Concomitant achondroplasia and Chiari II malformation: A double-hit at the cervicomedullary junction

Abstract

We report the first case of a neonate with concurrent Chiari II malformation and achondroplasia. Although rare, both these conditions contribute to several deleterious anatomical changes at the cervicomedullary junction and thus predispose to acute hydrocephalus. Although our patient was initially asymptomatic, hydrocephalus ensued several weeks after birth and required cerebral spinal fluid diversion. We discuss the potential links between the two conditions, the pathophysiology, and the important clinical implications for the management of the increased risk of hydrocephalus.

Keywords: Achondroplasia; Chiari II malformation; Hydrocephalus; Shunt failure; Cervicomedullary junction; Cerebral spinal fluid diversion

Core tip: Achondroplasia and Chiari II malformations can induce similar anatomical changes at the cervicomedullary junction which increase the risk of acute hydrocephalus. Chiari decompression may not always be necessary, however, diligent and acute follow-up is important to monitor for signs of impeding hydrocephalus. If cerebral spinal fluid diversion is required, remember that shunt failure is common in the pediatric age group and also requires close follow-up.