The distribution of postnatally repaired myelomengocele (MMC) lesions, characterized by neurologic and radiologic assessment, and the incidence of shunting were determined and correlated by a retrospective chart review of 297 patients followed at the spina bifida clinic at the Children’s Hospital of Philadelphia. The rate of ventricular shunting was 81%, and was correlated with the level of the lesion. The more cephalad the MMC, the higher the incidence of shunting. Levels determined by functional neurologic examination were generally higher or equal to the vertebral level of the lesion defined by spine radiographs. Sacral lesions categorized radiologically rather than neurologically had a higher shunt rate. [1]

COMMENT. In this series of patients, the proportion of lumbar MMC was 62% in contrast to 80% reported by Emery and Lendon in a study published in 1973. The authors of the Philadelphia study comment that differences in the distribution of MMC lesions in this compared to earlier studies may reflect prenatal diagnosis and termination or the effects of maternal folic acid supplementation. Their findings, emphasizing the relation of rate of shunting and functional level of lesion, are considered important in counseling and also in the design of fetal intervention studies. Fetal MMC closure may be associated with a delayed development of symptomatic hydrocephalus and lower rate of shunting than postnatal closure. Reversal of the hindbrain hernia in fetal Chiari II malformation might open the cerebrospinal fluid drainage and prevent the obstructive hydrocephalus (McLone DG, Knepper PA. 1989).

Risk of major birth defects is more than doubled in infants conceived after intracytoplasmic sperm injection or in vitro fertilization, according to data obtained from birth registries in Western Australia between 1993 and 1997. [2]