Table 1. Characteristics of the 72 Patients with Clinical Polyneuropathy and Normal Large Fiber Tests According to Presence and Nature of Small Fiber Neuropathy.
| Clinical Characteristic | Normal | Small Fiber Sensory Neuropathy | P-values* |
| (IENFD≥5.4) | (IENFD <5.4) | ||
| (n = 48) | (n = 26) | ||
| Age (yr) | 49.2±13.1 | 57.0±12.9 | 0.015 |
| Female Gender (%) | 30 (63%) | 9 (35%) | 0.02 |
| Duration of symptoms (y) | 5.6±5.0 | 4.3±2.6 | 0.22 |
| Visual Analogue Scale for Pain (cm) | 7.0±2.2 | 7.3±2.2 | 0.59 |
| Sensory Examination Abnormal | 35 (73%) | 22 (85%) | 0.24 |
| Abnormal Pin Prick Exam | 25 (52%) | 13 (50%) | 0.86 |
| Abnormal Temperature Exam | 34 (71%) | 20 (77%) | 0.57 |
| Abnormal Light Touch Exam | 27 (56%) | 17 (65%) | 0.44 |
| Abnormal Vibration Exam | 19 (40%) | 13 (50%) | 0.39 |
| Abnormal Position Exam | 4 (8%) | 3 (12%) | 0.66 |
| Abnormal Deep Tendon Reflexes | 9 (19%) | 6 (23%) | 0.66 |
| IENFD | 9.9±2.9 | 3.3±1.7 | <0.0001 |
| Large Fiber Tests | |||
| Vibration Perception Threshold | |||
| Toe | 9.7±3.4 | 12.5±5.8 | 0.015 |
| Finger | 3.9±1.1 | 4.3±1.0 | 0.13 |
| Sural Nerve Amplitude (µV) | 16.0±7.4 | 10.5±5.9 | 0.002 |
| Sural Nerve Conduction Velocity (m/s) | 49.9±4.9 | 47.0±5.6 | 0.02 |
| Small Fiber Tests | |||
| CDT Foot (°C) | 26.7±6.4 | 21.6±9.1 | 0.007 |
| CDT Hand (°C) | 28.4±3.6 | 27.2±6.3 | 0.30 |
| HP Foot (°C) | 46.9±3.4 | 48.3±2.9 | 0.09 |
| HP Hand (°C) | 45.2±5.1 | 46.4±4.2 | 0.31 |
| LDI flare (cm) | 2.3±1.2 | 2.1±1.1 | 0.59 |
*
P values for dichotomous variables were calculated with the χ2 test and t-test was used for continuous variables.
For VPT, the normal values are highly age-dependent, but values ≤5 are normal in the finger and ≤15 Volts are normal in the toe. For VPT, data are available in 42 patients with normal IENFD and on 24 patients with SFSN.
Cut-offs for quantitative sensory thresholds are age-dependent although, generally a normal CDT would be ≥25°C. The normal values for heat pain are ≤50°C.