Phrenic Nerve Conduction in Healthy Subjects.

Abstract

Assessment of diaphragm compound muscle action potential by noninvasive phrenic nerve stimulation at the neck is well described. However, normal values in a large cohort of healthy subjects are lacking. Our objective was to determine reference values of phrenic nerve conduction in healthy subjects. We recruited 155 healthy subjects (25-79 years old) and measured mean amplitude (PhrenAmp) and latency (PhrenLat) of motor responses according to Bolton's method. The lower limit for PhrenAmp was 0.28 and 0.25 mV and the upper limit for PhrenLat was 8.41 and 8.56 ms for right and left side, respectively. PhrenLat was correlated with age. PhrenAmp, PhrenLat and area were significantly higher in men. Tolerance to phrenic nerve stimulation was excellent. Our study provides normative values of phrenic nerve motor responses in a large cohort of healthy subjects and identifies age and sex as factors of variation. Muscle Nerve 59:451-456, 2019.