title: Factors contributing improvement of syringomyelia and surgical outcome in type I Chiari malformation.
abstract: OBJECTIVE
  The aim of our study was to compare pre- and postoperative radiologic data of posterior fossa and the improvement of syringomyelia after posterior fossa decompression (PFD) with and without tonsillar management in Chiari type capital I, Ukrainian malformation (CM-I).
  
  
  METHODS
  A retrospective analysis was made of all patients who underwent PFD between Oct 1991 and March 2007 for CM-I. Fifty-seven patients treated for CM-I at a single institution were included in the study. Patients were divided into two groups according to the procedures used during their PFD: PFD vs. PFD with tonsillar management. To determine whether the tonsillar management or changes of posterior fossa volume relate with surgical outcome, we measure posterior fossa size and syringomyelia pre- and postoperatively using magnetic resonance imaging.
  
  
  RESULTS
  Forty patients (70.2%) received PFD and 17 patients (29.8%) received PFD with tonsillar management. The length of syringomyelia affected improvement of syringomyelia (alteration rate, A-rate). Clinical symptoms, craniectomy size, syringomyelia type, and the surgeon's specialty did not affect A-rate. Tonsillar management has no significant effect on improvement of syringomyelia. Four patients need repeated surgery due to recurrence.
  
  
  CONCLUSIONS
  We have shown that tonsillar management do not lead to improve A-rate, and the radiologic changes of posterior fossa volume do not relate with radiologic improvement of syringomyelia. PFD without tonsillar management is sufficient to improve syringomyelia. The longer syrinx, the more A-rate improve in our study. However, a wider craniectomy is unrelated to A-rate. In cases of recurrent patients, we obtained good results with tonsillar management or syringosubarachnoid shunt.
authors.affiliation: Department of Pediatric Neurosurgery, Brain Research Institute, College of Medicine, Yonsei University, Seoul, South Korea.
authors.forename: Young Seok
authors.initials: YS
authors.lastname: Park
authors.forename: Dong-Seok
authors.initials: DS
authors.lastname: Kim
authors.forename: Kyu-Won
authors.initials: KW
authors.lastname: Shim
authors.forename: Jung-Hee
authors.initials: JH
authors.lastname: Kim
authors.forename: Joong-Uhn
authors.initials: JU
authors.lastname: Choi
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001139:Arnold-Chiari Malformation / Q000150:complications / Q000601:surgery*; D002531:Cerebellum / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D003388:Cranial Fossa, Posterior / Q000601:surgery*; D003399:Craniotomy; D019299:Decompression, Surgical; D005260:Female; D006257:Head / Q000473:pathology / Q000601:surgery; D006801:Humans; D007223:Infant; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013595:Syringomyelia / Q000209:etiology / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult