Abstract
Objectives: To determine the frequency of neural
tube defects among patients who were delivered at Prince Rashid
Bin Al-Hassan
Military Hospital
and to discuss possible ways to reduce them.
Methods: This descriptive review study of
11,852 medical records was conducted over a period of two years between the 1st
of August 2005 and end of July 2007 at Prince Rashid Bin-Al-Hassan Military Hospital
in Irbid-Jordan.
Results: During the study period, there
were 17 cases of neural tube defects (1.4/1000 births), of these there were five
cases of spina bifida (0.42/1000 births), three cases of encephalocele
(0.25/1000 births), and nine cases of anencephaly (0.76/1000 births). The
overall female to male ratio was 1 : 0.89. The most common neural tube defect was
anencephaly (52.9%), and the commonest site of spina bifida was the lumbosacral
region in 2/5 (40%). One case of encephalocele was associated with
malformations while four cases (80%) of spina bifida were associated with other
malformations.
Conclusion: The frequency of neural tube defects is high
and probably on the decreasing in Jordan. We may be able to reduce
such defects by recommending women of childbearing age to take daily Folic acid
(400mcg) for at least three months before they become pregnant and throughout
the first trimester.
Key words: Anencephaly, Neural tube defects,
Spina bifida
JRMS
December 2010; 17(4): 24-27
Introduction
Neural tube defects (NTDs) are
congenital structural abnormalities of the brain and vertebral column that
occur either as an isolated malformation, along with other malformations, or as
part of genetic syndrome and are the second most common major congenital
anomaly worldwide.(1) The exact cause of these defects is not known,
however, they are currently considered to be "complex" disorders where
both genetic and environmental factors play important roles in their causation.
Nutritional factors such as diet and vitamins appear to be important
contributors to the etiology of NTDs.(2)
Neural tube defects are among the
few birth defects for which primary prevention is possible, prenatal screening
and diagnosis are widely available, and prenatal therapy is being investigated.(3)
The incidence of NTDs has long
been recognized to vary widely according to geographical distribution; ethnic
background, maternal and various socio-economic factors.(4,5) Regions with the highest incidence include the Ukraine, China, and India.(6-8) There are few reports about the frequency of NTDs in Jordan and the Middle East.(9) Jordan lacks an ongoing surveillance system for congenital anomalies. However, the incidence of NTDs in Jordan is reported to be as high as 6.5 per 1000 live births based on a study carried out at King Hussein Medical Centre.(10)
Table I. Frequency of NTDs by type of defect
|
Type of NTD
|
No.
|
%
|
Incidence/1000
deliveries
|
Male-Female
ratio
|
|
Spina bifida
-Meningocele
-Myelomeningocele
|
5
1
4
|
29.4
5.9
23.5
|
0.42
0.08
0.34
|
1.5:1
|
|
Encephalocele
|
3
|
17.7
|
0.25
|
0.5:1
|
|
Anencephaly
|
9
|
52.9
|
0.76
|
0.8:1
|
|
All NTDs
|
17
|
100
|
1.4
|
0.89:1
|
NTDs: neural tube
defects
|
Table II. Spina bifida –site of lesion (n=5)
|
Level
|
No.
|
%
|
|
Cervical
|
0
|
0
|
|
Dorsolumbar
|
1
|
20
|
|
Lumber
|
1
|
20
|
|
Lumbosacral
|
2
|
40
|
|
Sacral
|
1
|
20
|
|
Total
|
5
|
100
|
|
Table III. Spina bifida
associated anomalies
|
Anomaly
|
No.
of cases
|
|
Club foot
|
1
|
|
Hydrocephalus
|
1
|
|
Anencephaly
|
2
|
|
The Frequency of NTDs is showing
steady and significant decrease throughout the world including many parts of the
Middle East.(11,12) This is largely attributed to the
improvement of the socioeconomic conditions.(13) In societies where abortion is permitted, the
frequency of live born NTDs has been greatly reduced by antenatal screening and
termination of pregnancy.(14) Also a meta-analysis found that
periconceptional folic acid supplementation reduced the incidence of neural
tube defects by about 72%.(15)
In this study, we assess the frequency
of NTDs among patients attending Prince
Rashid Bin
Al-Hassan Military
Hospital in the North of
Jordan.
Methods
Prince Rashid Bin-Al-Hassan
Military hospital is the main referral hospital in the North of Jordan. It serves
a population of about 800,000 and the maternity care unit receive about 400-500
deliveries monthly. The majority of our patients are of low and middle
socioeconomic class; most of them never received folic acid supplements. The practice
of cooking vegetables at high temperatures is common and I s believed to make the meals deficient in
folic acid by destruction of folate.
We reviewed the obstetric data of
all cases of NTDs delivered at this hospital between the 1st of August
2005 and the end of July 2007. During this period a total of 11,852 births took
place at this hospital. The majority of our patients were un-booked cases and
attended the hospital for the first time for delivery. The records of all mothers
who delivered cases of spina bifida, anencephaly, and encephalocele at this
hospital were reviewed and analyzed.
Results
During the study period (2005-2007),
there were 11,852 hospital deliveries and 17 cases of NTDs. The overall frequency of NTDs was 1.4/1000
births. Of these, there were five cases of spina bifida (0.42/1000 births), three
cases of encephalocele (0.25/1000 births), and nine cases of anencephaly
(0.76/1000 births) as shown in Table I.
The most common NTD was anencephaly
(52.94%) followed by spina bifida (29.41%) and encephalocele (17.65%). The overall female to male ratio was 1 : 0.89. The female to male ratio for spina bifida
was 1 : 1.5, for encephalocele was 1 : 0.5 and for anencephaly was 1 : 0.8 (Table
I).
The sites of spina bifida were
lumbosacral in 2/5 (40%), dorsolumbar in 1/5 (20%), lumbar in 1/5 (20%) and sacral
in 1/5 (20%) (Table II).
All cases of encephalocele were
in the occipital region. In one case there were other malformations such as
cleft lip and palate, polydactyly and polycystic kidney disease.
Table IV. Incidence of
NTDs in some countries in the Middle East and
other selected countries in the world
|
Location
|
Period(years)
|
Incidence No/1000
|
|
Shanxi
Province-China(7)
|
2003
|
13.8
|
|
Ukraine(8)
|
2000-2002
|
2.1
|
|
United States(11)
|
1992-1998
|
0.95
|
|
Saudi Arabia(12)
|
2001-2005
|
0.76
|
|
Izmir-Turkey(16)
|
2000
|
1.5
|
|
Northern
Iran(17)
|
1993-2002
|
2.8
|
|
British
Columbia-Canada(18)
|
1997-1999
|
1.16
|
|
Jordan(10)
|
2002-2003
|
6.5
|
Table III shows the other
congenital malformations which were present in four cases of spina bifida (80%); the most common malformations were
anencephaly (two cases), club foot (one case) and hydrocephalus (one case).
Discussion
NTDs are serious birth defects of
the brain and the spine. Anencephaly is defined as the absence of the
membranous skull and the cerebral hemispheres. Encephalocele is defined as
herniation of the brain through a defect in the skull. Spina bifida includes
meningocele and meningomyelocele. Meningocele is defined as herniation of the
meninges and the defect is covered by normal skin, whereas meningomyelocele
occurs when both the meninges and the spinal cord herniate through the
vertebral defects.
Nowadays, NTDs can be diagnosed
by performing detailed anomaly scan between 18-20 weeks gestation or even
before this date, so termination of pregnancy could be offered. However, the law
in Jordan
does not allow termination of pregnancy for congenital abnormalities. The
recognition of the incidence of neural tube defects and its trend over the
years may be very important for the health care programs. Our data may not
represent the overall incidence of the NTDs, because the cases reported in this
study included only those delivered at our hospital. Generally, babies born at
home are not referred to the hospital after delivery. We believe that the
overall incidence may be higher.
Table IV shows the incidence of
NTDs in some countries in the Middle East and
other countries in the world. These variations between different studies could
be explained by the effect of different racial, ethnic and social factors in
various parts of the world or different geographical, nutritional and
socioeconomic factors. As shown in Table IV northern China Shanxi
Province has reported the
highest incidence of NTDs in the world.
In our study, we found that the
overall frequency of NTD was 1.4/1000 births, very similar to the frequency of
NTD in Izmir –Turkey,(16) and much lower than that reported
previously in Jordan,(10) but is higher than other parts of
the Middle East such as Saudi Arabia.(12) The frequency of
NTDs in British Colombia-Canada was found to be 1.16/1000.(18)
We noted female predominance in the
rates of anencephaly and encephalocele which seems to be a universal feature.(11,17)
Also we have noted that 62.5% of spina bifida and encephalocele cases were
associated with other major congenital malformation. This rate is higher than
the international rates and higher than that reported in other studies.(19,20)
The most common site of spina bifida was in the lumbosacral region. The occipital
encephalocele was the predominant site in these cases, this was also true of
the Western studies.(19)
All the interventional studies
have shown a significant protective effect of vitamins and folic acid
supplements. The Medical Research Council multicentre, double-blind trial
involving 33 centers in seven countries found that folic acid gave a 72%
protection from NTDs when given to women who had previously had an affected
baby.(15) Since then, observational studies demonstrated a reduced
risk among women who took multivitamins supplements containing folic acid
during early pregnancy.(21,22)
Since 1998, the US Food and Drug
Administration has required folic acid fortification of cereal grains, also it
became mandatory in Canada, and a marked decrease in prevalence rate of NTDs
was observed after food fortification.(23) This was supported
by a study from Canada which confirmed that the prevalence of NTDs had
decreased by 46% since food fortification.(24) Another study from Nova Scotia showed a
reduction of NTDs by more than 50%.(25)
In Jordan it is important to increase
the awareness of women in the childbearing age, to the need to take vitamins
that contain at least 0.4 mg of folic acid daily before they become pregnant.
Women with previously affected fetus/infant may need a higher dose of folic
acid (5mg). This may be the only realistic option available to reduce the
incidence of NTD in our country for the time being.
Conclusion
The frequency of NTDs is high and
probably on the decreasing in Jordan.
We may be able to reduce such defects by recommending women of childbearing age
to take daily Folic acid (400mcg) for at least three months before they become
pregnant and throughout the first trimester.
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