الفهرس 
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Abstract
The diaphragm is the main respiratory muscle. Phrenic nerve provides the primary motor supply to the diaphragm. Phrenic nerve lesion may be due to compression by adjacent neoplastic masses, tumor of neural origin such as schwannomas, toxic or inflammatory neuropathies as GBS, or iatrogenic causes e.g., after coronary artery bypass grafting surgery. Phrenic nerve conduction study provides a sensitive indicator of phrenic nerve function when the nerve is affected either by local lesions or by generalized neuropathies. Only limited information has been published on normative data of phrenic nerve conduction study.
Our objective was to determine reference values of phrenic nerve conduction parameters in healthy population.
Seventy-three healthy individuals (47 men and 26 women) aged from 18 to 61 years participated in the study. Exclusion criteria included extremes of ages.
Motor conduction study of the phrenic nerve was performed bilaterally both during inspiration and expiration. The phrenic nerve was stimulated at the posterior border of the sternocleidomastoid muscle at the level of the cricoid cartilage. Recordings were made from both sternal and costal diaphragm (sternal and intercostal recordings).
Measured parameters were latency, amplitude, area and duration of the DCMAP at each recording site. Side-side differences were determined. Amplitude differences were expressed as a ratio between both sides.
The results of the study showed that the mean and the normative values of the measured parameters were generally comparable to those available in the literature.
The parameters of the recorded DCMAPs were overall significantly different between men and women, the right and left sides, inspiration and expiration, and sternal and intercostal sites.
Women had significantly shorter latency, lower amplitude and smaller area compared to men.
The latency and duration of the DCMAPs were significantly longer on the right side whereas the amplitude values (except from sternal recordings during expiration) were significantly higher on the left side. The area did not differ significantly between the two sides.
The latency of sternal DCMAPs and the duration and area of sternal and intercostal recordings were significantly shorter during inspiration. The amplitude was significantly higher during inspiration (higher lung volumes).
Parameters of the DCMAPs were significantly different between sternal and intercostal recordings. The latency of sternal recordings was significantly shorter with significantly larger amplitude and area compared to intercostal recordings both during inspiration and expiration. The duration did not differ significantly between the two recording sites.