Assessment of patient preference for constant voltage and constant current spinal cord stimulation.

Objectives:   Spinal cord stimulation devices control energy by generating either constant voltage (CV) pulses or constant current (CC) pulses. This study aimed to investigate: 1) whether patients feel differences between CV and CC stimulation; 2) if patients prefer CV or CC stimulation.

Methods:   Fourteen patients blinded to the type of pulse generation received 20 randomized pairs of 15-sec pulse trains (CC-CV, CV-CC, CV-CV, or CC-CC). Patients identified whether the pairs were the same or different, and if they preferred the first or second train.

Results:   There was no difference in charge-per-pulse input between CV and CC modes. Patients performed at chance level in identifying identical pairs (55.7 ± 24.1% correct, 10 trials), and slightly better in identifying different pairs (67.1 ± 25.2% correct, 10 trials). No patients correctly identified all pairs. Patients were categorized based on their performance in this task. Only three patients fell into a category where preference could be established with some confidence with respect to the group averages. Two of these patients preferred CV, while one patient preferred CC.

Conclusion:   The lack of patient ability to discriminate in this preliminary investigation suggests that patient preference for a stimulation type should not be the key determining factor in choosing a spinal cord stimulation system.