title: Syrinx resolution after posterior fossa decompression in patients with scoliosis secondary to Chiari malformation type I.
abstract: BACKGROUND
  Description of syrinx resolution after posterior fossa decompression (PFD) in patients with scoliosis secondary to Chiari malformation type I (CMI) and syringomyelia (SM) has been rarely reported in the literature. This study was performed to investigate the outcome of PFD in patients with scoliosis secondary to CMI and to identify potential predictive factors for better outcome after PFD.
  
  
  METHODS
  Patients with scoliosis secondary to CMI and SM, who had undergone PFD during the period 2000 through 2009, were recruited. Inclusion criteria were (1) age ≤ 18 years, (2) diagnosis of SM associated with CMI, (3) scoliosis as the first complaint, (4) having undergone preoperative and follow-up magnetic resonance imaging (MRI). Patients with acquired CMI anomalies or who had received syringosubarachnoid shunting were excluded. The maximal S/C ratio and syrinx length were measured to evaluate syrinx resolution after PFD. A 20% decrease in S/C ratio or length at the latest follow-up was defined as a significant radiographic improvement and complete resolution was used to describe the syrinx disappearing after PFD.
  
  
  RESULTS
  44 patients were recruited. Follow-up MRI was conducted for all 44 patients at 6 ± 3 months postoperatively, for 37 patients at 2 years ± 3 months, for 26 patients at 4 years ± 3 months, and for 15 patients at 6 years ± 3 months. 97.7% (43 of 44) of patients showed significant radiographic improvement by MRI. The distance of tonsillar descent (mm) was correlated significantly with the surgical outcome (r = 0.116, P = 0.013). Significant improvement was observed within 6 months postoperatively, with continued slow improvement after that.
  
  
  CONCLUSIONS
  Syringes showed significant improvement after PFD in most patients with scoliosis secondary to CMI. Resolution generally occurred within 6 months follow-up and continued at a slow rate for several years. In addition, the severity of tonsillar descent is a potential predictor for better improvement after standard PFD.
authors.affiliation: Department of Spine Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Zhongshan Road No. 321, Nanjing, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wu
authors.forename: Zezhang
authors.initials: Z
authors.lastname: Zhu
authors.forename: Jian
authors.initials: J
authors.lastname: Jiang
authors.forename: Xin
authors.initials: X
authors.lastname: Zheng
authors.forename: Xu
authors.initials: X
authors.lastname: Sun
authors.forename: Bangping
authors.initials: B
authors.lastname: Qian
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.forename: Yong
authors.initials: Y
authors.lastname: Qiu
mesh_terms: D000293:Adolescent; D001139:Arnold-Chiari Malformation / Q000150:complications* / Q000601:surgery*; D002648:Child; D003388:Cranial Fossa, Posterior / Q000601:surgery; D056424:Decompressive Craniectomy; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D012600:Scoliosis / Q000209:etiology* / Q000601:surgery; D013595:Syringomyelia / Q000150:complications* / Q000601:surgery*
references.citation: J Pediatr Orthop. 2008 Jan-Feb;28(1):128-33
references.pmid: 18157058
references.citation: Acta Neurochir (Wien). 2010 Jul;152(7):1117-27
references.pmid: 20440631
references.citation: Childs Nerv Syst. 2007 Nov;23(11):1239-50
references.pmid: 17639419
references.citation: Neurosurgery. 1995 Oct;37(4):673-8; discussion 678-9
references.pmid: 8559295
references.citation: Neurosurg Rev. 2004 Jul;27(3):173-7
references.pmid: 15138848
references.citation: Childs Nerv Syst. 2004 May;20(5):349-56
references.pmid: 15022006
references.citation: Clin Neurol Neurosurg. 2000 Jun;102(2):91-6
references.pmid: 10817895
references.citation: Childs Nerv Syst. 2008 Nov;24(11):1333-9
references.pmid: 18516609
references.citation: J Neurosurg. 2007 Mar;106(3 Suppl):187-95
references.pmid: 17465383
references.citation: Childs Nerv Syst. 2009 Apr;25(4):453-9
references.pmid: 19057907
references.citation: Neurosurgery. 1993 Nov;33(5):845-9; discussion 849-50
references.pmid: 8264881
references.citation: Neurosurgery. 2008 Jun;62(6):1307-13; discussion 1313
references.pmid: 18824997
references.citation: Pediatr Neurosurg. 1999 Sep;31(3):143-9
references.pmid: 10708356
references.citation: Neurosurgery. 1992 Aug;31(2):231-44; discussion 244-5
references.pmid: 1513429
references.citation: Childs Nerv Syst. 2008 Jul;24(7):833-40
references.pmid: 18205006
references.citation: Eur Spine J. 2011 Jul;20(7):1106-13
references.pmid: 21399931
references.citation: J Neurosurg Pediatr. 2008 Jul;2(1):42-9
references.pmid: 18590394
references.citation: Spine (Phila Pa 1976). 2002 Jan 15;27(2):E23-8
references.pmid: 11805676
references.citation: J Neurosurg. 2003 Aug;99(2):291-6
references.pmid: 12924703
references.citation: Semin Pediatr Neurol. 1997 Sep;4(3):179-91
references.pmid: 9323788
references.citation: J Neurosurg Pediatr. 2008 Feb;1(2):118-23
references.pmid: 18352779
references.citation: Neurosurg Focus. 2001 Jul 15;11(1):E3
references.pmid: 16724813
references.citation: Neurosurgery. 2000 Jun;46(6):1384-9; discussion 1389-90
references.pmid: 10834643
references.citation: Neurosurgery. 2004 Jun;54(6):1430-4; discussion 1434-5
references.pmid: 15157300
references.citation: Spine (Phila Pa 1976). 1997 Jun 15;22(12):1313-7; discussion 1318
references.pmid: 9201833
references.citation: Neurosurg Clin N Am. 2007 Jul;18(3):549-68
references.pmid: 17678754
references.citation: Neurosurgery. 1995 Aug;37(2):214-8
references.pmid: 7477771