General Description:

-The vertebral column and spinal column do not close folly before birth, allowing portions of the spinal cord and the meninges to herniate outside the back in a membranous sac.

-The portion of the spinal cord and the covering membranes herniated outside the body are usually abnormal or damaged, though the meninges and spinal cord that remain inside the body generally are normal.

-Myelomeningoceles usually occur lower in the back, in the lower thoracic or lumbar or even as low as the high sacral areas of the spine.

Causes and Prevalence:

-Hereditary and genetic links along with devlopmental factors, such as diet and environmental toxins, are thought of as the most dominant causes, though the exact cause is unknown.

-Spina bifida is known to occur as a part of some hereditary syndromes and also as a result of chromosomal disorders; exposure to agents that cause developmental defects, such as valproic acid, aminopterin, and thalidomide can cause spina bifida. Myelomeningoceles do appear to run in families.

-A viral cause has been suggested due to myelomeningocele's increased occurence in the winter months, but no definite evidence has been found to support this..

-Internal environmental factors, such as folic acid level, as well as external environmental factors, such as radiation, are felt to play a role in the occurence of myelomeningoceles.

-It is known that the factors causing spina bifida act on the fetus between the 16th and 16th day of development, following fertilization.

-Spina bifida is the most common CNS disorder.

-In approximately 85% of cases diagnosed as spina bifida, the spina bifida is either myelomeningocele or a meningocele, as opposed to occulta. Around 75% of all diagnosed cases of spina bifida are myelomeningoceles.

-Myelomeningocele-type spina bifida is believed to occur as often as 1:800 births.

Symptoms, Tests, Treatment, and Prevention:

-Along with the acutal spina bifida lesion, several other anomalies can accompany: various other skull and brain malformations, hip dislocations, syringomelia and often hydrocephalus (impaired ventricular flow and drainage leading to increased cranial pressure).

-Arnold-Chiari Type II malformation is frequently present with all types of spina bifida. In this malformation, the brain stem is slightly smaller than normal and can become lodged in the lower passage out of the skull. This blocks the flow of CSF and increases the pressure inside the head.

-It is also known that a large portion of those with spina bifida also possess a latex allergy; although, it not known whether this is inherent or developed from large amount of exposure to latex in surgeries and examinations.

-Symptoms of myelomeningoceles are relative to the level they are located at on the spine: depending on the level symptoms can include partial or complete paralysis, partial or complete lack of sensation, and loss of bladder or bowel control.

-Myelomeningoceles can sometimes be detected before birth from a combination of ultrasound and amniocentesis, though myelomeningoceles are readily apparent at birth.

-Several treatment options are available for pregnancies with spina bifida, depending on the severity: for severe malformation the pregnancy can be terminated, corrective surgery can be employed immediately following birth, to a limited extent intrauterine surgery is employed, and expectant management of the spina bifida without correction is also a viable option.

-Through these methods, myelomeningoeles are treatable without a significant decrease in life span, though any nervous damage is usually permanent.

-Standard prevention for spina bifida is the same dietary and lifestyle suggestions as other NTDs, particularly a presecribed amount of folic acid taken daily.