What is Spina Bifida
The term "spina bifida" takes its origins from Latin, "spina" meaning "thorn" or "spine", and "bifida" meaning "split". The first recorded case was in 1085 AD in Arabia. The name was given to the condition by Nicolaas Tulgius, a Dutchman, in 1637. In 1881 a foetus was found which showed that spina bifida occurs within the first month of pregnancy.
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bifida (“cleft spine”) is a birth defect affecting the spinal column. Spina
bifida progresses from a cleft, or splitlike opening, in the back part
of the backbones (the spinal vertebrae). In more severe cases, it involves
the spinal cord. Spina bifida is the most common of a group of
birth defects known as neural tube defects, which affect the central nervous
system (brain and spinal cord).
Spina bifida begins in the womb, when the tissues that fold to form the neural tube do not close or do not stay closed completely. This causes an opening in the vertebrae, which surround and protect the spinal cord. This occurs just a few weeks (21 to 28 days) after conception—usually before the woman knows that she is pregnant.
There are 3 types of spina bifida:
Spina Bifida Occulta: “Occulta” means hidden, and the defect is not visible. Spina bifida occulta is rarely linked with complications or symptoms. Spina bifida occulta is usually discovered accidentally when the person has an x-ray or MRI for some other reason. The prevalence of occulta is not known, but it is probably the most common type of spina bifida. Estimates of prevalence from 5% to as high as 40% have been proposed.
Spina Bifida Occulta
Spina Bifida Aperta. In Spina Bifida Aperta there are two types:
membrane that surrounds the spinal cord may enlarge, creating a lump or
“cyst.” This is often invisible through the skin and causes no problems. If
the spinal canal is cleft, or “bifid,” the cyst may expand and come to the
surface. In such cases, since the cyst does not enclose the spinal cord, the
cord is not exposed. The cyst varies in size, but it can almost always be
removed surgically if necessary, leaving no permanent disability. This is an
uncommon type of spina bifida.
Spina Bifida Aperta Meningocele
Myelomeningocele: This is the most complex and severe form of spina bifida. Spina bifida cystica usually involves neurological problems that can be very serious or even fatal. A section of the spinal cord and the nerves that stem from the cord are exposed and visible on the outside of the body. Or, if there is a cyst, it encloses part of the cord and the nerves. This condition, which was documented 4000 years ago, accounts for 94% of cases of true spina bifida.
Spina Bifida Aperta Myelomeningocele
The effects of myelomeningocele, the most
serious form of spina bifida, may include muscle weakness or paralysis below the
area of the spine where the incomplete closure (or cleft) occurs, loss of
sensation below the cleft, and loss of bowel and bladder control. In addition,
fluid may build up and cause an accumulation of fluid in the brain (a condition
known as hydrocephalus). A large percentage (70%-90%) of children born with
myelomeningocele have hydrocephalus. Hydrocephalus is controlled by a surgical
procedure called "shunting," which relieves the fluid buildup in the
brain. If a drain (shunt) is not implanted, the pressure buildup can cause brain
damage, seizures or blindness. Hydrocephalus may occur without spina bifida, but
the two conditions often occur together.
Other cases related to Spina bifida
Anencephaly is due to failure of primary neurulation (neurulation is the process which progenitors of the central nervous system are shaped, separated from and brought beneath the epidermis). In the normal human embryo, the neural plate arises approximately 18 days after fertilization. During the fourth week of development, the neural plate invaginates along the embryonic midline to form the neural groove. The neural tube is formed as closure of the neural groove proceeds from the middle of the groove and progresses toward the ends in both directions, with completion between day 24 for the cranial end and day 26 for the caudal end. Disruptions of the normal closure process give rise to neural tube defects (NTDs). Anencephaly results from failure of neural tube closure at the cranial end of the developing embryo. Absence of the brain and calvaria may be partial or complete.
* Robert G. Best, Professor Departement of Obstetrics and Gynecologie wrote a very good article about anencephaly: http://www.emedicine.com/neuro/topic639.htm
* National Institute of Neurological Disorders and Stroke
Anencephaly Information Page: http://www.ninds.nih.gov/health_and_medical/disorders/anencephaly_doc.htm
Cephalic Disorders Fact Sheed: http://www.ninds.nih.gov/health_and_medical/pubs/cephalic disorders.htm