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Home , Acrania, Anencephaly, Chiari malformation, Iniencephaly

Prenatal Diagnosis and Management of Congenital Abnormalities of Central

Ülkü BAYAR1, Mustafa BAŞARAN1, Deniz USAL1, Oya ÖZCAN1, Murat KALAYCI2 Zonguldak-Turkey

Among the congenital anomalies, malformations are the most commonly seen ones whose antenatal sonographic diagnosis is very important. Sixteen cases, attempted to Karaelmas University Obstetrics Clinic, diagnosed as having central nervous system anomaly were presented. Ultrasonographic screening is a noninvasive method that should be recommended to all pregnant women. Second trimester ultrasonography is generally performed between 20-22 gestational weeks in order to detect fetal structural defects. In the early antenatal period the ultrasonographic diagnosis of major and minor anomalies will provide the chance of giving to families. (Gynecol Obstet Reprod Med 2006; 12:202-208) Key Words: Central nervous system anomaly, Prenatal diagnosis, Ultrasonography

Central nervous system (CNS) anomalies are seen appro- In this review we repo rt most recent diagnoses of CNS ximately 1/100 incidence second only to cardiovascular sys- abnormalities in our clinic and discuss their management tem anomalies. Fetal CNS is known to undergo major deve- with the current guidelines. lopmental changes throughout the gestation and some time CASES after gestation. Therefore it is crucial to have a working knowledge of CNS embryology in order to perform prenatal Case 1: Arnold Chiari (Chiari II) ultrasonographic diagnosis of CNS abnormalities. Besides Twentythree year-old G: 2 P: 0 A: 1 woman without any its frequency, most congenital CNS anomalies are usually significant obstetric risk factor was followed until 20th week carrying poor prognosis. Therefore CNS examination should of gestation. Ventriculomegaly, lemon sign, lo- be examined in all diagnostic ultrasonographic studies. Since cated in the lumbar region was detected with second associations with other congenital and genetic abnormalities trimester ultrasonographic examination. Interventricular antenatal diagnosis and genetic counseling are also neces- distance mas measured as 12 mm. After counseling the sary.1 parents with the presumptive diagnosis of Chiari type II (Arnold Chiari) malformation termination of pregnancy was CNS is the first organ system begins to develop in embr- decided. Pregnancy was terminated in another institution due yo. It is also the last one that completes development postna- to insurance problems. tally. For these reason teratogenic effects, matern al diseas es and infectious causes could affect CNS at almost any time Case 2: Arnold Chiari (Chiari II) throughout the pregnancy. After the completion of early de- Twentyfour year-old G: 1 P:0 pregnant woman referred velopment of , most of the abnormalities were already with the diagnosis of at 21st week o f established. Therefore it is also important to know etiologic gestation. Ultrasonographic scan revealed spina bifida at causes and eliminate them prenatally to prevent CNS abnor- sacral region, ventriculomegaly, and lemon sign in the malities. Current technology enables only early diagnosis of cranial region (Figure 1A-B). Corpus callosum couldn’t be congenital abnormalities. Therefore elimination of CNS ab- visualized and interventricular distan ce was measured 14 normalities generally depends on early diagnosis and termi- mm. Intrauterin growth restriction was also diagnosed in this 1 nation of pregnancy in severe CNS malformations. fetus. Pregnancy was terminated with the diagnoses o f Chiari II malformation (Arnold Chiari) diagnoses. Further 1Zonguldak Karaelmas University Faculty of Medicine, Department of follow-up and termination of pregnancy was performed in Ob st et ri cs and G yn ecol og y, 2Zonguldak Karaelmas University Faculty referring cent er. of Medicine, Department of , Zonguldak, Turkey Case 3: Address of Correspondence Ülkü Bayar, During routine follow-up of uncomplicated pregnancy o f Zonguldak Karaelmas 29 year-old G2P1L1 patient bilateral multiple choroid Üniversitesi Tıp Fakültesi plexus was detected at 18 weeks of gestation (Figure Dekanlık Binası 2A). Ultrasonographic examination of other organ systems Esenköy, Kozlu was normal. Previous nuchal translucency (p erformed at 13th Zonguldak/ Turkey weeks of gestation) was 1.5 mm. Triple screening was also within normal range. was performed and Submitted for Publication: 22.08.2006 resulted as normal. At 38th gestational weeks, the female Accepted for Publication: 04.09.2006 baby was born without any . 202 Gynecology Obstetric & Reproductive Medicine 2006; 12:202-208 203 normal. After discussion with family about possible outco- mes pregnancy was continued.

Figure 2. Ultrasonographic Finding of Dandy-Walker , Choroid Plexus Cyst, Hemivertebra (A Multiple Choroid Plexus Cysts;B- Dandy-Walker Syndrome- ventriculomegaly and hypoplasia of ; C Hemivertebra at T12-L1 region).

Case 6: Ventriculomegaly, spina bifida Twentytwo year-old G 3 P 1 A 1 pregnant woman referred with the diagnosis of ventriculomegaly at 28th week of gestation. Ultrasonographic scan revealed ventriculomegaly (figure 3A), (interventricular distance was measured 20.5 mm), and spina bifida located in the lumbar Figure 1. Ultrasonographic finding of Arnold Chiari (Chiari II) malformation A: Ventriculomegaly, lemon sign B: Spina bifida region (Figure 3B). Pregnancy was terminated with the located in the lumbar region. diagnoses of ventriculomegaly and spina bifida.

Case 4: Dandy-Walker Syndrome A late admission pregnancy was referred to our clinic from a clinic in rural area with the diagnosis of hydrocepha- lus. 32 year-old women with 37-week gestation according to last menstrual period were hospitalized after ultrasonograp- hic detection of posterior fossa cyst, severe ventriculome- galy and hypoplasia of cerebellar vermis (Figure 2B). Age- nesis of corpus callosum was also detected. Neurosurgical consultation was ordered with prenatal diagnosis of Dandy- Walker syndrome. After planned caesarean section at 38-we- ek of gestation the diagnosis of Dandy-Walker syndrome was confirmed with cranial magnetic resonance imaging. Ventriculoperitoneal was implanted by neurosurgical Figure 3. Ultrasonographic Finding of A Ventriculomegaly; B department. Spina bifida located in the lumbar region; C Diaphragmatic ; D Hydrocephalus and ventriculomegaly. Case 5: Hemivertebra Hemivertebra was detected in 26 year-old women during Case 7: Hydrocephalus, diaphragmatic hernia routine ultrasonographic examination at 20th week o f ges ta- tion. Level of vertebral abnormality was reported at T12-L1 Twentynine year-old G 5 P 3 D/C1 pregnant woman and no other associated abnormality was detected (Figure referred to our obsterics outpatient clinic with the diagnosis st 2C-D). After genetic consultation karyotype analysis was of hydrocephalus at 21 week of gestation. Ultrasonographic performed with amniocentesis. Karyotype was found to be examination revealed as diaphragmatic hernia (Figure 3C),

204 Bay ar et al . hydrocephalus, ventriculomegaly (Figure 3D), (interventri- Case 12: Hydrocephalus, lumbosacral cular distance was measured as 22 mm), and polyhdramnios. myelomeningocele Pregnancy was terminated and fetus was diagnosed as hydr- A late admission pregnancy was referred to our clinic ocephalus, diaphragmatic hernia and polyhdramnios. from a clinic in rural area with the diagnosis of hydrocepha- Case 8: , spina bifida, cleft lip lus. Thirty-eight year-old women was at 32 gestationional week. Ultrasonographic scan revealed hydrocephalus (bipa- Twenty year-old G 1 P0 pregnant woman referred with rietal diameter 93 mm, cortical thickness 7.5 mm) and lum- the diagnosis of anencephaly at 21st week of gestation. Ultra- bosacral myelomeningocele. Planned caesarean section was sonographic examination revealed anencephaly, spina bifida made at 38-week of gestation. One day after; ventriculoperi- located in the lumbatoro ca-servi cal region and cleft lip (Fı- toneal shunt was implanted and meningocele sac was closed gure 4A) .Pregnancy was terminated with the diagnoses o f by neurosurgical department. anen cephaly, spina bifida and cleft lip. Case 13: Hydrocephalus, corpus callasum agenesis, spina bifida Thirty five years old pregnant women G2P1A1 with the pre-diagnosis of defect was attended to our out- patient clinic of obstetrics. Ultrasonographic examination was reveal ed as hyd rocephaly, corpus callasum agenesis, spina bifida and microgynati at 22nd week of gestation age. Termination was advised and 520 gr ex male fetus was born. Case 14: Anencephaly, spina bifida Thirty one years old twin pregnancy G3P2 L2 was refer- red as one fetus with anencephaly and the other one with normal appearan ce at 18th weeks of gestation. Utrasonogra-

Figure 4. Ultrasonographic finding of A Cleft Lip; B Anencephaly pic examination was revealed as dichorionic-diamniotic twin and Spina Bifida; C Occipital Encephalocel; D Lumbosacral pregnancy. Intraabdominal ascites, pericardial effusion, Meningocele Sac. anencephaly and spina bifida (Figure 4B) was diagnosed in one of the twin. The other twin was normal in appearance. Case 9: , spina bifida The fetus with anomaly was terminated. The normal fetus Nineteen year-old G 1 P0 pregnant woman referred with was born at 38th of gestational age with caesarean section. st the diagnosis of anencephaly at 15 week of gestation. Ultra- Case 15: Occipital encephalocel sonographic scan revealed iniencephaly, spina bifida located in the lumbotorocaservical region. Pregnancy was Twenty years old pregnant women G2P1 was admitted to th terminated with the diagnoses of iniencephaly, spina bifida. our outpatient clinic of obstetrics at the 16 weeks o f ges ta- Autopsy was identical with intrauterine diagnosis tion. Ultrasonographic examination was revealed as occipital encephalocel (Figure 4C), small mouth and jaw, and cardiac Case 10: and gastroshisis hyperechogenic focus. After the family counseling, termina- Twentyseven year-old G 1 P0 pregnant woman attended tion was made. to our outpatient clinic of obsterics. Ultrasonographic scan Case 16: Lumbosacral meningocele revealed acrania and gastroshisis at 16th week of gestation. Pregnancy was terminated with the diagnoses of acrania. Thirty three years old woman G7P3A3 was admitted our hospital at the 37th gestational week. At sonographic exami- Case 11: Bilateral ventriculomegaly nation, lumbosacral meningocele sac (Figure 4D) was diag- Nineteen year-old G1 P0 pregnant woman referred with nosed. Caesarian section was made with indication of fetal the diagnosis of bilateral ventriculomegaly at 31st week o f stress. The meningocele was repaired at 40th postpartum day gestation. Ultrasonographic scan revealed bilateral ventricu- by neurosurgery department. lomegaly, (interventricular distance was measured riht 15.9 Discussion mm, left 18.2 mm).After discussion with family about th possible outcomes pregnancy was continued. At 40 Central nervous system abnormalities were seen in 1-3% gestational weeks, the female baby was born without any of live births.1 However this rate increases to 40% in still- complication. Postpartum neurological examination was births. Etiology of developmental abnormalities ranges from normal. genetic causes to environmental factors that affect develop-

Gynecology Obstetric & Reproductive Medicine 2006; 12:202-208 203205 ment. Most of the abnormalities related with development malformations may develop. Similarly ventral induction ta- neural tube occur in the first 28 days of gestation. On the ot- kes place during the p eriod o f 5-10th weeks of gestation. her hand abnormalities related with the cellular proliferation Dandy-Walker malformation, , cerebellar and migration usually takes place after 28th day of gestation. hypoplasia, Arnold-Chiari IV malformations might develop during this period of development.6,7 Incidence of fetal ventriculomegaly changes from 0.3/1000 to 1.5/1000 in some series. The term fetal ventricu- CHIARI MALFORMATIONS lomegaly defines an abnormal finding irrespective of eti- Prof. is a german pathologist, first defined ology. Therefore includes numerous pathologies with hete- the malformation. It is defined as a neuronal migration de- rogeneous etiologies. In general mechanism that leads to de- fect characterized by cerebellar displacement. According to velopment of ventriculomegaly might be secondary to follo- severity it is divided into 4 types. These types are not related wing: obstruction of normal circulation of cerebrospinal embryologically and anatomically. Chiari II, III and IV are fluid, hypersecretion of CSF, defective filtration, and abnor- life threatening abnormalities that are typically diagnosed mal development of intracranial structures. antenatally. However Chiari I malformation might not be 8 The most common cause of fetal hydrocephalus is obst- diagnosed until 24.9±15.8 weeks of gestation. ruction of CSF circulation. Hydrocephalus could be classi- Chiari I malformation fied according to level of obstruction: noncommunicating intraventricular hydrocephalus (aqueductal stenosis, Dandy- The malformation is defined as greater than 5 mm down- ward herniation of cerebellar tonsils through foramen mag- Walker malformation, intracranial mass) and communica- 9 ting-extraventricular hydrocephalus (, num. Hydrocephalus seen in 90% of patients and in 30-40% , fibrosis secondary to intracranial hemorrha- associated with syrenomelic cavity. In this spectrum this is ge).Throughout the gestation fetal brain and lateral ventric- the mildest form of anomaly. Cerebellar tonsils and someti- les undergo structural changes that cause different ultraso- mes medulla might elongate towards the lower limit of fora- nographic appearance at different gestational weeks. There- men magnum. Posterior fossa is small and is short. T here is a relation between size o f post erior fossa and cere- fore in order to prevent false positive diagnosis size and sha- 6 2,3 bellar ectopy. pe of ventricles at specific time period should be known. Atrial measurements in axial plane are the simplest and best Chiari II malformation (Arnold-Chiari method for diagnosis of ventriculomegaly. Measurements up malformation) to 10 mm are interpreted as normal. In the absence o f as soci- ated abnormalities measurements between 10-14 mm are In addition to Chiari I there is caudal displacement o f 4th ventricle. It is most commonly seen abnormality. Fourth considered intermediate and follow-up is required. Fetal or ventricle frequently located below medulla oblangata, poste- perinatal death and neurodevelopment in survivors are di- rior to as a cystic structure. 10,11 Size of posterior rectly related to the presence of other malformations and ch- fossa is small and cisterna magna is flattened. Due to lower romosomal defects. Although mildventriculomegaly is gene- displacement o f cervical spinal cord upper cervical nerve rally associated with a good prognosis, affected fetuses form roots tensioned in their foramina.12 A characteristic folding the group with the highest incidence of chromosomal abnor- in cervicomedullary junction is seen in 70% of cases. Lum- malities (often trisomy 21). Fifteen mm and greater measu- bar myelocele and similar congenital abnormalities might be rements are diagnosed as ventriculomegaly.4 Most common associated. Meningomyelocele is seen in 80% of patients causes of fetal ventriculomegaly are aqueductal stenosis (33- and might cause hydrocephalus.13 Hydrocephalus risk is pro- 43%), Chiari II malformation (25-30%), Dandy-Walker portional to degree of rostral location.6 syndrome and corpus callosum agenesis (7-10%) 5. Chiari III malformation After 2nd week of gestation neural plate and neural tube begins development from . Forebrain (proencepha- It is characterized by the herniation of all posterior fossa lon), (mesencephalon) and hindbrain (rhombencep- structures and b rain stem into encephalocele. T his is an un- common form of this malformation.14 halon) are formed at 25-28 days of gestation in the rostral part of neural tube. These parts differentiate into prosencep- Chiari IV malformation halon, telencephalon and after 6th week of de- It is characterized by hypoplasia of . Some velopment. T hese structures l ater form cortex, h emispheres, authors consider this entity as a variant of Dandy-Walker thalamus and hypophysis. Inner parts of mesencephalon ori- malformation.15 ginate from mesencephalon. Rhombencephalon gives rise to DANDY-WALKER COMPLEX , cerebellum and .6 Dandy-Walker syndrome is a complex cerebellar vermis th During the period of 2-5 weeks in which dorsal induc- anomaly that is charact erized by cystic dilatation o f 4th tion takes place anencephaly, myelocele, Arnold-Chiari I-II ventricle and enlargement of cisterna magna. Dandy-Walker

206204 Bay ar et al . complex is divided into three groups: first, Dandy-Walker trisomy 18 is increased in patients with choroid plexus cyst malformation (partial or total agenesis of cerebellar vermis, associated other congenital abnormalities. Therefore careful cystic dilatation of posterior fossa and hydrocephalus).16 Se- ultrasonographic examination and karyotype analysis are cond, Dandy-Walker variant (partial agenesis of cerebellar required in fetuses with choroid plexus cyst.30 ,3 1 vermis and cystic dilatation of fourth ventricle without enlar- In conclusion widespread use of prenatalultrasonography gement of posterior fossa).17 Third, Mega cisterna magna enabled early diagnosis of congenital fetal central nervous (cystic dilatation of fourth ventricle without dilatation of system abnormalities. Craniospinal abnormalities are most posterior fossa and normal cerebellar vermis). frequent diagnoses. In suspected cases serial determination Dandy-Walker malformation is seen in 1/30,000 live for measurement might be required. Associated congenital births. Hydrocephalus might be absent at birth and might abnormalities might indicate a karyotype examination due to develop later in life. Dilatation of lateral ventricle is not the increased risk of chromosomal abnormalities. In mild same extent as dilatation of 4th ventricles. Most commonly defects careful consultation with family is necess ary. In this associated abnormality is the absence of corpus callosum.18 report we presented our experience with consecutive diag- Ultrasonographic diagnosis depends on the demonstration of noses of 5 patients with ultrasonographic detection of fetal dilated 4th ventricle and associated total or partial vermal central nervous system abnormalities. agenesis. 15 ,19 ,20 Diagnosis of mega cysterna magna is attribu- NEURAL TUBE DEFECTS ted by means o f measu rement o f the distance b etween cere- bellar vermis and inner border of greater than T he prevalence o f neu ral tube defects which include 10 mm. anencephaly, spina bifida and cephalocele is about 5 per 1.000 births. are cranial defects, frequently HEMIVERTEBRA occipital, with herniated fluid-filled or brain-filled cysts. In Hemivertebra or butterfly shaped is developed spina bifida th e neural arch, commonly in the lumbosacral secondary to a defect in the formation of vertebral segment. region, is incomplete with resulting damage to the exposed Hemivertebra creates a bridge in the that nerves. In anencephaly, the cranial vault is absent (acrania) causes bending in the opposite direction. However hemiver- with secondary degeneration of the brain.32 The exact etio- tebra located in the lower lumbar and sacral levels does not logy for the majority of these defects is unknown. Chromo- cause a deformity. Prenatal ultrasonographic findings somal abnormalities, single mutant genes, and maternal dia- include asymmetric vertebral body in sagittal or coronal betes mellitus or ingestion of teratogens, such as antiepilep- planes and focal defect in the verteb ral colon in either sides tic drugs, are concerned in about 10% of the cases. The risk 21 of axial plane. Since vertebral anomalies can frequ ently be of recurrence is about 5-10%. The diagnosis of anencephaly seen in association with VATER or VACTERL , is reveal ed as abs ent cranial vault and cerebral h emispheres. all other organ systems must be investigated carefully when But, the facial bones, brain stem and portions of the occipital 22 such anomalies are encountered. Prenatal diagnosis of bones and mid brain are frequ ently present. Spinal lesions vertebral anomalies could help earlier recognition of are found in up to 50% of cases of anencephaly.32 problems like or kyphoscoliosis and planning for treatment.23 Diagnosis of spina bifida necessitates the systematic examination o f each neural arch from the cervical to the CHOROID PLEXUS CYST sacral region both transversely and longitudinally. In the These cysts are usually bilateral and located in the transvers e scan the norm al neural arch appears as a clos ed choroid plexus in the lateral cerebral ventricle. These circle with an intact skin covering, but in spina bifida the sonolucent areas are actually developing fetal choroid plexus arch is "U" shap ed and an associated bulging meningocel e and do not contain any cystic areas. Generally these cysts (thin-walled cyst) or myelomeningocoele are found. The are d etected in 16-18 weeks o f gestation. 24 Prevalence is diagnosis of spina bifida has been significantly increased by about 2% in 20 weeks of gestation. Most of these cysts the recognition of related abnormalities in the and (90%) resorbed until 26 weeks of gestation.25 Ultrasono- brain. These anomalies are resulting to the Arnold-Chiari graphic d etection o f single cyst great er than 2 mm diameter malformation and include frontal bone scalloping (lemon or multiple cysts is a significant finding. Cysts might be sign), and obliteration of the cisterna magna with either an multiloculated and borders might be irregular. Larger cysts "absent" cerebellum or abnormal anterior curvature of the 26 might cause ventricular dilatation. cerebellar hemispheres (ban ana sign). 33 Isolated choroid plexus cysts are seen in 1% of all Anencephaly is fatal. In cephalocele the prognosis is pregnancies. Chromosomal abnormalities are seen in 1-2% inversely related to the amount of herniated cerebral tissue; of these cases.27,28 Choroid plexus cysts are frequently seen the neonatal mortality is about 40% and more that 80% of in trisomy 18 (Edward’s syndrome), trisomy 21 (Down survivors are intellectually and neurologically handicapped. syndrome) and other chromosomal abnormalities.29 Risk of In spina bifida the survivors are strictly handicapped, with

Gynecology Obstetric & Reproductive Medicine 2006; 12:202-208 203207 in the lower limbs and double incontinence; despite nervous system in the first and early second trimesters. the associated hydrocephalus requiring surgery, intelligence Am J Obstet Gynecol 1991; 164:497-503. 34 may be normal. 4. Pilu GE, Reece A, Goldstein I, Hobbins JC, Bovicelli L. AGENESİS OF CORPUS CALLOSUM Sonographic evaluation of the normal developmental anatomy o f the fet al cerebral ventricles: II. T he atria. The corpus callosum is a bundle of fibers, joins the two Obstet Gynecol 1989; 73:250-56. cerebral hemispheres. It develops at 12-18 weeks of 5. D'Addario V. The role of ultrasonography in recognizing gestation. Agenesis of the corpus callosum is established in the cause of fetal cerebral ventriculomegaly. J Perinat about 5 per 1.000 births, it may be either complete or partial Med 2004; 32:4-12. (usually affecting the posterior part). Agenesis of the corpus 6. Barkovich AJ, Gressens P, Evrard P. 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