Spina bifida (Latin
Latin is an Italic
: "split spine") is a developmental birth defect involving the neural tube
In the developing vertebrate, the neural tube is the embryo's precursor to the central nervous system, which comprises the brain and spinal cord....
: incomplete closure of the embryo
An embryo is a multicellular organism ploidy eukaryote in its earliest stage of development, from the time of first cell division until birth, Egg , or germination....
nic neural tube results in an incompletely formed spinal cord
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
In anatomy, lumbar is an adjective that means of or pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum ....
and sacral
The sacrum is a large, triangular bone at the base of the vertebral column and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones....
areas of the spinal cord. The lumbar nerves
The lumbar nerves are the five spinal nerves emerging from the lumbar vertebrae. They are divided into posterior and anterior divisions....
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
In anatomy, the urinary bladder is a solid, muscle, and distensible organ that sits on the pelvic floor in mammals. It is the organ that collects urine excreted by the kidneys prior to disposal by urination....
, and the ability to have an erection
An erection of the penis, clitoris or a nipple is its enlarged and firm state. It is the result of a complex interaction of psychological, neural, vascular and endocrine factors, and is usually, though not exclusively, associated with sexual arousal....
. 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 as well as curvature of the spine (scoliosis
Scoliosis is a medical condition in which a person's Vertebral column is curved from side to side, shaped like a "s", and may also be rotated....
) (depending on the severity and location of the lesion
A lesion is any abnormal tissue found on or in an organism, usually damaged by disease or trauma. Lesion is derived from the Latin word laesio which means injury....
damage on the spine). These individuals are rarely intellectually disabled. Children with spina bifida often have hydrocephalus
Hydrocephalus is a term derived from the Greek words "hydro" meaning water, and "cephalus" meaning head, and this condition is sometimes known as "water on the brain"....
, which consists of excessive accumulation of cerebrospinal fluid
Cerebrospinal fluid , Liquor cerebrospinalis, is a clear bodily fluid that occupies the subarachnoid space and the ventricular system around and inside the brain....
in the ventricles of the brain
The ventricular system is a set of structures in the brain continuous with the central canal of the spinal cord....
.
Tethered Spinal Cord syndrome
Tethered Spinal Cord Syndrome or Occult Spinal Dysraphism Sequence is a rare Neurology caused by tissue attachments that limit the movement of the spinal cord within the Vertebral column....
, (with symptoms such as lower body pain, leg weakness, incontinence, scoliosis, numbness) is a common problem associated with spina bifida. Indeed, all spina bifida myelomeningocele patients have Tethered Cord on imaging studies such as Magnetic resonance imaging
GaneshMagnetic resonance imaging , or nuclear magnetic resonance imaging , is primarily a medical imaging technique most commonly used in radiology to visualize the structure and function of the body....
, 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 percent of people with spina bifida develop an allergy
Allergy is a Disorder of the immune system often also referred to as atopy. Allergic reactions occur to Natural environmental substances known as allergens; these reactions are Acquired disorder, predictable and rapid....
to latex
LaTeX is a document markup language and Word processor for the TeX typesetting program. Within the typesetting system, its name is styled as ....
, 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, and many of the products used by dentists.
Occulta is Latin
Latin is an Italic language, historically spoken in Latium and Ancient Rome. Through the Military history of the Roman Empire, Latin spread throughout the Mediterranean and a large part of Europe....
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
A lesion is any abnormal tissue found on or in an organism, usually damaged by disease or trauma. Lesion is derived from the Latin word laesio which means injury....
may be normal, or it may have some hair growing from it; there may be a dimple in the skin, a lipoma
A lipoma is a benign tumor composed of adipose tissue. These are the most common form of soft tissue tumor. Lipomas are soft to the touch, usually moveable, and are generally painless....
, a dermal sinus or a birthmark
A birthmark is a blemish on the skin formed before birth. A little over 1 in 10 babies have a vascular birthmark. They are part of the group of skin lesions known as "nevus"....
.
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 from diastematomyelia
Diastomatomyelia is a congenital disorder in which a part of the spinal cord is split, usually at the level of the upper lumbar vertebra.Diastomatomyelia is a rare congenital anomaly that results in the "splitting" of the spinal cord in a longitudinal direction....
or the lipoma in lipomyelomeningocele, 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
Radiography is the use of X-rays to view unseen or hard-to-image objects. The main diagnostic purposes of X-rays are to see inside one's body, most commonly the bones which can be viewed at an optimum resolution ....
research studies found no relationship between spina bifida occulta and back pain. More recent studies not included in the review support the negative findings.
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.
The least common form of spina bifida is a posterior meningocele (or meningeal cyst).
In a posterior meningocele, the outer faces of some vertebrae are open (unfused) and the meninges
The meninges is the system of Mesotheliums which envelops the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater....
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 anterior meningocele, the inner faces of vertebrae are affected and the cyst protrudes into the retroperitoneum
The retroperitoneum is the anatomical space in the abdominal cavity behind the peritoneum. It has no specific delineating anatomical structures....
or the presacral space
In human anatomy, the presacral space is inside the pelvis, behind the rectum and in front of the coccyx and sacrum. Normally it is empty, or it contains a pocket of fat....
.
Apart from spina bifida, causes of meningocele include teratoma
A teratoma is a kind of tumor . Definitive diagnosis of a teratoma is based on its histology: a teratoma is a tumor with biological tissue or organ components resembling normal derivatives of all three germ layers....
and other tumor
A tumor or tumour is the name for a swelling or lesion formed by an abnormal growth of cells . Tumor is not synonymous with cancer. A tumor can be Benign neoplasm, Carcinoma in situ or malignant, whereas cancer is by definition malignant....
s of the sacrococcyx
Sacrococcygeal teratoma is a teratoma located at the base of the coccyx . It is thought to be a derivative of the primitive streak....
and of the presacral space
In human anatomy, the presacral space is inside the pelvis, behind the rectum and in front of the coccyx and sacrum. Normally it is empty, or it contains a pocket of fat....
, and Currarino syndrome
The Currarino syndrome is an inherited congenital disorder where the sacrum is not formed properly, there is a mass in the presacral space in front of the sacrum, and there are malformations of the anus or rectum....
. Usually a meningocele has no negative long-term effects, although there are reports of tethered cord
Tethered Spinal Cord Syndrome or Occult Spinal Dysraphism Sequence is a rare Neurology caused by tissue attachments that limit the movement of the spinal cord within the Vertebral column....
.
Spina bifida cystica is also known as meningomyelocele. In this, the most serious and common 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
A cyst is a closed sac having a distinct biological membrane and cell division on the nearby Biological tissue. It may contain air, fluids, or semi-solid material....
may resemble an unrelated defect, sacrococcygeal teratoma
Sacrococcygeal teratoma is a teratoma located at the base of the coccyx . It is thought to be a derivative of the primitive streak....
. 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 exposure of these nerves and tissues make the baby more prone to life-threatening infections. 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
Paralysis is the complete loss of muscle function for one or more muscle groups. Paralysis can cause loss of feeling or loss of mobility in the affected area....
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 incontinence from neurogenic bladder
Neurogenic bladder refers to dysfunction of the urinary bladder due to disease of the central nervous system or peripheral nerves involved in the control of micturition....
.
Many individuals with spina bifida will have an associated abnormality of the cerebellum
The cerebellum is a region of the brain that plays an important role in the integration of perception, coordination and motoneuron control. In order to coordinate motor control, there are many neural pathways linking the cerebellum with the cerebrum motor cortex and the spinocerebellar tract ....
, 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 percent of the people with myelomeningocele, hydrocephalus
Hydrocephalus is a term derived from the Greek words "hydro" meaning water, and "cephalus" meaning head, and this condition is sometimes known as "water on the brain"....
will also occur because the displaced cerebellum interferes with the normal flow of cerebrospinal fluid
Cerebrospinal fluid , Liquor cerebrospinalis, is a clear bodily fluid that occupies the subarachnoid space and the ventricular system around and inside the brain....
.
The myelomeningocele (or perhaps the scarring due to surgery) tethers the spinal cord
Tethered Spinal Cord Syndrome or Occult Spinal Dysraphism Sequence is a rare Neurology caused by tissue attachments that limit the movement of the spinal cord within the Vertebral column....
to the enveloping vertebra
In human anatomy, the vertebral column is a column of 24 vertebrae, the sacrum, intervertebral discs, and the coccyx situated in the dorsum aspect of the torso, separated by spinal discs....
. In some individuals this causes significant traction on the spinal cord and can lead to a worsening of the paralysis, scoliosis
Scoliosis is a medical condition in which a person's Vertebral column is curved from side to side, shaped like a "s", and may also be rotated....
, back pain, or worsening bowel and/or bladder function.
Spina bifida is caused by the failure of the neural tube
In the developing vertebrate, the neural tube is the embryo's precursor to the central nervous system, which comprises the brain and spinal cord....
to close during the first month of embryo
An embryo is a multicellular organism ploidy eukaryote in its earliest stage of development, from the time of first cell division until birth, Egg , or germination....
nic development (often before the mother knows she is pregnant).
Normally the closure of the neural tube occurs around 28 days 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
Obesity is a condition in which excess body fat has accumulated to an extent that health may be negatively affected. It is commonly defined as a body mass index of 30 kg/m2 or higher....
, and an increased body temperature from fever
Fever is a frequent medical sign that describes an increase in internal body temperature to levels above normal. Fever is most accurately characterized as a temporary elevation in the body's thermoregulatory set-point, usually by about 1?2 ?C ....
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
Cancer is a class of diseases in which a group of cell display uncontrolled growth , invasion , and sometimes metastasis . These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, do not invade or metastasize....
, hypertension
Hypertension, also referred to as high blood pressure, HTN or HPN, is a medical condition in which the blood pressure is chronically elevated....
and atherosclerosis
Atherosclerosis is a syndrome affecting artery blood vessels. It is a chronic inflammatory response in the walls of arteries, in large part due to the accumulation of macrophage white blood cells and promoted by low density lipoproteins without adequate removal of fats and cholesterol from the macrophages by functional high density lipoprot...
(coronary artery disease), spina bifida likely results from the interaction of multiple gene
A gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cell and pass genetic trait to offspring....
s and environmental factors.
Research has shown that lack of folic acid
Folic acid and Folate are forms of the water-soluble B vitamins. Vitamin B9 is essential to numerous bodily functions ranging from nucleotide synthesis to the remethylation of homocysteine....
(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 percent, and can also decrease the severity of these defects when they occur. As yet it is unknown how or why folic acid has this effect.
Spina bifida does not follow direct patterns of heredity
Heredity is the passing of traits to offspring . This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism....
like muscular dystrophy
Muscular dystrophy refers to a group of genetics, hereditary muscle diseases that weaken the muscles that move the human body. Muscular dystrophies are characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cell and biological tissue....
or haemophilia
Haemophilia is a group of heredity genetic disorders that impair the body's ability to control blood clotting or coagulation, which is used to enclose cuts on your skin....
. Studies show that a woman who has had one child with a neural tube defects such as spina bifida, have about a three percent risk of having another child with a neural tube defect. This risk can be reduced to about one percent 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 known 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
The meninges is the system of Mesotheliums which envelops the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater....
. In addition, a shunt
In medicine, a shunt is a hole or passage which moves, or allows movement of bodily fluid from one part of the Human anatomy to another. The term may describe either congenital or acquired shunts; and acquired shunts may be either wikt:biologicial or wikt:mechanical....
may be surgically installed to provide a continuous drain for the cerebrospinal fluid produced in the brain, as happens with hydrocephalus
Hydrocephalus is a term derived from the Greek words "hydro" meaning water, and "cephalus" meaning head, and this condition is sometimes known as "water on the brain"....
. Shunts most commonly drain into the abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity....
. However, if spina bifida is detected during pregnancy, then open fetal surgery
"Fetal surgery" covers a broad range of surgical techniques used in treatment of birth defectss where the fetus is operated on while still in the pregnant uterus....
can be performed.
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. Most will also require some sort of bowel management program.
Management of Myelomeningocele Study
The MOMS Trial is a Eunice Kennedy Shriver National Institute of Child Health andHuman Development sponsored study of prenatal and postnatal closure of myelomeningocele; a collaboration of The Children's Hospital of Philadelphia, the University of California at San Francisco, Vanderbilt University Medical Center in Nashville and the George Wa...
(MOMS) is a phase III clinical trial
In health care, clinical trials are conducted to allow safety and efficacy data to be collected for new drugs or devices. These trials can only take place once satisfactory information has been gathered on the quality of the product and its non-clinical safety, and Institutional review board approval is granted in the country where the trial...
to evaluate the safety and efficacy of fetal surgery
"Fetal surgery" covers a broad range of surgical techniques used in treatment of birth defectss where the fetus is operated on while still in the pregnant uterus....
to close a myelomeningocele. This involves surgically opening the pregnant mother's abdomen and uterus
The uterus is a major female hormone-responsive reproductive sex organ of most mammals, including humans. It is within the uterus that the fetus develops during gestation....
to operate on the fetus
A fetus is a developing mammal or other viviparous vertebrate, after the embryonic stage and before childbirth. The plural is fetuses, or sometimes feti....
. 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, but at some risk to both the fetus and the pregnant woman.
Spina bifida is one of the most common birth defects, with an average worldwide incidence
Incidence is a measure of the risk of developing some new condition within a specified period of time. Although sometimes loosely expressed simply as the number of new cases during some time period, it is better expressed as a proportion or a rate with a denominator....
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.
The highest incidence rates worldwide were found in Ireland and Wales, where 3–4 cases of myelomeningocele per 1000 population have been reported during the 1970s, along with more than six cases of anencephaly (both live births and stillbirth
A stillbirth occurs when a fetus which has death in the uterus or during labor or childbirth, while exiting a woman's human body. The term is often used in distinction to live birth or miscarriage....
s) per 1000 population. The reported overall incidence of myelomeningocele in the British Isles was 2–3.5 cases per 1000 births. Since then, the rate has fallen dramatically with 0.15 per 1000 live births reported in 1998.
Parents of children with spina bifida have an increased risk of having a second child with a neural tube defect.
This condition is more likely to appear in females; the cause for this is unknown.
There is no single cause of spina bifida nor any known way to prevent it entirely. However, dietary supplementation with folic acid has been shown to be helpful in preventing spina bifida (see above). Sources of folic acid include whole grain
Whole grains are cereal that contain bran and cereal germ as well as the endosperm, in contrast to refined grains, which retain only the endosperm....
s, fortified breakfast cereal
A breakfast cereal is a Fast moving consumer goods food product intended to be consumed as part of a breakfast. It is usually eaten cold as a ready-to-eat meal and mixed with a liquid, such as milk or water, though occasionally Nut and fruit are also added....
s, dried bean
Bean is a common name for large plant seeds of several genus of the Family Fabaceae used for human food or animal feed.The whole young pods of bean plants, if picked before the pods ripen and dry, can be tender enough to eat whole, whether cooked or raw....
s, leaf vegetable
Leaf vegetables, also called potherbs, greens, or leafy greens, are plant leaf eaten as a vegetable, sometimes accompanied by tender Petiole s and shoots....
s and fruit
The term fruit has different meanings dependent on context, and the term is not synonymous in food preparation and biology. In botany, which is the scientific study of plants, fruits are the ripened Ovary of flowering plants....
s.
Folate fortification of enriched grain products has been mandatory in the United States since 1998. The U.S. Food and Drug Administration, Public Health Agency of Canada
The Public Health Agency of Canada is an Government agency of the Government of Canada that is responsible for public health, emergency preparedness, and response and infectious disease and chronic disease control and prevention....
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. Women who have already had a baby with spina bifida or other type of neural tube defect, or are taking anticonvulsant
Neural tube defects can usually be detected during pregnancy by testing the mother's blood (AFP screening) or a detailed fetal ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing . Although this limit varies from person to person, it is approximately 20 Hertz in healthy, young adults and thus, 20 kHz serves as a useful lower limit in describing ultrasound....
. Spina bifida may be associated with other malformations as in dysmorphic syndromes, often resulting in spontaneous miscarriage
Miscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving, generally defined in humans at prior to 20 weeks of gestation....
. However, in the majority of cases spina bifida is an isolated malformation.
Genetic counseling
Genetic counseling is the process by which patients or relatives, at risk of an inherited disorder, are advised of the consequences and nature of the disorder, the probability of developing or transmitting it, and the options open to them in management and family planning in order to prevent, avoid or ameliorate it....
and further genetic testing
Genetic testing allows the Genetics diagnosis of vulnerabilities to inherit diseases, and can also be used to determine a person's ancestry. Normally, every person carries two copies of every gene, one inherited from their mother, one inherited from their father....
, such as amniocentesis
Amniocentesis , is a medicine procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections , in which a small amount of amniotic fluid, which contains fetal tissues, is extracted from the amnion or amniotic sac surrounding a developing fetus, and the fetal DNA is examined for genetic abnormalities....
, 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
An abortion is the termination of a pregnancy by the removal or expulsion of an embryo or fetus from the uterus, resulting in or caused by its death....
out of fear that a newborn might have a poor future quality of life
Quality of life is the degree of well-being felt by an individual or group of people.Quality of life cannot be measured directly, however the perception of QOL is made up of of two components: the physical and the psychological....
. With modern medical care, the quality of life of patients has greatly improved.
People of note born with spina bifida: