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Meningomyeleocele (MMC) belongs to a class of birth defects called spina bifida. Though treatment for these defects can commence as soon as they are diagnosed (even in an unborn child), management of these conditions typically require an iterative multidisciplinary approach with physiotherapy every step of the way.

Spina bifida

Spina bifida is a variable defect in which the vertebral arch of the spinal column is either incompletely formed or absent. The term bifida is from the Latin word bifidus, or “left in 2 parts.”1 It is classified as a defect of the neural tube (i.e. the embryonic structure that develops into the spinal cord and brain).1

Neural tube defects have a range of presentations, from stillbirth to incidental radiographic findings of spina bifida occulta.2 The term myelodysplasia has been used as a synonym for spina bifida.1  Lesions most commonly occur in the lumbar and sacral regions, but can be found anywhere along the entire length of the spine.1

Types of Spina Bifida

Spina bifida is a treatable spinal cord malformation that occurs in varying degrees of severity. 2

  • Spina bifida occulta: It can occur without neurologic defects.
  • Meningocele: A cystic swelling of the dura and arachnoid, protrudes through the spina bifida defect in the vertebral arch.
  • Meningomyelocele: when cord tissue extends into the meningocele.
  • If the spinal cord is exposed on the surface of the back, the condition is called myeloschisis.3

Embryology/Pathophysiology

Neural tube defects occur between the 17th and 30th day of gestation.4 This defect then disrupts all of the overlying tissues, preventing the vertebral arch from closing.4

If the posterior vertebral arch and overlying tissues do not form normally, the normal spinal cord and meninges may then herniate out through the defect and cause a meningomyelocele (MMC).2

If the vertebral arch fails to grow and fuse normally and the spinal cord and meninges are not disturbed, spina bifida occulta results.2

Meningomyelocele

MMC is associated with abnormal development of the cranial neural tube, which results in several characteristic CNS anomalies.2 The Chiari type II malformation is characterized by cerebellar hypoplasia and varying degrees of caudal displacement of the lower brainstem into the upper cervical canal through the foramen magnum.2 This deformity impedes the flow and absorption of cerebrospinal fluid (CSF) and causes hydrocephalus, which occurs in more than 90% of infants with MMC.2

Numerous other associated nervous system malformations include syringomyelia, diastematomyelia, and agenesis of the corpus callosum.2 Non-neurologic associations include spine malformations, hydronephrosis, cardiac defects, and gastrointestinal anomalies.2

Epidemiology

There are variations in incidence between some racial populations. The incidence of MMC in America: 1.1 in 1000 births.5 The current incidence in America is about 0.6 per 1000, and there is good evidence that this has been steadily declining. African-American cases are often a third of those found for white Americans, while those for Hispanic-Americans are two to three times greater.2 1 case in 10,000 is reported in Finland and 5 in 1000 in Northern Ireland.5 There are at least 2000 cases/year in the US.5

Aetiology

The risk of an adult with MMC having a child with a neural tube defect is 5%.6 Women with low RBC cell folate levels during early pregnancy have up to a 6x greater risk of having a child with a neural tube defect.2 Intrauterine exposure to antiepileptic drugs, particularly valproate and carbamazepine, and to drugs used to induce ovulation.2 Maternal exposures to fumonisins, EM fields, hazardous waste sites, disinfection by-products found in drinking water, and pesticides.2

Other risk factors for MMC include maternal obesity, hyperthermia (as a result of maternal fever or febrile illness or the use of saunas, hot tubs, or tanning beds), and maternal diarrhoea.6

Diagnosis

Measurement of maternal serum α-fetoprotein (MSAFP) levels is a common screening test. If the level is elevated, indicating that any portion of the foetus is not covered by skin, this screening test is then followed by detailed ultrasonography.

Ultrasound scans will diagnose 92% of neural tube defects.2

Mothers with elevated MSAFP levels and a normal appearing ultrasound scan may be evaluated by amniocentesis for the presence of elevated acetylcholinesterase levels in the amniotic fluid.2

Management of MMC

Common complications of MMC range from neurosurgical to psychosocial issues. Children with MMC might at some point point deal with organ impairment, musculoskeletal deformities, infections, hydrocephalus, chronic headaches and obesity which can severely limit functional ability. Each of these complications warrant physiotherapy and might be the patient’s best chance at gain normal function and integration into the society.

A multidisciplinary approach towards managing patients with MMC is essential for successful outcomes. Patient should be assessed as soon after birth as possible. At different stages the focus of physiotherapy will change with changing needs of the patient. Regular review is essential to meet up with patient needs. Parents and care-givers should be involved in patient care.

Generally surgery follows within the first few days of life to close the spinal cord defect.2 It is also important to prevent infection and additional trauma to the exposed tissues. Additional surgeries may be required to manage other problems in the feet, hips, or spine.

Conclusion

Due to improved management, about 90% of babies born with Spina Bifida now live to be adults. About 80% have normal intelligence and about 75% play sports and do other fun activities . Most of them do well in school and even participate in sports.

References

  • Lundy-Ekman L (2007). Neuroscience: Fundamentals for Rehabilitation. 3rd edition. St. Louis: Saunders, 2007.
  • Foster, MR (2016). Medscape Drugs & Diseases – Medscape Reference. Retrieved October 24, 2016, from http://emedicine.medscape.com/article/311113-overview
  • Burke R, Liptak G (2011). Providing a Primary Care Medical Home for Children and Youth with Spina Bifida. American Academy of Pediatrics. 128:1645-1657
  • Fletcher JM, Copeland K, Frederick JA (2005). Spinal lesion level in spina bifida: a source of neural and cognitive heterogeneity. Journal of Neurosurgery. 102(3 Suppl):268-79.
  • Shin M, Besser LM, Siffel C, Kucik JE, Shaw GM, Lu C, Correa A, and the Congenital Anomaly Multistate Prevalence and Collaborative (2010). Prevalence of Spina Bifida Among Children and Adolescents in 10 Regions in the United States. Pediatrics.
  • Canfield MA, Ramadhani TA, Shaw GM (2009). Anencephaly and spina bifida among Hispanics: maternal, sociodemographic, and acculturation factors in the National Birth Defects Prevention Study. Birth Defects Res A Clin Mol Teratol. Jul. 85(7):637-46.