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

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Authors: Alon H. Kashanian; Julie Chan, MD, PhD; Debraj Mukherjee, MD, MPH; Barry Pressman, MD; Deborah Krakow, MD; Moise Danielpour, MD (Los Angeles, CA)


There has been controversy as to whether foramen magnum decompression can improve hydrocephalus in children with achondroplasia who present with concordant symptomatic 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 in these children.


The authors retrospectively reviewed 14 patients with achondroplasia who presented with symptomatic foramen magnum stenosis and signs of progressive ventriculomegaly. These children underwent cervicomedullary decompression between the years 2000 and 2018. Clinical outcomes included changes in fontanel characteristics, head circumference (HC) percentile, and incidence of ventriculoperitoneal shunting. Radiographic outcomes included changes in Evans ratio.


Sixteen children were identified to have symptomatic foramen magnum stenosis and full anterior fontanelle or increasing HC percentiles on achondroplasia growth curves at presentation. Two children underwent placement of a shunt for progressive ventriculomegaly prior to foramen magnum decompression. Of the remaining 14 children who underwent decompression, 13 (93%) showed softening and/or flattening of their fontanelles post-operatively. Ten children had both pre- and post-operative HC percentile records available, with 8 showing increasing HC percentiles before surgery. Seven of those 8 children (88%) showed a deceleration or stabilization of HC growth velocity upon latest followup after decompressive surgery. Not all children had both pre- and post-operative imaging available. When comparing ventricular size in the ten that did, 50% improved, 20% stabilized and 30% increased in Evans ratio after decompression. Two children (14%) required a shunt after decompression of the foramen magnum.


A significant proportion of children with concomitant signs of progressive ventriculomegaly and foramen magnum stenosis may have improvement or stabilization of progressive ventriculomegaly following cervicomedullary decompression. During close follow-up of these patients, including the two children that required a ventriculoperitoneal shunt, none developed a fixed deficit.