Table 3.
Exploration results (based on the final diagnosis).
| Group comparison | |||||||
|---|---|---|---|---|---|---|---|
| Total population | Definite SFN | Possible SFN | No SFN | “Definite SFN” and “No SFN” | “Definite SFN” and “Possible SFN” | “No SFN” and “Possible SFN” | |
| n = 245 | n = 102 | n = 53 | n = 90 | ||||
| Skin biopsy | |||||||
| IntraEpidermal nerve Fiber Density (fibers/mm) | 6.21 ± 3.41 | 4.61 ± 3.04 | 6.58 ± 4.01 | 7.83 ± 2.53 | <0.0001 | 0.0006 | 0.003 |
| Quantitative Sensory Testing (QST) | |||||||
| Perceptual threshold in the foot (°C) | 43.5 ± 4.25 | 44.48 ± 4.13 | 43.11 ± 4.18 | 42.62 ± 4.24 | 0.003 | 0.05 | 0.44 |
| Heat painful threshold in the foot (°C) | 46.94 ± 3.12 | 47.32 ± 3.2 | 47.06 ± 2.49 | 46.43 ± 3.31 | 0.03 | 0.08 | 0.52 |
| Perceptual threshold in the hand (°C) | 37.97 ± 4.09 | 38.84 ± 4.39 | 37.35 ± 3.38 | 37.34 ± 3.97 | 0.004 | 0.06 | 0.28 |
| Heat pain threshold in the hand (°C) | 45.09 ± 4.33 | 44.97 ± 4.74 | 45.4 ± 3.99 | 45.06 ± 4.04 | 0.88 | 0.87 | 0.72 |
| Quantitative sweat measurement (Q-Sweat) | |||||||
| Sweat volume (foot) (μL) | 0.32 ± 0.31 | 0.28 ± 0.28 | 0.35 ± 0.42 | 0.34 ± 0.28 | 0.05 | 0.45 | 0.31 |
| Sweat volume (proximal leg) (μL) | 0.45 ± 0.42 | 0.41 ± 0.44 | 0.5 ± 0.48 | 0.47 ± 0.36 | 0.02 | 0.15 | 0.61 |
| Sweat volume (forearm) (μL) | 0.39 ± 0.45 | 0.39 ± 0.53 | 0.39 ± 0.38 | 0.38 ± 0.4 | 0.18 | 0.30 | 0.99 |
| Electrochemical Skin Conductance (ESC) study | |||||||
| Mean conductance in the hands (μS) | 66.36 ± 15.62 | 60.09 ± 16.87 | 64.32 ± 15.95 | 74.67 ± 8.95 | <0.0001 | 0.20 | 0.0004 |
| Mean conductance in the feet (μS) | 75.73 ± 13.6 | 70.08 ± 16.63 | 76.71 ± 11.26 | 81.56 ± 6.88 | <0.0001 | 0.02 | 0.002 |
| Laser Evoked Potentials (LEP) | |||||||
| N2P2 complex amplitude (foot stimulation) (μV) | 18.78 ± 13.78 | 13.94 ± 13.41 | 19.68 ± 14.04 | 23.98 ± 12.13 | <0.0001 | 0.01 | 0.10 |
| N2 latency (foot stimulation) (ms) | 287.16 ± 56.48 | 308.27 ± 63.72 | 287.35 ± 64.93 | 269.29 ± 36.14 | 0.0005 | 0.06 | 0.33 |
| P2 latency (foot stimulation) (ms) | 398.13 ± 66.03 | 420.88 ± 70.7 | 401.85 ± 71.27 | 377.01 ± 51.62 | 0.0008 | 0.10 | 0.21 |
| N2P2 complex amplitude (hand stimulation) (μV) | 21.79 ± 16.09 | 18.48 ± 18.03 | 22.38 ± 15.29 | 25.45 ± 13.14 | 0.0003 | 0.07 | 0.22 |
| N2 latency (hand stimulation) (ms) | 221.85 ± 41.78 | 232.41 ± 50.16 | 215.5 ± 29.51 | 215.32 ± 37.02 | 0.01 | 0.15 | 0.51 |
| P2 latency (hand stimulation) (ms) | 320.27 ± 54.73 | 326.83 ± 66.96 | 317.81 ± 42.72 | 315.38 ± 47.3 | 0.52 | 0.79 | 0.62 |
| Cardio-vascular Testing (CVT) | |||||||
| Baseline systolic blood pressure (mmHg) | 124.45 ± 15.65 | 127.68 ± 16.36 | 120.64 ± 15.49 | 123.02 ± 14.31 | 0.01 | 0.001 | 0.21 |
| Baseline diastolic blood pressure (mmHg) | 73.46 ± 9.62 | 73.42 ± 10.16 | 72.83 ± 9.56 | 73.9 ± 9.08 | 0.83 | 0.86 | 0.71 |
| Valsalva ratio | 1.67 ± 1.06 | 1.72 ± 1.6 | 1.6 ± 0.25 | 1.65 ± 0.33 | 0.06 | 0.22 | 0.56 |
| Heart rate variation during deep breathing (bpm) | 17.98 ± 8.57 | 16.32 ± 8.96 | 18.67 ± 7.53 | 19.4 ± 8.47 | 0.01 | 0.03 | 0.74 |
| 30:15 ratio | 1.27 ± 0.19 | 1.23 ± 0.18 | 1.26 ± 0.16 | 1.31 ± 0.21 | 0.005 | 0.14 | 0.29 |
| SBP during isometric handgrip (mmHg) | 24.05 ± 15.17 | 23.4 ± 14.47 | 24.66 ± 17.97 | 24.45 ± 14.32 | 0.73 | 0.93 | 0.66 |
| DBP variation during isometric handgrip (mmHg) | 16.30 ± 8.95 | 16.86 ± 9.44 | 15.00 ± 9.10 | 16.41 ± 6.87 | 0.83 | 0.27 | 0.16 |
| SBP variation in upright posture (mmHg) | −3.42 ± 13.72 | −3.75 ± 14.46 | −5.38 ± 14.58 | −1.89 ± 12.25 | 0.49 | 0.75 | 0.37 |
| DB variation in upright posture (mmHg) | 3.31 ± 8.95 | 4.44 ± 7.55 | 1.47 ± 12.19 | 3.15 ± 7.98 | 0.53 | 0.44 | 0.68 |
| Ewing score | 0.72 ± 0.78 | 0.83 ± 0.84 | 0.91 ± 0.9 | 0.48 ± 0.56 | 0.006 | 0.69 | 0.008 |
SFN, Small Fiber Neuropathy, SBP, Systolic Blood Pressure, DBP, Diastolic Blood Pressure. Bold values refer to statistically significant results.