Meningomyelocele is a neural tube defect, presenting as a protrusion of the spinal cord and meninges, due to incomplete closure of the neural tube. It represents one of the most common birth defects. Meningomyelocele is often associated with type II Arnold-Chiari malformation.
Meningomyelocele is a congenital anomaly which presents in utero or at birth. At birth, it presents as a midline defect in the posterior aspect of the skin and vertebrae, associated with an outward protrusion of the cord, meninges and other neural components.
Meningomyelocele is commonly associated with Chiari type II malformation, which may result in symptoms of compression of the brainstem and cervical spinal cord including apnea, dysphagia, nystagmus, laryngeal and pharyngeal paralysis, stridor, and upper limb paresthesias. This malformation may also cause cerebellar compression and dysfunction resulting in ataxia.
Children with meningomyelocele often present with joint contractures, spinal and lower limb deformities. These may be attributed to intrauterine malpositioning, muscle imbalance, poor posture, progressive neurologic deficits, and reduced joint function. Children with meningomyelocele are also commonly of short stature, attributable to skeletal abnormalities including spinal cord and vertebral abnormalities, lower extremity contracture, and endocrine involvement. The endocrine involvement is primarily due to growth hormone deficiency, which may result from a secondary dysfunction of the hypothalamic-pituitary axis.
Laboratory workup, amniocentesis, and prenatal ultrasonography are the main approach considerations to the diagnosis of neural tube defects. Prenatal ultrasonography, however, confirms the diagnosis.
Since neural tube defects predispose to abnormalities in micturition, urinalysis, urine cultures, and blood urea nitrogen are recommended to evaluate kidney function in patients with these disorders. Furthermore, a voiding cystogram and urodynamic evaluation should be employed, in order to assess anatomic and functional abnormalities of the urinary tract.
Serum alpha-fetoprotein (AFP) is elevated in 75% of the cases of open spinal cord defects. Samples should be taken in the second trimester.
The standard initial imaging modality to identify the level of the meningomyelocele lesion, after the baby has been delivered, is a plain radiograph. Plain radiographs are also helpful in the evaluation of comorbidities including dysplasias, scoliosis, and hip dislocation. Radiographs are also indicated in the presence of bone pain, because of the frequent occurrence of pathologic fractures in these patients.
3D and 4D ultrasonography are best for identifying the Chiari II malformation, while hydrocephalus can be detected with serial cranial ultrasound scans and CT scans. Magnetic resonance imaging (MRI) provides excellent imaging for comparisons and assessment of progression or regression of the disorder.
The standard treatment of neural tube defects includes sac closure, prophylactic antibiotics to forestall meningitis, and insertion of a ventriculoperitoneal shunt. Palliative care is opted for in cases associated with a high risk of mortality including active severe CNS bleeding or infection, irreparable sac, and other severe comorbidities.
Typically, the management of neural tube defects involves concerted efforts of various specialists and it typically centers on neonatal neurosurgery, assessment and management of urinary and bowel function, motor function, and cognitive abilities. Regular catheterizations may be employed to assist urinary function. Routine orthopedic evaluation would include assessment of muscle strength, joint range of motion, and possible pathologies. Continuous occupational and physical therapy are also critical in the management of meningomyelocele. A psychologist or personal trainer is necessary to help the patient cope emotionally and psychologically with the symptoms. Speech therapy may be necessary for patients with dysphagia and speech problems. Orthotics are necessary to assist in the ambulation of the patient.
The surgical closure of meningomyelocele is performed within the first 24-48 hours of neonatal life if there is no CSF leakage; however, in the presence of CSF leakage, closure is done immediately after delivery. For the former case, closure can be delayed for a few more days if the patient's clinical status permits it. This is necessary to help parents and family members properly handle the situation and learn about the condition .
In up to 35% of the patients with meningomyelocele, Chiari II malformation could present with complications which require surgery. Such complications include stridor, apnea, aspiration, and vocal cord paralysis. The initial intervention involves control of the hydrocephalus, however, if the status keeps deteriorating, surgical repair of the malformation is opted for. The surgical procedures for the repair of chiari II malformation include occipital craniotomy and upper cervical laminectomy for brainstem and upper cervical decompression.
Furthermore, orthopedic surgical procedures may be necessary for debilitating musculoskeletal abnormalities presenting in this condition. Such procedures aim at improving the quality of life of the patient.
The main problems associated with meningomyelocele are the potential debilitating complications of the disorder including hydrocephalus, difficulty with ambulation and motor functions, orthopedic problems, and a reduction in the quality of life.
Meningomyelocele that is left untreated results in meningitis, hydrocephalus, and sepsis which significantly increases the risk of mortality. In the past, treatment for myelomeningocele was difficult and almost impossible, however, during the past 30 years in the United States, treatment has evolved and advanced; it is presently available in various pediatric centers   .
Management of meningomyelocele requires a multidisciplinary approach involving a pediatrician, neurologist, pediatric neurosurgeon, orthopedic surgeon, physiotherapist, pediatric urological surgeon, nutritionist, and psychologist.
Genetic and several acquired abnormalities play a critical role in the etiogenesis of meningomyelocele and other neural tube defects. Chromosomal abnormalities including trisomy 13, 18, and 21 have been implicated in the pathogenesis of these neural tube defects. Genetic causes are more common than environmental ones.
Common acquired or environmental causes of meningomyelocele and other neural tube defects include maternal diabetes, maternal age, socioeconomic class, season of conception, maternal alcohol toxicity, maternal use of anticonvulsants, intrauterine hyperthermia, geographic location, maternal folate and zinc deficiencies.
The season of conception affects the pathogenesis of these defects: conceptions which occur in springtime are more likely to be associated with anencephaly and spina bifida in the fetus. Nevertheless, this phenomenon has not been confirmed in studies conducted in the United States.
Generally, neural tube defects are amongst the most common birth defects. The disorder exhibits significant geographical variation, being most prevalent in northern China, and least prevalent in Japan. Among the Caucasian population, the disorder is most prevalent in great Britain. Northern China has an incidence rate of 3.7 cases in 1000 live births. Neural tube defects are also very prevalent in India and among eastern Mediterranean people.
In the United States, between 1970 and 1989, meningomyelocele and other neural tube defects occurred at a rate of 6-13 cases per 10,000 live births. Cases of anencephaly were, however, more than those of spina bifida. Over the length of this period, the proportion of Caucasians with neural tube defects in relation to other ethnicities has been substantially reduced.
The incidence of neural tube defects is higher in the eastern part of the United States than the western areas.
Neural tube defects occur as a result of an interruption in the neurulation process. The process of neural formation occurs in two stages; a primary stage, in which the neural plates elevate and close in towards each other, forming a neural tube, and a secondary stage, that involves further neural development, including the formation of the terminal fibres of the spinal cord. This stage is described as the stage of canalization.
Defects or interruptions in the primary stage of neurulation cause the open neural tube defects, while defects in the secondary neurulation are responsible for closed neural tube defects. Open neural tube defects are those in which all parts of the central nervous system (brain and spinal cord) are affected, while the closed neural tube defects are localized to the spine. However, cases of closed neural tube defects may occur from disrupted primary neurulation.
Approximately 70% of meningomyelocele cases can be prevented by increasing serum folate levels just before conception and up to the seventh week of gestation, at which time, the neural tube has closed completely. This can lead to a 40% reduction, rather than the expected estimate of 70%, in the incidence of meningomyelocele .
Meningomyelocele is a neural tube defect resulting from the failure of closure of the neural tube, which typically begins in the third week of gestation. Meningomyelocele can also be called myelomeningocele and is one of the most common types of neural tube defects with an incidence rate of up to 2 cases per 10,000 live births.
Meningomyelocele presents with a number of comorbidities and complications including motor dysfunctions, vocal cord paralysis, urinary and bowel dysfunctions, skeletal malformations, hydrocephalus, and meningitis.
Treatment of meningomyelocele involves a multidisciplinary approach with concerted inputs from a neurosurgeon, pediatrician, neonatologist, orthopedic surgeon, urologist, physiotherapist, and psychologist. The timing for closure of the open sac depends on the presence of CSF leakage and other neurologic problems requiring urgent surgical intervention. In such cases, surgery is done immediately after the delivery of the baby. However, the prognosis of the condition with surgery is often poor, with the patient living with severe complications.
Chiari malformation II, which is often associated with meningomyelocele, presents with brain stem and upper cervical cord dysfunctions and often requires ventriculoperitoneal shunting because of the ensuing hydrocephalus    .
Meningomyelocele is an abnormality in children detected at birth and characterised by a protrusion of the spinal cord and the tissues which cover the cord (meninges), due to the incomplete closure of the structures which would form the backbone and the skin over it. This condition can also be called myelomeningocele.
This condition may be caused by abnormalities in the chromosomes. Chromosomes contain genes which code for every structure of the body and the functions of all these structures. Non-genetic factors also cause this condition, and the main factor is a reduced folic acid level in the blood. This may be caused by reduced or lack of intake of folic acid during pregnancy or medications, especially drugs for treating convulsions; these drugs could reduce folic acid levels in the blood. Other causes include diabetes and chronic alcohol use in a pregnant woman.
The disorder occurs in one out of about 800 live births. Furthermore, it is very common in Asia. Babies born with this condition have an opening at their lower back containing a protrusion of the spinal cord. The disorder could present with varying levels of severity. It typically presents with compression of some parts of the spinal cord and brain, causing uncontrollable bowel movements and urination, inability to move the legs, inability to swallow or speak, and problems keeping the eyeballs in place. There are also abnormalities associated with the bones and joints, some of which may require orthopedic surgical procedures to help the patient manage with moving the bones and joints. Hydrocephalus, a term which describes excessive build up of fluid in the brain that causes it to swell, is a very common complication of meningomyelocele.
This condition can be diagnosed during early pregnancy by blood tests that reveal the level of a chemical called alpha-fetoprotein (AFP), which usually rises in this condition. If the blood test is positive, further tests such as an obstetric ultrasound would be needed to confirm the diagnosis.
After diagnosis during early pregnancy, some women may choose to terminate the pregnancy. In those who don't, the babies would require surgery after birth and multiple specialist management. Sometimes, immediate surgery may be necessary to close the opening as soon as the baby is born to prevent infections. Treatment may be lifelong and such patients need to be routinely evaluated by specialists of multiple specialties, in order to assess any improvement or deterioration.
These neural tube defects can all be caused by low blood levels of folic acid, therefore, pregnant women are advised to routinely take folic acid supplements and completely avoid medications which reduce the blood levels of folic acid. Women are also advised to take folic acid supplements even before they get pregnant.