title: Usefulness of phrenic latency and forced vital capacity in patients with ALS with latent respiratory dysfunction.
abstract: OBJECTIVE
  The pulmonary function test (PFT) is a non-invasive and easily available technique to assess respiratory function in patients with amyotrophic lateral sclerosis (ALS); however, patients with dyspnea sometimes show normal PFT findings. Herein, we investigated whether phrenic nerve conduction study (NCS) and PFT are useful to evaluate respiratory function of patients with ALS with normal value ranges in the PFT.
  
  
  METHODS
  We prospectively enrolled 34 patients with definite or probable ALS, who showed FVC (%) ⩾80 of predicted and 78 healthy subjects. PFT and phrenic NCS were performed with the measurement of forced vital capacity (FVC, %), forced expiratory volumes in 1s (FEV1, %), FEV1/FCV ratio (%), and phrenic compound muscle action potential amplitude, and latency.
  
  
  RESULTS
  Compared to healthy controls, ALS patients showed delayed phrenic nerve latency and the decrease of FVC (%) (p=0.006 and p<0.0001, respectively). ROC curve analysis demonstrated that phrenic latency (AUC=0.7655) and FVC (%) (AUC=0.8239) discriminated ALS patients from healthy subjects.
  
  
  CONCLUSIONS
  We demonstrated that ALS patients had early respiratory dysfunction, despite normal PFT findings.
  
  
  CONCLUSIONS
  Phrenic latency and FVC (%) can be helpful to discriminate ALS patients with latent respiratory dysfunction from healthy subjects.
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Soonwook
authors.initials: S
authors.lastname: Kwon
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: juhongm@gmail.com.
authors.forename: Ju-Hong
authors.initials: JH
authors.lastname: Min
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Cho
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Byung-Euk
authors.initials: BE
authors.lastname: Joo
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Eun Bin
authors.initials: EB
authors.lastname: Cho
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jin Myoung
authors.initials: JM
authors.lastname: Seok
authors.affiliation: Biostatistics and Clinical Epidemiology Center, Research Institute for Future Medicine, Samsung Medical Center, Seoul, Republic of Korea.
authors.forename: Min-Ji
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Byoung Joon
authors.initials: BJ
authors.lastname: Kim
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D016022:Case-Control Studies; D003964:Diaphragm / Q000294:innervation / Q000502:physiology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D010791:Phrenic Nerve / Q000503:physiopathology*; D011446:Prospective Studies; D012372:ROC Curve; D011930:Reaction Time / Q000502:physiology*; D012129:Respiratory Function Tests; D014797:Vital Capacity / Q000502:physiology*
keywords: Amyotrophic lateral sclerosis; Forced vital capacity; Nerve conduction study; Phrenic nerve; Pulmonary function test; Respiratory dysfunction