title: Visualization of the diaphragm muscle with ultrasound improves diagnostic accuracy of phrenic nerve conduction studies.
abstract: BACKGROUND
  Evaluation of phrenic neuropathy (PN) with phrenic nerve conduction studies (PNCS) is associated with false negatives. Visualization of diaphragmatic muscle twitch with diaphragm ultrasound (DUS) when performing PNCS may help to solve this problem.
  
  
  METHODS
  We performed bilateral, simultaneous DUS-PNCS in 10 healthy adults and 12 patients with PN. The amplitude of the diaphragm compound muscle action potential (CMAP) (on PNCS) and twitch (on DUS) was calculated.
  
  
  RESULTS
  Control subjects had <38% side-to-side asymmetry in twitch amplitude (on DUS) and 53% asymmetry in phrenic CMAP (on PCNS). In the 12 patients with PN, 12 phrenic neuropathies were detected. Three of these patients had either significant side-to-side asymmetry or absolute reduction in diaphragm movement that was not detected with PNCS. There were no cases in which the PNCS showed an abnormality but the DUS did not.
  
  
  CONCLUSIONS
  The addition of DUS to PNCS enhances diagnostic accuracy in PN.
authors.affiliation: Department of Neurology, University of Rochester, Rochester, New York, USA.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Johnson
authors.forename: Michael
authors.initials: M
authors.lastname: Utz
authors.forename: Erica
authors.initials: E
authors.lastname: Patrick
authors.forename: Nicole
authors.initials: N
authors.lastname: Rheinwald
authors.forename: Marlene
authors.initials: M
authors.lastname: Downs
authors.forename: Nuran
authors.initials: N
authors.lastname: Dilek
authors.forename: Vikram
authors.initials: V
authors.lastname: Dogra
authors.forename: Eric L
authors.initials: EL
authors.lastname: Logigian
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003964:Diaphragm / Q000000981:diagnostic imaging* / Q000294:innervation; D004568:Electrodiagnosis / Q000379:methods*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D010791:Phrenic Nerve / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012189:Retrospective Studies; D014463:Ultrasonography
keywords: diaphragm ultrasound; nerve conduction studies; phrenic nerve conduction study; phrenic neuropathy; ultrasound