1309. Improvement in Ventriculomegaly Following Cervicomedullary Decompressive Surgery in Children with Achondroplasia and Foramen Magnum Stenosis

Authors: Alon H. Kashanian; Julie Chan, MD, PhD; Debraj Mukherjee, MD, MPH; Deborah Krakow, MD; Moise Danielpour, MD (Beverly Hills, CA)

Introduction: There has been contradictory evidence as to whether foramen magnum decompression can improve hydrocephalus in children with achondroplasia who present with concordant foramen magnum stenosis. In the current study the authors reviewed their records to determine if there is stabilization or improvement in ventriculomegaly following foramen magnum decompression performed for cervicomedullary stenosis. Methods: The authors retrospectively reviewed 15 patients with achondroplasia who presented to the neurosurgical service at Cedars-Sinai medical center with symptomatic foramen magnum stenosis and signs of progressive ventriculomegaly. These children underwent cervicomedullary decompression between the years 2000 and 2017. Clinical outcomes included changes in fontanel characteristics, head circumference (HC) percentile, and incidence of ventriculoperitoneal shunting. Radiographic outcomes included changes in Evans ratio. Results: Fifteen children were identified to have symptomatic foramen magnum stenosis and full anterior fontanelle or increasing HC percentiles on the achondroplasia growth curves at presentation. Two of these children underwent placement of a shunt for progressive ventriculomegaly prior to foramen magnum decompression. Of the remaining 13 children with full anterior fontanelles, nearly all, or 92%, showed softening and/or flattening of their fontanelles, and 83% of those with increasing HC percentiles showed a decrease or stabilization in their percentiles following surgery. Not all children had both pre- and post-operative brain imaging available. When comparing ventricular size in the five that did, 60% improved, 20% stabilized and 20% increased in Evans ratio after decompression. Two (15%) children required a shunt after decompression of the foramen magnum. Conclusion: A significant proportion of children with concomitant signs of progressive ventriculomegaly and foramen magnum stenosis may have improvement or stabilization in their signs following cervicomedullary decompression. During close follow-up of these patients, including the two children that required a ventriculoperitoneal shunt, none developed a fixed deficit.