gms | German Medical Science

Objective: Due to nerve damage, neuropathic pain often affects also other sensitive nerve fibre qualities. The aim of our study was to investigate the effects and possible differences of tonic and BurstDRTM stimulation (SCS) on the somatosensory profiles of patients with chronic neuropathic pain of one limb using quantitative sensory testing (QST).

Methods: We examined from 1/2017 until 12/2017 14 patients (9 female, 5 male; mean age 55,8 years, range 28-84 years) with previously implanted SCS systems for chronic neuropathic pain of one limb using QST (7 tests and 13 parameters for thermal, tactile, allodynia, pressure, vibration, and pain sensation). SCS was discontinued for 4 hours and the basic measurement was taken on the painful limb. Then in randomized fashion either tonic or BurstDRTM stimulation was performed for 30 minutes and the second measurement was performed. After another 30 min stimulation period using the remaining mode of stimulation, the third measurement was taken. The mean of each QST parameter was calculated for each stimulation method and compared. We also computed Z values using standard data and analyzed them for an approximation to zero, indicating a normalization tendency of the corresponding nerve fibre function.

Results: The QST raw data showed a statistically significant improved vibration sensation (Aβ) (P=0,019) and lower mechanical pain threshold (Aδ) (P=0,031) with BurstDRTM in comparison to tonic SCS. In the Z-value analysis, we found a significant improvement in vibration sensation and thus Aβ fibre function under BurstDRTM compared to tonic SCS. As a trend under activated SCS, we found an improvement in the tactile detection threshold (Aβ). With regard to the Z values, BurstDRTM seemed to be superior regarding the normalization tendency of the Aδ fibre function for the mechanical pain threshold and tonic SCS regarding the heat detection threshold (C) and cold pain threshold (C and Aδ).In the Z-profile of the examined patients, a normalization (Z-value within the 95% CI of the standard data) of individual parameters under active SCS was found.

Conclusion: Due to the small number of cases and the numerically small differences, the data we collected, does not permit any definite conclusions as to the influence of the different fibre functions by the various stimulation methods. However, we have been able to show that for some QST parameters and the fibre functions tested, normalization tendencies are recognizable.