Abstract: Down syndrome (DS) occurs when an individual has a full or partial extra copy of chromosome 21 and is the most common of all malformation syndromes. Associating with numerous pathologies like anterior atlantoaxial subluxation (AAAS) which is an increase in the space between the anterior arch of the first cervical vertebra (C1) and the odontoid process of the second vertebra (C2), most of the time its asymptomatic, only 1–2% to all the 30% who may have the AAAS and DS develop clinical symptoms. In this occasion, we present the case of a patient with SD and Juvenile chronic arthritis (JCA) who has atlantoaxial subluxation of approximately 11mm, basilar impression and platybasia with severe medullary compression in 2 points, requiring surgical management by the Neurological Surgery Service in Bucaramanga-Colombia.