|
| |
Spina bifida drawinggif
|
| |
|
| |
12306
|
| |
,
|
| |
,
|
| |
|
| |
182940
|
| |
|
| |
orthoped
|
| |
557
|
| |
Spina+Bifida
|
| |
C10500680800
|
(nic neural tube results in an incompletely formed spinal cord. In addition, the bones of the spine (
Vertebrae ) overlying the open portion of the spinal cord do not fully form and remain unfused and open. This allows the abnormal portion of the spinal cord to protrude through the opening in the bones. There may or may not be a fluid filled sac surrounding the open spinal cord. Other neural tube defects include
Anencephaly , a condition in which the portion of the neural tube which will become the
Cerebrum (front of the brain) does not close, and
Encephalocele , which results when other parts of the brain remain unfused.
Spina bifida malformations fall into three categories: ''spina bifida occulta'', ''spina bifida cystica (myelomeningocele)'', and ''meningocele''. The most common location of the malformations is the
Lumbar and
Sacral areas of the spinal cord. Myelomeningocele is the most significant form and is that which leads to disability in most affected individuals. The terms spina bifida and myelomeningocele are usually used interchangeably.
Spina bifida can be surgically closed after birth, but this does not restore normal function to the affected part of the spinal cord and an individual with this condition will have dysfunction of the spinal cord and associated nerves from the point of the open defect and below. Intrauterine surgery for spina bifida has also been performed and the safety and efficacy of this procedure is currently being investigated with an
NICHD -funded grant. The incidence of spina bifida can be decreased up to 70% when daily
Folic Acid supplements are taken prior to
Conception .
Spina bifida is one of the most common birth defects, with an average worldwide
Incidence of 1-2 cases per 1000 births, but certain populations have a significantly greater risk.
In the
United States , the average incidence is 0.7 per 1000 live births. The incidence is higher on the East Coast than on the West Coast, and higher in whites (1 case per 1000 live births) than in blacks (0.1-0.4 case per 1000 live births). Immigrants from Ireland have a higher incidence of spina bifida than do nonimmigrants.Lemire RJ (1988). "Neural tube defects". ''
JAMA '' (4): 558–62. PMID 3275817.Cotton P (1993). "Finding neural tube 'zippers' may let geneticists tailor prevention of defects". ''JAMA'' '''270''' (14): 1663–4. PMID 8411482.
The highest incidence rates worldwide were found in parts of the British Isles, mainly Ireland and Wales, where 3-4 cases of myelomeningocele per 1000 population have been reported during the 1970s, along with more than 6 cases of anencephaly (both live births and stillbirths) per 1000 population. The reported overall incidence of myelomeningocele in the British Isles is 2-3.5 cases per 1000 births. Since then, the rate has fallen dramatically with 0.15 per 1000 live births reported in 1998.T. Lissauer, G. Clayden. Illustrated Textbook of Paediatrics (Second Edition). Mosby, 2003. ISBN 0-723-43178-7
Parents of children with spina bifida have an increased risk of having a second child with a neural tube defect.
These vary with the extent of the spinal defect, and differ between the subtypes described below.
The most common location of the malformations is the
Lumbar and
Sacral areas of the spinal cord. The lumbar nerves control the muscles in the hip, leg, knee and foot, and help to keep the body erect. The sacral nerves control some of the muscles in the feet, bowel and urinary bladder, and the ability to have an erection. Some degree of impairment can be expected in these areas, resulting in varying degrees of paralysis, absence of skin sensation, and poor or absent bowel and/or bladder control, curvature of the spine (
Scoliosis ), depending on the severity and location of the lesion damage on the spine. Although these individuals are rarely mentally retarded, in most cases there are cognitive problems.
Tethered Spinal Cord Syndrome , with symptoms such as lower body pain, leg weakness, incontinence, curvature of the spine (
Scoliosis ), numbness, is a common problem associated with spina bifida. Indeed 100% of spina bifida myelomeningocele patients have Tethered Cord on imaging studies such as
Magnetic Resonance Imaging , but not all will develop symptoms. A tethered cord is thought to result from scar tissue which forms following the initial surgery to close the open defect. Symptoms caused by a tethered cord are rare in infancy and early childhood. Once symptoms develop it is important to make the diagnosis early, before permanent damage is done to the spinal cord and nerves.
According to the
Spina Bifida Association of America (SBAA), over 73% of people with spina bifida develop an allergy to
Latex , ranging from mild to life-threatening. The common use of latex in medical facilities makes this a particularly serious concern. The most common approach is to try to avoid development of the allergy by avoiding contact with latex containing products such as examination gloves,
Catheters (tubes used in the management of bladder dysfunction, inserted through the
Urethra to evacuate urine), and many of the products used by dentists.
''Occulta'' is
Latin for "hidden." This is one of the mildest forms of spina bifida although the degree of disability can vary depending upon the location of the lesion.
In occulta there is no opening of the back, but the outer part of some of the vertebrae are not completely closed. The split in the vertebrae is so small that the spinal cord does not protrude. The skin at the site of the
Lesion may be normal, or it may have some hair growing from it; there may be a dimple in the skin, a
Lipoma , a
Dermal Sinus or a
Birthmark .
Many people with the mildest form of this type of spina bifida do not even know they have it, or symptoms do not appear until later in life. People with spina bifida occulta may suffer from a
Tethered Cord (diastematomyelia), when the spinal cord gets trapped below the affected level of the growing spine. This may cause neurological problems of the legs and bladder.
A systematic review of radiographic research studies found no relationship between spina bifida occulta and back pain.
1 More recent studies not included in the review support the negative findings.
234
However, other studies suggest spina bifida occulta is not always harmless. One study found that among patients with back pain, severity is worse if spina bifida occulta is present.
5 Another study found that spina bifida occulta may predispose to disk herniation.
6
In this, the most serious form, the unfused portion of the spinal column allows the spinal cord to protrude through an opening in the overlying vertebrae. The meningeal membranes that cover the spinal cord may or may not form a sac enclosing the spinal elements. Superficially, the cyst may resemble an unrelated defect,
Sacrococcygeal Teratoma . Spina bifida with myeloschisis is the most severe form of spina bifida cystica. In this defect, the neural folds fail to meet and fuse leaving the spinal cord open and the involved area represented by a flattened, plate-like mass of nervous tissue with no overlying skin or membrane. The unfused elements of the spinal cord can be surgically closed along with the overlying muscle and skin shortly after birth (see treatment section below).
The incompletely closed portion of the spinal cord and the nerves which originate at that level of the cord are damaged or not properly developed. As a result, there is usually some degree of
Paralysis and loss of sensation below the level of the spinal cord defect. Thus, the higher the level of the defect the more severe the associated nerve dysfunction and resultant paralysis. People may have ambulatory problems, loss of sensation, deformities of the hips, knees or feet and loss of muscle tone. Depending on the location of the lesion, intense pain may occur originating in the lower back, and continuing down the leg to the back of the knee.
Most children and adults with this condition experience problems with bowel and bladder control since the nerves which control these functions originate at the lowest part of the spinal cord. This may result in
Urinary Incontinence from
Neurogenic Bladder .
Many individuals with spina bifida will have an associated abnormality of the back of the brain, or
Cerebellum , called the
Arnold Chiari II Malformation . In affected individuals the back portion of the brain is displaced from the back of the skull down into the upper neck. In approximately 90% of the people with myelomeningocele,
Hydrocephalus —extra fluid in the
Ventricles of the brain— will also occur because the displaced cerebellum interferes with the normal flow of
Cerebrospinal Fluid .
The myelomeningocele (or perhaps the scarring due to surgery) tethers the
Spinal Cord to the
Enveloping Vertebra . In some individuals this causes significant traction on the spinal cord and can lead to a worsening of the paralysis, curvature of the spine, also known as
Scoliosis , back pain, or worsening bowel and/or bladder function.
The least common form of spina bifida is a posterior (or '''meningeal cyst''').
In a , the outer faces of some vertebrae are open (unfused) and the
Meninges are damaged and pushed out through the opening, appearing as a sac or
Cyst which contains cerebrospinal fluid. The spinal cord and nerves are not involved and their function is normal.
In an , the inner faces of vertebrae are affected and the cyst protrudes into the
Retroperitoneum or the
Presacral Space .
Apart from spina bifida, causes of meningocele include
Teratoma and other
Tumor s of the
Sacrococcyx and of the
Presacral Space , and
Currarino Syndrome . Usually a meningocele has no negative long-term effects, although there are reports of
Tethered Cord .
Spina bifida is caused by the failure of the
Neural Tube to close during the first month of
Embryo nic development (often before the mother knows she is pregnant).
Normally the closure of the neural tube occurs around the twenty-eighth day after
Fertilization . However, if something interferes and the tube fails to close properly, a neural tube defect will occur. Medications such as some
Anticonvulsants ,
Diabetes , having a relative with spina bifida,
Obesity , and an increased body temperature from
Fever or external sources such as hot tubs and electric blankets can increase the chances a woman will conceive a baby with a spina bifida. However, most women who give birth to babies with spina bifida have none of these risk factors, and so in spite of much research, it is still unknown what causes the majority of cases.
The varying prevalence of spina bifida in different human populations and extensive evidence from mouse strains with spina bifida suggests a genetic basis for the condition. As with other human diseases such as
Cancer ,
Hypertension and
Atherosclerosis (coronary artery disease), spina bifida likely results from the interaction of multiple genes and environmental factors.
Research has shown that lack of
Folic Acid (folate) is a contributing factor in the pathogenesis of neural tube defects, including spina bifida. Supplementation of the mother's diet with folate can reduce the incidence of neural tube defects by about 70%, and can also decrease the severity of these defects when they occur.
789 As yet it is unknown how or why folic acid has this effect.
Spina bifida does not follow direct patterns of heredity like
Muscular Dystrophy or
Haemophilia . Studies show that a woman who has had one child with a neural tube defects such as spina bifida, have about a 3% risk to have another child with a
Neural Tube Defect . This risk can be reduced to about 1% if the woman takes high doses (4 mg/day) of folic acid before and during pregnancy. For the general population, low-dose folic acid supplements are advised (0.4 mg/day).
There is no cure for nerve damage due to spina bifida. To prevent further damage of the nervous tissue and to prevent infection
Pediatric Neurosurgeons operate to close the opening on the back. During the operation, the spinal cord and its nerve roots are put back inside the spine and covered with
Meninges , muscle and skin. In addition, a
Shunt may be surgically installed to provide a continuous drain for the cerebrospinal fluid produced in the brain, as happens with
Hydrocephalus . Shunts most commonly drain into the abdomen.
Most individuals with myelomeningocele will need periodic evaluations by specialists including orthopedists to check on their bones and muscles, neurosurgeons to evaluate the brain and spinal cord and urologists for the kidneys and bladder. Such care is best begun immediately after birth. Most affected individuals will require braces, crutches, walkers or wheelchairs to maximize their mobility. The higher the level of the spina bifida defect the more severe the paralysis. Thus, those with low levels may need only short leg braces while those with higher levels do best with a wheelchair. Many will need to manage their urinary system with a program of catheterization. They will need to insert a tube into their bladders to drain urine, of which the intervals vary from person to person, and may need medications to improve their dryness. Most will also require some sort of bowel management program.
'''Management of to evaluate the safety and efficacy of
Fetal Surgery to close a myelomeningocele. This involves surgically opening the pregnant mother's
Abdomen and
Uterus to operate on the
Fetus . Fetal skin grafts are used to cover the exposed spinal cord, to protect it from further damage caused by prolonged exposure to amniotic fluid. The fetal surgery may decrease some of the damaging effects of the spina bifida.
Pregnant women who consent to participate and meet all eligibility criteria are referred to one of three centers in the
United States , located in
California ,
Tennessee , and
Pennsylvania . The centers provide final evaluation, randomization, surgery and follow-up assessments. Participants' travel, lodging, relevant medical and surgical procedures, and related costs are covered by the clinical trial, not by the participants' medical insurance.
Major Eligibility Criteria:
- Gestational age at randomization: 19 – 25 weeks
- Myelomeningocele defect must start at: T1-S1 (may extend below S1)
- Fetal hindbrain herniation ( Arnold-Chiari Malformation type II)
- Maternal Body Mass Index < 35
- United States resident
There is no single cause of spina bifida nor any known way to prevent it entirely. However, dietary supplementation with s, fortified
Breakfast Cereal s, dried
Bean s,
Leaf Vegetable s and
Fruit s.
10
Folate fortification of enriched grain products has been mandatory in the United States since 1998. The FDA and UK recommended amount of folic acid for women of childbearing age and women planning to become pregnant is at least 0.4 mg/day of folic acid from at least three months before
Conception , and continued for the first 12 weeks of pregnancy.
11
Women who have already had a baby with spina bifida or other type of neural tube defect, or are taking
Anticonvulsant medication should take a higher dose of 4–5 mg/day.
Recent (as of 2007) research has shown that there is a specific gene that causes spina bifida, allowing parents to identify embryos that may develop the condition.
12
Neural tube defects can usually be detected during pregnancy by testing the mother's blood (
AFP Screening ) or a detailed fetal
Ultrasound . Spina bifida may be associated with other malformations as in dysmorphic syndromes, often resulting in spontaneous miscarriage. However, in the majority of cases spina bifida is an isolated malformation.
Genetic Counseling and further
Genetic Testing , such as
Amniocentesis , may be offered during the pregnancy as some neural tube defects are associated with genetic disorders such as
Trisomy 18 .
Ultrasound screening for spina bifida is partly responsible for the decline in new cases, because many pregnancies are terminated out of fear that a newborn might have a poor future
Quality Of Life . With modern medical care, the quality of life of patients has greatly improved.
People of note born with spina bifida:
- and eight-time Boston Marathon winner
- Tanni Grey-Thompson , Welsh Paralympian
- Lawrence Gwozdz , U.S. saxophonist
- Blaine Harrison , of the British band Mystery Jets
- Rene Kirby , U.S. actor, starred in Shallow Hal , 2001http://movies.about.com/library/weekly/aa110201g.htm
- John Mellencamp , U.S. rock and roll musician
- Bobby Steele , U.S. Punk Rock guitarist and songwriter
- Jeffrey Tate , British conductor
- Hank Williams , U.S. country music singer
- Justin Yoder , American Soap Box Racer
- Mighty Mike McGee , American 2006 World Slam Poetry Champion
- James Connelly , U.S. Paralympian , 2006 Bronze Medal Winner ; Sled Hockey
- Aaron Fotheringham , US Wheelchair skateboarder
- Ruben Melendez , Jazz and Blues musician
