ICON trial
paresthesia
PARESTHESIA
The parent study (ICON trial) was an investigator-initiated, international, multicentre, randomised, double-blind, phase 3, electrical dose-controlled clinical trial. After 12 weeks of baseline observation, participants were randomised to 24 weeks of occipital nerve stimulation at either 100% or 30% of the individually determined range between paresthesia threshold and near-discomfort (double-blind phase of the study). In weeks 25–48, participants received individually optimised open-label ONS.At the beginning of the ICON study, it was assumed that 30% stimulation was clinically ineffective, yet caused the same paresthesia as the 100% stimulation and thus was useful as a blinded sham/placebo comparison. At the end of the study, however, 30% stimulation was found to be as effective as 100% stimulation. Blinding remained throughout the first double-blind phase of the study.