Category Archives: Neurological Birth Defects

Congenital Hydrocephalus

Accumulation of cerebrospinal fluid in the ventricles or chambers in the brain, leads to hydrocephalus which results in the enlargement of the head, and the impairment of the normal growth and development of the brain.

  • Hydrocephalus results from the lack of drainage of the cerebrospinal fluid in the ventricles of the brain.
  • Enlargement of the head, and impairment of mental and intellectual development of the baby, are the usual symptoms.
  • An ultrasound scan, CT scan, or magnetic resonance imaging can help determine the severity of the condition.
  • Surgical insertion of a shunt which drains the excess fluid out of the brain is often required.

The cerebrospinal fluid which surrounds the brain is produced in the ventricles of the brain. The fluid normally drains from the brain to another area where the blood absorbs it. When the drainage is not proper, the fluid accumulates in the brain, resulting in hydrocephalus, which is commonly referred to as ‘water in the brain’. The excess fluid leads to pressure build up and compression of the brain. The cerebrospinal fluid drainage may be prevented due to various reasons. Congenital defects, brain tumors, or brain hemorrhage in infants, especially in prematurely born babies, may impede proper drainage of the fluid.

When congenital hydrocephalus is not treated, the infant’s development may suffer, and the head may remain very large. The extent and severity of brain compression due to hydrocephalus can be determined by an ultrasound scan or a CT scan. Magnetic resonance imaging of the head can also help in accurate diagnosis.

The pressure inside the brain is kept normal by various treatment procedures. A lumbar puncture can relieve the pressure temporarily, but a shunt can open up a permanent drainage for the excess cerebrospinal fluid accumulating in the brain, thus keeping the pressure within limits. In a ventriculoperitoneal shunt, the fluid from the ventricles of the brain is shunted via a tube which runs under the skin to the abdominal lining. A valve in the shunt regulates the pressure in the ventricles by channeling the excess volume of fluid away from the brain. The shunt is often left in place even after the child outgrows the need for it later on in life. Ventriculostomy is another surgical procedure, in which a hole is made between the third ventricle and the fourth one, which is often helpful in treating hydrocephalus in certain cases.

Lumbar punctures are often done to reduce the pressure in the brain till a permanent shunt can be fixed surgically to regulate the pressure.

Reduced mental development and learning difficulties occur in many children who have congenital hydrocephalus, especially when the condition had developed early in the fetus. When this condition develops later in pregnancy, the associated symptoms are less severe. Some children with hydrocephaly may have normal levels of intelligence.

Watch This Explanatory Video About Hydrocephalus

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Neural Tube Defects

Abnormal development of the neural tube in the early stages of embryonic development results in various defects of the brain and the spinal cord which originate from the tissues of the neural tube.

  • Severe nerve damage, often leading to mental retardation, learning disabilities, lack of bowel control, paralysis and even death may result from neural tube defects.
  • A blood test for alpha fetoprotein, amniocentesis and ultrasound scan can diagnose the presence of neural tube defects in the fetus.
  • Taking folic acid supplements prior to and in the first three months of pregnancy significantly reduces the risk of neural tube defects.
  • Surgical correction of neural tube defects is required in most cases.

During embryonic development, the neural tube develops from the folding over of a groove into a tube-like structure. The brain, spinal cord, and their protective coverings called meninges, develop from the different tissue layers of the neural tube. When abnormalities occur in the development of the neural tube, it affects the development of these structures which originate from it. Complete absence of brain may result from a severe defect in the neural tube development. This condition, known as anencephaly, is always fatal. Incomplete closure of the neural tube may result in abnormalities of various degrees. In mild cases, the open channel may cause only a bone defect such as spina bifida occulta. In this condition, the spinal cord and the meninges covering it are intact, but the bony tissue that makes up the spine does not close completely. It does not cause any symptoms in infants. In some cases of open channel defects, a meningocele may protrude through the opening. If part of the brain tissue protrudes along with the meninges, it is known as a meningoencephalocele. In a similar condition called meningomyelocele, the spinal cord tissue and the meninges protrude. When the brain tissue is exposed without the meninges, it is called an encephalocele and the protrusion of the spinal cord without the meninges is termed myelocele. The protrusion of the brain tissue or the spinal cord tissue through incompletely closed openings results in greater damage to them.

Abnormalities such as tufts of hair, small tissue masses, and openings in the surface of the skin known as dermal sinuses, may be present at the lower back of infants who have a condition called occult spinal dysraphism. Dark pigmented patches known as flame nevus and hemangioma may occur in less serious cases. If the spinal cord is exposed to the outside through an opening, the chances of bacterial infections developing and leading to meningitis are very high. Gradual damage to the spinal cord may occur due to continued exposure. Sometimes, a fatty tumor known as lipoma may develop on the spinal cord, which damages the nerves in the spinal cord. It is essential that any opening exposing the spinal cord tissues or the meninges should be surgically closed to prevent further damage. Infants born with these visible abnormalities should have further investigations such as an ultrasound scan or an MRI scan to examine the defects in the underlying spinal cord and associated tissues.

Some neural tube defects occur due to genetic abnormalities. The defects begin to develop in the very first weeks of pregnancy, even before pregnancy is recognized by the mother. The symptoms of neural tube defects depend on the damage caused to the brain and spinal cord.  Meningomyeloceles and meningoencephaloceles are conditions resulting in significant disability in the infant. Fluid accumulation in the brain, known as hydrocephaly, may develop in some cases. Bone and joint defects, lack of sensation of certain body parts and the skin, lack of control over bowel movements and urination, learning disabilities, and even paralysis, may be caused by neural defects.

Prenatal testing of the amniotic fluid or mother’s blood can detect neural tube defects present in the fetus. When alpha-fetoprotein is present in high levels, it is an indication of abnormalities in neural tube development. The defects can be detected by an ultrasound scan done later in pregnancy too. Folic acid supplements taken prior to, and in the first trimester of pregnancy can significantly reduce the risk of neural tube defects in the infants. All women who are likely to conceive should take folate supplements as a precautionary measure. Surgical closure of the defect after birth is the treatment for this condition.

Watch This Video about Spina Bifida:

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Overview Of Neurological Birth Defects

Neurological Birth defects may occur in the brain and spinal code of the infants due to incomplete or faulty development of these structures in the fetus.

  • Some defects occur very early in the fetus while others develop later in pregnancy.
  • Paralysis, retardation of mental and intellectual development, lack of sensation in certain parts of the body, and incontinence, are some of the usual symptoms.
  • CT scan or Magnetic resonance imaging can diagnose brain and spinal cord defects.
  • Surgical repair of certain abnormalities resulting from these defects is possible, but many defects cause permanent disabilities.

Certain brain and spinal cord defects such as neural tube defects develop very early in pregnancy, usually in the first few weeks. Others like hydrocephaly and porencephaly may develop much later. Many characteristic structural and morphological abnormalities result from defects in the brain and spinal cord.

When the brain tissue or the tissue of the spinal cord is affected by defective development, it results in symptoms typical of brain damage or those of spinal cord damage. Severe brain damage can have fatal consequences but less severe defects often result in various degrees of disability depending on the extent of damage caused to the brain. The usual symptoms of brain damage include paralysis, seizures, lack of mental development, reduced intellectual ability and learning difficulties.

Severe spinal cord damage can also result in paralysis. Other common symptoms include incontinence, lack of control over bowel movements, lack of sensation in the body parts below defective area of the spinal cord, decreased sensation of the skin etc. Computed tomography, as well as magnetic resonance imaging, can provide accurate images of the structure of the brain and the spinal cord, and help detect any defect occurring in these organs.

Abnormal growths, swellings, and incompletely closed openings are surgically corrected as soon as possible. The damage that has already occurred to the brain as well as to the spinal cord may be irreversible, but surgical repair of abnormalities help in improving function and reducing complications in future. Immediate medical intervention and surgical correction of certain defects facilitates further normal growth and development of the infants.

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