Aging of phrenic nerve conduction in the elderly

Objective We elucidated the possible relationship between age and conduction parameters of phrenic nerve in subjects above the sixth decade, comparing with the data from middle-age controls. Methods Diaphragmatic action potentials (DAPs) were recorded on bilateral hemithoraces of 41 volunteers aged 60–101 years (old group) and 25 volunteers aged 35–55 years (middle-age group). Statistical analyses were performed to assess the effects of aging on latency, latency corrected by size (Lat/Dist), amplitude, and the right–left difference of these DAP parameters. Results In all 61 subjects, age showed a significant quadratic correlation with latency and with Lat/Dist, and a linear correlation with amplitude. The right–left differences ranged from 0.0 to 14.5% for latency and from 6.5 to 112.4% for amplitude in the elderly. Conclusions The normal ranges of DAP parameters should be determined according to age. The left–right difference may be a useful reference in diagnosing unilateral phrenic nerve lesion. Significance The precise normal ranges of phrenic nerve conduction parameters presented will encourage investigations of neuropathies in subjects aged above 60.