Table 2.
Published ultrasound studies of the vagus nerve in patients with Parkinson's disease.
| Study | Sample size PD/controls | PD disease duration [years] | Precision of ultrasound measurement | CSA definition | Left vagus CSA PD/controls | Right vagus CSA PD/controls | Significant difference PD vs. controls |
|---|---|---|---|---|---|---|---|
| Tsukita et al. (16) | 21/21 | 5 | 0.01 mm2 | Online tracing | 1.46/1.91 | 1.58/2.35 | Yes |
| Fedtke et al. (20) | 35/30 | N/A | 1 mm2 | Online tracing | 2.6/2.4 | 2.9/2.7 | No |
| Pelz et al. (18) | 35/35 | 10.6 | 0.1 mm2 | Offline tracing | 1.5/1.8 | 2.1/2.3 | Yes |
| Walter et al. (17) | 20/20 | 10.1 | 0.01 mm | Calculation | 0.69/0.87 | 0.64/1.04 | Yes |
| Laucius et al. (21) | 20/20 | 4.0 | N/A | Online | 1.17/1.13a | No | |
| Sijben et al. (22) | 31/51 | 7.9 | N/A | Online tracing | 2.10/1.90 | 2.54/2.24 | No |
| Sartucci et al. (19) | 20/20 | 10.1 | 1 mm2 | Online tracing | 1.87/5.6 | 2.37/6.0 | Yes |
| Present study | 63/56 | 0.67 | 0.01 mm2 | Offline tracing | 1.89/1.97 | 2.23/2.37 | No/Yesb |
Disease duration is defined as median- or mean time since diagnosis. Precision of ultrasound measurement depicts in how many decimals the measurements were extracted, that is, how exact the vagus caliber was defined. Cross-sectional area (CSA) of the vagus was defined by either (1) tracing the epineural rim on the ultrasound machine (online tracing), (2) by calculating the area of an ellipse based on longest diameter and the diameter perpendicular to the longest diameter, or (3) exporting images to dedicated “offline” software and tracing the epineural rim (offline tracing). CSA are presented as mean or median.
Average diameter in mm.
Sex-adjusted right vagus CSA was significantly reduced (see results section in the present paper).