Clubfoot deformity secondary to the myelomeningocele
Almost all cases of spina bifida are associated with the Arnold-Chiari type II malformation, characterized by herniation of the cerebellar vermis through the foramen Magnum. In these cases, the fourth ventricle is dislocated towards the neural canal, the posterior fossa is shallow and the tentorium is also displaced downwards. This finding is almost invariably associated with obstructive hydrocephalus.
Congenital hip dislocation and clubfeet are frequently associated with spina bifida and are secondary to variable inervation deficits of the hip and thigh muscles.
The most common location for spina bifida is the lumbosacral region. In 85% of the cases the defect is open and in 15% of the cases spina bifida is classified as occulta. In spinal bifida occulta the defect is covered by skin and is not usually diagnosed prenatally. In open spina bifida, the most common presentation is a cystic tumor in the lumbosacral region, containing cerebrospinal fluid (CSF) and some times neural content covered by meninges. When the herniation sac contains only CSF, the anomaly is called meningocele; if neural tissue is present, the anomaly is called meningomyelocele.
Spina bifida is a serious congenital anomaly. The neonatal morbidity and mortality rate is estimated as 25%. The majority of the children without treatment die in the first few months of life. Survival rate of those treated in the immediate neonatal period approaches 40% at seven years. Twenty five percent of these children are almost totally paralyzed, 25% require intense rehabilitation and 25% do not have a significant lower extremity dysfunction. Seventeen percent will have normal continence in long term follow up. The presence of severe hydrocephalus is considered a poor prognostic sign.
Genetic counseling and recurrence risk
Similar to anencephaly, the majority of the cases of spina bifida are compatible with a multifactorial model. Genetic factors seem important because of familial incidence, whereas geographic variation suggests an environmental cause. Concordance and discordance have occurred in monozygous twins. An increased incidence of neural tube defects occurs in women who have diabetes during pregnancy. Also, women who take valproic acid for a seizure disorder are at increased risk for anencephaly if their medication has been consumed prior to conception or during the first trimester of pregnancy.
Causative factors act on the developing embryo between the 16th and 26th day after conception.
The recurrence risk is 1:20 (5%) and if there is a second affected child the risk rises to 13%.
All women of reproductive age should consume at least 0.4 mg (400 mcg) of folic acid daily to prevent neural tube defects. For women who have previously had a fetus affected with anencephaly, the Centers for Disease Control and Prevention (CDC), recommends increasing the intake of folic acid to 4 mg (4000 mcg) per day beginning at least one month prior to conception (Committee on Genetics, 1999).
The three options available once a fetus with spina bifida is diagnosed are:
termination of the pregnancy
intrauterine surgery (see links below)
expectant management with closure of the vertebral defect and correction of associated anomalies in the neonatal period
Children´s Hospital of Philadelphia
Jama - Fetal Surgery for Spina Bifida at Philadelphia
Fetal Surgery for Spina Bifida at Vanderbilt University
Jama - Fetal Surgery for Spina Bifida at Vanderbilt
 Romero R, Pilu G, Jeanty P, Ghidini A, Hobbins JC. Prenatal Diagnosis of Congenital Anomalies. Norwalk: Appleton&Lange, 1988.
 Moore KL, Persaud TV: The Developing Human: Clinically Oriented Embryology, 5th edition, Philadelphia: WB Saunders Company, 1993.
 Campbell J, Gilbert WM, Nicolaides KH, Campbell S. Ultrasound screenign for spina bifida: carnial and cerebellar signs in a high risk population. Obstet Gynecol 1987;70:247.
 Bianchi DW, Cromblehome TM, D"Alton ME. Fetology: : Diagnosis & Management of the Fetal Patient. McGrawHill, 2000.
 Folic acid for the prevention of neural tube defects. American Academy of Pediatrics. Committee on Genetics. Pediatrics 1999;104: 325-7.