title: Phrenic nerve injury after radiofrequency ablation of lung tumors: retrospective evaluation of the incidence and risk factors.
abstract: OBJECTIVE
  To retrospectively investigate the incidence of and risk factors for phrenic nerve injury after radiofrequency (RF) ablation of lung tumors.
  
  
  METHODS
  The study included 814 RF ablation procedures of lung tumors. To evaluate the development of phrenic nerve injury, chest radiographs obtained before and after the procedure were examined. Phrenic nerve injury was assumed to have developed if the diaphragmatic level was elevated after the procedure. To identify risk factors for phrenic nerve injury, multiple variables were compared between cases of phrenic nerve injury and randomly selected controls by using univariate analyses. Multivariate analysis was then performed to identify independent risk factors.
  
  
  RESULTS
  Evaluation of phrenic nerve injury from chest radiographs was possible after 786 procedures. Evidence of phrenic nerve injury developed after 10 cases (1.3%). Univariate analysis revealed that larger tumor size (≥ 20 mm; P = .014), proximity of the phrenic nerve to the tumor (< 10 mm; P < .001), the use of larger electrodes (array diameter or noninsulated tip length ≥ 3 cm; P = .001), and higher maximum power applied during ablation (≥ 100 W; P < .001) were significantly associated with the development of phrenic nerve injury. Multivariate analysis demonstrated that the proximity of the phrenic nerve to the tumor (< 10 mm; P < .001) was a significant independent risk factor.
  
  
  CONCLUSIONS
  The incidence of phrenic nerve injury after RF ablation was 1.3%. The proximity of the phrenic nerve to the tumor was an independent risk factor for phrenic nerve injury.
authors.affiliation: Department of Radiology, Okayama University Medical School, 2-5-1 Shikatacho, Kita-ku, Okayama 700-8558, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Matsui
authors.forename: Takao
authors.initials: T
authors.lastname: Hiraki
authors.forename: Hideo
authors.initials: H
authors.lastname: Gobara
authors.forename: Mayu
authors.initials: M
authors.lastname: Uka
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Masaoka
authors.forename: Akihiro
authors.initials: A
authors.lastname: Tada
authors.forename: Shinichi
authors.initials: S
authors.lastname: Toyooka
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Mitsuhashi
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Mimura
authors.forename: Susumu
authors.initials: S
authors.lastname: Kanazawa
mesh_terms: D000328:Adult; D000368:Aged; D017115:Catheter Ablation / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D059348:Peripheral Nerve Injuries / Q000000981:diagnostic imaging / Q000453:epidemiology*; D010791:Phrenic Nerve / Q000000981:diagnostic imaging / Q000293:injuries*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden