Prenatal unilateral cerebellar hypoplasia in a series of 26 cases
Transcription
Prenatal unilateral cerebellar hypoplasia in a series of 26 cases
Ultrasound Obstet Gynecol 2014; 44: 447–454 Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/uog.13217 Prenatal unilateral cerebellar hypoplasia in a series of 26 cases: significance and implications for prenatal diagnosis M. MASSOUD*, M. CAGNEAUX*†, C. GAREL‡§, N. VARENE§, M.-L. MOUTARD‡, T. BILLETTE‡, A. BENEZIT¶, C. ROUGEOT¶, J.-M. JOUANNIC**, J. MASSARDIER*, P. GAUCHERAND*, V. DESPORTES‡¶ and L. GUIBAUD*†‡ *Centre Pluridisciplinaire de Diagnostic Prénatal, Hôpital Femme Mère Enfant, Université Claude Bernard Lyon I, Lyon, France; †Département d’Imagerie Pédiatrique et Fœtale, Hôpital Femme Mère Enfant, Université Claude Bernard Lyon I, Lyon, France; ‡Centre de Référence des Malformations du Cervelet, Hôpital Femme Mère Enfant, Lyon et Hôpital Armand Trousseau, Paris, France; §Service de Radiologie, Hôpital d’Enfants Armand-Trousseau, Paris, France; ¶Département de Neuropédiatrie, Hôpital Femme Mère Enfant, Université Claude Bernard Lyon I, Lyon, France; **Service d’Obstétrique, Hôpital Armand Trousseau, Paris, France K E Y W O R D S: cerebellum; clastic lesion; PHACE syndrome; posterior fossa; ultrasound ABSTRACT Objective To define imaging patterns of unilateral cerebellar hypoplasia (UCH), discuss possible pathophysiological mechanisms and underline the etiology and prognosis associated with these lesions. Methods In this retrospective study we reviewed the charts of 26 fetuses diagnosed between 2003 and 2011 with UCH, defined by asymmetrical cerebellar hemispheres with or without decreased transverse cerebellar diameter. The review included analysis of the anatomy of the cerebellar hemispheres, including foliation, borders and parenchymal echogenicity, and of the severity of the hypoplasia. Data from clinical and biological work-up and follow-up were obtained. Results Our series could be divided into two groups according to whether imaging features changed progressively or remained constant during follow-up. In Group 1 (n = 8), the progression of imaging features, echogenic cerebellar changes and/or hyposignal in T2*-weighted MR images were highly suggestive of ischemic/hemorrhagic insult. In Group 2 (n = 18), imaging features remained constant during follow-up; UCH was associated with abnormal foliation in three proven cases of clastic lesions, a cystic lesion was noted in three cases of PHACE (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac abnormalities/aortic coarctation, eye abnormalities) syndrome and, in the remaining cases, UCH remained unchanged, with no imaging pattern typical of hemorrhage. In 24 cases the infant was liveborn and follow-up was continued in 23, for a mean period of 3 years. Among these, neurological complications were identified in seven (in one of seven (at a mean of 46 months) in Group 1 and in six of 16 (at a mean of 35 months) in Group 2). The surface loss of cerebellar hemisphere was > 50% in 19/24 fetuses and the vermis was clearly normal in appearance in 19/24. Predisposing factors for fetal vascular insult were identified in eight cases: these included maternal alcohol addiction, diabetes mellitus, congenital cytomegalovirus infection and pathological placenta with thrombotic vasculopathy and infarctions. Conclusion UCH is defined as a focal lesion of the cerebellum that may be secondary to hemorrhage and/or ischemic insult, suggesting a clastic origin, particularly when imaging follow-up reveals changes over time. UCH may also be a clue for the prenatal diagnosis of PHACE syndrome. The amount of surface loss of cerebellar hemisphere does not correlate with poor prognosis. UCH with normal vermis is often associated with normal outcome. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd. INTRODUCTION Unilateral cerebellar hypoplasia (UCH) is defined as a loss of volume of one cerebellar hemisphere. The sonographic diagnosis is based on asymmetry of the cerebellar hemispheres and/or a decrease in the transverse cerebellar diameter (TCD)1 . UCH is a rare pathological condition and its underlying etiopathogenesis is unclear2 . According to Barkovich in 19983 , UCH is suggestive of a primary disorder of cerebellar formation; however, advances in prenatal imaging, as reported in a few prenatal case reports4 – 9 and postnatal short series10,11 , have led us to Correspondence: Dr L. Guibaud, Université Claude Bernard Lyon 1, Imagerie Pédiatrique et Fœtale, Hôpital Femme Mère Enfant, 59, Boulevard Pinel, 69677 Lyon, Bron, France (e-mail: [email protected]) Accepted: 16 September 2013 Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd. ORIGINAL PAPER 448 conclude that occurrence of UCH prenatally is probably caused by vascular insult secondary to multiple etiologies and leading to a disruption in cerebellar development11,12 . The resulting clastic lesions of the cerebellar hemispheres can mimic cerebellar malformations3,8,12,13 ; however, the pathogenesis and consequent prognosis may differ. Based on our prenatal series of UCH, to our knowledge the largest to date, our objective was to define the imaging patterns of these cerebellar lesions, discuss their possible pathophysiological mechanisms (clastic vs malformative origin) and determine their etiology and associated prognosis. SUBJECTS AND METHODS In the database of our national referral center for cerebellar malformations (Hospital Femme-MèreEnfants, Lyon and Hopital Armand Trousseau, Paris), we identified and reviewed retrospectively the charts of 26 fetuses diagnosed between 2003 and 2011 with UCH, defined by asymmetrical cerebellar hemispheres with/without decreased TCD. According to the anatomical approach proposed by Guibaud and des Portes1 , the posterior fossa had been assessed in an axial plane by measuring the TCD and the depth of the cisterna magna, and by analyzing cerebellar anatomy, which normally includes a distinct vermis surrounded by two well-defined symmetrical hemispheres, with no communication between the fourth ventricle anteriorly and the cisterna magna posteriorly. The ultrasound and magnetic resonance imaging (MRI) data of these 26 patients were reviewed by two experienced pediatric neuroradiologists (L.G. and C.G.). This included analysis of the anatomy of the cerebellar hemispheres, including foliation, borders and parenchymal echogenicity. The severity of the cerebellar hypoplasia was assessed on the MRI axial views by comparing the surface of the reduced cerebellar hemisphere relative to that of the normal contralateral hemisphere; this surface estimation was calculated by measuring the orthogonal diameters of each hemisphere. Data from clinical and biological work-up and follow-up were provided by the corresponding physicians. RESULTS Our series included 26 fetuses with UCH, referred at a mean gestational age of 26 (range, 21–35) gestational weeks; the diagnosis was made between 21 and 26 weeks in 18 (72%) patients, between 28 and 32 weeks in six (20%) patients and after 32 weeks in two (8%) patients. The second-trimester ultrasound examination was reported as normal in all cases diagnosed at or after 26 weeks, with the exception of two: Case 16, which had no follow-up during pregnancy, and Case 22, in which there was a conotruncal anomaly. UCH was observed in the left cerebellar hemisphere in 17 patients and in the right hemisphere in nine. Our series could be divided into two groups according to imaging follow-up: Group 1 (n = 8, Cases 1–8) Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd. Massoud et al. showed a progressive change of imaging features during follow-up and in Group 2 (n = 18, Cases 9–26) lesions appeared unchanged over time. In Group 1 (Table S1), the progression during follow-up of imaging features, as well as echogenic cerebellar changes and/or hyposignal in T2*-weighted images, were highly suggestive of ischemic/hemorrhagic insult. In Group 2 (Table S2), with cerebellar lesions remaining constant on prenatal imaging follow-up, there were three cases of proven clastic lesions, four cases of PHACE (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac abnormalities/aortic coarctation, eye abnormalities) syndrome, one case of congenital cytomegalovirus (CMV) infection and 10 cases of possible clastic lesions of undetermined origin. UCH was associated with both central nervous system (CNS) and non-CNS lesions. Associated CNS lesions included abnormal foliation, which was noted in eight cases (Cases 1, 9, 10, 11, 17, 18, 21 and 23) on prenatal imaging and confirmed in two cases on postnatal MRI (Cases 17 and 23) and one case on pathological examination of the cerebellar hemisphere (Case 9). Abnormal foliation was also noted on postnatal MRI in two additional cases (Cases 16 and 24). Contralateral asymmetrical brainstem suggestive of Wallerian degeneration was noted in two cases prenatally (Cases 24 and 25) and four additional cases on postnatal MRI (Cases 2, 5, 14 and 25). Anomalies of the supratentorial level were found in two cases: severe ventriculomegaly in a case of congenital CMV infection (Case 16) and a cystic lesion close to the splenium in a case of PHACE syndrome (Case 12). A cystic lesion of the posterior fossa was associated with UCH in four cases (Cases 12–15), including three cases of PHACE syndrome and one case of clastic insult with a porencephalic cyst (Case 7). Typically, the diagnosis of PHACE syndrome is made in the postnatal period on the basis of facial infantile hemangioma associated with arterial anomalies. Associated non-CNS findings were found in three cases: there was echogenicity of the left colon in one case (Case 23), conotruncal heart malformation in one case (Case 22) and severely restricted growth in a fetus of a twin pregnancy complicated by twin-to-twin transfusion syndrome (TTTS) which benefited from selective laser photocoagulation of chorionic vessels at 23 gestational weeks (Case 11). Fetal karyotyping was performed in 11 cases, with normal results (Cases 1, 3, 4, 5, 7, 9, 10, 12, 19, 22 and 25). There were predisposing maternal factors for fetal vascular insult in eight cases; these included alcohol addiction in one case (Case 2), diabetes mellitus in two cases (Cases 2 and 19), congenital CMV infection in one case (Case 16), abnormal coagulopathy in three cases involving a heterozygous mutation in the methylene tetrahydrofolate reductase gene (MTHFR) in both parents in one case (Case 9), antiphospholipid syndrome in one case (Case 7) and positive platelet cross-matching in one case (Case 6), and a mother with hypertension treated by calcium inhibitor in one case (Case 24). A pathological placenta with thrombotic vasculopathy and infarctions was identified on pathological examination in two cases (Cases 7 and 10). Ultrasound Obstet Gynecol 2014; 44: 447–454. Prenatal unilateral cerebellar hypoplasia 449 Figure 1 Case 2. (a) Ultrasound image in a patient with medical history of alcohol addiction referred at 23 gestational weeks for abnormal echogenicity of the left cerebellar hemisphere, which was confirmed in our department. (b) Ultrasound follow-up at 25 weeks showed partial absence of the left cerebellar hemisphere, as well as echogenic thickening of the meninges facing the abnormal hemisphere (arrow). Dotted line indicates transcerebellar diameter. (c,d) Axial fetal magnetic resonance images confirmed both focal decrease of volume of the left cerebellar hemisphere and thickening of adjacent meninges, which demonstrated hypo- and hyperintensity (arrows) on T2-weighted (c) and T1-weighted (d) sequences, respectively, suggestive of ischemohemorrhagic insult. Regarding prenatal counseling, postnatal prognosis was characterized, as suggested in the literature11,12 , on the basis of extension of the clastic process to the vermis and the severity of surface loss of the affected hemisphere. The surface loss of cerebellar hemisphere was below 25% in one case, between 25 and 50% in five cases and above 50% in 19 cases; in one case this information was not available. The vermis appeared normal in 19 cases and abnormal in four cases, and was difficult to evaluate in three cases. Among the 19 fetuses with normal vermis on prenatal imaging, normal vermis was also reported on postnatal MRI for 18 infants and focal hypoplasia of the vermis was noted in one case with normal development (Case 2). Among the four fetuses with abnormal vermis, termination of pregnancy was performed in one case (Case 9) and a stillbirth occurred in another (Case 10); the vermian lesion was confirmed on pathological examination in these two cases. In the remaining two cases, postnatal MRI was not performed; in one case (Case 6), the infant demonstrated normal development at 20 months, while in the other case (Case 1), follow-up was not possible. Among the three fetuses in which the analysis of the vermis was limited during the prenatal period, Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd. postnatal imaging showed normal vermis in two cases (Cases 24 and 25) and confirmed the suspicion of a caudal lesion of the vermis in the other (Case 7). Twenty-four cases were live-born; the parents elected for termination of pregnancy in one case in which UCH was associated with a vermian lesion (Case 9) and a stillbirth was diagnosed at 32 gestational weeks in another case (Case 10). The mean gestational age at delivery was 38 (range, 34–41) weeks. One fetus (Case 11), the ex-donor of a monochorionic twin pregnancy treated by laser, had presented with restricted growth and had a birth weight of 930 g at 35 weeks; all other newborns were appropriate-for-gestational age. Based on the collected data, UCH was likely to have been associated with primitive hemorrhagic or ischemic/hemorrhagic insults in 11 cases (Cases 1–11), PHACE syndrome in four cases (Cases 12–15) and a congenital CMV infection in one case (Case 16). Regarding clinical follow-up, among the 24 living infants, 16 had normal neurological outcome and seven had abnormal outcome (including mild speech delay (n = 2; Cases 5, 20), serious delay in developmental milestones (n = 3; Cases 11, 12, 16), oculomotor disorders (n = 1; Case 25) Ultrasound Obstet Gynecol 2014; 44: 447–454. 450 Massoud et al. Figure 2 Case 8. Patient referred at 31 gestational weeks for anatomical disorganization of the left cerebellar hemisphere. (a,b) Axial ultrasound images focusing on the left cerebellar hemisphere showed both focal decrease of volume and abnormal parenchymal echogenicity (arrow) of the upper part of the hemisphere (a), as well as a cystic lesion (arrow) on its inferior part (b), suggestive of a porencephalic lesion. (c) T2-weighted axial magnetic resonance (MR) image demonstrated large parenchymal dysgenesis of the inferior part of the cerebellar hemisphere, which was replaced by a cystic lesion (arrow). (d) T2*-weighted axial MR image, at the same level as that in (c), showed hypointensity of the residual parenchyma, which confirmed hemosiderin deposits (arrow) related to an ischemohemorrhagic insult. Neonatal axial (e), coronal (f) and sagittal (g) T2-weighted MR images confirmed reduction of volume of the left cerebellar hemisphere associated with porencephalic cyst (e), replacing the inferior part of the hemisphere, with hypointensity at the junction between the cyst and the residual cerebellar parenchyma (arrow) on coronal image (f), suggestive of hemosiderin deposits. Note that the vermis was confirmed to be anatomically intact (g). Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd. Ultrasound Obstet Gynecol 2014; 44: 447–454. Prenatal unilateral cerebellar hypoplasia and dyspraxia (n = 1; Case 17)); regular follow-up visits were not possible for one infant. The mean follow-up period was 3 years, ranging from 2 months to 9 years. DISCUSSION Among lesions of the posterior fossa, UCH is rare and the pathophysiological mechanisms are unclear2 . Cerebellar injuries have been described mainly as a complication of low birth weight and extreme prematurity9 – 11 ; however, similar lesions have been reported throughout pregnancy12 – 14 . To our knowledge, to date this is the largest prenatal series of focal reduction of one cerebellar hemisphere, referred to as UCH according to the anatomical approach proposed by Guibaud and des Portes1 . Cerebellar clastic lesions have been described as early as 17 gestational weeks4 . In our series, as a result of the timing of ultrasound imaging, the mean gestational age at diagnosis was 26 weeks. Between 24 and 32 weeks, the cerebellum exhibits asymptotic growth related to high proliferation of neuroblasts and differentiation of the adult cerebellar cortex14 – 16 , which leads to significant susceptibility to vascular insults and abnormalities. Our series could be divided into two groups according to imaging follow-up. In the eight patients of Group 1 (Table S1), the progression of imaging features, as well as of echogenic cerebellar changes and/or hyposignal in T2*-weighted images (Figure 1, Case 2), were highly suggestive of hemorrhagic insult. Cerebellar hemorrhage is generally visualized as an echogenic cerebellar hemisphere, or a mixed echogenic lesion within the cerebellum, with subsequent liquefaction leading to a porencephalic lesion5,6 , as typically shown in Case 8 (Figure 2). In Case 7, UCH was associated with a cystic lesion, reported at 25 gestational weeks as an arachnoid cyst with a mass effect on the vermis, suggestive of malformative origin. However, repeat imaging at 33 weeks revealed a porencephalic cyst associated with destruction of the left CH and presence of a clastic lesion, which was confirmed by postnatal MRI. Yuksel and Batukan8 described a similar case, which was misdiagnosed as a Dandy–Walker malformation. Although ultrasound examination can depict changes in parenchymal echogenicity, suggestive of clastic lesions, over time, MRI can confirm more accurately the presence of hemorrhage, especially when using T2*-gradient echo sequences (Cases 2, 6 and 8). However, it is not possible to assess whether these lesions are inherently hemorrhagic or related to hemorrhagic changes due to an underlying ischemic insult17 . In the 18 patients of Group 2 (Table S2), the lesion remained unchanged on prenatal imaging follow-up. In two cases, clastic origin was confirmed, associated with abnormal vermis (Cases 9 and 10) which led to termination of pregnancy in one (Case 9) (Figure 3) and stillbirth in the other (Case 10). Pathological examination showed important ischemic/hemorrhagic lesions in both cases. In a third case (Case 11), UCH was encountered in a severely growth-restricted ex-donor of a monochorionic twin pregnancy, which had been treated Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd. 451 by laser coagulation at 23 weeks for TTTS. Postnatal MRI demonstrated hemosiderin deposition suggestive of clastic infarction, secondary to TTTS. Interestingly, in Group 2, there were four cases of PHACE syndrome (Figure 4), a vascular neurocutaneous disorder of undetermined origin18 . A spectrum of congenital malformations of the posterior fossa has been described for PHACE syndrome, ranging from Dandy– Walker malformation to focal dysplasia–hypoplasia of the cerebellum. In such cases, it is hypothesized that UCH is related to underdevelopment of the cerebellar hemisphere, as a consequence of arterial anomalies, resulting in reduction of cerebellar arterial supply. UCH was associated with a cystic lesion in three of our four cases (Cases 13–15). Only three prenatal cases suggestive of PHACE syndrome have been described previously19,20 ; in one of these, UCH was reported. Congenital CMV infection was associated with UCH in one case (Case 16). Initial ultrasound examination performed at 34 weeks, immediately before premature delivery, demonstrated right UCH associated with severe ventriculomegaly. Postnatal MRI confirmed prenatal findings and showed a pattern typical of CMV fetopathy, which was confirmed by serological testing. Vermian hypoplasia has been reported in congenital CMV infection20,21 . The immune inflammatory response and the direct cytopathic effect of CMV on precursor cells of the neuroepithelium are responsible for brain damage22,23 . However, in our case, UCH was most likely due to inflammatory vasculopathy rather than direct cytotoxicity of CMV, since the lesion was unilateral. In our 10 remaining patients (Cases 17–26), the imaging pattern of UCH remained constant during follow-up, without any features to suggest the presence of hemorrhage. Imaging findings were confirmed in the postnatal period in only seven cases, since MRI was not performed in one infant (Case 20). Postnatal outcome was normal in all cases, with the exception of Case 17 (Figure 5); thus genetic or syndromic entities, in which UCH has occasionally been reported24 – 27 , were excluded. Defective foliation was associated with UCH in eight cases. The possible vascular injury in these cases may have caused abnormal migration and misorientation of Purkinje cells, and subsequent disorganization of external granular cells, leading to abnormal foliation, as described in mutant rats28 . Contralateral asymmetrical brainstem, suggestive of Wallerian degeneration, was seen in two of our series prenatally (Cases 24 and 25) and four cases postnatally (Cases 2, 5, 14 and 25); this has also been noted in association with clastic lesions of the cerebellum29 . Since risk factors for clastic lesions have been described previously17 and were also identified in eight cases of our series, we recommend, in accordance with Malinger et al.6 , that in cases of UCH it is important to investigate the possibility of any maternal drug use, alcohol consumption or recent trauma, as well as thrombocytopenia and coagulation disorders (including factor VII and X deficiencies17 , platelet cross-matching Ultrasound Obstet Gynecol 2014; 44: 447–454. 452 Massoud et al. Figure 3 Case 9. Patient referred at 28.5 gestational weeks for focal decreased cerebellar biometry. Axial ultrasound (a) and T2-weighted magnetic resonance (MR) (b) images showed focal volume loss (arrows) of the left cerebellar hemisphere, without any anomaly of echogenicity or intensity, respectively. (c) Sagittal ultrasound imaging showed both a reduction of volume and a lack of foliation (arrow) of the left cerebellar hemisphere, compared with normal volume and foliation (d, arrow) of the contralateral right cerebellar hemisphere. (e) Mid-sagittal ultrasound image demonstrated decreased height of the vermis (arrow) (height, 11–12 mm) with an abnormally distal fourth ventricle, compared with the normal appearance of the fourth ventricle and vermis (height, 16 mm) at the same gestational age in a control fetus (f). These imaging findings, demonstrated also in mid-sagittal T2-weighted MR image (g), were suggestive of clastic lesion extending to the cranial part of the vermis, which was confirmed in the pathological specimen (h). Double-headed arrow in (h) indicates height of vermis. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd. Ultrasound Obstet Gynecol 2014; 44: 447–454. Prenatal unilateral cerebellar hypoplasia 453 Figure 4 Case 13. Patient referred at 27 gestational weeks for anatomical disorganization of the posterior fossa. (a) Axial ultrasound image showed focal decrease of volume of the left cerebellar hemisphere and a cystic lesion facing the left cerebellar hemisphere (arrow), demonstrating mass effect on the adjacent vault of the skull. (b) T2-weighted axial magnetic resonance image showed discrete focal low signal (arrow) of the left cerebellar hemisphere, suggestive of a clastic lesion. (c) Postnatal clinical follow-up demonstrated development of segmental hemangioma on the left part of the face, which led to a diagnosis of PHACE syndrome. Figure 5 Case 17. Patient referred at 35 gestational weeks for focal decreased cerebellar biometry (transcerebellar diameter, 41 mm; 50th percentile, 46 mm). Axial ultrasound image confirmed abnormal cerebellar biometry and showed focal volume loss and increased echogenicity (arrow) of the left cerebellar hemisphere. Axial (b), mid-sagittal (c) and coronal (d) T2-weighted fetal magnetic resonance images confirmed decreased volume (arrows) of the left hemisphere and showed focal low signal, suggestive of a clastic lesion. The vermis was otherwise normal. and CMV infection), and to perform pathological analysis of the placenta17 . Regarding prenatal counseling, postnatal prognosis may be characterized, as suggested in the literature10,11 , on the basis of extension of the clastic process to the vermis and the severity of surface loss of the affected hemisphere. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd. The majority of our cases were liveborn (n = 24) and showed normal development in infancy (n = 16), even though cerebellar surface loss prenatally was > 50% in the majority of cases (n = 19). The vermis was normal in 14 of these 16 normally developed cases, based on postnatal MRI. The three infants with severe developmental Ultrasound Obstet Gynecol 2014; 44: 447–454. Massoud et al. 454 delay (Cases 11, 12 and 16) had presented prenatally with severely restricted growth, PHACE syndrome and congenital CMV infection, respectively, with normal vermis on postnatal MRI. Of the remaining four patients with abnormal outcome (speech delay, Cases 5 and 20; ocular disorders (Case 25); dyspraxia (Case 17)), postnatal MRI showed normal vermis in three (Cases 5, 17 and 25) and asymmetrical brainstem in two (Cases 5 and 25). Postnatal MRI was not performed in Case 20. Based on our collection of data, the surface loss of cerebellar hemisphere did not correlate with poor prognosis, and UCH with normal vermis was often associated with normal outcome in the absence of associated pathologies. However, despite the normal outcome of our two infants with abnormal vermis, we believe that in these cases the prognosis is of concern, as noted by Poretti et al.10 , since vermian lesion is often associated with poor cognitive outcome. REFERENCES 1. Guibaud L, Des Portes V. Plea for an anatomical approach to abnormalities of the posterior fossa in prenatal diagnosis. Ultrasound Obstet Gynecol 2006; 27: 477–481. 2. Baulhauser E. Cerebellum - small brain but large confusion: a review of selected cerebellar malformations and disruptions. Am J Med Genet A 2004; 126A: 376–385. 3. Barkovich AJ. Neuroimaging manifestations and classification of congenital muscular dystrophies. AJNR Am J Neuroradiol 1998; 19: 1389–1396. 4. Mancini J, Lathel V, Hugonenq C, Charbol B. Brain injuries in early foetal life: consequences for brain development. Dev Med Child Neurol 2001; 43: 52–55. 5. Gorincour G, Rypens F, Lapierre C, Costa T, Audibert F, Robitaille Y. Fetal magnetic resonance imaging in the prenatal diagnosis of cerebellar hemorrhage. Ultrasound Obstet Gynecol 2006; 27: 78–80. 6. Malinger G, Zahalka N, Kidron D, Ben-Sira L, Lev D, Lerman-Sagie T. Fatal outcome following foetal cerebellar haemorrhage associated with placental thrombosis. Eur J Paediatr Neurol 2006; 10: 93–96. 7. Sharony R, Kidron D, Aviram R, Beyth Y, Tepper R. Prenatal diagnosis of fetal cerebellar lesions: a case report and review of the literature. Prenat Diagn 1999; 19: 1077–1080. 8. Yuksel A, Batukan C. Foetal cerebellar haemorrhage in a severely growth-restricted fetus: natural history and differential diagnosis from Dandy–Walker malformation. Ultrasound Obstet Gynecol 2003; 22: 178–181. 9. Ranzini AC, Shen-Schwarz S, Guzman ER, Fisher AJ, White M, Vintzileos AM. Prenatal sonographic appearance of haemorrhagic cerebellar infarction. J Ultrasound Med 1998; 17: 725–727. 10. Poretti A, Limperopoulos C, Roulet-Perez E, Wolf NI, Rauscher C, Prayer D, Müller A, Weissert M, Kotzaeridou U, Du Plessis AJ, Huisman TA, Boltshauser E. Outcome of severe unilateral cerebellar hypoplasia. Dev Med Child Neurol 2010; 52: 718–724. 11. Benbir G, Kara S, Yalcinkaya BC, Karhkaya G, Tuysuz B, Kocer N, Yalcinkaya C. Unilateral cerebellar hypoplasia with different clinical features. Cerebellum 2011; 10: 49–60. 12. Boltshauser E, Steinlin M, Martin E, Deonna TH. Unilateral cerebellar aplasia. Neropediatrics 1996; 27: 50–53. 13. Patel S, Barkovich AJ. Analysis and classification of cerebellar malformations. AJNR Am J Neuroradiol 2002; 23: 1074–1087. 14. Guibaud L, Garel C, Annie B, Pascal G, Francois V, Vavasseur C, Oury JF, Pracros JP. Prenatal diagnosis of capillary telangiectasia of the cerebellum - ultrasound and MRI features. Prenat Diagn 2003; 23: 791–796. 15. Messerschmidt A, Brugger PC, Boltshauser E, Zoder G, Sterniste W, Birnbacher R, Prayer D. Disruption of cerebellar development: potential complication of extreme prematurity. AJNR Am J Neuroradiol 2005; 26: 1659–1667. 16. Goldstein I, Reece EA, Pilu G, Bovicelli, Hobbins JC. Cerebellar measurements with ultrasonography in the evaluation of fetal growth and development. Am J Obstet Gynecol1987; 156: 1065–1069. 17. Govaert P. Prenatal stroke. Semin Fetal Neonatal Med 2009; 14: 250–266. 18. Metry D, Heyer G, Hess C, Garzon M, Haggstrom , Frommelt P, Adams D, Siegel D, Hall K, Powell J, Frieden I, Drolet B. PHACE Syndrome Research Conference. Consensus Statement on Diagnostic Criteria for PHACE Syndrome. Pediatrics 2009; 124: 1447–1456. 19. Carles D, Pelluard F, Alberti EM, Maugey-Laulom B, Lin TY, Saura R, Roux D, Lacombe D. Fetal presentation of PHACES syndrome. Am J Med Genet A 2005; 132: 110. 20. Recio-Rodrı́guez M, Martı́n Fernández-Mayoralas D, Jiménez-de-la-Peña M, Fernández-Jaén A. PHACES syndrome (Pascual Castroviejo type II): prenatal and postnatal magnetic resonance imaging. Radiologia 2013; 55: 537–540. 21. de Vries LS, Gunardi H, Barth PG, Bok LA, Verboon-Maciolek MA, Groenendaal F. The spectrum of cranial ultrasound and magnetic resonance imaging abnormalities in congenital cytomegalovirus infection. Neuropediatrics 2004; 35: 113–119. 22. Malinger G, Lev D, Zahalka N, Ben Aroia Z, Watemberg N, Kidron D, Sira LB, Lerman-Sagie T. Fetal cytomegalovirus infection of the brain: the spectrum of sonographic findings. AJNR Am J Neuroradiol 2003; 24: 28–32. 23. Bissinger AL, Sinzger C, Kaiserling E, Jahn G. Human cytomegalovirus as a direct pathogen: correlation of multiorgan involvement and cell distribution with clinical and pathological findings in a case of congenital inclusion disease. J Med Virol 2002; 67: 200–206. 24. Harbord MG, Finn JP, Hall-Craggs MA, Brett EM, Baraitser M. Moebius’ syndrome with unilateral cerebellar hypoplasia. J Med Genet 1989; 26: 579–582. 25. Martinelli P, Maruotti GM, Agangi A, Mazzarelli LL, Bifulco G, Paladini D. Prenatal diagnosis of hemifacial microsomia and ipsilateral cerebellar hypoplasia in a fetus with oculoauriculovertebral spectrum. Ultrasound Obstet Gynecol 2004; 24: 199–201. 26. Titomanlio L, De Brasi D, Romano A, Genesio R, Diano AA, Del Giudice E. Partial cerebellar hypoplasia in a patient with Prader–Willi syndrome. Acta Paediatr 2006; 95: 861–863. 27. Serrano-Gonzalez C, Prats Vinas JM. [Unilateral aplasia of the cerebellum in Aicardi’s syndrome]. Neurolgia 1998; 13: 254–256. 28. Conradi NG. Cerebellar foliation in rats. 1. Cortical changes preceding the formation of a fissure. Acta Pathol Microbiol Immunol Scand 1985; 93: 385–389. 29. Garel C. Posterior fossa malformations: main features and limits in prenatal diagnosis. Pediatr Radiol 2010; 40: 1038–1045. SUPPORTING INFORMATION ON THE INTERNET Tables S1 and S2 Summary of clinical and imaging findings and neonatal outcome of fetuses with asymmetrical cerebellar hemispheres which showed progressive changes in imaging features during follow-up (Group 1, Table S1) or no change in imaging features during follow-up (Group 2, Table S2) Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd. Ultrasound Obstet Gynecol 2014; 44: 447–454.