3,4 Most RES cases are sporadic and, therefore, assumed to be related to de novo dominant mutations. 5,6 RES is a rare anomaly with a wide range of clinical presentations and variable neurodevelopmental outcomes; ranging from an incidental finding in otherwise normal people, to complex syndromes (VACTERL-RES, Gomez-Lopez-Hernandez) with severe neurological impairment. With increased use of advanced fetal neuroimaging techniques RES is being identified more often than previously thought, but it is still underdiagnosed even in the setting of aqueductal stenosis and congenital hydrocephalus. ...
... With increased use of advanced fetal neuroimaging techniques RES is being identified more often than previously thought, but it is still underdiagnosed even in the setting of aqueductal stenosis and congenital hydrocephalus. 6 The neuroimaging features have been discussed in the adult and pediatric literature, but scarcely addressed in prenatal studies. [6][7][8][9][10] The classical features of RES have been previously described in altogether 82 prenatal cases. ...
... 6 The neuroimaging features have been discussed in the adult and pediatric literature, but scarcely addressed in prenatal studies. [6][7][8][9][10] The classical features of RES have been previously described in altogether 82 prenatal cases. However, the associated brain anomalies, the degree of vermian agenesis and the clinical significance have never been investigated in a large prenatal series. ...
Objectives:
To describe the prenatal neuroimaging spectrum of rhombencephalosynapsis (RES) and the criteria for the classification according to the severity of the vermian anomaly. Methods In this multicenter retrospective study of fetuses with a diagnosis of RES, the medical records, ultrasound and brain MR images were comprehensively evaluated for the severity of the vermian anomaly and the presence of associated brain findings. RES was classified based on the criteria suggested by Ishak et al. regarding the vermian anomaly: complete absence - complete; partial agenesis - according to the fusion region: a) anterior, b) posterior, c) severe partial and d) mixed. The findings, observed in complete and partial RES, cases were compared.
Results:
Sixty-two fetuses (12-37 weeks of gestation) were included. Most had complete absence of the vermis (77.4%), a 'round-shaped' cerebellum (72.6%) and a transverse cerebellar diameter below the 3rd centile (87.1%). The 4th ventricle was considered normal in only 5/62 cases. Ventriculomegaly was observed in 80.6%. Midbrain and pontine anomalies were frequent and found in 93.5 and 77.4% respectively.
Conclusions:
This study provides the prenatal neuroimaging criteria for diagnosis, classification and identification of related features of RES, by ultrasound and MRI. RES should be considered in fetuses with a small transverse cerebellar diameter and a round-shaped cerebellum, especially when associated with ventriculomegaly. Partial rhombencephalosynapsis is more common than previously thought and presents an extreme diagnostic challenge, especially in cases with a normal or near-normal transverse cerebellar diameter. This article is protected by copyright. All rights reserved.
