title: Vascular loops causing otological symptoms: a systematic review and meta-analysis.
abstract: OBJECTIVE
  To determine evidence for a relationship between vascular loops in contact with the vestibulocochlear nerve (CN VIII) and otological symptoms.
  
  
  METHODS
  Systematic review and meta-analysis of observational studies.
  
  
  METHODS
  Comprehensive search of MEDLINE, EMBASE, CINAHL, Cochrane Library, Clinical Evidence and Cochrane Central Register of Trials. Reference lists cross-referenced and authors contacted for missing data. No language restrictions.
  
  
  METHODS
  
  
  
  METHODS
  (1) compared symptoms in subjects with a vascular loop contacting CN VIII to subjects without (inter-subject control); (2) compared the prevalence of vascular loop in contact with CN VIII in symptomatic ears to contra-lateral asymptomatic ears (intra-subject control). Study quality systematically appraised.
  
  
  RESULTS
  Five case-control studies included. A statistically significant association was demonstrated for the prevalence of vascular loops in contact with CN VIII, with unilateral sensorineural hearing loss: pooled odds ratio (OR) 2.0 [95% confidence interval (CI): 1.5-2.6]. No association was demonstrated for non-pulsatile tinnitus. A highly significant association with vascular loops was shown in subjects having pulsatile tinnitus, with pooled OR: 78.8 (95% CI: 10.9-821.8).
  
  
  CONCLUSIONS
  Vascular loops in contact with CN VIII are a normal variant. Subjects with unilateral hearing loss were twice as likely to have these vascular loops in the symptomatic ear, than in the asymptomatic ear. Subjects with pulsatile tinnitus were 80 times more likely to have a contacting vascular loop than patients with non-pulsatile tinnitus, suggesting in some cases a causal relationship exists for pulsatile tinnitus, where surgical intervention may be occasionally indicated.
authors.affiliation: Department of ENT, Royal Devon and Exeter Hospital, Exeter, Devon, UK. neil@chadhanet.com
authors.forename: N K
authors.initials: NK
authors.lastname: Chadha
authors.forename: G M
authors.initials: GM
authors.lastname: Weiner
mesh_terms: D002536:Cerebral Arteries / Q000473:pathology*; D002550:Cerebral Veins / Q000473:pathology*; D006311:Hearing Disorders / Q000209:etiology*; D006801:Humans; D009408:Nerve Compression Syndromes / Q000209:etiology*; D000160:Vestibulocochlear Nerve Diseases / Q000209:etiology*