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Hannah M Tully - One of the best experts on this subject based on the ideXlab platform.
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Rhombencephalosynapsis fused cerebellum confused geneticists
2018Co-Authors: Kimberly A Aldinger, Jennifer C Dempsey, Hannah M Tully, Megan E Grout, Michele G Mehaffey, William B Dobyns, Dan DohertyAbstract:Rhombencephalosynapsis (RES) is a unique cerebellar malformation characterized by fusion of the cerebellar hemispheres with partial or complete absence of a recognizable cerebellar vermis. Subsets of patients also have other brain malformations such as midbrain fusion with aqueductal stenosis, characteristic craniofacial features (prominent forehead, flat midface, hypertelorism, ear abnormalities), and somatic malformations (heart, kidney, spine and limb defects). Similar to known genetic brain malformations, the RES cerebellar malformation is highly stereotyped, yet no genetic causes have not been identified. Here, we outline our current understanding of the genetic basis for RES, discuss limitations, and outline future approaches to identifying the causes of this fascinating brain malformation.
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persistent figure eight and side to side head shaking is a marker for Rhombencephalosynapsis
2013Co-Authors: Hannah M Tully, Jennifer C Dempsey, William B Dobyns, M P Adam, Gisele Ishak, Jonathan W Mink, Sidney M Gospe, Avery H Weiss, James O Phillips, Dan DohertyAbstract:Background Head-shaking stereotypies have been described in patients with neurological impairment. We noted an unusual preponderance of head shaking in patients with Rhombencephalosynapsis (RES). We sought to delineate the movements further and determine whether oculomotor and vestibular testing could reveal their cause. Methods Information was collected from direct observation, video review and parental questionnaire from 59 patients with RES. Oculomotor and vestibular testing was performed in 4 children. Results Of 59 patients, 50 had persistent head shaking that was often observed years before RES was recognized. Three affected children demonstrated abnormal central vestibular processing. Conclusions Head-shaking is common in RES. These characteristic movements may provide input to a defective vestibular system or may represent a motor pattern that is usually suppressed by vestibular feedback. Persistent head shaking should alert clinicians to the possible presence of a congenital hindbrain abnormality that affects the vestibulocerebellum, particularly RES.
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beyond gomez lopez hernandez syndrome recurring phenotypic themes in Rhombencephalosynapsis
2012Co-Authors: Hannah M Tully, Jennifer C Dempsey, Gisele E Ishak, M P Adam, Pedro A Sanchezlara, Cynthia J Curry, Alasdair G W Hunter, Karen W Gripp, Judith E Allanson, Christopher CunniffAbstract:Rhombencephalosynapsis (RES) is an uncommon cerebellar malformation characterized by fusion of the hemispheres without an intervening vermis. Frequently described in association with Gomez-Lopez-Hernandez syndrome, RES also occurs in conjunction with VACTERL features and with holoprosencephaly (HPE). We sought to determine the full phenotypic spectrum of RES in a large cohort of patients. Information was obtained through database review, patient questionnaire, radiographic, and morphologic assessment, and statistical analysis. We assessed 53 patients. Thirty-three had alopecia, 3 had trigeminal anesthesia, 14 had VACTERL features, and 2 had HPE with aventriculy. Specific craniofacial features were seen throughout the cohort, but were more common in patients with alopecia. We noted substantial overlap between groups. We conclude that although some distinct subgroups can be delineated, the overlapping features seen in our cohort suggest an underlying spectrum of RES-associated malformations rather than a collection of discrete syndromes.
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Rhombencephalosynapsis a hindbrain malformation associated with incomplete separation of midbrain and forebrain hydrocephalus and a broad spectrum of severity
2012Co-Authors: Gisele E Ishak, Jennifer C Dempsey, Hannah M Tully, Dennis W W Shaw, M P Adam, Pedro A Sanchezlara, Ian A GlassAbstract: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. Gomez-Lopez-Hernandez syndrome combines Rhombencephalosynapsis with parietal/temporal alopecia and sometimes trigeminal anaesthesia, towering skull shape and dysmorphic features. Rhombencephalosynapsis can also be seen in patients with features of vertebral anomalies, anal atresia, cardiovascular anomalies, trachea-oesophageal fistula, renal anomalies, limb defects (VACTERL) association. Based on a comprehensive evaluation of neuroimaging findings in 42 patients with Rhombencephalosynapsis, we propose a spectrum of severity, ranging from mild (the partial absence of nodulus, anterior and posterior vermis), to moderate (the absence of posterior vermis with some anterior vermis and nodulus present), to severe (the absence of posterior and anterior vermis with some nodulus present), to complete (the absence of the entire vermis including nodulus). We demonstrate that the severity of Rhombencephalosynapsis correlates with fusion of the tonsils, as well as midbrain abnormalities including aqueductal stenosis and midline fusion of the tectum. Rhombencephalosynapsis is also associated with multiple forebrain abnormalities including absent olfactory bulbs, dysgenesis of the corpus callosum, absent septum pellucidum and, in rare patients, atypical forms of holoprosencephaly. The frequent association between Rhombencephalosynapsis and aqueductal stenosis prompted us to evaluate brain magnetic resonance images in other patients with aqueductal stenosis at our institution, and remarkably, we identified Rhombencephalosynapsis in 9%. Strikingly, subjects with more severe Rhombencephalosynapsis have more severely abnormal neurodevelopmental outcome, as do subjects with holoprosencephaly and patients with VACTERL features. In summary, our data provide improved diagnostic and prognostic information, and support disruption of dorsal-ventral patterning as a mechanism underlying Rhombencephalosynapsis.
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Rhombencephalosynapsis a hindbrain malformation associated with incomplete separation of midbrain and forebrain hydrocephalus and a broad spectrum of severity
2012Co-Authors: Gisele E Ishak, Jennifer C Dempsey, Hannah M Tully, Dennis W W Shaw, M P Adam, Pedro A Sanchezlara, Ian A GlassAbstract: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. Gomez-Lopez-Hernandez syndrome combines Rhombencephalosynapsis with parietal/temporal alopecia and sometimes trigeminal anaesthesia, towering skull shape and dysmorphic features. Rhombencephalosynapsis can also be seen in patients with features of vertebral anomalies, anal atresia, cardiovascular anomalies, trachea–oesophageal fistula, renal anomalies, limb defects (VACTERL) association. Based on a comprehensive evaluation of neuroimaging findings in 42 patients with Rhombencephalosynapsis, we propose a spectrum of severity, ranging from mild (the partial absence of nodulus, anterior and posterior vermis), to moderate (the absence of posterior vermis with some anterior vermis and nodulus present), to severe (the absence of posterior and anterior vermis with some nodulus present), to complete (the absence of the entire vermis including nodulus). We demonstrate that the severity of Rhombencephalosynapsis correlates with fusion of the tonsils, as well as midbrain abnormalities including aqueductal stenosis and midline fusion of the tectum. Rhombencephalosynapsis is also associated with multiple forebrain abnormalities including absent olfactory bulbs, dysgenesis of the corpus callosum, absent septum pellucidum and, in rare patients, atypical forms of holoprosencephaly. The frequent association between Rhombencephalosynapsis and aqueductal stenosis prompted us to evaluate brain magnetic resonance images in other patients with aqueductal stenosis at our institution, and remarkably, we identified Rhombencephalosynapsis in 9%. Strikingly, subjects with more severe Rhombencephalosynapsis have more severely abnormal neurodevelopmental outcome, as do subjects with holoprosencephaly and patients with VACTERL features. In summary, our data provide improved diagnostic and prognostic information, and support disruption of dorsal–ventral patterning as a mechanism underlying Rhombencephalosynapsis. * Abbreviations : DTI : diffusion tensor imaging GLH : Gomez-Lopez-Hernandez syndrome HPE : holoprosencephaly NOS : not otherwise specified RES : Rhombencephalosynapsis VACTERL : vertebral anomalies, anal atresia, cardiovascular anomalies, trachea–oesophageal fistula, renal anomalies, limb defects
Richard C Roberts - One of the best experts on this subject based on the ideXlab platform.
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chiari ii malformation mimicking partial Rhombencephalosynapsis a case report
2010Co-Authors: Prasad Guntur Ramkumar, Avinash Kumar Kanodia, Ganapathy Ananthakrishnan, Richard C RobertsAbstract:Rhombencephalosynapsis is a rare congenital intracranial malformation with very few cases reported in literature. Partial Rhombencephalosynapsis is a variation of this anomaly with fewer reported cases. We present the case of a patient with Chiari II malformation mimicking partial Rhombencephalosynapsis.
Dan Doherty - One of the best experts on this subject based on the ideXlab platform.
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mn1 c terminal truncation syndrome is a novel neurodevelopmental and craniofacial disorder with partial Rhombencephalosynapsis
2020Co-Authors: Christopher C Y Mak, Dan Doherty, Angela E Lin, Nancy Vegas, Megan T Cho, Geraldine Viot, Clemantine DimartinoAbstract:MN1 encodes a transcriptional co-regulator without homology to other proteins, previously implicated in acute myeloid leukaemia and development of the palate. Large deletions encompassing MN1 have been reported in individuals with variable neurodevelopmental anomalies and non-specific facial features. We identified a cluster of de novo truncating mutations in MN1 in a cohort of 23 individuals with strikingly similar dysmorphic facial features, especially midface hypoplasia, and intellectual disability with severe expressive language delay. Imaging revealed an atypical form of Rhombencephalosynapsis, a distinctive brain malformation characterized by partial or complete loss of the cerebellar vermis with fusion of the cerebellar hemispheres, in 8/10 individuals. Rhombencephalosynapsis has no previously known definitive genetic or environmental causes. Other frequent features included perisylvian polymicrogyria, abnormal posterior clinoid processes and persistent trigeminal artery. MN1 is encoded by only two exons. All mutations, including the recurrent variant p.Arg1295* observed in 8/21 probands, fall in the terminal exon or the extreme 3' region of exon 1, and are therefore predicted to result in escape from nonsense-mediated mRNA decay. This was confirmed in fibroblasts from three individuals. We propose that the condition described here, MN1 C-terminal truncation (MCTT) syndrome, is not due to MN1 haploinsufficiency but rather is the result of dominantly acting C-terminally truncated MN1 protein. Our data show that MN1 plays a critical role in human craniofacial and brain development, and opens the door to understanding the biological mechanisms underlying Rhombencephalosynapsis.
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Rhombencephalosynapsis fused cerebellum confused geneticists
2018Co-Authors: Kimberly A Aldinger, Jennifer C Dempsey, Hannah M Tully, Megan E Grout, Michele G Mehaffey, William B Dobyns, Dan DohertyAbstract:Rhombencephalosynapsis (RES) is a unique cerebellar malformation characterized by fusion of the cerebellar hemispheres with partial or complete absence of a recognizable cerebellar vermis. Subsets of patients also have other brain malformations such as midbrain fusion with aqueductal stenosis, characteristic craniofacial features (prominent forehead, flat midface, hypertelorism, ear abnormalities), and somatic malformations (heart, kidney, spine and limb defects). Similar to known genetic brain malformations, the RES cerebellar malformation is highly stereotyped, yet no genetic causes have not been identified. Here, we outline our current understanding of the genetic basis for RES, discuss limitations, and outline future approaches to identifying the causes of this fascinating brain malformation.
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cerebellar hypoplasia differential diagnosis and diagnostic approach
2014Co-Authors: Andrea Poretti, Eugen Boltshauser, Dan DohertyAbstract:Cerebellar hypoplasia (CH) refers to a cerebellum with a reduced volume, and is a common, but non-specific neuroimaging finding. The etiological spectrum of CH is wide and includes both primary (malformative) and secondary (disruptive) conditions. Primary conditions include chromosomal aberrations (e.g., trisomy 13 and 18), metabolic disorders (e.g., molybdenum cofactor deficiency, Smith-Lemli-Opitz syndrome, and adenylosuccinase deficiency), genetic syndromes (e.g., Ritscher-Schinzel, Joubert, and CHARGE syndromes), and brain malformations (primary posterior fossa malformations e.g., Dandy-Walker malformation, pontine tegmental cap dysplasia and Rhombencephalosynapsis, or global brain malformations such as tubulinopathies and α-dystroglycanopathies). Secondary (disruptive) conditions include prenatal infections (e.g., cytomegalovirus), exposure to teratogens, and extreme prematurity. The distinction between malformations and disruptions is important for pathogenesis and genetic counseling. Neuroimaging provides key information to categorize CH based on the pattern of involvement: unilateral CH, CH with mainly vermis involvement, global CH with involvement of both vermis and hemispheres, and pontocerebellar hypoplasia. The category of CH, associated neuroimaging findings and clinical features may suggest a specific disorder or help plan further investigations and interpret their results. Over the past decade, advances in neuroimaging and genetic testing have greatly improved clinical diagnosis, diagnostic testing, recurrence risk counseling, and information about prognosis for patients and their families. In the next decade, these advances will be translated into deeper understanding of these disorders and more specific treatments.
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persistent figure eight and side to side head shaking is a marker for Rhombencephalosynapsis
2013Co-Authors: Hannah M Tully, Jennifer C Dempsey, William B Dobyns, M P Adam, Gisele Ishak, Jonathan W Mink, Sidney M Gospe, Avery H Weiss, James O Phillips, Dan DohertyAbstract:Background Head-shaking stereotypies have been described in patients with neurological impairment. We noted an unusual preponderance of head shaking in patients with Rhombencephalosynapsis (RES). We sought to delineate the movements further and determine whether oculomotor and vestibular testing could reveal their cause. Methods Information was collected from direct observation, video review and parental questionnaire from 59 patients with RES. Oculomotor and vestibular testing was performed in 4 children. Results Of 59 patients, 50 had persistent head shaking that was often observed years before RES was recognized. Three affected children demonstrated abnormal central vestibular processing. Conclusions Head-shaking is common in RES. These characteristic movements may provide input to a defective vestibular system or may represent a motor pattern that is usually suppressed by vestibular feedback. Persistent head shaking should alert clinicians to the possible presence of a congenital hindbrain abnormality that affects the vestibulocerebellum, particularly RES.
Pedro A Sanchezlara - One of the best experts on this subject based on the ideXlab platform.
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beyond gomez lopez hernandez syndrome recurring phenotypic themes in Rhombencephalosynapsis
2012Co-Authors: Hannah M Tully, Jennifer C Dempsey, Gisele E Ishak, M P Adam, Pedro A Sanchezlara, Cynthia J Curry, Alasdair G W Hunter, Karen W Gripp, Judith E Allanson, Christopher CunniffAbstract:Rhombencephalosynapsis (RES) is an uncommon cerebellar malformation characterized by fusion of the hemispheres without an intervening vermis. Frequently described in association with Gomez-Lopez-Hernandez syndrome, RES also occurs in conjunction with VACTERL features and with holoprosencephaly (HPE). We sought to determine the full phenotypic spectrum of RES in a large cohort of patients. Information was obtained through database review, patient questionnaire, radiographic, and morphologic assessment, and statistical analysis. We assessed 53 patients. Thirty-three had alopecia, 3 had trigeminal anesthesia, 14 had VACTERL features, and 2 had HPE with aventriculy. Specific craniofacial features were seen throughout the cohort, but were more common in patients with alopecia. We noted substantial overlap between groups. We conclude that although some distinct subgroups can be delineated, the overlapping features seen in our cohort suggest an underlying spectrum of RES-associated malformations rather than a collection of discrete syndromes.
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Rhombencephalosynapsis a hindbrain malformation associated with incomplete separation of midbrain and forebrain hydrocephalus and a broad spectrum of severity
2012Co-Authors: Gisele E Ishak, Jennifer C Dempsey, Hannah M Tully, Dennis W W Shaw, M P Adam, Pedro A Sanchezlara, Ian A GlassAbstract: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. Gomez-Lopez-Hernandez syndrome combines Rhombencephalosynapsis with parietal/temporal alopecia and sometimes trigeminal anaesthesia, towering skull shape and dysmorphic features. Rhombencephalosynapsis can also be seen in patients with features of vertebral anomalies, anal atresia, cardiovascular anomalies, trachea-oesophageal fistula, renal anomalies, limb defects (VACTERL) association. Based on a comprehensive evaluation of neuroimaging findings in 42 patients with Rhombencephalosynapsis, we propose a spectrum of severity, ranging from mild (the partial absence of nodulus, anterior and posterior vermis), to moderate (the absence of posterior vermis with some anterior vermis and nodulus present), to severe (the absence of posterior and anterior vermis with some nodulus present), to complete (the absence of the entire vermis including nodulus). We demonstrate that the severity of Rhombencephalosynapsis correlates with fusion of the tonsils, as well as midbrain abnormalities including aqueductal stenosis and midline fusion of the tectum. Rhombencephalosynapsis is also associated with multiple forebrain abnormalities including absent olfactory bulbs, dysgenesis of the corpus callosum, absent septum pellucidum and, in rare patients, atypical forms of holoprosencephaly. The frequent association between Rhombencephalosynapsis and aqueductal stenosis prompted us to evaluate brain magnetic resonance images in other patients with aqueductal stenosis at our institution, and remarkably, we identified Rhombencephalosynapsis in 9%. Strikingly, subjects with more severe Rhombencephalosynapsis have more severely abnormal neurodevelopmental outcome, as do subjects with holoprosencephaly and patients with VACTERL features. In summary, our data provide improved diagnostic and prognostic information, and support disruption of dorsal-ventral patterning as a mechanism underlying Rhombencephalosynapsis.
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Rhombencephalosynapsis a hindbrain malformation associated with incomplete separation of midbrain and forebrain hydrocephalus and a broad spectrum of severity
2012Co-Authors: Gisele E Ishak, Jennifer C Dempsey, Hannah M Tully, Dennis W W Shaw, M P Adam, Pedro A Sanchezlara, Ian A GlassAbstract: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. Gomez-Lopez-Hernandez syndrome combines Rhombencephalosynapsis with parietal/temporal alopecia and sometimes trigeminal anaesthesia, towering skull shape and dysmorphic features. Rhombencephalosynapsis can also be seen in patients with features of vertebral anomalies, anal atresia, cardiovascular anomalies, trachea–oesophageal fistula, renal anomalies, limb defects (VACTERL) association. Based on a comprehensive evaluation of neuroimaging findings in 42 patients with Rhombencephalosynapsis, we propose a spectrum of severity, ranging from mild (the partial absence of nodulus, anterior and posterior vermis), to moderate (the absence of posterior vermis with some anterior vermis and nodulus present), to severe (the absence of posterior and anterior vermis with some nodulus present), to complete (the absence of the entire vermis including nodulus). We demonstrate that the severity of Rhombencephalosynapsis correlates with fusion of the tonsils, as well as midbrain abnormalities including aqueductal stenosis and midline fusion of the tectum. Rhombencephalosynapsis is also associated with multiple forebrain abnormalities including absent olfactory bulbs, dysgenesis of the corpus callosum, absent septum pellucidum and, in rare patients, atypical forms of holoprosencephaly. The frequent association between Rhombencephalosynapsis and aqueductal stenosis prompted us to evaluate brain magnetic resonance images in other patients with aqueductal stenosis at our institution, and remarkably, we identified Rhombencephalosynapsis in 9%. Strikingly, subjects with more severe Rhombencephalosynapsis have more severely abnormal neurodevelopmental outcome, as do subjects with holoprosencephaly and patients with VACTERL features. In summary, our data provide improved diagnostic and prognostic information, and support disruption of dorsal–ventral patterning as a mechanism underlying Rhombencephalosynapsis. * Abbreviations : DTI : diffusion tensor imaging GLH : Gomez-Lopez-Hernandez syndrome HPE : holoprosencephaly NOS : not otherwise specified RES : Rhombencephalosynapsis VACTERL : vertebral anomalies, anal atresia, cardiovascular anomalies, trachea–oesophageal fistula, renal anomalies, limb defects
Andrea Poretti - One of the best experts on this subject based on the ideXlab platform.
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Pre- and Postnatal Neuroimaging of Congenital Cerebellar Abnormalities
2016Co-Authors: Andrea Poretti, Eugen Boltshauser, Thierry A. G. M. HuismanAbstract:The human cerebellum has a protracted development that makes it vulnerable to a broad spectrum of developmental disorders including malformations and disruptions. Starting from 19 to 20 weeks of gestation, prenatal magnetic resonance imaging (MRI) can reliably study the developing cerebellum. Pre- and postnatal neuroimaging plays a key role in the diagnostic work-up of congenital cerebellar abnormalities. Diagnostic criteria for cerebellar malformations and disruptions are based mostly on neuroimaging findings. The diagnosis of a Dandy-Walker malformation is based on the presence of hypoplasia, elevation, and counterclockwise upward rotation of the cerebellar vermis and cystic dilatation of the fourth ventricle, which extends posteriorly filling out the posterior fossa. For the diagnosis of Joubert syndrome, the presence of the molar tooth sign (thickened, elongated, and horizontally orientated superior cerebellar peduncles and an abnormally deep interpeduncular fossa) is needed. The diagnostic criteria of Rhombencephalosynapsis include a complete or partial absence of the cerebellar vermis and continuity of the cerebellar hemispheres across the midline. Unilateral cerebellar hypoplasia is defined by the complete aplasia or hypoplasia of one cerebellar hemisphere. Familiarity with these diagnostic criteria as well as the broad spectrum of additional neuroimaging findings is important for a correct pre- and postnatal diagnosis. A correct diagnosis is essential for management, prognosis, and counseling of the affected children and their family.
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cerebellar hypoplasia differential diagnosis and diagnostic approach
2014Co-Authors: Andrea Poretti, Eugen Boltshauser, Dan DohertyAbstract:Cerebellar hypoplasia (CH) refers to a cerebellum with a reduced volume, and is a common, but non-specific neuroimaging finding. The etiological spectrum of CH is wide and includes both primary (malformative) and secondary (disruptive) conditions. Primary conditions include chromosomal aberrations (e.g., trisomy 13 and 18), metabolic disorders (e.g., molybdenum cofactor deficiency, Smith-Lemli-Opitz syndrome, and adenylosuccinase deficiency), genetic syndromes (e.g., Ritscher-Schinzel, Joubert, and CHARGE syndromes), and brain malformations (primary posterior fossa malformations e.g., Dandy-Walker malformation, pontine tegmental cap dysplasia and Rhombencephalosynapsis, or global brain malformations such as tubulinopathies and α-dystroglycanopathies). Secondary (disruptive) conditions include prenatal infections (e.g., cytomegalovirus), exposure to teratogens, and extreme prematurity. The distinction between malformations and disruptions is important for pathogenesis and genetic counseling. Neuroimaging provides key information to categorize CH based on the pattern of involvement: unilateral CH, CH with mainly vermis involvement, global CH with involvement of both vermis and hemispheres, and pontocerebellar hypoplasia. The category of CH, associated neuroimaging findings and clinical features may suggest a specific disorder or help plan further investigations and interpret their results. Over the past decade, advances in neuroimaging and genetic testing have greatly improved clinical diagnosis, diagnostic testing, recurrence risk counseling, and information about prognosis for patients and their families. In the next decade, these advances will be translated into deeper understanding of these disorders and more specific treatments.
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ORIGINAL PAPER Gómez–López-Hernández syndrome: reappraisal of the diagnostic criteria
2010Co-Authors: Biayna Sukhudyan, Eugen Boltshauser, Varsine Jaladyan, Gayane Melikyan, Jan Ulrich Schlump, Andrea PorettiAbstract:Abstract Gómez–López-Hernández syndrome (GLHS) is a rare and possibly underdiagnosed condition. So far, 21 patients have been reported and all of them were sporadic observations. We report six additional patients. The hallmark triad of GLHS, also named cerebellotrigeminal dermal dysplasia, consists of Rhombencephalosynapsis, trigeminal anesthesia (often giving rise to corneal opacities), and bilateral parietal or parieto-occipital alopecia. Our patients had Rhombencephalosynapsis and alopecia, but none had trigeminal dysfunction. In this respect, the term cerebellotrigeminal dermal dysplasia is potentially misleading. In conclusion, only rhombencephalo-synapsis and alopecia are consistently present in GLHS and are required diagnostic criteria, while trigeminal anesthesia, dys-morphic features, and ataxia are inconsistent findings. A high index of suspicion is required to diagnose GLHS, particularly as alopecia tends to be hidden by surrounding scalp hair
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Rhombencephalosynapsis associated with dandy walker malformation is a molar tooth malformation
2009Co-Authors: Andrea Poretti, Eugen BoltshauserAbstract:We have previously reported the largest pediatric series (n = 9) of Rhombencephalosynapsis (RS),1 and we are currently reviewing and updating our patients with RS and the syndromic form Gomez-Lopez-Hernandez syndrome. Therefore, we read with interest the case report by R.N. Sener entitled “Rhombencephalosynapsis associated with Dandy-Walker malformation.”2 We do not agree with Sener’s neuroimaging interpretation of RS: there is no fusion of the cerebellar hemispheres, in contrast, these are clearly separated, particularly evident on coronal cuts. The superior cerebellar peduncles are not fused, as required within the definition of RS, but they are even widely separated. We consider the following alternative neuroimaging interpretation: there is clear evidence of a molar tooth sign (MTS) on axial view, with deep interpeduncular fossa, narrow pontomesencephalic isthmus, and elongated superior cerebellar peduncles.3 We have seen this identical MRI constellation in 3 infants (2 of them siblings of consanguineous parents). Remarkably, all infants had an occipital encephalocele, as had Sener’s patient. Parental consanguinity of his patient and the presence of bilateral optic nerve coloboma are additional arguments in favor of a disorder within the spectrum of Joubert syndrome and related disorders (JSRD).4 The interpretation of neuroimaging findings may be relevant for genetic counseling: so far all patients with RS were sporadic, while JSRD are inherited as autosomal recessive. In Sener’s and our patients the superior cerebellar peduncles are thinner than in typical MTS. However, some variability in the MTS morphology within JSRD is well known (see figures in ref. 3), in particular patients with NPHP1 (nephronophthisis 1) gene deletion tend to have thinner superior cerebellar peduncles.4-6
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cognitive outcome in children with Rhombencephalosynapsis
2009Co-Authors: Andrea Poretti, Sandra P Toelle, Fabienne Dietrich Alber, Sarah Burki, Eugen BoltshauserAbstract:Abstract Purpose Rhombencephalosynapsis is a rare congenital cerebellar malformation increasingly recognized by prenatal and neonatal neuroimaging. Cognitive outcome seems to be variable but is not well documented. Aims and methods To study neurological, behavioural, and cognitive functions of patients with non-syndromic Rhombencephalosynapsis, five patients (three female and two male, mean age at the time of this study 8.9 years, range 4.3–17.3 years) were assessed by neurological examination and several tests of behaviour and cognitive functions. Results Ataxia was present in all patients, but daily life activities were partly restricted in only one. Other symptoms were muscular hypotonia, abnormal eye movements, and head stereotypies. Three patients had pathological scores on both attention and hyperactivity/impulsivity scales. Only two patients had normal full-scale IQ (IQ value of 109 and 114, respectively). Verbal and/or performance IQ were impaired in three. Conclusion In non-syndromic Rhombencephalosynapsis the clinical presentation is variable. Attention deficit and hyperactivity disorders are frequent behavioural problems. Cognitive functions are mostly impaired, as mild intellectual impairment without a typical cognitive profile. However, Rhombencephalosynapsis is compatible with normal cognitive functions. No definitive correlation between cognitive impairment and additional supratentorial abnormalities could be established.