title: Long-Term Outcomes After Small-Bone-Window Posterior Fossa Decompression and Duraplasty in Adults with Chiari Malformation Type I.
abstract: BACKGROUND
  Small-bone-window posterior fossa decompression with duraplasty is one of the popular surgical options for Chiari malformation type I, but its efficacy is controversial and the risk factors of clinical outcome remain unclear.
  
  
  METHODS
  The study cohort included 152 patients with Chiari malformation type I who received small-bone-window posterior fossa decompression at Beijing Tiantan hospital from January 2008 to September 2009. All patients underwent combined surgical procedures: a small-bone-window suboccipital decompression (diameter, 2.5-3 cm) and a C1 laminectomy (1.5- to 2-cm wide) followed by a duraplasty with an autologous graft. Clinical manifestations, radiologic features, and follow-up data during a 6-year span were analyzed. Risk factors associated with outcome were investigated by the use of χ(2) analysis and logistic regression analysis.
  
  
  RESULTS
  The average follow-up duration was 74 months. Symptoms were improved in 126 patients (82.9%), remained stable in 21 patients (13.8%), and deteriorated in 5 patients (3.3%). There was no mortality. Postoperative magnetic resonance imaging scans were available for all patients. Preoperatively, 112 patients were associated with syringomyelia, and the follow-up magnetic resonance images showed obvious reduction of syringomyelia in 73 patients (65.2%) and no significant change in 39 patients (34.8%). In addition, enlargement of the cistern magna was observed in 92 patients (85.2%). Regression analysis indicates preoperative motor dysfunction, brainstem herniation and basilar invagination may influence the clinical outcome (P < 0.05).
  
  
  CONCLUSIONS
  Small-bone-window posterior fossa decompression with duraplasty is an effective and safe treatment option with a low complication rate. Motor dysfunction, brainstem herniation, and basilar invagination are predictors of poor clinical prognosis.
authors.affiliation: Department of Neurosurgery, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, No. 6 Tiantan Xili, Dongcheng District, Beijing 100050, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Deng
authors.affiliation: Department of Neurosurgery, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, No. 6 Tiantan Xili, Dongcheng District, Beijing 100050, China.
authors.forename: Chenlong
authors.initials: C
authors.lastname: Yang
authors.affiliation: School of Clinical Medicine, Capital Medical University, No. 10 Xitoutiao, Youanmen, Fengtai District, Beijing 100069, China.
authors.forename: Jiahe
authors.initials: J
authors.lastname: Gan
authors.affiliation: Department of Neurosurgery, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, No. 6 Tiantan Xili, Dongcheng District, Beijing 100050, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Wu
authors.affiliation: Department of Neurosurgery, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, No. 6 Tiantan Xili, Dongcheng District, Beijing 100050, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.affiliation: Department of Neurosurgery, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, No. 6 Tiantan Xili, Dongcheng District, Beijing 100050, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Neurosurgery, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, No. 6 Tiantan Xili, Dongcheng District, Beijing 100050, China. Electronic address: xuhuxi@sina.com.
authors.forename: Yulun
authors.initials: Y
authors.lastname: Xu
mesh_terms: D000293:Adolescent; D000328:Adult; D001139:Arnold-Chiari Malformation / Q000601:surgery*; D015331:Cohort Studies; D003388:Cranial Fossa, Posterior / Q000601:surgery*; D004388:Dura Mater / Q000601:surgery* / Q000637:transplantation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007796:Laminectomy; D008279:Magnetic Resonance Imaging; D008297:Male; D061145:Microvascular Decompression Surgery / Q000379:methods*; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology / Q000473:pathology; D011379:Prognosis; D012307:Risk Factors; D016896:Treatment Outcome; D055815:Young Adult
keywords: Chiari malformation; Posterior fossa decompression; Small bone window; Syringomyelia; Tonsillar herniation