title: Surgical Outcome of Adult Idiopathic Chiari Malformation Type 1.
abstract: OBJECTIVE
  The pathophysiology of idiopathic Chiari malformation (CM) type 1 is disturbance of free cerebrospinal fluid (CSF) flow and restoration of normal CSF flow is the mainstay of treatment. Additional migration of the medulla oblongata in pediatric patients is referred to as CM type 1.5, but its significance in adult patients is unknown. This study is to compare surgical outcomes of adult idiopathic CM type 1.5 with that of type 1.
  
  
  METHODS
  Thirty-eight consecutive adult patients (M : F=11 : 27; median, 33.5; range, 18-63) with syringomyelia due to idiopathic CM type 1 were reviewed. Migration of the medulla oblongata was noted in 13 patients. The modified McCormick scale (MMS) was used to evaluate functional status before and one year after surgery. All patients underwent foramen magnum decompression and duroplasty. Factors related to radiological success (≥50% decrease in the diameter of the syrinx) were investigated. The follow-up period was 72.7±55.6 months.
  
  
  RESULTS
  Preoperative functional status were MMS I in 11 patients and MMS II in 14 of CM type 1 and MMS I in 8 and II in 5 of CM type 1.5. Of patients with MMS II, 5/14 patients in group A and 3/5 patients in group B showed improvement and there was no case of deterioration. Radiological success was achieved in 32 (84%) patients and restoration of the cisterna magna (p=0.01; OR, 46.5) was the only significant factor.
  
  
  CONCLUSIONS
  Migration of the medulla oblongata did not make a difference in the surgical outcome when the cisterna magna was restored.
authors.affiliation: Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea.
authors.forename: Woon Tak
authors.initials: WT
authors.lastname: Yuh
authors.affiliation: Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea.; Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.; Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, Korea.; Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.
authors.forename: Chi Heon
authors.initials: CH
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea.; Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.; Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, Korea.; Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.; Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, Korea.
authors.forename: Chun Kee
authors.initials: CK
authors.lastname: Chung
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.; Department of Neurosurgery, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Hyun-Jib
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.; Department of Neurosurgery, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Tae-Ahn
authors.initials: TA
authors.lastname: Jahng
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.; Department of Neurosurgery, Seoul National University Boramae Hospital, Seoul, Korea.
authors.forename: Sung Bae
authors.initials: SB
authors.lastname: Park
keywords: Arachnoid; Chiari malformation; Hindbrain; Medulla oblongata; Surgery; Syringomyelia