Fig. 1

Reasons for prescreening failures for the five core sites. Diagnosis change = initial diagnosis of classical trigeminal neuralgia (TN), but later recorded as not classical trigeminal neuralgia (TN). Age > 80 years = noneligible because of age over the upper limit of 80 years per trial inclusion criteria. Language/distance/mobility = unable to participate in trial due to language barriers, distance from trial sites, or limited mobility prohibiting attendance at required study visits. Noncardiac medical problems = noneligible because of noncardiac medical issues prohibited under trial entry criteria. Cardiac problems = noneligible because of cardiac medical issues prohibited under trial entry criteria, including Fridericia’s formula requirements (< 450 ms in two of three electrocardiograms done at screening). Nonresponder/allergy = noneligible because known nonresponders to sodium channel blockers at therapeutic doses, or due to a history of hypersensitivity, or due to a history of drug or other allergy that contraindicates their participation