A STUDY ON CONGENITAL ANOMALIES OF CENTRAL NERVOUS SYSTEM

Address for Correspondence: Dr. Sailaja. K, Assistant Professor, Department of Anatomy, Govt. Medical College, Calicut, India. E-Mail: sailajakrishnapadam@rediffmail.com Background: CNS malformations are one of the most common among congenital malformations rating to 5-10% of total malformations. Therefore, the present study was performed to evaluate the congenital anomalies in the central nervous system. Materials and Methods: Patients of paediatric age group (1-12) years suspect to have congenital anomalies of CNS were followed up. Data on imaging studies were collected and tabulated. Antenatally diagnosed cases of CNS anomalies were followed up. Examination for associated anomalies of head, eyes, ears, nose, face, palate, thorax, abdomen and genitalia, back, upper limb, lower limb and additional points if any was also recorded. The Ultrasound, CT scan, MRI scan and other relevant investigations if any was also performed. Results: In the present study 30 cases of congenital malformations were identified. Out of 30 cases 14 of them were neural tube defects, 13 microcephaly, 2 Dandy Walker alformations and one holoprosencephaly. Out of 14 neural tube defects 9 of them are lumbar myelomeningocoele, two encephalocoeles in the occipital area, one cephalocoele in the parietal area and one cephalocoele in the frontoethmoidal region and one anencephaly. Maximum number of cases of CNS anomaly were of neural tube defects 14/30 (47%). Microcephaly was found to be 13/30 (43.3%). Neural tube defects were found to be more in primigravida and microcephaly in multigravida. Conclusion: Recognition of aetiological factors permits implementation of preventive measures in the society to decrease the incidence of this dreadful condition. In all cases of microcephaly, associated anomalies of eyes or ears or facial dysmorphism were noticed.

A STUDY ON CONGENITAL ANOMALIES OF CENTRAL NERVOUS SYSTEM kypho-scoliosis [1].In 18 th and 19 th century embryology developed as a science.Embryologic research flourished and causations of malformations were understood and they were given a scientific basis.In early 20 th century more explorations were done and the mechanism of malformations was more clearly understood.Environmental causations of malformations particularly of central nervous system (CNS) were first described by Aschenheim in 1920 [2].
Malformations were known to exist from time immemorial.About 2500 BC gross malformations were recognized in ancient Egypt.In fourth century BC Aristotle recognized malformations.
To begin with structural abnormalities which were readily visible were recognized as malformation.There are a lot of such characters in Indian mythology like Kabanthan who had his head low positioned and Ashtavakram with He published a child with microcephaly whose mother was exposed to radiation during pregnancy.Gregg-I discovered that rubella infection can cause serious malformation [3].
Lenz described chemical induction of malformation by thalidomide [4].By the end of 19 th century X-rays were discovered which started a new era in the research methodology of anatomy.
We were able to identify the anomalies of internal organs with imaging techniques.By the mid 20 th century cross sectional imaging was produced which helped a lot in understanding and characterizing the lesions.CNS malformations are one of the most common among congenital malformations rating to 5-10% of total malformations.Most of CNS malformations lead to death of foetus in utero or death in infancy or early childhood.They cause severe disability and patients have a short life span.Some of them are caused by gene mutations and some of them by environmental factors.But majority of malformations are of unknown aetiology.National Institute of Health of United States in 1975 a panel of experts from Bethesda Maryland, discussed and suggested the following definitions -"A malformation is a primary structural defect that results from an error in morphogenesis".Deformation is an alteration in shape and structure of a previously formed part [5].
There are several aetiological factors thought to be responsible for congenital anomalies of CNS.They include drugs, alcohol, viral infection, exposure to radiation, exposure to chemicals.CNS develops from ectoderm.Knowledge of the development of brain is essential for understanding the congenital anomalies.
In this study anomalies resulting from disturbance of CNS development upto stage 3 were included.Disorders arising from stage IV, V and VI are beyond the scope of this work, as those cases constitute part of cliniteria of neurophysicians.Therefore, the present study was performed to evaluate the congenital anomalies in the central nervous system.
suspect to have congenital anomalies of CNS were followed up.Imaging studies were collected and tabulated.Other relevant investigations were collected to arrive at meaningful conclusions.Antenatally diagnosed cases of CNS anomalies were followed up.The anthopometric and aetiological parameters like gender, age, district, community, socio-economic status, consanguinity, family history of congenital anomalies, gravida, abortion, still birth, maternal diabetes, drug intake, maternal age, exposure to radiation,exposure to chemotherapy, febrile illness in 1 st trimester, obesity, maternal malnutrition, folic acid supplementation, zinc supplementation, psychological condition of mother and contraceptive failure was recorded.
Examination for associated anomalies of head, eyes, ears, nose, face, palate, thorax, abdomen and genitalia, back, upper limb, lower limb and additional points if any was also recorded.The Ultrasound, CT scan, MRI scan and other relevant investigations if any was also performed.

RESULTS
In the present study 30 cases of congenital malformations were identified.Out of 30 cases 14 of them were neural tube defects, 13 microcephaly, 2 Dandy Walker malformations and one holoprosencephaly (Fig- 1).
Out of 14 neural tube defects 9 of them are lumbar myelomeningocoele, two encephalocoeles in the occipital area, one cephalocoele in the parietal area and one cephalocoele in the frontoethmoidal region and one anencephaly (Fig- 2).5).Eleven patients showed abnormalities of ears.Eight patients had anomalies of both eyes and ears.Six of them are microcephalics and two of them with neural tube defects (Table -6).In the present study conducted, maximum number of cases of CNS anomaly were of neural tube defects 14/30 (47%).Microcephaly was found to be 13/30 (43.3%).Neural tube defects were found to be more in primigravida and microcephaly in multigravida (Table -7).

Zinc supplementation
No mothers give a positive history of regular intake of zinc tablets.

DISCUSSION
The aetiological factors which are having important roles are found to be intake of drugs like glibenclamide and sodium valproate, consanguinity, irregular intake of folic acid, low In this study 27 out of 30 patients belong to low socioeconomic class.They are educationally backward.Their nutritional status is poor.They cannot afford to take balanced diet with plenty of fruits and vegetables in their diet.Fruits and vegetables are good source of folic acid.They do not know the importance of prenatal care.
Family studies show multiple affected siblings' in microcephaly.Consanguinity provides strong evidence for an autosomal recessive mode of inheritance in microcephaly (Penrose 1956, Koch 1959) [8,9].It was also noted that abnormalities of the neural tube were common among siblings.6.5% in anencephaly and 4.4% in spina bifida [10].
Though maternal age was found to be associated with various anomalies, there was no association of maternal age and congenital anomalies in the present study.Abortion is the way of nature to get rid of nonviable embryos.
In this study 4 cases out of 30 (13.3%) give history of previous abortions.Products of conception of 25 cases were analysed and no causes of malformations were detected and the incidence of malformations in offsprings of mothers taking anticonvulsants drugs was 6%.
In the present study two epileptic mothers taking valproic acid and two diabetic mothers taking glibenclamide gave birth to offsprings with CNS malformation.Two epileptic mothers are having babies with neural tube defects.Out of two diabetic mothers, one gave birth to baby with encephalocoele and one to baby with microcephaly.Fever and hyperthermia in early pregnancy increased the risk of neural tube defects [11].It was reported that the viruses interfere with production of neurons as well as their migration [12].In the present study mothers of two babies gave history of febrile illness in the first trimester.One gave birth to baby with neural tube defect and one to baby with microcephaly.
The importance of folic acid supplementation in the prevention of neural tube defects is given in much literature.As a method of primary prevention of neural tube defect, daily intake of 400 micrograms of folic acid is advised to women of reproductive age group by Public Health Service in 1992.In other countries like Australia and Netherlands women are advised to take 400 micrograms of folic acid every day.Grain flour is fortified with folic acid and women are advised to take plenty of fruits and vegetables.
Aetiological factors having important roles are found to be intake of drugs like glibenclamide and sodium valproate, consanguinity, irregular intake of folic acid, low socio economic conditions and febrile illness during first trimester.Low socioeconomic condition denotes nutritional deficiency during pregnancy, when the cells are undergoing active proliferation in the embryo.Recognition of aetiological factors permits implementation of preventive measures in the society to decrease the incidence of this dreadful condition.In all cases of microcephaly, associated anomalies of eyes or ears or facial dysmorphism were noticed.

Fig. 1 :
Fig. 1: Different types of congenital malformations identified in the study.

Fig. 2 :
Fig. 2: Different types of neural tube anomalies identified in the study.
ignorant about regular intake of folic acid during pregnancy.
Sailaja.K.A STUDY ON CONGENITAL ANOMALIES OF CENTRAL NERVOUS SYSTEM.socio economic conditions and febrile illness during first trimester.Low socioeconomic condition denotes nutritional deficiency during pregnancy, when the cells are undergoing active proliferation in the embryo[6].Recognition of aetiological factors permits implementation of preventive measures in the society to decrease the incidence of this dreadful condition.In all cases of microcephaly, associated anomalies of eyes or ears or facial dysmorphism were noticed.Ultrasound screening of pregnant ladies is a very useful and harmless method of investigation for the early diagnosis of anomalies, so that a foetus with a gross anomaly can be terminated.Early diagnosis also helps in intrauterine correction of anomalies like spina bifida.Increased risk of neural tube defects among people in low socio economic group has offered a clue to the factors that poor families are different form affluent families.Poor nutrition is the obvious reason.Effect of poor nutrition is magnified in the developing embryo where active cell proliferation occurs[7].Risk factor for microcephaly includes alcohol use, inadequate weight gain during pregnancy, inadequate prenatal care, black race and low education.

Table 1 :
Community wise distribution of patients in the study.

Table 2 :
Socioeconomic status of patients in the study.

Table 3 :
Gender wise distribution of patients in the study.

Table 4 :
Number of patients depending on various parameters.

Table 5 :
Number of patients belongs to associated anomalies with eyes.

Table 6 :
Number of patients belongs to associated anomalies with ears.

Table 7 :
Number of patients belongs to other associated anomalies.