Soonwook Kwon1, Ju-Hong Min2, Hye-Jin Cho1, Byung-Euk Joo1, Eun Bin Cho1, Jin Myoung Seok1, Min-Ji Kim3, Byoung Joon Kim1. 1. Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. 2. Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: juhongm@gmail.com. 3. Biostatistics and Clinical Epidemiology Center, Research Institute for Future Medicine, Samsung Medical Center, Seoul, Republic of Korea.
Abstract
OBJECTIVES: 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. CONCLUSION: We demonstrated that ALS patients had early respiratory dysfunction, despite normal PFT findings. SIGNIFICANCE: Phrenic latency and FVC (%) can be helpful to discriminate ALS patients with latent respiratory dysfunction from healthy subjects.
OBJECTIVES: 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, ALSpatients 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 ALSpatients from healthy subjects. CONCLUSION: We demonstrated that ALSpatients had early respiratory dysfunction, despite normal PFT findings. SIGNIFICANCE: Phrenic latency and FVC (%) can be helpful to discriminate ALSpatients with latent respiratory dysfunction from healthy subjects.