الفهرس 
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Abstract
The brain and spinal cord make up the central nervous system. Similar to the skin, they both originate in the embryonic ectoderm. The process of neurulation, or the formation of the neural tube, starts their growth and maturation in the third and fourth weeks of embryonic life. The neural tube naturally shuts in both the dorsal and ventral regions. The prosencephalic stage of brain development begins around week 5 or 6, when the brain first becomes visible. The three parts of the primitive brain are the prosencephalon, mesencephalon, and rhombencephalon. Through a progression of phases, the prosencephalon splits into the telencephalon and diencephalon. These stages include creation, cleavage, and midline development. Malformations of the developing brain are the result of any disruption in this process.
Central nervous system disorders in the foetus are the second most common congenital anomaly, behind heart defects. In order to provide better prenatal counselling and facilitate appropriate referral, an early and correct diagnosis during prenatal US is crucial.
Congenital disorders involving the central nervous system are quite prevalent. The most common central nervous system abnormality is a neural tube defect, which affects roughly 1-2 newborns out of every 1000. CNS abnormalities can have a dire prognosis and are linked to a variety of hereditary diseases, making prenatal discovery and precise diagnosis all the more crucial. The maturation of the brain and spinal cord is a long and intricate process that often does not conclude until late adulthood. It is estimated that as many as 75% of foetal fatalities and 40% of infant mortality are caused by CNS abnormalities. The brain’s appearance changes during pregnancy, so it’s crucial to know what a healthy central nervous system looks like at various stages of pregnancy. Mid-pregnancy has been the focal point of most diagnostic attempts for neurological abnormalities. Prenatal screenings are often done at approximately the 20-week mark. The second trimester anatomy scan typically includes four standard suggested views that offer an overview of foetal intracranial anatomy: the transventricular, falx, cavum, and posterior fossa or transcerebellar views.
Prenatal ultrasound may classify disorders of the central nervous system into six broad groups. Disorders of neuronal migration and neural tube malformations are examples of developmental anomalies. Dandy-Walker malformation variations and Chiari malformation type II are examples of posterior fossa abnormalities. Aqueductal stenosis is an example of a defect in the ventricles. Examples of midline diseases include agenesis of the corpus callosum, septo-optic dysplasia, and holoprosencephaly. Malformations of the veins of Galen are considered vascular abnormalities. Hydranencephaly, porencephaly, tumours, and cerebral bleeding are all examples of rare and unusual brain conditions.
As the most frequent kind of neural tube malfunction, anencephaly is a devastating brain deformity. The origin of the term is the combination of two Greek words: ”an,” meaning ”without,” and ”enkephalos,” meaning ”encephalon.” It’s a symbol for a lack of a calvarium and, by extension, a lack of brain tissue. Normal brain anatomy includes the brainstem, cerebellum, and diencephalon.
If the foramen magnum remains unaffected, the anencephaly is known as meroacrania; if the defect extends beyond the foramen magnum, it is known as holoacrania; and if spina bifida is also present, it is known as holoacrania with rachischisis.
According to the morphological technique suggested by Tortori-Donati et al., the following abnormalities were identified in the posterior fossa:
Dandy-Walker malformation, characterised by cerebellar vermis agenesis of varying degrees, fourth ventricle cyst, and posterior fossa enlargement with tentorial, truncal, and transverse sinuses displacement upward; (2) mega cisterna magna, characterised by a cisterna magna measuring > 10 mm and a normal vermis; (3) Blake’s pouch cyst , characterised by the presence of an
The prosencephalon is malformed in holoprosencephaly, a condition that causes the brain to develop abnormally. Holoprosencephaly and gestational diabetes are both more likely to occur in cases with chromosomal abnormalities such Patau and Edward syndromes. The condition most often linked to trisomy 13 is Patau syndrome. Most infants born with holoprosencephaly do not survive through the neonatal period due to the severity of their condition. Middle interhemispheric, lobar, semi-lobar, and alobar are the subtypes of holoprosencephaly, from mildest to most severe. Confirming the diagnosis and distinguishing between holoprosencephaly forms requires a brain CT scan or MRI.
The corpus callosum is the bridge between the left and right sides of the brain, and its absence or incomplete development is known as agenesis of Corpus Callosum. Agenesis of the corpus callosum is associated with a frameshift (loss of function) mutation in the DCC Netrin 1 receptor gene; nonetheless, most affected individuals had no neurological symptoms. This illness has a wide range of clinical and radiological presentations, making MRI a useful diagnostic tool. Researchers have shown that people with ACC exhibit many of the same characteristics as those with autism. Callosal dysgenesis is also often accompanied with antisocial conduct and dishonesty.
Forebrain anomaly known as septooptical dysplasia is characterised by a combination of three conditions: hypoplasia of the optic nerve (cranial nerve II), pituitary insufficiency, and agenesis of the septum pellucidum (with or without agenesis of the corpus callosum). It usually happens between weeks 4 and 6 of a baby’s life. It affects just one in every 10,000 newborns, making it very rare. A mutated form of HESX1, SOX2, SOX3, or OXT2 may be involved. These result in a variety of clinical symptoms, including pituitary insufficiencies and anomalies of the optic nerve, such as nystagmus.
Our research aimed to determine whether or whether ultrasonography was effective in detecting CNS abnormalities that might be confirmed after birth.
Mid anatomical scans were performed on 567 pregnant women who presented for prenatal treatment in the Sohag governorate.
Summary of our results:
• Average age was 29.72 (5.97) years, with a range of ages 16-48. The average body mass index was 28.92 (4.10) kg/m2, with a spread of 4.06 between the extremes.
• Fifty patients (87.72 percent) had negative maternal medical history, whereas 7 patients (12.28 percent) did. Five (8.77%) individuals had a positive maternal medical history due to a TOURCH infection, whereas 1 (1.75%) had a teratogenic medication exposure, and 1 (1.75%) had brain atrophy.
• There was a wide variation in age, from 16 to 48 years, with a mean age of 29.72 (5.97 years). There was a wide variety of body mass index values, with a mean ( SD) of 28.92 (4.06) kg/m2.
• Fifty patients (87.72%) had negative maternal medical histories, whereas seven patients (12.28%) did. Five (8.77%) individuals had a positive maternal medical history due to a TOURCH infection, whereas 1 (1.75%) had a positive history due to teratogenic medications and 1 (1.75%) had a positive history due to brain atrophy.
• Only 44 patients (7.76%) were found to have a consanguineous relationship, whereas 523 (92.24%) were not.
• Nineteen individuals (33.33%) had clinical confirmation of the pregnancy after birth. One patient (1.75 percent) was diagnosed with hydrocephalus, substantially dilated ventricles, and ambiguous genitalia on the first day of clinical meningitis; six patients (10.53 percent) had hydrocephalus confirmed by CT. Dandy-walker syndrome (CT hydrocephalus), hydrocephalus, HIE, noncommunicating hydrocephalus, communicative hydrocephalus, hypogenesis of the corpus callosum, ventricular septal defect, CT molar tooth, moderate brain atrophy, CT semilobar holoprosencephaly, butterfly vertebra, and ataxic encephalopathy. Clinically, one patient (1.75%) had a CT showing a significantly reduced brain volume due to a dilated ventricular system; eleven patients (19.3%) had this finding confirmed by MRI. Hydrocephalus, biventricular enlargement, and atrophy of the brain on MRI One patient (1.75 percent) was found to have diffuse brain atrophy on MRI, multi cystic brain encephalomalacia on MRI at 5 months of age, moderate hypoplastic corpus callosum on MRI, dilated ventricles PVL on MRI, left ventriculomegaly on MRI, and squent.
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Conclusion
Based on these findings, we can say that ultrasonography is useful for detecting and diagnosing some defects of the foetal central nervous system. However, because of the positioning of the foetus, it may be difficult to identify certain defects using two-dimensional ultrasonography. Our results also imply that imaging tools like CT and MRI scans are effective for confirming diagnoses of neurological and developmental abnormalities in babies, even if clinical assessment is a crucial tool in making the initial diagnosis.
Recommendations
• Our results need to be confirmed by more multicenter clinical trials.
• Ultrasound examinations at different stages of pregnancy are highly recommended for all pregnant women.
• To get a clearer picture of the foetal anatomy when prenatal ultrasonography is ambiguous, more sophisticated imaging methods should be used.
• Scanning again and again.
Limitations
• Inability to adequately compare various imaging techniques.
• Prenatal ultrasonography’s precision may be impacted by the fetus’s positioning.
• Prenatal ultrasonography accuracy may also be impacted by maternal body habitus, namely obesity.
• Subtle neurological abnormalities that do not result in substantial structural alterations or functional impairments may not be detected by prenatal ultrasonography.
• Although prenatal ultrasonography is helpful in determining if and to what degree a foetus has a birth defect, it may not be able to foretell the long-term effects of such defects, which may be affected by both hereditary and environmental variables.