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Microcephaly

Definition:
Microcephaly (my-kroh-SEF-uh-lee) is a rare  neurodevelopmental disorder in which the circumference of the head is more than two standard deviations smaller than average for the person’s age and sex. Microcephaly may be congenital or it may develop in the first few years of life. The disorder may stem from a wide variety of conditions that cause abnormal growth of the brain, or from syndromes associated with chromosomal abnormalities. Two copies of a loss-of-function mutation in one of the microcephalin genes causes primary microcephaly.

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Sometimes detected at birth, microcephaly usually is the result of the brain developing abnormally in the womb or not growing as it should after birth.

Microcephaly can be caused by a variety of genetic and environmental factors. Children with microcephaly often have developmental issues. Generally there’s no treatment for microcephaly, but early intervention may help enhance your child’s development and improve quality of life.

Symptoms:
The primary sign of microcephaly is:

*A head size significantly smaller than that of other children of the same age and sex.

Head size is measured as the distance around the top of the child’s head (circumference). Using standardized growth charts, the measurement is compared with other children’s measurements in percentiles. Some children just have small heads, which may measure in the third, second or even first percentiles. In children with microcephaly, head size measures significantly below the first percentile.

These characteristics may accompany severe microcephaly:

*Backward sloping forehead
*Large ears
*Visual impairment


Depending on the severity of the accompanying syndrome, children with microcephaly may have:

*mental retardation,
*delayed motor functions and speech,
*facial distortions,
*dwarfism or short stature,
*hyperactivity,
*seizures,
*difficulties with coordination and balance, and
*other brain or neurological abnormalities.

Some children with microcephaly will have normal intelligence and a head that will grow bigger, but they will track below the normal growth curves for head circumference.


Causes:

It is most often caused by genetic abnormalities that interfere with the growth of the cerebral cortex during the early months of fetal development. It is associated with Down’s syndrome, chromosomal syndromes, and neurometabolic syndromes. :

Babies born with microcephaly will have a smaller than normal head that will fail to grow as they progress through infancy.

Microcephaly usually is the result of abnormal brain development, which can occur in the womb (congenital) or in infancy. Microcephaly may be genetic. Other causes may include:

*Craniosynostosis.
The premature fusing of the joints (sutures) between the bony plates that form an infant’s skull keeps the brain from growing. Treating craniosynostosis usually means your infant needs surgery to separate the fused bones. If there’s no underlying brain abnormality, the surgery allows the brain adequate space to grow and develop.

*Chromosomal abnormalities.
Down syndrome and other conditions may result in microcephaly.

*Decreased oxygen to the fetal brain (cerebral anoxia).
Certain complications of pregnancy or delivery can impair oxygen delivery to the fetal brain.

*Infections of the fetus during pregnancy. These include toxoplasmosis, cytomegalovirus, German measles (rubella) and chickenpox (varicella).

*Exposure to drugs, alcohol or certain toxic chemicals in the womb.
Any of these put your baby at risk of brain abnormalities.

*Severe malnutrition
. Not getting adequate nutrition during pregnancy can affect your baby’s development.

*Uncontrolled phenylketonuria (fen-ul-kee-toe-NU-ree-uh), also known as PKU, in the mother. PKU is a birth defect that hampers the body’s ability to break down the amino acid phenylalanine.

Complecations & Risk Factoirs:

Some children with microcephaly will be of normal intelligence and development, even though their heads will always be small for their age and sex. But depending on the cause and severity of the microcephaly, complications may include:

*Developmental delays, such as in speech and movement
*Difficulties with coordination and balance
*Dwarfism or short stature
*Facial distortions
*Hyperactivity
*Mental retardation
*Seizures

In general, life expectancy for individuals with microcephaly is reduced and the prognosis for normal brain function is poor. The prognosis varies depending on the presence of associated abnormalities.

Diagnosis:
To determine whether your child has microcephaly, your doctor likely will take a thorough prenatal, birth and family history and do a physical exam. He or she will measure the circumference of your child’s head, compare it with a growth chart, and remeasure and plot the growth at subsequent visits. Parents’ head sizes also may be measured to determine whether small heads run in the family.

In some cases, particularly if your child’s development is delayed, your doctor may request tests such as a head CT or MRI and blood tests to help determine the underlying cause of the delay.

Treatment :

Generally, there’s no treatment that will enlarge your child’s head or reverse complications of microcephaly.  Early childhood intervention programs that include speech, physical and occupational therapy may help your child strengthen abilities.

Treatment focuses on ways to decrease the impact of the associated deformities and neurological disabilities. Children with microcephaly and developmental delays are usually evaluated by a pediatric neurologist and followed by a medical management team. Early childhood intervention programs that involve physical, speech, and occupational therapists help to maximize abilities and minimize dysfunction. Medications are often used to control seizures, hyperactivity, and neuromuscular symptoms. Genetic counseling may help families understand the risk for microcephaly in subsequent pregnancies.

Certain complications of microcephaly, such as seizures or hyperactivity, may be treated with medication.

Prognosis:

Some children will only have mild disability. Others, especially if they are otherwise growing and developing normally, will have normal intelligence and continue to develop and meet regular age-appropriate milestones.

When you learn your child has microcephaly, you may experience a range of emotions, including anger, fear, worry, sorrow and guilt. You may not know what to expect, and you may worry about your child’s future. The best antidote for fear and worry is information and support. Prepare yourself:

*Find a team of trusted professionals. You’ll need to make important decisions about your child’s education and treatment. Seek a team of doctors, teachers and therapists you trust. These professionals can help evaluate the resources in your area and help explain state and federal programs for children with disabilities.

*Seek out other families who are dealing with the same issues. Your community may have support groups for parents of children with developmental disabilities. You may also find Internet support groups.

Prevention:
Learning your child has microcephaly may raise questions about future pregnancies. Work with your doctor to determine the cause of the microcephaly. If the cause is genetic, you and your spouse may want to talk to a genetic counselor about risks for future pregnancies.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.medicinenet.com/microcephaly/page2.htm
http://www.mayoclinic.com/health/microcephaly/DS01169
http://en.wikipedia.org/wiki/Microcephaly

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Of older moms and Down Syndrome

India‘s urban elite has plenty of DINKs (Double Income, No Kids). These people get married later than their rural counterparts, often after they are financially and professionally independent and secure. They can afford the best, as far as pregnancy, antenatal care and delivery are concerned. Eventually, they limit their families to one or maybe two children for whom they wish to provide the best opportunities in life.

Under these circumstances, the birth of a child with Down’s Syndrome (trisomy 21 or mongolism) becomes an unbearable tragedy.

One in 800 children is born with Down’s Syndrome. Such children have a characteristic mongoloid  appearance at birth itself, irrespective of the parents’ ethnic backgrounds. The head may be smaller than normal with a sloping forehead, upward slanting eyes, a small flattened nose, low set ears, short stumpy fingers, a protuberant abdomen and a tongue which sticks out of a small mouth. Also, the palm shows just two lines instead of the usual three.

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Down’s Syndrome usually occurs spontaneously as a result of an anomaly during early embryonic cell proliferation producing an abnormal chromosome 21. During cell division it may have divided abnormally, producing three parts instead of the normal two. Sometimes a piece from the chromosome may have attached (translocated) itself to another chromosome.

These anomalies are more likely with increased maternal age at the time of the pregnancy. Many doctors and researchers consider the age 35 as the cut off.

The child shows all the typical features of Down’s Syndrome if all the cells contain the abnormal chromosomes. Sometimes the person may be a mosaic, with a mixture of normal and abnormal cells. The appearance may then be atypical.

The risk of recurrence is greater if the condition has arisen as a result of translocation. This is because one of the parents is then likely to be a carrier. The risk is around 3 per cent if the father is the carrier, and 12 per cent if the mother carries the abnormal gene. Also, a mother with a Down’s Syndrome child has a one per cent chance of producing another similarly affected child.

Life is difficult for children suffering from Down’s Syndrome as they often have subnormal intelligence. They may also have abnormalities in other organs like the heart. There may be blocks or malfunction of the gastrointestinal tract with constipation and intestinal bloating. Hearing loss or visual defects may also occur. The chromosomal abnormality causes a decreased immune response, causing frequent infections as the children grow. The incidence of leukaemia is 20 times greater than in the general population. Dementia too sets in during early adult life (around 40). All this means a lifetime of nurturing and extra care.

So does this mean that women should sacrifice education and professional careers for early marriage and childbirth?

Not really, as advances in medical science have made it possible to diagnose Down’s Syndrome during the antenatal period itself.

Ultrasound examination during the first trimester has a detection rate of approximately 95 per cent of all Down’s Syndrome cases. The measurement of nuchal translucency — the size of a collection of fluid at the base of the foetal neck  correlates with the risk of Downs Syndrome. Other markers like the size of the head, the nose, the presence or absence of heart and intestinal defects can be evaluated with a scan. The presence of several abnormal markers may be an indication of Down’s Syndrome.

Moreover, certain blood tests performed on the mother can show abnormal results if the foetus is affected. Of these, the one commonly available in India is the alpha-fetoprotein level which tends to be less than normal in Down’s Syndrome.

To confirm the diagnosis, the chromosomes of the foetus can be examined. This can be done with amniocentesis (an examination of the cells in the amniotic fluid that surrounds the baby in the uterus). The diagnosis takes two weeks.

The cells of the placenta can be also tested during the 10th and 12th weeks of pregnancy by Chorionic Villus Sampling (CVS). If a rapid diagnosis is required, Percutaneous Umbilical Blood Sampling (PUBS) can be done after 18 weeks of gestation. Each of these three tests is 98 to 99 per cent accurate in diagnosing Down’s Syndrome. However, all these tests carry a risk of miscarriage.

After birth, Down’s Syndrome is suspected because of the typical appearance of the baby. It is confirmed by karyotyping or checking the baby’s chromosomes to demonstrate the extra chromosome in the cells.

Unfortunately, much of this high-tech diagnosis is out of reach for the average Indian woman. Financial constraints, poor education and lack of facilities are major drawbacks to good antenatal care and prenatal diagnosis.
Source:Thr Telegraph (Kolkata,India)