Ultrasound Diagnosis of Congenital Brain Anomalies: about 46 cases

Introduction:

Congenital malformations affect approximately 2 – 3% of all live births every year. Congenital brain anomalies, whether they are isolated (single) or part of syndromes, are a common cause of medical intervention, long-term illness, and death. Ultrasound (US) examination is an effective modality for the diagnosis of these anomalies in experienced hands. Cranial US correlate well with anatomical and pathological findings and clinical outcomes. Cranial US detection of congenital brain anomalies is useful for diagnostic purposes, and it also may allow for more appropriate management and more accurate neurological prognostication.

Objective:

The objective of this study is to determine the different malformations accessible to prenatal screening and the contribution of ultrasound to reduce their impact.

Methods:

A retrospective study conducted in Department of Obstetrics and Gynecology „A“ in the Center of Maternity and Neonatology of Tunis. During two years: from January 2013 to December 2015.

Inclusion criteria: all patients who had a therapeutic abortion on morphological malformations detected by ultrasound.

Results:

The average age of patients was 32 years. Prenatal diagnosis was carried out in all patients in "A" Department of Obstetrics and Gynecology in CMNT.

We found 46 cases of brain anomalities.

The average age at diagnosis was 22 SA.

In 20 cases there were multiple malformations.

Malformation	Number of cases
Cerebral ventriculomegaly and hydrocephaly	14
Cystic hygroma	7
Posterior fossa abnormalities	10
Spina bifida	9
Anencephaly	3
Microcephaly	3

15 malformations were detected at the first trimester (32%) meanwhile 24 were found at the morphological ultrasound exam (52%) and 7 during the third trimester of pregnancy (16%).

Fetal brain MRI were performed in 10 cases, and have demonstrated additional findings in 5 cases.

Fetal autopsy was performed in 11 cases confirmed the diagnosis in all cases (100%).

Discussion:

In the neonatal period cranial US can be used as the initial modality to exclude a major structural malformation.

The rapid changes occurring in the fetal brain during pregnancy make the systematic evaluation of the brain anatomy a difficult task. During the first trimester, the brain vesicles are the main landmarks visualized by ultrasound evaluation. Around 10 – 11 weeks, the lateral ventricle choroid plexuses may be observed. It is important to emphasize that only a very limited number of CNS malformations are expected to be diagnosed during this period. The early second trimester offers an excellent window for a more complete study of the fetal brain and spine. The examination may be performed using the transabdominal and/or transvaginal (TVS) approach; usually TVS provides better resolution. With a combination of these two approaches or by the use of 3D multiplanar US, orthogonal planes (axial, sagittal and coronal) are obtained. Axial planes are useful for assessment of cranial biometry and the measurement of the lateral ventricles, cerebellar transverse diameter and cisterna magna width. Coronal planes, at this early stage, may provide the first visualization of the anterior portion of the corpus callosum and help in ruling out cranial.

It is non-invasive highly sensitive, safe, easily repeatable, accurate and cost effective neuroimaging technique. The advantages of cranial US are that it can be performed at the bedside with minimal disturbance to the neonates and patients do not require sedation. It is a useful modality for detecting congenital and acquired anomalies of the brain and the most frequently occurring patterns of brain injury in both preterm and full-term neonates. Cranial US is also suitable for assessing brain maturation and timing of cerebral injury.

Cranial US are correlated with anatomical and pathological findings and clinical outcomes. Appropriate correlation of the US features with clinical history can assist in improving the diagnostic yield. Familiarity with the US features of congenital brain anomalies is therefore an extremely valuable tool, as it facilitates an accurate diagnosis and treatment these anomalies.

More recently three-dimensional ultrasound may facilitate the examination of the fetal brain and spine.

Conclusion:

Congenital brain anomalies are some of the most common of all congenital abnormalities. In the neonatal period cranial US can be used as the initial modality to exclude a major structural malformation. Cranial US is non-invasive highly sensitive, safe, easily repeatable and cost effective for detecting congenital anomalies of the brain in both preterm and full-term neonates. It may provide important information regarding the anatomic location, size, and shape of congenital brain anomalies as well as their mass effect on adjacent structures. Cranial US are correlated with anatomical and pathological findings and clinical outcomes. Familiarity with the US features of congenital brain anomalies is therefore an extremely valuable tool, as it facilitates an accurate diagnosis and treatment when necessary.