Ben Miled S, Loeuillet L, Van Huyen JPD, et al. - Although midtrimester prenatal surgery has undisputable benefits, it is not a cure for myelomeningocele (MMC): residual intracranial and motor deficits leading to lifelong handicap question the timing of prenatal surgery. Researchers aimed at describing the natural history of neuronal loss in MMC in utero via analyzing postmortem pathology in 186 cases of myelomeningocele with lesion level between S1 and T1. They conducted a case-control, cross-sectional study examining the timewise progression and topographic extension of neuronal loss between 13 and 39 weeks. In 54 isolated MMC meeting quality criteria for cell counting, they counted motor neurons on histology at several spinal levels. The exposed cord showed significant neuronal loss at ≤ 16 weeks and the loss progressively extends cranially. Increase in Chiari II malformation from 30.7% to 91.6% was noted after 16 weeks. Via performing earlier prenatal repair (< 16 weeks), Chiari II malformation could be prevented in 69.3% of cases, 17% remaining motor neurons in the exposed cord could be rescued, and the extension to the upper spinal cord could be prevented.