The location of the PNI
The number of instances of PNI from the records reached n = 783
(studies: 48) while the precise location as to right superior or
inferior phrenic nerve was found in n = 627 (studies: 40). It was not
surprising that most PNI were most frequently found in RSPV.
Five-hundred eighteen PNI (82.6%) occurred in RSPV and 109 (17.4%) in
RIPV (p < 0.005). In the CMAP/no-CMAP group, 206 were found in
RSPV (77.4%), 60 in RIPV (23.6%), 312 in RSPV (86.4%), and 49 in RIPV
(13.6%) based on results from the chi-square test (p = 0.003) as shown
in figure 4. It was impossible to collect precise data concerning the
transition of transient PNI to persistent PNI combined with vein
location in selected studies.