Migraine is a unique neurologic condition, in that a person can't prove they have it and there are few objective tools neurologists have to guide their diagnostic process. The recognition of the role of the vasoactive peptide calcitonin gene-related peptide (CGRP) in the 1990s changed the way many researchers and clinicians conceptualized migraine. Subsequent studies have used CGRP as a human model for migraine, and most recently pituitary adenylate cyclase–activating polypeptide 38 (PACAP-38) has also been recognized for its important role in migraine propagation. All of the existing data have been in adults, and no studies until now have specifically investigated the presence of these peptides in children with migraine.
Pediatric migraine is unique in a number of ways. Children with migraine present less unilaterally, the duration of their attacks is typically shorter, and the associated symptoms can often be more prominent than the headache pain during an attack. There are unique pediatric migraine subtypes that are exceptionally rare in adults, such as periodic paralysis attacks and abdominal migraine. For this reason, it is not entirely clear whether the same biomarkers of disease in adults would also be present in the pediatric population.
In the study by Liu and colleagues , the investigators enrolled 76 pediatric patients with migraine (the diagnosis was confirmed by at least two neurologists). Patients were excluded if there was any analgesic medication use over the past 2 months; if there was concern for secondary headache; or any underlying mood disorders, congenital disease, or other major medical conditions. An additional 77 controls were matched for age and sex. Blood was collected from all participants after an 8-hour fast to avoid collecting after potentially ingesting a food trigger. Blood samples were obtained during an ictal period (within 8 hours of a migraine attack) as well as interictally (not taken if the participant had a migraine attack within the past 24 hours).
The plasma CGRP and PACAP-38 levels were significantly higher in pediatric patients with migraine than in those without a migraine history, in both the ictal state and the interictal state. Among patients with migraine, there was a nonsignificant trend toward a higher CGRP level in the ictal phase, and no difference in these phases with PACAP-38. There was no difference in the CGRP or PACAP-38 levels between participants with and those without aura. When different aura groups were compared (with the participants separated on the basis of a history of motor vs vision vs sensory aura), no difference was seen among the different aura groups. Binary logistic regression testing and analysis of variance also showed that CGRP and PACAP-38 are independent risk factors for pediatric migraine, and specific levels of each were associated with an 11 and a 13 times increased risk, respectively.
Biomarker testing is still not clinically performed for migraine either in adults or children. This is primarily due to cost and the fact that most commercially available laboratories do not currently offer these tests. The results above do shed additional light on migraine pathogenesis and indicate that the phenotypic differences seen in pediatric migraine are less likely related to differences in brain function in children.
Levetiracetam is a commonly used antiepileptic medication. Prior studies have investigated the use of this medication for migraine, both acutely and preventively. Other antiepileptic medications have been shown to be very effective for both of these indications. Topiramate and valproic acid are both commonly used for migraine: topiramate primarily preventively and valproic acid both for prevention and, commonly in its intravenous form, for acute treatment. Levetiracetam is currently not commonly used for migraine, although some institutions will use the intravenous formulation for severe refractory status migrainosus.
Evers and colleagues investigated the open label use of levetiracetam for migraine prevention at a dose of 1000 mg twice daily in a small population of 50 persons. The study participants were started at a dose of 500 mg twice daily for 4 weeks, then increased to 1000 mg twice daily for a total of 12 weeks. The primary endpoint was migraine attack frequency during the last 4 weeks of treatment.
A 50% reduction in headache frequency was seen in 46% of the enrolled participants. The most common reported side effects were sedation, nausea, and weight gain, as well as cognitive change (five patients dropped out of the study owing to intolerance of the treatment). A post hoc comparison between the patients with and without response to levetiracetam revealed that those who responded were those with a less refractory history — they had tried fewer medications and were using fewer acute medications as well.
The antiepileptic class of preventive migraine medications is notorious for issues with tolerance. Among the antiepileptic medications, levetiracetam is commonly used but also commonly stopped owing to mood and cognitive complaints. Although the researchers here do show early evidence for a moderate amount of efficacy for treating migraine, the fact that there are now more migraine-specific preventive medications that are better tolerated and overall more efficacious make choosing levetiracetam for prevention less necessary.
Now that there are multiple classes of migraine-specific acute medications, the outstanding question remains: What are the potential benefits and drawbacks for the use of triptans compared with the oral CGRP receptor antagonists (gepants)? Most obviously, triptan medications are contraindicated in patients with significant vascular risk factors; however, what is not known is whether some of the other adverse events associated with triptans are more or less prominent with gepant use. Lee and colleagues conducted a meta-analysis of 15 studies to review this data.
A previous meta-analysis demonstrated that oral CGRP receptor antagonists are more effective than placebo, but less effective than triptans against acute migraine. The most common intolerances for gepants are nausea, somnolence, and dry mouth, but the safety and tolerability of gepants have not been compared with that of triptans. These authors pooled the data on five gepant medications (BI44370TA, MK-3207, rimegepant, telcagepant, and ubrogepant). The primary outcome was incidence of treatment-related adverse events and the secondary outcome was the incidence of the specific intolerances of diarrhea, dizziness, dry mouth, fatigue, nausea, paresthesia, somnolence, upper abdominal pain, and vomiting.
Compared with placebo, the relative risk for any adverse event was found to be low, at 1.15, and the relative risk for treatment-related adverse events was only slightly higher, at 1.18. Gepants were found to be significantly more associated with an increased risk for fatigue, nausea, and somnolence vs placebo. Compared with triptans, the CGRP antagonists were associated with significantly less treatment-related adverse events as well as any adverse event. There was no significant difference in the incidence of diarrhea, nausea, and vomiting between the two groups.
This study helps elucidate some of the differences between the two classes of migraine-specific acute medications. As noted above, a prior meta-analysis did reveal some benefits with the triptan class, specifically better effectiveness. When choosing a better-tolerated medication for your patients, you may want to consider a gepant; when considering a stronger or more potent option, you might stick with a triptan.