Myelomeningocele (MMC) is the most common congenital non-fatal anomaly of the central nervous system. It is a failure of closure of the neural tube within the first 6 weeks of gestation [1, 9]. Epidemiologic studies of MMC normally include related congenital central nervous system defects under the general classification of neural tube defects (NTDs). It is estimated that within 300,000–400,000 infants worldwide are born with NTDs annually . In order to reduce the prevalence of MMC, it is recommended for women of childbearing age to consume folic acid of minimum 400–800 mg daily [2, 10].
MMC is associated with a wide clinical spectrum, including motor deficiencies, orthopedic abnormalities, neurocognitive abnormalities, urinary, anal incontinence and sexual dysfunction, as well as sensitivity alteration below the affected lesion level. Hydrocephalus associated with MMC develops secondarily together with the Arnold-Chiari (AC) malformation type 2, defined by permanent herniation of the medulla oblongata and the cerebellum through the foramen magnum [8, 21]. According to the “two-hit” hypothesis, development of hydrocephalus is associated with fluid leakage that results into cerebellar tonsils and brainstem herniation. Neurological disorders are associated with incorrect formation of spinal cord at the level of a defect and the toxic effect of amniotic fluid on the spinal cord [1, 9].
The diagnosis of fetal MMC is frequently performed by ultrasonography or magnetic resonance imaging in routine prenatal scans after 16 weeks of gestation. Amniocentesis is performed to determine genetic syndromes and measure alpha-fetoprotein levels in order to find out a patient’s risk of having a fetus with open neural tube defects (ONTD) between 15 weeks and 21 weeks, 6 days gestation [13, 16].
Mostly, MMC repair surgery takes place in the neonatal period although intrauterine repair of MMC may reverse AC and limit hydrocephalus progression and alleviate the severity of the defect’s resulting sequel and further deterioration of nerve tissue in the spine . Obstetric complications after repair MMC in uterus are rare. The most common medical complications are pulmonary edema occurring in 2,8% of the cases, gestational diabetes - in 3,7%, gestational hypertension/preeclampsia - in 3,7%, blood transfusions - in 3,2%. The rates of perinatal mortality vary from 1,8 to 6,0% depending on the experience in different centers. Paulista Medical School performed a trial with 220 cases showing perinatal mortality rate of 1,8%; MOMS trial − 2,5% and the Children’s Hospital of Philadelphia (CHOP) − 6% [4, 12, 14].
MOMS results have been widely described in the modern literature. MOMS trial was terminated earlier due to its efficacy in the prenatal period: at 187 patients of the originally planned 200 randomized ones. Decrease in the ventricular-peritoneal shunt rates 40% versus 82%. Radiographic findings at the 12-month follow-up were also more favorable in the prenatal surgery group, showing lesser degrees of hindbrain herniation, brainstem kinking, and syringomyelia observed relative to the postnatal group. Different outcomes were found between prenatal and postnatal MMC repair. Bayley Mental Development Index and motor level improvement at 30 months were better in the prenatal surgery group. Patients treated prenatally were more likely to have a level of function two or more levels better than it was expected according to anatomical level, despite having more severe lesions than their postnatally treated counterparts. Regarding the urological outcomes, no significant difference was found between the patients operated prenatally and postnatally, which, however, is still not enough to determine the impact on renal insufficiency [5, 10, 17].
The operative principle of MMC repair consists of consecutive separate closure of the neural placode, dura mater, lumbar fascia, subcutaneous layer, and skin. The neurosurgical technique for the closure of the neural placode and dura mater has remained unchanged over decades, but different soft tissue closure techniques are still being discussed in the literature . Recent animal data suggest the potential for the use of materials to aid in closure of MMC defects and to isolate exposed neural tissue from amniotic fluid and surrounding tissues to prevent damage of spinal cord, tethering and its long-term sequelae. Materials utilized as scaffolds and/or defect coverings for in utero MMC defect repair in animal models include collagen- or gelatin-based scaffolds, small intestinal submucosa, and polymeric materials including silicone, high density poly ethylene, and polypropylene .
The use of bovine pericardial patch and fibrin sealant for the soft tissue postnatal closure of MMC was successful in eight infants by Bora Gürer et al . Fetoscopic repair technique and the closure of MMC using a biocellulose patch (Bionext) over the placode were described in the literature earlier. The biocellulose patch induces the development of the neodura mater as a result of fetal wound healing [3, 11, 20].
The aim of this report is to describe this first successful experience in utero repair of MMC with bovine pericardial patch, as well as the treatment process.