Myelomeningocele

Wesley J Whitson MD (Dr. Whitson of Dartmouth-Hitchcock Medical Center has no relevant financial relationships to disclose.)
Robert J Singer MD (Dr. Singer of Dartmouth-Hitchcock Medical Center/Geisel School of Medicine at Dartmouth has no relevant financial relationships to disclose.)
Michael V Johnston MD, editor. (Dr. Johnston of Johns Hopkins University School of Medicine and Chief Medical Officer at Kennedy Krieger Institute has no relevant financial relationships to disclose.)
Originally released July 29, 1996; last updated August 9, 2016; expires August 9, 2019

This article includes discussion myelomeningocele, meningomyelocele, myelodysplasia, neural tube defect, spina bifida, spinal dysraphism, lipomyelomeningocele, and terminal myelocystocele. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Myelomeningocele is a significantly disabling birth defect that relatively spares cognitive function. It affects both the central and peripheral nervous systems, typically causing some degree of paralysis and bowel and bladder dysfunction. It is associated with several other anomalies including hydrocephalus, Chiari II malformation, tethered cord syndrome, and syringomyelia. For this reason, new neurologic problems can present throughout life. Patients require regular multidisciplinary follow-up to manage these conditions. Nevertheless, patient reported quality of life is typically very good. A multicenter trial for prenatal myelomeningocele repair has raised important questions about the optimal time for surgical intervention in these patients. The authors update these issues in this article.

Key points

 

• Myelomeningocele is a disabling birth defect associated with multiple other neurologic conditions.

 

• Adequate folic acid intake in the periconceptual and early pregnancy periods significantly reduces the risk of myelomeningocele.

 

• Myelomeningocele level is the most important predictor of functional outcome.

 

• Myelomeningocele repair is traditionally done within 72 hours of birth to minimize the risk of meningitis. The results of a trial on prenatal myelomeningocele repair have encouraged some neurosurgeons to consider in utero surgery.

 

• Most myelomeningocele patients will develop shunt-dependent hydrocephalus.

 

• Myelomeningocele patients require close multidisciplinary follow-up throughout life to promote maximum functional outcomes and to minimize further neurologic decline from associated anomalies.

Historical note and terminology

Malformations involving the formation of the distal spinal cord and spinal column have been identified for centuries. The term "spina bifida" was used to describe all these lesions, from the mildest to the most severe. The term "spinal dysraphism" is actually more appropriate, as "dysraphism" refers to the spinal cord defect. Most of these defects are felt to result from abnormal neurulation; therefore, they are also known as "neural tube defects." This section will discuss the most common clinically significant neural tube defect, myelomeningocele, a form of spina bifida associated with outpouching of the spinal cord and its coverings through an open defect in the vertebral arches. This form of spina bifida has effects on much of the remaining neuraxis with the frequent presence of hydrocephalus, Chiari II malformation, and syringomyelia.

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