Exencefalia: diagnóstico prenatal y reporte de caso / Exencephaly: prenatal diagnosis and case report

Resumen La exencefalia es una malformación fetal, donde restos de materia encefálica se encuentran afuera de la bóveda craneal. Las malformaciones congénitas constituyen un problema de salud en nuestro país, la tasa de malformaciones es del orden del 2 al 6% de los recién nacidos. Las malformaciones del sistema nervioso central ocupan el segundo lugar en población de México. Al igual que la mayoría de las malformaciones congénitas, las del sistema nervioso central son un grupo de afecciones de etiología multifactorial, producto de una interacción de factores genéticos, infecciosos, ambientales, raciales, agentes físicos y químicos, y la deficiencia o alteración en el metabolismo del ácido fólico. Se presenta un caso de exencefalia, así como una revisión de la embriología de esta entidad, con énfasis en la importancia del uso del ácido fólico en la etapa de embriogénesis del sistema nervioso central, así como la importancia del abordaje prenatal.

Abstract Exencephaly is a type of cephalic disorder, where the brain is located outside of the skull. Congenital malformations constitute a public health problem in Mexico, affecting approximately 2-6% of newborns. Central nervous system malformations are the second most frequent malformations in the population of Mexico. As with most congenital malformations, the etiology of central nervous system anomalies is multifactorial, resulting from interactions among genetic, infectious, environmental, racial, physical and chemical factors, and deficiency or alteration of folic acid metabolism. We also review the embryology of this entity, with emphasis of the importance of folic acid intake at the stage of central nervous system embryogenesis, and also the importance of the prenatal care.

Prevalence and Factors Associated at Presence of Central Nervous System Congenital Malformations.

Introduction: Congenital malformations are currently an important cause of morbidity and mortality in many countries, though in most cases their etiology is unknown. The central nervous system (CNS) is involved in many of these defects. Objective: To study the factors associated with CNS congenital malformations and their prevalence in infants born at a high risk maternity hospital in Northeastern Brazil. Materials and Methods: A case-control study performed from January 2010 to December 2011, with data from The Latin American Collaborative Study of Congenital Malformations. Results: Among the 8.405 registered births, 187 were malformed newborns (2.2%). Nervous system malformations were diagnosed in 61 patients (32.6% (CI = 95% 27.5 to 38.0)), the most frequent being neural tube defects and congenital hydrocephaly. Previous history of miscarriage and/or stillbirth (p = 0.008), family history of malformations (p < 0.001) and parental consanguinity (p = 0.028) are associated with CNS malformation. Environmental factors such as maternal chronic diseases, smoking, exposure to teratogenic drugs and alcohol presented no statistically significant differences. Conclusions: The genetic component was an important contributing factor to the etiology of the malformations studied.

The prenatal diagnosis for absence of fetal cavum septum pellucidum by ultrasonography / 中华医学超声杂志（电子版）

Objective To explore the clinical significance of prenatal diagnosis for absence of fetal cavum septum pellucidum (CSP) by ultrasonography. Methods The ultrasonographic characteristics were retrospectively analyzed in 63 fetuses, whose CSPs were not detected in prenatal two and three dimensional ultrasonography in Nanjing Medical University Affiliated Suzhou Hospital. Results In 63 fetuses with absent CSP, the related malformations included:(1) Five cases were diagnosed as agenesis of corpus callosum (ACC, including four complete ACC and one partial ACC);(2) Twenty-seven cases were diagnosed as holoprosencephaly (HPE, including 18 alobar HPE, ifve semilobar HPE and four lobar HPE);(3) One case was diagnosed as schizencephaly;(4) Two cases were diagnosed as porencephaly;(5) Five cases were diagnosed as hydranencephaly;(6) Twenty-three cases were diagnosed as severe hydrocephalus, among which ifve cases were caused by aqueductal stenosis and the other 18 cases were caused by open spina biifda (Chiari Ⅱ malformation). These absent CSP fetuses had other abnormalities including one case of Dandy-Walker Malformation, one case of Dandy-Walker Variation, 14 cases of median cleft lip, ifve cases of single naris, two cases of proboscis nose, three cases of talipes foot and four cases of single umbilical artery, etc. These 63 cases were all followed up after prenatal ultrasonography but 4 cases were missed and one case of septo-optic dysplasia was misdiagnosed as lobar HPE. The diagnoses of other 58 fetuses by ultrasonography were conifrmed by follow up. Conclusions CSP is considered as an essential part in prenatal evaluations of the fetal central nervous system during second-and third-trimester. Absence of CSP is always accompanied with an extremely wide spectrum of fetal neuroanatomic malformations, including prosencephalon diseases, intracranial midline anomalies, etc. Prenatal ultrasonography is the best choice for the observation of CSP.

Malformações do sistema nervoso central e malformações associadas diagnosticadas pela ultrassonografia obstétrica / Central nervous system malformations and associated defects diagnosed by obstetric ultrasonography

OBJETIVO: Identificar a prevalência de malformações congênitas do sistema nervoso central (SNC) e malformações associadas diagnosticadas pela ultrassonografia obstétrica. MATERIAIS E MÉTODOS: Estudo observacional, transversal, descritivo, em instituição de referência para gestações de alto risco. RESULTADOS: Malformações congênitas do SNC estiveram presentes sem outras malformações associadas em 65,78%, com a distribuição: hidrocefalia (37,5%), mielomeningocele (15%), encefalocele (12,5%), agenesia de corpo caloso (12,5%), anencefalia (12,5%), holoprosencefalia (7,5%), Dandy-Walker (7,5%), Arnold-Chiari (5,0%), hidranencefalia (5,0%), meningocele (5,0%), cisto aracnoideo (2,5%). Malformações congênitas de outros sistemas estiveram associadas às do SNC: craniofacial (73,9%), ortopédica (65,2%), cardiovascular (34,8%), geniturinária (30,4%), gastrintestinal (30,4%), respiratória (8,7%), sindrômica (8,7), oftalmológica (4,3%). A sensibilidade ultrassonográfica no estudo de malformações fetais do SNC foi 79,4%. A taxa de falso-negativos foi 20,5%. Dentre as limitações quantificáveis destaca-se o oligodrâmnio, presente em 25% dos falso-negativos. CONCLUSÃO: A ultrassonografia obstétrica possui boa sensibilidade no rastreio de malformações fetais do SNC, em especial com o aperfeiçoamento constante e domínio na utilização de métodos especializados, como o Doppler e a ultrassonografia volumétrica (3D/4D), contribuindo para firmar-se como modalidade de escolha nesta rotina. Complementar ao método, a ressonância magnética pode vir a fornecer subsídios para uma ainda melhor assistência perinatal.

OBJECTIVE: To identify and evaluate the prevalence of congenital central nervous system (CNS) malformations and associated defects diagnosed by obstetric ultrasonography. MATERIALS AND METHODS: Observational, descriptive, cross-sectional study developed in an institution of reference for high-risk pregnancies. RESULTS: Congenital CNS malformations without other associated defects were present in 65.78% of cases, as follows: hydrocephalus (37.5%), myelomeningocele (15%), encephalocele (12.5%), corpus callosum agenesis (12.5%), anencephaly (12.5%), holoprosencephaly (7.5%), Dandy-Walker (7.5%), Arnold-Chiari (5.0%), hydranencephaly (5.0%), meningocele (5.0%), arachnoid cyst (2.5%). Congenital malformations of other systems were associated with such malformations, as follows: craniofacial (73.9%), orthopedic (65.2%), cardiovascular (34.8%), genitourinary (30.4%), gastrointestinal (30.4%), respiratory (8.7%), syndromic (8.7%), ophthalmologic (4.3%). The sonographic sensitivity in the study of CNS malformations was 79.4%. The rate of false-negative results was 20.5%. Oligohydramnios, present in 25% of false-negative studies, stands out among the quantifiable limitations. CONCLUSION: Obstetric ultrasonography presents good sensitivity in the screening for fetal CNS malformations, specially with the constant improvement and control of specialized methods such as Doppler and volumetric ultrasonography (3D/4D), contributing to consolidate its role as a modality of choice in this routine. Magnetic resonance imaging may play a supplementary role, providing information for an even better perinatal care.