DANDY WALKER MALFORMATION WITH UNUSUAL FINDINGS IN FETAL AUTOPSIES

The Dandy-Walker malformation is a rare group of congenital abnormalities of brain, typically involving the fourth ventricle and the cerebellum. The Dandy-Walker malformation has an estimated prevalence of about 1 in 25,000 to 35000 live births with a slight female preponderance and is responsible for 4-12% of infantile hydrocephalus. Dandy-Walker malformation is frequently associated with other intracranial anomalies such as agenesis of the corpus callosum, holoprosencephaly, occipital encephaloceles and ocular abnormalities. Extra-cranial anomalies include polycystic kidneys, cardiovascular defects, polydactyly and cleft palate. Present study was conducted on 1200 fetuses obtained from department of Obstetrics and Gynecology, Government medical college and hospital, Chandigarh. Autopsy was done in department of Anatomy, GMCH Chandigarh. In our present study the incidence of Dandy walker syndrome was 0.4% (out of 1200 fetuses DWS was noted in 5 fetuses). Associated anomalies were noted in each case. Prenatal diagnosis of DWS is important to detect and avoid further complications in life.


INTRODUCTION
Dandy-Walker malformation is a rare congenital abnormality of brain, characterized by hypoplasia or absence of cerebellar vermis, cystic dilatation of fourth ventricle and hydrocephalus 1 . Dandy-Walker malformations (DWM) accounts for about 1 in 25,000 to 35000 live births 2 . Sutton was the first one to described DWM, which was further described by Dandy and Black fan followed by Tagart and Walker. Finally in 1954 Benda labeled this disease as Dandy Walker 3 . Associated congenital anomalies such as cleft palate, micrognathia, hypertelorism, cardiac anomalies, renal and skeletal malformation are said to be present in 48% cases 4 . In the present cases DWS is associated with unusual associations such as agenesis of corpus callosum, agenesis of vermis, agenesis of spleen along with some associated anomalies such as microphtalmia, cardiac anomalies, duplicated ureter, diaphragmatic hernia. DWS is a frequent cause of termination of fetus diagnosed prenatally 5 .

MATERIALS AND METHODOLOGY
The present study was conducted on 1200 humans fetuses (since Jan 2008-july 2016) in the Department of Anatomy, Government Medical College & Hospital, Chandigarh.
Fetuses were sent by the Department of Obstetrics & Gynaecology of the same institute for routine autopsy. These included the spontaneous abortions, stillbirths, intra-uterine deaths and therapeutic abortions after recognition of congenital malformations on ultrasonography or by karyotyping. The consent was taken from the parents. Before autopsy relevant maternal and family history along with antenatal USG findings were recorded. The sex, gestational age of fetus were noted. External features were noted and photographed. Radiography was also done in revelant cases. Internal examination of the fetus was done after performing routine autopsy procedure and photographed .The associated anomalies, found, if any, was also noted

Case 1
First case reported was a male fetus of 19 +6 weeks. Mother of fetus was 22yrs old, primi gravida. Medical history and past history of parents were not suggestive of any etiological factors responsible for the defect. The indication of MTP was DWS.

INTRODUCTION
Dandy-Walker malformation is a rare congenital abnormality of brain, characterized by hypoplasia or absence of cerebellar vermis, cystic dilatation of fourth ventricle and hydrocephalus 1 . Dandy-Walker malformations (DWM) accounts for about 1 in 25,000 to 35000 live births 2 . Sutton was the first one to described DWM, which was further described by Dandy and Black fan followed by Tagart and Walker. Finally in 1954 Benda labeled this disease as Dandy Walker 3 . Associated congenital anomalies such as cleft palate, micrognathia, hypertelorism, cardiac anomalies, renal and skeletal malformation are said to be present in 48% cases 4 . In the present cases DWS is associated with unusual associations such as agenesis of corpus callosum, agenesis of vermis, agenesis of spleen along with some associated anomalies such as microphtalmia, cardiac anomalies, duplicated ureter, diaphragmatic hernia. DWS is a frequent cause of termination of fetus diagnosed prenatally 5 .

MATERIALS AND METHODOLOGY
The present study was conducted on 1200 humans fetuses (since Jan 2008-july 2016) in the Department of Anatomy, Government Medical College & Hospital, Chandigarh.
Fetuses were sent by the Department of Obstetrics & Gynaecology of the same institute for routine autopsy. These included the spontaneous abortions, stillbirths, intra-uterine deaths and therapeutic abortions after recognition of congenital malformations on ultrasonography or by karyotyping. The consent was taken from the parents. Before autopsy relevant maternal and family history along with antenatal USG findings were recorded. The sex, gestational age of fetus were noted. External features were noted and photographed. Radiography was also done in revelant cases. Internal examination of the fetus was done after performing routine autopsy procedure and photographed .The associated anomalies, found, if any, was also noted

Case 1
First case reported was a male fetus of 19 +6 weeks. Mother of fetus was 22yrs old, primi gravida. Medical history and past history of parents were not suggestive of any etiological factors responsible for the defect. The indication of MTP was DWS.

External examination
Internal examination  Large head  bilateral club foot with over ridding of 4 th toe on right side and 2 nd toe on left side.
 Cerebrum had pachygyria  hypoplasia of cerebellum making floor of fourth ventricle visible  Right side cerebral hemisphere was smaller than left  posterior cranial fossa appeared larger

INTRODUCTION
Dandy-Walker malformation is a rare congenital abnormality of brain, characterized by hypoplasia or absence of cerebellar vermis, cystic dilatation of fourth ventricle and hydrocephalus 1 . Dandy-Walker malformations (DWM) accounts for about 1 in 25,000 to 35000 live births 2 . Sutton was the first one to described DWM, which was further described by Dandy and Black fan followed by Tagart and Walker. Finally in 1954 Benda labeled this disease as Dandy Walker 3 . Associated congenital anomalies such as cleft palate, micrognathia, hypertelorism, cardiac anomalies, renal and skeletal malformation are said to be present in 48% cases 4 . In the present cases DWS is associated with unusual associations such as agenesis of corpus callosum, agenesis of vermis, agenesis of spleen along with some associated anomalies such as microphtalmia, cardiac anomalies, duplicated ureter, diaphragmatic hernia. DWS is a frequent cause of termination of fetus diagnosed prenatally 5 .

MATERIALS AND METHODOLOGY
The present study was conducted on 1200 humans fetuses (since Jan 2008-july 2016) in the Department of Anatomy, Government Medical College & Hospital, Chandigarh.
Fetuses were sent by the Department of Obstetrics & Gynaecology of the same institute for routine autopsy. These included the spontaneous abortions, stillbirths, intra-uterine deaths and therapeutic abortions after recognition of congenital malformations on ultrasonography or by karyotyping. The consent was taken from the parents. Before autopsy relevant maternal and family history along with antenatal USG findings were recorded. The sex, gestational age of fetus were noted. External features were noted and photographed. Radiography was also done in revelant cases. Internal examination of the fetus was done after performing routine autopsy procedure and photographed .The associated anomalies, found, if any, was also noted

Case 1
First case reported was a male fetus of 19 +6 weeks. Mother of fetus was 22yrs old, primi gravida. Medical history and past history of parents were not suggestive of any etiological factors responsible for the defect. The indication of MTP was DWS.

Case 2
22 +1 week female fetus born to 20 yr old mother who had a obstetric history of G 5 P 1 A 4 L 1. Her first child was born alive but died at the age of 2 1/2 yrs, due to bilateral retinoblastoma.In rest of the pregnancies spontaneous abortion occured at 2-3 months. In present case indication for MTP was Dandy Walker Syndrome, Microphtalmia, pyelectasis, echogenic shadow in heart, VSD, club foot on ultra sonogram. Maternal history showed that she had unilateral retinoblastoma which got operated at age of 6yrs.Paternal history showed excessive use of drugs, tobacco, smoke and anti depressant drugs.     Out of 1220 autopsies, dandy walker malformation was found in 5 fetuses(0.4 %)

Gross examination
Internal examination  normal  heart horizontally placed with right atrium and ventricle enlarged ( fig 14) .

Incidence of dandy walker syndrome
Male Female 2(40%) 3 (60%)      9 . In our present study agenesis of corpus callosum was noted in one case, cardiac anomalies were noted in two cases, renal anomalies in one case, polydactyly in one case, CTEV in one case.
According to Dandy and Walker dilatation of ventricular system occurred due to atresia of the foramina of Luschka and Magendie.How ever Benda suggested that it's difficult to understand how atresia of these foraminas would lead to cerebellar vermis hypoplasia 10 16 . In our case, we came across a fetus with CVS defect we noted that aorta and pulmonary trunk were arising from right ventricle and left ventricle and left atrium were Figure 14 showing horizontally placed heart with right atrium and ventricle enlarged hypoplastic, same case had a left sided congenital diaphragmatic hernia with liver, stomach, intestines herniating into thoracic cavity, asplenia.
Eventhough hydrocephalus is considered as a major diagnostic element of DWS, recent research had suggested that in most cases hydrocephalus is not present at the time of birth and they had noted that hydrocephalus develops usually at first month of life. In such cases the diagnosis can only be made prenatally depending on the posterior cranial fossa abnormalities 13 . Positive diagnosis before viability gives a option for pregnancy termination.
Generally, DWS is treated with surgery, especially when there is concomitant hydrocephalus as well as signs of intracranial hypertension. There are a number of surgical options, ranging from a ventriculo peritoneal shunt to fenestration of the cystic membrane, a primary cystoperitoneal shunt or a ventriculocysto-peritioneal shunt 17 .

CONCLUSION
Agenesis of corpus callosum interference with medullary control of respiration which often results in respiratory failure 14 . DWS association with congenital diaphragmatic hernia and asplenia is very rare ultrasound & pathologic examination are indicated in DWS for screening of concurrent cranial and extra cranial malformation. Proper diagnosis of DWS is necessary for further treatment Eventhough hydrocephalus is considered as a diagnostic element in DWS in most cases it appears after birth .So the posterior cranial fossa abnormalities should be noted prenataly as a diagnostic tool.