Rizatriptan in Acute Treatment of Migraine in Patients With Unilateral Trigeminal-autonomic Symptoms.

Triptans are first choice drugs in the acute treatment of migraine and cluster headache. However, while in cluster headache the response rate to subcutaneous sumatriptan is 96%, around 30% of patients fail to respond to a particular triptan. Nonresponse is likely to be due to a variety of factors, including low and inconsistent absorption, inadequate dosing, and variability in individual response5. Timing of administration is also a crucial issue. In fact, an early treatment of the attack, when the pain is still mild, may increase the responders rate by circumventing the development of cutaneous allodynia (expression of central sensitization of pain pathway) during the course of the attack. Several studies have been performed in an attempt to genetically, psychologically and clinically characterize the triptan responders but failed to provide conclusive results. Nevertheless, we suggested that the presence of UAs during the migraine attack might predict a good response to triptans. UAs are common in migraine patients. They have been reported in almost one out of two migraineurs (45.8%) attending a tertiary headache centre and in more than one out of four (26.9%) in a population-based study. In an open study with sumatriptan 50 mg performed on 72 migraine patients with UAs, we described pain relief in 65.3% of the patients at 1 h and in 81.9% at 2 h, while pain-free in 30.6% at 1 h and in 61.1% at 2 h. We hypothesized a large-scale recruitment of peripheral neurovascular 5-HT1B/1D receptors consequent to the activation of the trigeminal-autonomic reflex in such patients. Our hypothesis has received further confirmation by the demonstration of higher levels of calcitonin gene-related peptide, neurokinin A and vasoactive intestinal peptide (the hallmark of the activation of the trigeminal autonomic reflex) in external jugular blood in rizatriptan responders than in non-responders. The investigators therefore postulate that migraineurs with UAs may respond better to