To the Editor.
—Dr Maizels and colleagues1 provide an interesting discussion of a hypothesized mechanism of migraine headache pain. However, I am concerned how, if at all, clinicians will use this information. The 55% efficacy of intranasal lidocaine is significantly lower than that reported for other headache medications (eg, prochlorperazine, 82%2; and sumatriptan, 75%3) administered in urgent care and emergency department settings. According to the authors, this efficacy may be inflated because the adverse effects of intranasal lidocaine likely allowed patients to discover when they received the study medication.Although the relapse rate of 42% for patients treated with intranasal lidocaine is comparable with that for sumatriptane, 5 of the 29 responders were lost to follow-up. Had these 5 patients experienced recurrence of their headaches, the relapse rate would be as high as 52%. Moreover, the authors note that adverse effects were limited to nasal and ocular burning and numbness,