title: Spinal glomus (type II) arteriovenous malformations: a pooled analysis of hemorrhage risk and results of intervention.
abstract: BACKGROUND
  The natural history and treatment results for spinal glomus (type II) arteriovenous malformations (AVMs) remain relatively obscure.
  
  
  OBJECTIVE
  To calculate spinal glomus (type II) AVM hemorrhages rates and amalgamate results of intervention.
  
  
  METHODS
  We performed a pooled analysis via the PubMed database through May 2012, including studies with at least 3 cases. Data on individual patients were extracted and analyzed using a Cox proportional hazards regression model to obtain hazard ratios for hemorrhage risk factors.
  
  
  RESULTS
  The annual hemorrhage rate before treatment was 4% (95% confidence interval [confidence interval]: 3%-6%), increasing to 10% (95% CI: 7%-16%) for AVMs with previous hemorrhage. The hazard ratio for hemorrhage after hemorrhagic presentation was 2.25 (95% CI: 0.71-7.07), increasing to 13.0 within the first 10 years (95% CI: 1.44-118). The overall rates of complete obliteration were 78% (95% CI: 72%-83%) for surgery and 33% (95% CI: 24%-43%) for endovascular treatment. Long-term clinical worsening occurred in 12% of patients after surgical treatment (95% CI: 8%-16%) and in 13% after endovascular treatment (95% CI: 7%-21%). No hemorrhages occurred after complete obliteration. After partial surgical treatment, the annual hemorrhage rate was 3% (95% CI: 1%-6%); no hemorrhages were reported over 196 patient-years after partial endovascular treatment.
  
  
  CONCLUSIONS
  Spinal glomus (type II) AVMs with previous hemorrhage, particularly within 10 years, demonstrated a greater risk of hemorrhage. Complete obliteration and even partial endovascular treatment significantly decreased their hemorrhage rate.
authors.affiliation: Department of Neurological Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Bradley A
authors.initials: BA
authors.lastname: Gross
authors.forename: Rose
authors.initials: R
authors.lastname: Du
mesh_terms: D000328:Adult; D001165:Arteriovenous Malformations / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D016001:Confidence Intervals; D057510:Endovascular Procedures / Q000379:methods; D005260:Female; D006470:Hemorrhage / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D019635:Neurosurgical Procedures / Q000379:methods; D016016:Proportional Hazards Models; D016634:Radiosurgery; D012306:Risk; D013118:Spinal Cord Diseases / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome