Anesthesia for in utero repair of myelomeningocele

Abstract

Recently published results suggest that prenatal repair of fetal myelomeningocele is a potentially preferable alternative when compared to postnatal repair. In this article, the pathology of myelomeningocele, unique physiologic considerations, perioperative anesthetic management, and ethical considerations of open fetal surgery for prenatal myelomeningocele repair are discussed. Open fetal surgeries have many unique anesthetic issues such as inducing profound uterine relaxation, vigilance for maternal or fetal blood loss, fetal monitoring, and possible fetal resuscitation. Postoperative management, including the requirement for postoperative tocolysis and maternal analgesia, are also reviewed. The success of intrauterine myelomeningocele repair relies on a well-coordinated multidisciplinary approach. Fetal surgery is an important topic for anesthesiologists to understand, as the number of fetal procedures is likely to increase as new fetal treatment centers are opened across the United States.

Figures

Figure 1

Term neonate with large lumbar myelomeningocele.

Figure 2. Operative Preparation for Open Myelomeningocele Repair

(A): Prior to uterine incision, the myelomeningocele is identified using ultrasound and positioned for repair. Arrows note sac border. This fetus has a L2 defect and is at a gestational age of 23 weeks. (B): The myelomeningocele sac is exposed for open surgical repair following uterine incision with use of lactomer uterine staples to prevent uterine wall hemorrhage. Profound uterine relaxation is achieved using high (>2 minimum alveolar concentration) inhalational anesthetic agent. Arrows labeled (MS) note myelomeningocele sac border and arrows labeled (LS) note lactomer staples. (C): An intramuscular muscle relaxant and opioid are injected into the fetus by the surgeon to ensure fetal immobility during the repair.

Figure 3. Intraoperative Myelomeningocele Repair

(A): Neural structures are exposed and separated from adjacent tissue. Labeled arrows note lactomer staples on the uterine wall (L), the skin edge (S), the myofascial flap (MF), and the neural placode (NP). (B): The dura is closed over the neural tube. (C): Once the dural closure is completed, surrounding tissue is mobilized for skin closure.

Figure 4. Prenatal fetal myelomeningocele defect primary closure

(A): Primary skin closure is performed when skin tissue can be approximated. (B): A scar over the surgical site remains at birth following a primary skin closure.

Figure 5. Prenatal fetal myelomeningocele defect closure using a patch

(A): An acellular dermal patch is used when the skin margins cannot be approximated to close the defect. (B): At birth, the patch is often not completely epithelilized, however, the majority of patients form granulation tissue over the patch in one-two weeks and further operative intervention is usually not necessary. (C): Occasionally the patch is completely covered by granulation tissue at birth.