Menu Healthy Lifestyle Diseases & Conditions First Aid Symptoms Tests & Procedures Videos Definitions FAQs Arnold-Chiari malformationUpdated: 2017-06-13OverviewArnold-Chiari malformation (Chiari malformation type II) is a condition at birth in which brain tissue extends into the spinal canal. It occurs when part of the skull is abnormally small or misshapen.SymptomsSymptoms include changes in breathing pattern and trouble swallowing.TreatmentsTreatment may involve monitoring, medication, and surgery. © 1998-2022 Mayo Foundation for Medical Education and Research(MFMER). All rights reserved. Terms of Use