Long-term neurofunctional outcome, executive functioning, and behavioral adaptive skills following fetal myelomeningocele surgery

Abstract

Myelomeningocele (MMC) represents the first nonlethal anomaly to be treated by prenatal intervention. Case series and a prospective, randomized study show that fetal surgery for MMC before 26 weeks' gestation may preserve neurological function. Long-term follow-up is a fundamental component to evaluate the overall efficacy of any new medical or surgical procedure. To further delineate the long-term impact of fMMC surgery, we continued to follow children treated in our institution before the Management of Myelomeningocele Study trial by the means of parental questionnaires to assess changes in functional, developmental, and cognitive status as these unique patients grow older. The objective of the study was to evaluate the long-term neurological outcome, executive functioning (EF), and behavioral adaptive skills (BAS) following fetal myelomeningocele (fMMC) surgery. Prior to the Management of Myelomeningocele Study trial, 54 patients underwent fMMC surgery at our institution. Parents of 42 children (78%) participated in structured questionnaires focusing on neurofunctional outcome. EF and BAS were measured by the Behavior Rating Inventory of Executive Function (BRIEF) and the Adaptive Behavioral Assessment System II. The BRIEF is organized into 3 primary indices including the following: Global Executive Composite, Metacognition Index, and Behavioral Regulation Index. The Adaptive Behavioral Assessment System II results in a general adaptive composite score. Based on SD intervals, EF and BAS were categorized as being average, borderline, or impaired. At a median follow-up age of 10 years (range, 8-14 years), 33 (79%) are community ambulators, 3 (9%) are household ambulators, and 6 (14%) are wheelchair dependent. Preschool ambulation was predictive of long-term ambulation (P < .01), whereas the need for tethered cord surgery was associated with persistent deterioration of ambulatory status (P= .007). Normal bladder function was found in 26%. Although the majority scored within the average range for the Behavioral Regulation Index, Metacognition Index, and Global Executive Composite indices, significantly more children who had fMMC surgery had deficits in EF in all 3 BRIEF indices compared with the population norms. The general adaptive composite scores were also more likely to fall below average following fMMC surgery. Normal early neurodevelopmental outcomes were predictive of normal EF and BAS (P < .01). Need for shunting was associated with a significant impairment of BAS (P= .02). The present study suggests that fMMC surgery improves long-term functional outcome. The majority of fMMC children can successfully complete everyday tasks at home and at school. Abnormalities of BAS appear to be more common than impairments in EF and therefore offer an area for early screening and interventional therapy for these at-risk children. Non-shunted fMMC children with normal early neurodevelopmental outcome are less likely to experience problems with EF and BAS. fMMC surgery improves long-term ambulatory status. Symptomatic spinal cord tethering with or without intradural inclusion cyst is associated with functional loss. More than expected fMMC children are continent, but bowel and bladder control continue to be an ongoing challenge for the fMMC children.