Prenatal diagnosis of microcephaly with simplified gyral pattern: series of eight cases

Microcephaly with simplified gyral pattern (MSG) is an intrinsic genetic central nervous system disorder, characterized by microcephaly (a reduction of brain volume) and a simplified gyral pattern (a reduced number of gyri and shallow sulci associated with normal cortical thickness and neuroanatomical architecture), related to a reduced number of neuronal progenitors in the germinal matrix. We report the first prenatal series of MSG and define the prenatal imaging pattern, which should inform diagnosis and guide prenatal counseling in cases of fetal microcephaly. In this single-center retrospective study of fetuses with MSG, we assessed features on ultrasound and magnetic resonance imaging (MRI), as well as genetic and neuropathological/postnatal data. We included eight patients who had been referred following observation of microcephaly. Ultrasound examination confirmed microcephaly, with a mean growth delay in head circumference of 3.4 weeks, associated with both a lack of gyration and a lack of opercularization of the Sylvian fissure and without any extracephalic anomaly. Fetal brain MRI confirmed lack of gyration with normal cortical thickness and normal intensity of the white matter in all cases. These MRI features led to exclusion of migration/corticogenesis disorders (lissencephaly/polymicrogyria), instead suggesting MSG. The posterior fossa was normal in seven of the eight cases. The corpus callosum was thin in four cases, hypoplastic in two and dysgenetic in two. In four cases, the pregnancy was terminated. The diagnosis of MSG was confirmed from neuropathological and postnatal MRI data. MSG was associated with a genetic diagnosis of RTTN (n = 1) and ASPM (n = 2) biallelic variants in three of the six cases in which genetic work-up was performed. Mild or moderate intellectual deficit with speech delay was present in the three surviving children who were at least 5 years of age at their last examination, without seizures. In conclusion, in the presence of isolated fetal microcephaly with lack of gyration on ultrasound, fetal cerebral MRI is key to diagnosing MSG, which, in the majority of cases, affects the supratentorial space exclusively, and to ruling out other cortical malformations that show a similar sonographic pattern. In addition to imaging, genetic assessment may guide prenatal counseling, since the prenatal prognosis of MSG is different from that of both diffuse polymicrogyria and lissencephaly. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Does fetal cerebral magnetic resonance imaging have additional value in cytomegalovirus fetopathy with normal neurosonography?

Linked article: This Correspondence comments on Di Mascio et al. Click here to view the article.

Clinical and molecular data in cases of prenatal localized overgrowth disorder: major implication of genetic variants in PI3K-AKT-mTOR signaling pathway

OBJECTIVES

To describe clinical and molecular findings in a French multicenter cohort of fetuses with prenatal diagnosis of congenital abnormality and suspicion of a localized overgrowth disorder (LOD) suggestive of genetic variants in the PI3K-AKT-mTOR signaling pathway.

METHODS

We analyzed retrospectively data obtained between 1 January 2013 and 1 May 2020 from fetuses with brain and/or limb overgrowth referred for molecular diagnosis of PI3K-AKT-mTOR pathway genes by next-generation sequencing (NGS) using pathological tissue obtained by fetal autopsy. We also assessed the diagnostic yield of amniotic fluid.

RESULTS

During the study period, 21 subjects with LOD suspected of being secondary to a genetic variant of the PI3K-AKT-mTOR pathway were referred for analysis. Of these, 17 fetuses had brain overgrowth, including six with isolated megalencephaly (MEG) and 11 with hemimegalencephaly (HMEG). Of the six with MEG, germline variants were identified in four cases, in either PIK3R2, AKT3 or MTOR, and a postzygotic PIK3R2 variant was found in the other two cases. Of the 11 with HMEG, a postzygotic PIK3CA variant was found in three fetuses with extracerebral features of PIK3CA-related overgrowth spectrum, and in seven fetuses with isolated HMEG. No pathogenic variant was identified in the 11^th case with HMEG. Four fetuses with limb overgrowth also had one or more lymphatic malformations (LM) and harbored a postzygotic PIK3CA variant. NGS on cultured amniocytes performed in 10 cases, of which nine had been found positive on analysis of pathological fetal tissue, showed variants in four, in either PIK3CA, PIK3R2 or AKT3.

CONCLUSIONS

Isolated MEG or HMEG may lead to identification of genetic variants in the PI3K-AKT-mTOR signaling pathway. Cases of limb overgrowth and LM or isolated HMEG are likely associated with PIK3CA variants. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Two different prenatal imaging cerebral patterns of tubulinopathy

To illustrate the prenatal cerebral imaging features associated with tubulinopathy, we report on five affected fetuses from unrelated families, with a de-novo heterozygous variant in a tubulin gene (TUBA1A, TUBB2B or TUBB3). We identified two distinct prenatal imaging patterns related to tubulinopathy: a severe form, characterized by enlarged germinal matrices, microlissencephaly and a kinked brainstem; and a mild form which has not been reported previously in the prenatal literature. The latter form is associated with non-specific features, including an asymmetric brainstem, corpus callosal dysgenesis, a lack of Sylvian fissure operculization and distortion of the anterior part of the interhemispheric fissure with subsequent impacted medial borders of the frontal lobes, the combination of which, in the absence of additional extracerebral anomalies, is highly suggestive of tubulinopathy. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Prenatal diagnosis of pericallosal curvilinear lipoma: specific imaging pattern and diagnostic pitfalls

We report the first series of cases of pericallosal curvilinear lipoma (CL) diagnosed prenatally and highlight the limitations in identifying a specific prenatal imaging pattern using ultrasound and magnetic resonance imaging (MRI). In all five of our cases, on ultrasound, the main feature leading to referral was a short corpus callosum. This subtle callosal dysgenesis was associated with a band of hyperechogenicity surrounding the corpus callosum, mimicking the pericallosal sulcus, which increased in size during the third trimester in three of the four cases in which sonographic follow-up was performed. On T2-weighted MRI, this band showed typical hypointensity in all cases; in contrast, on T1-weighted imaging, in only one case was there hyperintensity, suggestive of fat, as seen typically in the postnatal period. For appropriate prenatal counseling regarding outcome, it is important to identify or rule out CL when mild corpus callosal dysgenesis is observed. One should be aware of subtle diagnostic findings, such as a thin band of echogenicity surrounding the corpus callosum that is seen as a band of hypointensity on T2-weighted fetal MRI, and which may increase in size during gestation. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Refining the phenotypical and mutational spectrum of Taybi-Linder syndrome

Taybi-Linder syndrome (TALS, OMIM 210710) is a rare autosomal recessive disorder belonging to the group of microcephalic osteodysplastic primordial dwarfisms (MOPD). This syndrome is characterized by short stature, skeletal anomalies, severe microcephaly with brain malformations and facial dysmorphism, and is caused by mutations in RNU4ATAC. RNU4ATAC is transcribed into a non-coding small nuclear RNA which is a critical component of the minor spliceosome. We report here four foetuses and four unrelated patients with RNU4ATAC mutations. We provide antenatal descriptions of this rare syndrome including unusual features found in two twin foetuses with compound heterozygosity for two rare mutations who presented with mild intrauterine growth retardation and atypical dysmorphic facial features. We also carried out a literature review of the patients described up to now with RNU4ATAC mutations, affected either with TALS or Roifman syndrome, a recently described allelic disorder.

[Fetal transcerebellar diameter measured in screening ultrasound: Feasibility and reproducibility]

OBJECTIVE

The aim of the study was to evaluate feasibility and reproducibility of fetal transcerebellar diameter measurement during second and third trimester ultrasound mass screening by junior and senior physicians.

MATERIALS AND METHODS

A monocentric prospective study was conducted at the tertiary care teaching hospital in Lyon, including patients undergoing their second or third trimester planned ultrasound exam. For each patient, a resident and a senior practitioner measured each fetal transcerebellar diameter, during a blinded experiment, according to the transcerebellar plane described by the International Society of Ultrasound in Obstetrics and Gynecology. Images have been scored on 4 criteria. The inter-observer variability for transcerebellar diameter and image quality was assessed using an intra-class correlation coefficient. Image quality has been analyzed according to pregnancy term and to fetal presentation.

RESULTS

Sixty-six patients were included, 44 patients before and 22 patients after 30 weeks. Inter-observer variability of transcerebellar diameter measurement was 0.4%. Inter-observer variability of image quality was 13.5%. Image quality was not significantly different between seniors and residents (P=0.06). Gestational age and fetal presentation did not affect significantly image quality (P=0.42) and (P=0.64) respectively.

CONCLUSION

Transcerebellar diameter measurement during mass screening is simple and reliable. Posterior fossa abnormalities can be explored through its measurement.

Prenatal diagnosis of cobblestone lissencephaly associated with Walker-Warburg syndrome based on a specific sonographic pattern

We report a specific sonographic cerebral pattern of cobblestone lissencephaly (CL) that has not been described previously. This pattern was encountered in four index cases and allowed prenatal diagnosis of CL associated with Walker-Warburg syndrome. The pattern included both an outer echogenic band with reduced pericerebral space, corresponding to an infra- and supratentorial extracortical layer of neuroglial overmigration on pathological examination, and a 'Z'-shaped appearance of the brainstem. This pattern was found as early as 14 weeks' gestation in one of our cases.

[Head and neck superficial venous malformations]

Management of vascular malformations and vascular tumors has recently been maximized by the establishment of an accurate clinical and histological classification and by the development of multidisciplinary expert consultations. Head and neck localizations of venous malformations are common, thus maxillo-facial surgeons should be aware of the characteristics of this pathology and the principles of its management. Diagnosis is mainly clinical and must be certified by Doppler-ultrasonography and contrast enhanced magnetic resonance imaging with T2 fat-saturation sequence. Therapeutic decision depends on the volume of the lesion, and on functional, cosmetic and psychological complaints. Sclerotherapy is now the preferred treatment of head and neck venous malformations. It is performed in specialized interventional radiology units by intralesional injections of sclerosing solution under fluoroscopic guidance. Surgery is useful in some cases, either on its own or following sclerotherapy. In case of bulky lesion, it is necessary to search for and prevent a severe coagulopathy before planning any intervention.

Prenatal unilateral cerebellar hypoplasia in a series of 26 cases: significance and implications for prenatal diagnosis

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.

Fetal thrombotic vasculopathy is associated with thromboembolic events and adverse perinatal outcome but not with neurologic complications: a retrospective cohort study of 54 cases with a 3-year follow-up of children

OBJECTIVE

to test the hypothesis that placental fetal thrombotic vasculopathy (FTV) is associated with obstetric complications and predisposes the child to unfavorable outcomes.

METHODS

54 placentas with FTV lesions and 100 placentas without FTV lesions were collected over a 5-year period at the Croix-Rousse Pathology Department. Clinical findings including maternal, fetal, neonatal condition and pediatric outcome up to three years were collected for each case and control observation. The statistical analyses were assessed with Wald's chi-square derived from conditional logistic regression modeling.

RESULTS

FTV was associated with a significantly higher frequency of obstetric complications: (pregnancy-induced hypertension (OR 3.620, CI 1.563-8.385), preeclampsia (OR 3.674, CI 1.500-8.998), emergency delivery procedures (OR 3.727, CI 1.477-9.403), cesarean sections (OR 2.684, CI 1.016-7.088)), poor fetal condition (intrauterine growth restriction (IUGR) (OR 5.440, CI 2.007-14.748), nonreassuring fetal heart tracing (OR 6.062, CI 2.280-16.115), difficulties in immediate ex utero adaptation (OR 3.416, CI 1.087-10.732)) and perinatal or early childhood demise (OR 3.043, CI 1.327-6.978). On pathological examination, FTV was associated with marginal cord insertion (OR 3.492, CI 1.350-9.035), cord stricture and hypercoiled cord (OR 3.936, CI 1.209-12.813). Thromboembolic events were significantly more frequent in cases with FTV (OR 2.154, CI 1.032-5.622). Neurological complications within the first 3 years of life were also more frequent in the FTV group compared to the control group, but this association was not statistically significant.

CONCLUSIONS

FTV is associated with maternal complications, pathological findings in the placenta, especially gross cord abnormalities, IUGR, and poor perinatal or early childhood outcome. It may also predispose children to somatic thromboembolic events.

Distortion of the anterior part of the interhemispheric fissure: significance and implications for prenatal diagnosis

In order to illustrate the significance of a new anatomical finding, distortion of the interhemispheric fissure (DIHF) associated with impacted medial borders of the frontal lobes, we report a retrospective observational study of 13 fetuses in which DIHF was identified on prenatal imaging. In 10 cases there were associated anatomical anomalies, including mainly midline anomalies (syntelencephaly (n=2), lobar holoprosencephaly (n=1), Aicardi syndrome (n=2)), but also schizencephaly (n=1), cortical dysplasia (n=1) and more complex cerebral malformations (n=3), including neural tube defect in two cases. Chromosomal anomaly was identified in two cases, including 6p deletion in a case without associated central nervous system anomalies and a complex mosaicism in one of the cases with syntelencephaly. In two cases, the finding was apparently isolated on both pre- and postnatal imaging, and the children were doing well at follow-up, aged 4 and 5 years. The presence of DIHF on prenatal imaging may help in the diagnosis of cerebral anomalies, especially those involving the midline. If DIHF is apparently isolated on prenatal ultrasound, magnetic resonance imaging is recommended for careful analysis of gyration and midline, especially optic and olfactory structures. Karyotyping is also recommended.

Prenatal abnormal features of the fourth ventricle in Joubert syndrome and related disorders

Joubert syndrome and related disorders (JSRD) are characterized by absence or underdevelopment of the cerebellar vermis and a malformed brainstem. This family of disorders is a member of an emerging class of diseases called ciliopathies. We describe the abnormal features of the brain, particularly the fourth ventricle, in seven fetuses affected by JSRD. In three cases abnormality of the fourth ventricle was isolated and in four cases there were associated malformations. The molar tooth sign (MTS) was always present and visible on two-dimensional ultrasound and, when performed, on three-dimensional ultrasound and magnetic resonance imaging. The fourth ventricle was always abnormal, in both axial and sagittal views, presenting pathognomonic deformities. It is important to identify JSRD, preferably prenatally or at least postnatally, due to its high risk of recurrence of about 25%. A detailed prenatal assessment of the fourth ventricle in several views may help to achieve this goal.

Severe second-trimester obstructive ventriculomegaly related to disorders of diencephalic, mesencephalic and rhombencephalic differentiation

By review of a series of cases, we set out to identify sonographic features suggestive of an obstructive mechanism in second-trimester fetuses with ventriculomegaly and describe developmental disorders related to pathological differentiation of the diencephalon, mesencephalon and rhombencephalon that lead to obstruction of cerebrospinal fluid flow. We studied retrospectively 11 fetuses referred for severe second-trimester ventriculomegaly of undetermined origin. Neurosonography was performed with detailed analysis of the third ventricle, thalami, cerebral aqueduct and cerebellum. The cerebral imaging data were compared with neuropathological data in eight patients, with a focus on the level and etiology of the obstruction. Parenchymal thinning and reduction of the pericerebral spaces were highly suggestive of ventriculomegaly due to an obstructive mechanism. The ventriculomegaly was related to diencephalosynapsis (thalamic fusion and third ventricle atresia) in five cases and partial/complete aqueduct stenosis in six; it was associated with cerebellar hypoplasia in six cases, including rhombencephalosynapsis in two cases. In nine patients, disorders of the diencephalon, mesencephalon and rhombencephalon were present. In cases of severe isolated ventriculomegaly in which sonographic features are suggestive of an obstructive mechanism, close examination of the third ventricle, thalami, aqueduct of Sylvius and cerebellum may reveal pathological differentiation of the diencephalon, mesencephalon or rhombencephalon, often in combination.

Role of three-dimensional ultrasound measurement of the optic tract in fetuses with agenesis of the septum pellucidum

OBJECTIVES

To construct reference ranges for fetal optic tract mean diameter and to report measurements in fetuses with agenesis of the septum pellucidum (SP).

METHODS

Three-dimensional volumes of the optic chiasm were acquired in 98 normal fetuses during routine sonographic examination at 21-36 weeks' gestation and the diameters of the posterior left and right optic tracts were measured offline. A polynomial regression approach (mean and SD model) was used to compute reference charts for the mean fetal optic tract diameter measurements. In addition, 23 volumes were acquired in fetuses with SP agenesis for offline measurement of optic tract diameter. Complete follow-up was obtained in 13 of these 23 cases.

RESULTS

In normal fetuses, the optic tract diameter increased linearly throughout gestation. There was no evidence of increased variability with gestational age (constant SD). Normal charts and equations for Z-score calculation were constructed. Among the 13 fetuses with SP agenesis and complete follow-up, nine had normal measurements, of which eight had normal vision postnatally. Four had hypoplastic optic tract, defined as mean optic tract diameter Z-score below - 3. Of these, two underwent termination of pregnancy and pathological examination confirmed hypoplasia of the tract, one showed signs of hypoplasia at magnetic resonance imaging and postnatal examination confirmed blindness, and one had a hypoplastic measurement for only one tract and was born with poor vision and abnormal bilateral eye movements.

CONCLUSION

We present new reference charts for mean fetal optic tract diameter. In fetuses with agenesis of the SP, sonography of the optic tract might be a useful tool to assess its development and may help in prenatal counseling.

[Aetiology and prognosis of prenatally diagnosed megacystis regarding gestational age at discovery. A six-year retrospective study]

OBJECTIVES

The purpose of this study is to describe the diagnosis, the care and the prognosis of the fetuses with an antenataly diagnosed megacystis.

PATIENTS AND METHODS

Six year retrospective study about 46 cases of megacystis (26 diagnosed during 1st trimester; 14 during 2nd trimester; 9 during 3rd trimester) referred in the prenatal fetal medicine unit of the Femme-Mère-Enfant hospital in Lyon (France).

RESULTS

The main aetiology is urethral occlusion, particularly for megacystis discovered during the 1st and the 2nd trimesters. Twenty-two terminations of pregnancy were performed (47.8%) and 6 pregnancies arrested spontaneously (13%). Eighteen children were born alive, but 2 died in neonatal period. Finally, 16 children survived (34.8%). Chromosomal abnormalities are frequent (22%).

DISCUSSION AND CONCLUSION

Antenatal discovery of a megacystis is a complex situation, and often of poor fetal prognosis. It requires a multidisciplinary approach to allow the concerned couple to be determined on the best care of this pregnancy.

Pericallosal lipoma associated with Pai syndrome: prenatal imaging findings

Pai syndrome is a rare disorder characterized by the association of a midline pericallosal lipoma, median cleft (palate or lip) and cutaneous polyps of the face. Only seven cases have been reported in the medical literature and we are not aware of any previously reported prenatally detected cases. In this article, we present the prenatal ultrasound and magnetic resonance imaging findings of a syndromic pericallosal lipoma with associated anomalies that led to the prenatal diagnosis of Pai syndrome. We underline the impact on parental counseling following prenatal detection of pericallosal lipoma.

Prenatal diagnosis of partial lumbar asoma by two- and three-dimensional ultrasound and computed tomography: embryological aspects and perinatal management

Asoma is an unusual type of hemivertebra distinct from lateral hemivertebra in its underlying mechanisms, its rarity, its often isolated nature and the high risk of it causing medullary compression. We report a case of isolated partial agenesis of a vertebral body (asoma) diagnosed at 23 weeks' gestation by ultrasonography, in a fetus showing hyperkyphosis with vertebral canal disruption. The diagnosis was established using ultrasound and computed tomography, which allowed measurement of the angle of kyphosis and helped in the determination of the postnatal orthopedic prognosis. In our patient, prenatal diagnosis of asoma facilitated optimization of postnatal management and reduced the neonate's risk of developing paralysis. The main anatomical parameters in the determination of the orthopedic risk are the level of the anomaly, the angle of kyphosis and the degree of vertebral canal disruption.

Assessment of fetal Sylvian fissure operculization between 22 and 32 weeks: a subjective approach

OBJECTIVE

Sylvian fissure operculization (SFO) is a dynamic process throughout gestation and is a reliable feature of fetal cortex gyration that is amenable to prenatal ultrasound examination. This study aimed to define a subjective and reproducible method for SFO assessment.

METHODS

This was a cross-sectional study of the sonographic anatomy of SFO conducted over a 9-month period in 200 fetuses with normal anatomical ultrasound examination at 22-32 weeks of gestation. We used a standardized view in an axial cerebral plane. SFO was scored according to a pre-defined scoring sheet based on the degree of overriding of the insula by the temporal lobe across gestational age. Because of the nested nature of the dataset, linear mixed effects models were used for concurrent assessment of inter- and intraobserver agreement of this scoring method. Subject-specific variance of the score was derived for each week of gestation from the whole repeated-measures dataset and the 5(th) and 95(th) percentiles of the score (mean score(week) +/- 1.645 SD(subject, week)) were determined.

RESULTS

The inter- and intraobserver agreement correlation coefficients were 0.91 (0.89-1.00) and 0.95 (0.93-1.00), respectively, with a standard error of measurement < 1 scoring unit, which corresponds to an accuracy of within 1 week. A reference chart was fitted, showing the increase of the SFO score between 22 and 32 weeks, along with age-specific 5(th) and 95(th) percentiles.

CONCLUSION

A simple scoring evaluation of the SFO is a reliable method for its assessment at between 22 and 32 weeks of gestation.

Abnormal Sylvian fissure on prenatal cerebral imaging: significance and correlation with neuropathological and postnatal data

OBJECTIVE

To illustrate and determine the significance of abnormal Sylvian fissure development (or abnormal operculization) in cases in which prenatal cerebral imaging is suggestive of underlying cortical dysplasia.

METHODS

This was a retrospective study of 15 fetuses at 24-34 weeks in which abnormal operculization was identified on prenatal cerebral imaging and for which follow-up data were available. The imaging findings were correlated to macro- and microscopic neuropathological data (n = 11) or to postnatal clinical and imaging findings (n = 4).

RESULTS

On microscopic examination of fetuses from 11 terminated pregnancies, abnormal operculization was associated with cortical dysplasia in four cases and the cortex was normal in seven. Abnormal operculization was associated with cortical dysplasia in only one of the four liveborn infants. Cases of abnormal Sylvian fissure development with normal cortical architecture were classified, according to associated anomalies of the central nervous system, into one of five groups: those with neural tube defects, microcephaly or frontal hypoplasia, glutaric aciduria, other cerebral abnormalities, and extracerebral anomalies.

CONCLUSION

Abnormal operculization on prenatal imaging does not systematically reflect underlying cortical dysplasia. It may be related to extracortical factors such as abnormal cerebral volume or other developmental anomalies of the central nervous system. An understanding of the significance of abnormal Sylvian fissure development could be useful in integrating its analysis into a more general one of the whole central nervous system.

Prenatal imaging findings in rapidly involuting congenital hemangioma of the skull

We report two cases of rapidly involuting congenital hemangioma (RICH) of the skull diagnosed in the third trimester of gestation, and also present a brief review of the literature. In both of our cases ultrasound examination showed a soft tissue vascular mass of the skull with a specific sonographic finding: a thin hyperechogenic line over the lesion and continuous with the calvaria, suggesting a subperiosteal origin and possibly accounting for a mass effect on the underlying skull. This was slight in one case and marked in the other (and associated with involvement of the calvaria). On prenatal T2-weighted magnetic resonance imaging, the signal of each of the lesions was less marked than the hypersignal encountered in the postnatal period. Postnatal clinical and radiological follow-up over the first few months after delivery confirmed the diagnosis of RICH in each case by demonstrating a significant decrease in the size of the tumor and regression of the vascular component, with complete involution of the lesion within a year.

[Acute hemiparesis revealing a neuroborreliosis in a child]

We report on a 11-year-old boy who had 2 acute hemiparesis episodes over a period of 1 month. He suffered from headache and fatigue since 1 year. He could not remember neither a tick bite nor a local erythematous skin lesion. The diagnosis of neuroborreliosis was based on intrathecal production of specifics antibodies. Furthermore, the CSF/blood glucose ratio was decreased (0.14), which was rarely described. Cranial MRI showed left capsulothalamic inflammation and a vasculitis. The patient was successfully treated by ceftriaxone. Neuroborreliosis should be considered in all children with stroke-like episode, even in the absence of a history of a tick bite.