Fetal myelomeningocele (MMC) repair reduces the need for postnatal ventriculoperitoneal shunting at 1 year by at least a half compared with postnatal repair.
Motor and bladder function outcome studies after fetal MMC repair are encouraging, and further study is underway.
Preliminary findings demonstrate that fetoscopic MMC repair seems to offer similar neonatal benefits to the open approach, with the advantage of allowing for safe vaginal delivery in the index and future pregnancies. Fetoscopic MMC repair is not associated with an increased risk for uterine rupture, compared to an 11% risk after open repair.
In 1986, a moratorium was placed on human fetal ventriculoperitoneal shunting. However, due to improvements in fetal diagnosis and intervention techniques that may translate to improved case selection and outcomes, there is renewed interest in further investigation of this treatment approach.
HISTORICAL BACKGROUND FOR FETAL NEUROSURGERY
The basic tenets of fetal surgery were developed in the 1980s and continue to guide fetal interventions to this day (see Table 24–1).1–4 Based on these principals, myelomeningocele (MMC) and fetal hydrocephalus are good candidates for fetal neurosurgical repair. If left untreated, progressive damage occurs in developing critical fetal structures. Prenatal intervention is technically feasible and may mitigate the destructive downstream cascade of in utero events for both conditions.
++ Table Graphic Jump Location Table 24–1.PRINCIPLES OF FETAL SURGERY ||Download (.pdf) Table 24–1. PRINCIPLES OF FETAL SURGERY
|The structural anomaly has downstream impact interfering with normal fetal development |
|Correction of the structural anomaly prenatally is reasonably achievable |
|Correction of the structural anomaly prenatally would allow for normal development that would not be achievable with postnatal correction |
|The natural history of the condition is well understood |
|Reasonable likelihood that the intervention will benefit the patient |
|Singleton pregnancy without additional abnormalities and normal karyotype |
|Appropriate consent is obtainable; the mother understands the risks/benefits of treatment and is agreeable for long-term follow-up |
|Multispecialty team with approval of an institutional review board and access to psychosocial and bioethical consultation |
|Outcomes should be reported in a fetal treatment registry and/or the literature |
For ultrasound findings of MMC lesions, see Chapter 6.
Background Concept of Fetal Surgery for MMC
Spinal dysraphisms are common congenital birth defects and occur in approximately 3 to 4 of 10,000 live births in the United States.5 These occur when the spinal column fails to fuse at 22 to 28 days of embryological life and nerve roots that are normally enclosed and protected within the bony spinal column are displaced and exposed. Depending on the degree of meningeal coverage, the two most common manifestations are MMC and myeloschisis. In MMC, a dural sac forms over the bony opening in the spine, and the disorganized nerve roots make their way to the exterior of the sac, creating ...