Myelomeningocele (MM) is a developmental birth defect of the neural tube (NT), resulting in an open spinal cord lesion. The following are types of NT defects:
- Anencephaly occurs when the cephalic end of the NT fails to close, resulting in absence of a large portion of the brain, skull, and scalp.
- Spina bifida occulta is a defect of the posterior bony elements of the spine only and is almost always asymptomatic.
- Meningocele is a protrusion of the meninges through the bony defect, without accompanying nervous tissue.
- MM is a spinal deformity involving the spinal cord, nerve roots, meninges, vertebrae and skin.
The focus of this article will be MM. Other NT defects, or spinal dysraphisms, are discussed in a separate article.
MM is a result of failure of the normal development of the NT, which typically starts on day 16 after conception and is complete by day 28.1
Epidemiology including risk factors and primary prevention
Estimates of the birth prevalence of MM in the United States range from 2 to 6 per 10,000.2-4 Most cases of MM occur sporadically and are felt to have a multifactorial etiology. Maternal risk factors include folic acid deficiency, obesity, and diabetes.5,6 The role of folate in NT closure led to mandatory folate fortification of all cereal and bread products in the U.S. in 1996. Exposure to hyperthermia and certain medications, such as valproic acid and carbamazepine, also increase the risk of MM.1 The risk of recurrence in a family with MM is felt to be 2-8%, and it is estimated that 60-70% of NT defects have a genetic component.1,2 Whole exome sequencing suggests a role for de novo mutations, and genes that regulate folate metabolism have also been implicated.2,7,8
The most widely believed mechanism for MM is a failure of NT closure (i.e., neurulation). Normally, the mesoderm adjacent to the notochord forms muscle and bone around the NT to protect it. Prolonged exposure of the neural tissue to amniotic fluid leads to neurodegeneration in utero.1 One theory also suggests that an open caudal NT creates a cranio-cervical pressure gradient that contributes to the development of the Chiari malformation.9
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time):
Although MM is a non-progressive lesion, secondary or associated conditions may clinically progress over time.
- Hydrocephalus commonly presents in the neonate. Brain stem dysfunction related to hydrocephalus or Chiari malformation can also present in infancy. Infants should be closely monitored by cranial imaging, serial head circumferences, developmental progress and for symptoms of increased intracranial pressure Signs and symptoms of increase intracranial pressure in infancy include: bulging fontanelle, vomiting, poor feeding tolerance, irritability, lethargy, upward gaze palsy, stridor, apnea and bradycardia.10
- Neurogenic bladder is common and often presents at birth. Infants can have a variety of changes on their urodynamics including decreased bladder capacity, decreased compliance, detrusor overactivity, detrusor sphincter dyssynergia, bladder outlet obstruction and complete denervation.11
- Developmental delays are common. Careful screening and referral to the infant’s local early intervention program by 6 months of age is recommended.12,13
- Ongoing surveillance for signs of worsening hydrocephalus, shunt malfunction, brain stem dysfunction, tethered cord and syrinx should be routine.12
- Vision and cognitive impairments may present at this time, and screening is important prior to school entry.12,13
Late childhood and adolescence
- Periods of rapid growth can be associated with progression of contractures in the lower extremities and increased risk for a tethered cord.13
- It is not uncommon for patients with MM to have increasing difficulty with ambulation during this period in life, related to increasing weight and musculoskeletal deformities. Emphasis should be placed on maintaining physical activity, including opportunities for participation in social activities with peers.13,14
- Risk for skin breakdown increases during adolescence and in patients with higher level lesions and poor sensation.15
- Close monitoring of nutrition and weight is important, due to the high risk for obesity in these individuals.13
- Sexuality should be discussed in a manner appropriate to the patient’s developmental abilities.13
- Discussions about future vocational goals and transition to adult care should occur during adolescence.13
- Obesity, metabolic syndrome, venous stasis and lymphedema are not uncommon.
- Bowel incontinence can be an important barrier to employment and is often associated with poorer quality of life.16,17
- Shoulder and wrist pain, including rotator cuff injuries are possible in those who are wheelchair users. The risk can be lessened with joint protection programs, appropriate wheelchair configuration and teaching of proper propulsion patterns.18
- Individuals with MM are felt to be underemployed. Vocational counselors, the use of assistive technology and minimizing transportation barriers are recommended to increase employment.18
Specific secondary or associated conditions and complications
- Arnold Chiari II malformation, brainstem dysfunction
- Hydrocephalus, shunt malfunction
- Tethered cord or syrinx
- Cognitive deficits are variable with greater difficulty with visual perceptual skills, executive functioning and attention and a relative strength in verbal skills
- Neurogenic bowel and bladder
- Musculoskeletal disorders, including scoliosis, hip dislocation, flexion contractures of the hips and knees, foot abnormalities, and rotational deformities18
- Sensory deficits and increased risk for pressure injury
- Osteoporosis, which can be associated with increased risk of fractures
- Obesity, short stature, and precocious puberty
- Sleep disordered breathing
- Sexual and fertility dysfunction
- Latex allergy
- Chromosomal abnormalities, such as trisomy 13 or 18, in up to 10% of cases (i.e., syndromic NT defect)1
Essentials of Assessment
- Signs of brain stem dysfunction, especially in an infant, include feeding difficulty (i.e. difficulty swallowing or choking), noisy breathing, aspiration pneumonia and apnea.
- Signs of shunt malfunction include headaches, cognitive changes, lethargy and nausea/vomiting.
- Signs of a tethered cord or syrinx include changes in bowel or bladder function, new weakness or sensory deficits, pain, and rapidly progressive scoliosis.
- Bowel and bladder function
- Neurologic exam: fundoscopic exam, cranial nerves, mental status, sensation, strength, tone, reflexes, and gait
- Musculoskeletal exam: spine, shoulders, hips, knees, and feet
- Head circumference in infants
- Skin integrity
- Evaluation of growth and nutrition
- Developmental screening including gross motor, fine motor, language, and cognitive abilities
- Independence with self-care skills
- Independence with mobility
- Evaluation of academic performance
- Evaluation of behavior, mood, and social functioning
- Prenatal maternal serum α-fetoprotein between 16-18 weeks gestation suggests that an open NT disorder may be present, which is typically confirmed with ultrasound. Chromosome microarray via amniocentesis may be considered to improve prenatal counseling.13
- Routine measurement of serum creatinine to evaluate kidney function.13
- Urinalysis and urine culture when symptoms of a urinary tract infection are present.13
- Prenatal ultrasound can detect the characteristic “lemon and banana” signs related to the shape of the head and the herniation of the cerebellar vermis.
- Magnetic resonance imaging (MRI) of the spine to evaluate for brainstem compression, syrinx, or tethered cord.
- Brain computed tomography or MRI to evaluate hydrocephalus.
- Plain films to evaluate musculoskeletal disorders, including scoliosis and hip dysplasia.
- Renal ultrasonography to rule out hydronephrosis or other renal anomalies (every 6 months for those under age 2, yearly for those above age 2).13.
- The indications and ideal frequency of voiding cystourethrography, urodynamics and dimercaptosuccinic acid renal scans continue to be debated.11,13
- Dual-energy x-ray absorptiometry (DEXA) scan should be considered with history of multiple fractures and concerns for osteoporosis in the setting of pathological fractures.
Supplemental assessment tools
- The International Myelodysplasia Study Group Criteria for Assigning Motor Levels provides a standard means of assigning motor levels19
- Neuropsychological testing
- Modified Ashworth Scale or Tardieu Scale when spasticity is present
- Vision and hearing screens
- Polysomnography to evaluate for sleep disordered breathing
Early prediction of outcomes
Muscle strength is strongly associated with ambulatory outcome20
- Grade 0-3/5 iliopsoas strength is associated with partial or complete reliance on wheelchair mobility
- Grade 4-5/5 iliopsoas strength is associated with community ambulation in the majority of patients
- Grade 4-5/5 gluteal and anterior tibialis function is associated with community ambulation, without aids or braces
Social role and social support system
Families who have a child with MM are at risk for significant psychological and financial stress, and sociodemographic factors, such as lack of health insurance, are associated with worse functional outcomes.21 Appropriate child care can be difficult to find, given the complex medical needs of some children with MM. Families are also faced with frequent medical appointments, unexpected illnesses, and the potential need to make costly home modifications.
Until the mid-1980’s, many medical centers used published prognostic criteria to select which infants born with MM to treat. In 1984, the Baby Doe Amendment was passed, which mandates provision of life-sustaining medical treatment to most seriously ill infants. This law was in part a response to a case of a baby girl with MM and hydrocephalus whose parents declined surgical intervention.22 Similar issues still present themselves when families are considering early termination of pregnancy based on prenatal screening and the option of prenatal repair of MM.
Rehabilitation Management and Treatments
Available or current treatment guidelines
Widely established, research-based guidelines for MM are limited. The Spina Bifida Association published the fourth edition of Guidelines for Spina Bifida Health Care Services throughout the Lifespan in 2018.13 The Congress of Neurological Surgeons more recently published five evidence-based recommendations for the surgical management of pediatric myelomeningocele. 23
At different neurologic levels
The rehabilitation plan will vary based on the level of the lesion, the developmental age of the child, family resources and individual comorbidities such as cognitive impairment. Evaluation of function and promotion of independence should be a primary focus for all patients.
- Kyphoscoliosis is extremely common. Early management includes supportive seating and consideration of a thoracolumbosacral orthosis (TLSO). Referral to orthopedic surgery should be considered.
- Functional ambulation is rare, and rehab providers should advocate early for wheelchair mobility.
- Dynamic or static standers should be encouraged by the age of 12-18 months. It is recommended that children spend at least one hour per day weightbearing.23
- Consideration can be given to the use of Reciprocating Gait Orthoses (RGOs) or Hip-Knee-Ankle-Foot Orthoses (HKAFOs) in early school age children. It is very unusual for children to continue to use these gait aides into adolescence due to the energy expenditure required for use.
- Hip and knee flexion contractures are common.
- Hip dislocations are common, but typically not a contraindication to walking.
- Ground reaction AFOs are typically needed to avoid the crouched gait caused plantarflexion weakness. KAFOs are also sometimes useful, especially to limit excessive valgus or varus knee motion.
- Adaptive gait aids, such as a reverse walker for young children and loftstrand crutches in slightly older children, can be very helpful.
- Wheelchair use should be considered early to facilitate independent community mobility.
- Hip and knee flexion contractures remain common, but hip dislocation is less likely.
- If the tibialis anterior is unopposed, a calcaneus foot is likely. Excessive pronation is also common, especially in weight bearing.
- Ground reactive AFOs are typically needed to avoid the crouched gait caused by plantarflexion weakness.
- If significant rotational deformities are present, consider the use of twister cables or derotation straps until surgical correction.
- Many children will benefit from adaptive gait aids, especially when they are learning to walk and as they get taller and heavier.
- Wheelchair use remains common in the community, especially in older children.
- Children can often learn to walk well without any adaptive aids or braces.
- Distal weakness can lead to significant foot deformities including pes cavus, which may benefit from orthotics.
Coordination of care
The multidisciplinary clinic remains the model for health care delivery to children with MM.23
Patient & family education
Caregivers of children with MM will require extensive education related to the complex nature of their medical needs. Family support, including financial counseling, options for respite care, and referrals to support and advocacy groups should be offered. Children with MM often have limited social interactions with their peers. Referrals to community resources for recreational activities and adaptive supports should be offered. As the child grows older, it is important to shift the focus to educating the child in a manner that is appropriate to their developmental or cognitive abilities. Adolescent patients should be encouraged to take increasing responsibility for their own care and advocacy.23
Measurement of Patient Outcomes
In 2008, the Centers for Disease Control and Prevention, in partnership with the Spina Bifida Association, launched the National Spina Bifida Registry. This created a funded computerized reporting and database system that is being used to evaluate important clinical questions using anonymous patient data.24
Cutting Edge/ Emerging and Unique Concepts and Practice
Cutting edge concepts and practice
A randomized trial (Management of Myelomeningocele Study, or MOMS) of prenatal versus postnatal repair of MM revealed a reduced need for shunting and improved motor outcomes at 30 months in the prenatal repair cohort, but prenatal repair was associated with maternal and fetal risks.25,26 A follow-up study at school age showed improved motor function and quality of life in the children who underwent prenatal repair.4 This landmark study has resulted in a number of centers offering prenatal repair, and the Congress of Neurological Surgeons has issued a recommendation to pursue prenatal repair when MOMS-specified fetal and maternal criteria are met23
Utilization of stem cell therapy in fetuses with MM is currently being studied using animal models.27
Up and coming imaging techniques, including 3D ultrasounds and virtual reconstruction are being studied to aid with prenatal repair as well as fetal counseling.28,29
Gaps in the Evidence-Based Knowledge
Many gaps in evidence-based knowledge have been identified including: the optimal treatment of hydrocephalus, indication for tethered cord release, management of hip dislocation, management of osteoporosis, prevention and treatment of pressure sores, instructional and developmental interventions to facilitate learning, orthotic use, and promotion of self-care.22
- Copp AJ, Adzick NS, Chitty LS, Fletcher JM, Holmbeck GN, Shaw GM. Spina bifida. Nature reviews Disease primers 2015;1(1):1-18.
- Au KS, Ashley‐Koch A, Northrup H. Epidemiologic and genetic aspects of spina bifida and other neural tube defects. Developmental disabilities research reviews 2010;16(1):6-15.
- Mai CT, Isenburg JL, Canfield MA, et al. National population‐based estimates for major birth defects, 2010–2014. Birth defects research 2019;111(18):1420-1435.
- Houtrow AJ, Thom EA, Fletcher JM, et al. Prenatal repair of myelomeningocele and school-age functional outcomes. Pediatrics 2020;145(2).
- Correa A, Gilboa SM, Besser LM, et al. Diabetes mellitus and birth defects. American journal of obstetrics and gynecology 2008;199(3):237. e1-237. e9.
- Waller DK, Shaw GM, Rasmussen SA, et al. Prepregnancy obesity as a risk factor for structural birth defects. Archives of pediatrics & adolescent medicine 2007;161(8):745-750.
- Avagliano L, Doi P, Tosi D, et al. Cell death and cell proliferation in human spina bifida. Birth Defects Research Part A: Clinical and Molecular Teratology 2016;106(2):104-113.
- Lupo PJ, Agopian A, Castillo H, et al. Genetic epidemiology of neural tube defects. Journal of pediatric rehabilitation medicine 2017;10(3-4):189-194.
- Williams H. A unifying hypothesis for hydrocephalus, Chiari malformation, syringomyelia, anencephaly and spina bifida. Cerebrospinal Fluid Research 2008;5(1):1-11.
- Rocque BG, Hopson BD, Blount JP. Caring for the Child with Spina Bifida. Pediatric Clinics of North America 2021;68(4):915-927.
- Le H-K, Cardona-Grau D, Chiang G. Evaluation and long-term management of neurogenic bladder in spinal dysraphism. NeoReviews 2019;20(12):e711-e724.
- Queally JT, Barnes MA, Castillo HA, Castillo J, Fletcher JM. Neuropsychological care guidelines for people with spina bifida. Journal of Pediatric Rehabilitation Medicine 2020(Preprint):1-11.
- Association SB. Guidelines for the care of people with spina bifida. Published online 2018.
- Simeonsson RJ, McMillen JS, Huntington GS. Secondary conditions in children with disabilities: spina bifida as a case example. Mental retardation and developmental disabilities research reviews 2002;8(3):198-205.
- Bradko V, Hill J, Castillo H, Castillo J. Team Approach: Guideline-Based Management of Skin Injury in Individuals with Myelomeningocele. JBJS reviews 2019;7(3):e1.
- Wiener JS, Suson KD, Castillo J, et al. Bowel management and continence in adults with spina bifida: Results from the National Spina Bifida Patient Registry 2009–15. Journal of pediatric rehabilitation medicine 2017;10(3-4):335-343.
- Szymanski KM, Cain MP, Whittam B, Kaefer M, Rink RC, Misseri R. All incontinence is not created equal: impact of urinary and fecal incontinence on quality of life in adults with spina bifida. The Journal of urology 2017;197(3 Part 2):885-891.
- Dicianno BE, Kurowski BG, Yang JMJ, et al. Rehabilitation and medical management of the adult with spina bifida. American journal of physical medicine & rehabilitation 2008;87(12):1027-1050.
- Shurtleff D. International Myelodysplasia Study Group Database Coordination. Seattle, WA: Department of Pediatrics, University of Washington 1993.
- McDonald CM, Jaffe KM, Mosca VS, Shurtleff DB. Ambulatory outcome of children with myelomeningocele: effect of lower‐extremity muscle strength. Developmental Medicine & Child Neurology 1991;33(6):482-490.
- Schechter MS, Liu T, Soe M, Swanson M, Ward E, Thibadeau J. Sociodemographic attributes and spina bifida outcomes. Pediatrics 2015;135(4):e957-e964.
- Sandler AD. Children with spina bifida: key clinical issues. Pediatric Clinics 2010;57(4):879-892.
- Mazzola CA, Assassi N, Baird LC, et al. Congress of neurological surgeons systematic review and evidence-based guidelines for pediatric myelomeningocele: executive summary. Neurosurgery 2019;85(3):299-301.
- CDC. About the National Spina Bifida Patient Registry. https://www.cdc.gov/ncbddd/spinabifida/nsbprregistry.html
- Adzick NS, Thom EA, Spong CY, et al. A randomized trial of prenatal versus postnatal repair of myelomeningocele. New England Journal of Medicine 2011;364(11):993-1004.
- Farmer DL, Thom EA, Brock III JW, et al. The Management of Myelomeningocele Study: full cohort 30-month pediatric outcomes. American journal of obstetrics and gynecology 2018;218(2):256. e1-256. e13.
- Kunpalin Y, Subramaniam S, Perin S, et al. Preclinical stem cell therapy in fetuses with myelomeningocele: A systematic review and meta‐analysis. Prenatal Diagnosis 2021;41(3):283-300.
- Werner H, Castro PT, da Silva MB, de Sá RAM, Júnior EA. Three-dimensional virtual reconstruction of a patch after fetal endoscopic surgery for myelomeningocele. Child’s Nervous System 2021:1-2.
- Werner H, Ribeiro G, Lopes J, et al. Virtual navigation for the improvement of parents counseling and the planning of fetal endoscopic myelomeningocele repair. Child’s Nervous System 2021;37(3):969-972.
Original Version of the Topic
Mary McMahon, MD. Myelomeningocele (Spina Bifida). 5/12/2013.
Previous Revision(s) of the Topic
Mary McMahon, MD, Ashlee Bolger, MD. Myelomeningocele (Spina Bifida). 3/29/2017
Caitlin Chicoine, MD
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Ashlee Bolger, MD, MEd
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Mary McMahon, MD
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