title: Spontaneous resolution of Chiari malformation Type I in monozygotic twins.
abstract: The spontaneous resolution of isolated tonsillar ectopia in Chiari malformation Type I (CM-I) is a known and reported entity in 2 previous single study case reports. However, it has not been previously described in monozygotic twins. Two children, approximately 1 year of age with CM-I and presumed episodes of pallid syncope or breath-holding spells presented for neurosurgical evaluation. Although Chiari decompression was considered, the authors decided to proceed with conservative management with close follow-up due to the uncertain nature of these episodes. Approximately 4 years later, both children's symptoms had resolved. Repeated MR imaging examinations also showed spontaneous resolution of the malformation in both girls. These cases emphasize that when patients with CM-I present with atypical symptoms, spontaneous resolution or improvement is possible, which may influence the decision to pursue a trial of nonsurgical management. The possible pathophysiological mechanisms and genetic influences of CM-I are also briefly discussed.
authors.affiliation: Department of Neurosurgery, St. Louis Children's Hospital, Washington University, St. Louis, Missouri 63110-1077, USA.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Miller
authors.forename: David D
authors.initials: DD
authors.lastname: Limbrick
authors.forename: Matthew
authors.initials: M
authors.lastname: Callen
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Smyth
mesh_terms: D001139:Arnold-Chiari Malformation / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D002675:Child, Preschool; D004200:Diseases in Twins / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007223:Infant; D012075:Remission, Spontaneous; D014430:Twins, Monozygotic