Meningomyelocele

Sondra M. De Antonio, MD and John F. Bertagnolli, Jr., DO Reviewed 06/2017
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Subject: Meningomyelocele

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BASICS

DESCRIPTION

  • Protrusion of nerve tissue and its covering through a defect in the vertebrae

  • Caused by incomplete neural tube closure during 3 to 4 weeks’ gestation, thus exposing meninges and spinal cord

  • Frequently associated with hydrocephalus, Chiari syndrome, and tethered cord syndrome

  • Significantly lower cognitive development than unaffected children

  • Nearly all have bladder dysfunction (i.e., neurogenic bladder).

  • Significant morbidity and mortality from hindbrain herniation (Chiari II malformation) (1)

  • Children with meningomyelocele do attain adulthood; consequently, developmental concerns must be addressed including driving and sexual activity.

  • System(s) affected: musculoskeletal; nervous; renal/urologic; skin/exocrine

  • Synonym(s): spina bifida; myelomeningocele; meningocele; lipomeningocele; spinal dysraphism; open neural tube defect

Alert

Always use latex precautions. ⅓; of spina bifida patients have latex allergy. Recommend alert identification bracelet once documented.

 
Pediatric Considerations

Congenital defect

 
Pregnancy Considerations

Ultrasound is the primary diagnostic measure during pregnancy. Prenatal MRI is increasingly used.

 

EPIDEMIOLOGY

  • Predominant age: congenital anomaly, apparent at birth

  • Predominant gender: male = female

INCIDENCE

  • Worldwide incidence is 1 to 10/1,000 births.

  • In the United States, 1,500 new cases per year

  • In the United States, 3.4/10,000 live births per year (1)[B]

ETIOLOGY

  • Maternal folic acid deficiency is an environmental factor strongly associated with neural tube defects.

  • The ultimate cause of spinal dysraphism is unclear.

  • Experimental and clinical evidence suggest that the primary cause is chronic, mechanical, and amniotic fluid–induced chemical trauma, which leads to progressive damage of neural tissue during gestation (2)[C]. Leakage of cerebrospinal fluid through the meningomyelocele leads to the development of hydrocephalus and brainstem herniation.

GENETICS

  • The majority of meningomyeloceles occurs as isolated incidents and is of multifactorial origin.

  • Data support fetal karyotype testing for diagnostic testing and for counseling regarding recurrence risk.

  • A large meta-analysis study suggests that the MTHFD 1 G1958A gene polymorphism is related to neural tube defects (3).

  • A woman who has delivered a child with meningomyelocele has a 2.5% risk of recurrence with subsequent pregnancies.

RISK FACTORS

  • Maternal diabetes, antiepileptic medication use, obesity, and use of folic acid antagonists (methotrexate) may increase risk of neural tube defects.

  • Maternal use of valproic acid and related compounds during the 1st trimester increases risk of neural tube defects.

  • Previous children with spina bifida

  • Insufficient maternal levels of folic acid

  • Vitamin B12 deficiency

GENERAL PREVENTION

  • The vital period of closure of the rostral and caudal neural pores is at 6 weeks of gestation (4).

  • Adequate folate intake (0.4 to 1.0 mg/day) by sexually active women begun at least 1 month before pregnancy and continuing through the 1st trimester.

  • Fetal surgery places both mother and fetus at risk for complications, including preterm delivery and uterine dehiscence.

  • Intrauterine repair before 26 weeks’ gestation has been shown to reduce the incidence of shunt-dependent hydrocephalus and decrease hindbrain herniation but does not seem to improve age at onset of walking.

ASSOCIATED CONDITIONS

  • About 10% may be associated with a genetic syndrome.

  • Less commonly associated with a chromosomal abnormality such as trisomies 13 and 18

  • High risk of infection at time of birth

  • Hydrocephalus

  • Chiari II malformation present in nearly all infants with meningomyelocele.

  • More than 80% of patients require ventriculoperitoneal shunting (VPS) and have ambulation impairments such that 2/3 of patients are wheelchair bound by adulthood (1).

  • Frequent fractures of lower extremities

  • Obesity

  • Hypertension

  • Frequent UTIs

  • High prevalence of end-stage renal disease in childhood

  • Kyphosis

  • Scoliosis

  • Pressure ulcers

DIAGNOSIS

HISTORY

Usually occur as isolated incidents 

PHYSICAL EXAM

  • Examination of an infant’s lower back reveals obvious meningomyelocele involving lumbosacral spine.

  • Typically flaccid paraparesis below the level of the cord lesion

  • Motor and sensory exam deficit levels may not correlate with each other.

TESTS

Prenatal diagnosis 
  • Elevated maternal serum α-fetoprotein levels at 16 to 18 weeks’ gestation should prompt further testing for fetal open neural tube defects.

  • Ultrasonography, particularly transvaginal ultrasound, has a 90–95% detection rate in 2nd trimester.

  • Amniocentesis: Elevated α-fetoprotein in amniotic fluid (by 14 weeks’ gestation) suggests open neural tube defects. This invasive testing is not necessary due to improved ultrasound techniques.

DIAGNOSTIC PROCEDURES/SURGERY

  • Serial cranial ultrasounds to track degree or potential progression of hydrocephalus

  • MRI of brain and spine is useful. MRI is helpful to identify tethered cord.

  • Urinalysis, culture, serum urea nitrogen, along with creatinine should be assessed at birth for baseline renal function analysis.

TREATMENT

GENERAL MEASURES

Pediatric specialists in neurosurgery, orthopedics, physiatry, urology, nursing, psychology, and social services are all necessary for a comprehensive integrated program of care for the child with a meningomyelocele. 

SURGERY

  • Meningomyelocele sac closure and cerebrospinal fluid diversion usually within 24 to 48 hours of birth

  • Tethered cord release surgery to dissect scarred portion of cord in the area of meningomyelocele repair.

  • Fetal surgery may improve hydrocephalus and hindbrain herniation and reduce need for VPS.

  • Fetal endoscopic surgery may provide spinal segmental neuroprotection (5)[B].

  • All pregnant women who are expecting a child with a neural tube defect should be advised of the possibility of fetal repair surgery and referred to a multidisciplinary team for counseling.

  • Open fetal meningomyelocele surgery benefits include reduction of need for VPS, decreased Chiari II malformation, and improved cognitive and neurodevelopmental status.

  • Fetal endoscopic surgery is associated with higher rates of birth at lower gestational age, premature rupture of amniotic membranes, placental abruption, and intraoperative complications (5)[B].

  • Open fetal meningomyelocele surgery concerns for subsequent pregnancies include uterine dehiscence and uterine rupture.

  • Urologic consultation for bladder continence concerns is imperative.

  • Neurogenic bladder secondary to meningomyelocele is primarily treated with clean intermittent catheterization accompanied by use of anticholinergic agents (6)[A].

  • Onabotulinumtoxin A has been shown to be safe and effective treatment for children and adolescents, with neurogenic overactive bladder related to myelomeningocele (6)[A].

  • Orthopedic surgery consultation may be required for correction of extremity and spinal deformities.

INPATIENT CONSIDERATIONS

Latex precautions 

ONGOING CARE

Periodic follow-up, usually every 6 months to assess 
  • Head circumference (infants)

  • Ocular status

  • Developmental status

  • Motor status, including grasp strength in cooperative patients

  • Urologic and orthopedic status

  • Body mass index

  • Blood pressure

  • Bone density screening

FOLLOWUP RECOMMENDATIONS

MONITORING

Regular assessments in spina bifida clinic, with a comprehensive integrated program of care including pediatrics, neurosurgery, orthopedics, and urology 

DIET

Dietary modifications should be made on an individual basis in order to decrease obesity risk and to improve bowel and bladder continence. 

PATIENT TEACHING

  • Genetic counseling early in the course of pregnancy and in reference to subsequent pregnancies

  • Signs and symptoms of shunt malfunction along with cord tethering should be reviewed with caregivers.

  • The importance of careful, clean bowel and bladder care should be emphasized.

  • Patient resources: Spina Bifida Association of America: http://www.spinabifidaassociation.org/

  • National Spina Bifida Patient Registry, established in 2008, provides the framework for a systematic approach to improving the quality of care received at spina bifida clinics nationwide.

PROGNOSIS

  • At all ages, the most common cause of death is renal failure.

  • Death rate of live born infants with meningomyelocele is approximately 10% (4)[B].

  • 14% die within the first 5 years of life, with 73% of those being due to hindbrain herniation.

  • Those who do not require shunting have higher IQ levels.

  • Aggressive integrated care programs with attention to proper urologic management have led to increased long-term survival rates into adulthood and advanced age.

COMPLICATIONS

  • UTI is most common.

  • Scoliosis

  • Neuropathic pain

  • Seizures

  • Pressure ulcers

  • Hypertension

  • Lower extremity fractures may be undiagnosed, or diagnosis may be delayed due to inability to perceive pain in the lower extremities.

REFERENCES

Kahn L, Mbabuike N, Valle-Giler EP et al. Fetal surgery: the ochsner experience with in utero spina bifida repair. Ochsner J.  2014;14(1):112–118.  [View Abstract]
Meuli M, Moehrlen U. Fetal surgery for myelomeningocele is effective: a critical look at the whys. Pediatr Surg Int.  2014;30(7):689–697.  [View Abstract]
Jiang J, Zhang Y, Wei L et al. Association between MTHFD1 G1958A polymorphism and neural tube defects susceptibility: a meta-analysis. PLoS One.  2014;9(6):e101169.  [View Abstract]
Adzick NS, Thom EA, Spong CY et al. A randomized trial of prenatal versus postnatal repair of myelomeningocele. N Engl J Med.  2011;364(11):993–1004.  [View Abstract]
Verbeek RJ, Heep A, Maurits NM et al. Fetal endoscopic myelomeningocele closure preserves segmental neurological function. Dev Med Child Neurol.  2012;54(1):15–22.  [View Abstract]
Marte A. Onabotulinumtoxin A for treating overactive/poor compliant bladders in children and adolescents with neurogenic bladder secondary to myelomeningocele. Toxins.  2012;5(1):16–24.  [View Abstract]

ADDITIONAL READING

  • Ganesh D, Sagayaraj BM, Barua RK et al. Arnold Chiari malformation with spina bifida: a lost opportunity of folic acid supplementation. J Clin Diagn Res.  2014;8(12):OD01–OD03.  [View Abstract]

  • Müslüman AM, Karşidağ S, Sucu DÖ et al. Clinical outcomes of myelomeningocele defect closure over 10 years. J Clin Neurosci.  2012;19(7):984–990.  [View Abstract]

  • Okurowska-Zawada B, Kułak W, Otapowicz D et al. Quality of life in children and adolescents with cerebral palsy and myelomeningocele. Pediatr Neurol.  2011;45(3):163–168.  [View Abstract]

  • Roach JW, Short BF, Saltzman HM. Adult consequences of spina bifida: a cohort study. Clin Orthop Relat Res.  2011;469(5):1246–1252.  [View Abstract]

  • Werhagen L, Gabrielsson H, Westgren N et al. Medical complication in adults with spina bifida. Clin Neurol Neurosurg.  2013;115(8):1226–1229.  [View Abstract]

CODES

ICD10

  • Q05.9 Spina bifida, unspecified

  • Q05.4 Unspecified spina bifida with hydrocephalus

  • Q07.03 Arnold-Chiari syndrome with spina bifida and hydrocephalus

  • Q05.6 Thoracic spina bifida without hydrocephalus

  • Q05.0 Cervical spina bifida with hydrocephalus

  • Q05.1 Thoracic spina bifida with hydrocephalus

  • Q05.2 Lumbar spina bifida with hydrocephalus

  • Q05.3 Sacral spina bifida with hydrocephalus

  • Q05.5 Cervical spina bifida without hydrocephalus

  • Q05.8 Sacral spina bifida without hydrocephalus

  • Q05.7 Lumbar spina bifida without hydrocephalus

ICD9

  • 741.90 Spina bifida without mention of hydrocephalus, unspecified region

  • 741.00 Spina bifida with hydrocephalus, unspecified region

  • 741.91 Spina bifida without mention of hydrocephalus, cervical region

  • 741.92 Spina bifida without mention of hydrocephalus, dorsal (thoracic) region

  • 741.93 Spina bifida without mention of hydrocephalus, lumbar region

  • 741.02 Spina bifida with hydrocephalus, dorsal (thoracic) region

  • 741.01 Spina bifida with hydrocephalus, cervical region

SNOMED

  • 414667000 meningomyelocele (disorder)

  • 40130009 Spina bifida without hydrocephalus

  • 4061000119104 Myelomeningocele without hydrocephalus (disorder)

  • 373587001 Chiari malformation type II

  • 17761000119109 High lumbar myelomeningocele (disorder)

  • 32232003 Spina bifida of cervical region (disorder)

  • 53318002 Spina bifida with hydrocephalus

  • 444860006 Meningomyelocele of lumbosacral spine (disorder)

  • 17771000119103 Low lumbar myelomeningocele (disorder)

PEARLS

  • Maternal folic acid and vitamin B12 supplementation prior to conception and through 1st trimester reduces risk significantly.

  • Referral to a comprehensive integrated team of specialists provides optimal care.

  • Antenatal option of fetal endoscopic surgery should be addressed.

  • At all ages, renal failure is the most common cause of death. Hence, careful monitoring of bladder continence measures along with renal function is imperative.

  • Advances in care have led to longevity (i.e., children with spina bifida grow into adults with spina bifida), thus necessitating attention to concerns such as driving, sexual function, and so forth.

  • Latex allergy is prominent.

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