Today November 21 is World Spina Bifida Day. We interviewed Dr. José Enrique Saura Rojas, renowned physician specialized in Neurosurgery, to give us the keys to this disease caused by a congenital malformation in pregnancy, between the second and third week of gestation.
Good morning Dr. Saura Rojas, to begin the interview we would like you to explain to us, broadly speaking, what spina bifida is.
Myelomeningocele (spina bifida) is the most serious and complex malformation affecting the central nervous system. Despite this, it is compatible with life.
This congenital alteration affects to a greater or lesser extent the closure of the neural tube and, therefore, from the anatomical point of view, it will present a defect in the closure or fusion of the posterior arch of one or more vertebrae. Neural tube closure defects correspond to structural defects of the nervous system, of multifactorial origin.
The neural tube is an embryonic structure that develops to form the brain and spinal cord. Several teratogenic mechanisms have been implicated in the development of spina bifida, mainly genetic, environmental and maternal. As the closure of the neural tube occurs between days 21 and 28 of the embryonic period, it is in this interval that the different types of spina bifida are most likely to occur.
Its incidence ranges from 0.7-0.8/1000 live births, with an important regional difference. Although some familial cases have been described, the risk of having spina bifida ranges between 0.03-0.05%, the existence of an affected sibling raises the risk to 1-2% and if there were two, it reaches 10-15%.
The incidence of CMM is progressively decreasing, at least in Western countries, due to improved social and economic conditions and the wide dissemination of fetal screening and prenatal diagnosis. In most cases, spina bifida is diagnosed before birth. However, some mild cases may go undetected until after birth.
How does this disease occur and what may be the causes?
With regard to its causes, maternal factors associated with the development of spina bifida have always been considered to be fundamental. For example, the socioeconomic level, considered for many years as a fundamental factor, does not seem to be very consistent nowadays, although indirectly the poorer diet could be related, especially with the folic acid deficiency in the diet. Other causes related to the development of neural tube defects are intrauterine infections, ionizing radiation and some drugs.
Are there different types of spina bifida?
Spina bifida is classified as either occult or cystic:
- Spina bifida occulta: represents a very frequent alteration (10% of the population). Defect in the closure of the posterior arch of one or more vertebrae, but with no involvement of the underlying structures. It is usually located in the last lumbar and first sacral segments. Most of the time it is an incidental radiological finding and does not require specific treatment.
- Cystic spina bifida:
- Meningocele: this is the most benign form and consists of a defect of the posterior arch through which the meninges project, without involvement of the nerve structures.
- Myelomeningocele: this is the most frequent and severe form. The meningeal coverings and neural elements (roots and/or spinal cord) project outward over the bony defect of the posterior arches. It is easily diagnosed at birth, when a mass of variable size, of soft consistency, located on the dorsal midline and covered by a layer of skin of greater or lesser viability is appreciated. It is not uncommon that the tumor is not covered by skin, in which case it is possible to visualize neural elements and cerebrospinal fluid outflow. Clinical examination is usually normal in cases of meningocele, while in myelomeningoceles there are varying degrees of impairment of mobility and sensibility of the lower limbs, depending on the extent of the defect and above all on the content and location of the cyst. The vast majority of myelomeningoceles have some form of neurogenic bladder as well as alteration of the anal sphincter.
Short film about people with Spina Bifida made by the Spanish Federation of Spina Bifida and Hydrocephalus Associations (FEBHI).
How is a fetus diagnosed as having spina bifida?
The most common screening methods used to detect spina bifida during pregnancy are second trimester maternal serum alpha fetoprotein and morphological ultrasound (around the 20th week). Alpha fetoprotein is a specific protein produced by the developing fetus. If the test reveals abnormally high levels of AFP, the fetus may be suspected of having a neural tube defect. Not all high alpha-fetoprotein levels mean that the fetus has a neural tube defect. AFP testing usually detects approximately 80% of babies with spina bifida. If a high level of AFP is detected, the doctor may order further tests, such as ultrasound or amniocentesis to help determine the cause.
Taking into account that spina bifida is the second cause of physical disability in childhood, after cerebral palsy, is there any type of prevention so that the baby is not born with this disease?
We know that the administration of a sustained dose of folic acid during the first weeks of pregnancy reduces the incidence of malformations of the nervous system by 72%. Foods that are naturally rich in folic acid are dark green vegetables such as broccoli and spinach, egg yolk and citrus fruits. Many foods have added folic acid.
The recommendation is that all women of childbearing age take a daily supplement of 400 micrograms (mcg) of folic acid or consume breakfast cereals fortified with 100 percent of the recommended daily allowance (400 mcg) of folic acid per serving.
Is there a treatment for spina bifida?
There is no cure for spina bifida. Damaged or missing nerve tissue cannot be replaced or repaired. Treatment depends on the type and severity of the neural tube closure defect. It must also be staged and multidisciplinary.
At birth, babies with cystic spina bifida require surgery within the first 24-48 hours in order to avoid infection of the nervous system, proceeding to the closure and repair of the skin defect that exposes the nervous system. Regarding intrautero repair of spina bifida, with the experience accumulated so far, preliminary results suggest that children treated intrautero will have a lower incidence of hydrocephalus.
Although more scientific studies are needed to better understand the pathophysiology of myelomeningocele, the ideal timing of surgical repair, as well as the long-term results, its use cannot be generalized at present, only under strict scientific control.
Subsequently, the objective of treatment is to treat the neurological complications associated with this type of malformation such as hydrocephalus, Chiari type II, etc. Likewise, the associated orthopedic deformities must be treated, which justifies the multidisciplinary approach and the continuous follow-up that these children must have.
Given the prospect of this disease, what is the prognosis for these patients?
The long-term outcome depends mainly on the management of the associated neurological problems. The prognosis is generally good for a child with healthy lifestyle habits and good family and caregiver support. Regular follow-up by multidisciplinary teams is essential. Most patients usually attend school, have social bladder continence and a high likelihood of participation in work. There is no evidence to suggest decreased fertility in this population. Women with CMM have normal menses, can become pregnant and have healthy babies. Men with CMM have reduced fertility, but a proportion, usually those with lower level lesions, can reproduce successfully.
Despite physical burdens and social difficulties, research suggests that young adults with CMM are just as satisfied with their lives.