Beyond Pain: The Effects of OnabotulinumtoxinA Therapy on Sensitization and Interictal Symptoms in Chronic Migraine

Chronic migraine is a disease with a high burden on patients from both a working and quality of life point of view. The pathophysiology of this subtype of migraine is due to several factors, such as medication overuse. Nevertheless, the detrimental recurring of headache attacks with central and peripheral sensitization plays a central role and explains some additional symptoms complained about by these patients even in the interictal phase. OnabotulinumtoxinA is a therapy indicated for chronic migraine since it has proven to reduce peripheral sensitization, showing even efficacy on central symptoms. The aim of this narrative review is to present the current evidence regarding the effect of OnabotulinumtoxinA on sensitization and interictal symptoms.

Effects of OnabotulinumtoxinA on Allodynia and Interictal Burden of Patients with Chronic Migraine

BACKGROUND

We primarily aimed to ascertain whether treatment with OnabotulinumtoxinA (BoNTA) might influence the extent of the interictal burden and cutaneous allodynia in patients with chronic migraine (CM).

METHODS

Seventy CM patients, who received three consecutive cycles of BoNTA, were studied. The interictal burden was assessed with the Migraine Interictal Burden Scale (MIBS-4), while cutaneous allodynia was examined with the Allodynia Symptom Checklist (ASC-12) together with PI-NRS VAS to obtain hair brushing scores, and then these were compared from baseline (T0) to the last efficacy evaluation follow-up (T1). Efficacy outcomes, mostly mean headache days (MHD) and "Headache Impact Test" scores, were also assessed between T0 and T1.

RESULTS

BONTA improved the interictal burden, with a decrease in MIBS-4 scoring by an average of -7 at T1, compared to baseline (p < 0.001). The percentage of patients with a moderate/severe interictal burden was substantially decreased. Likewise, BoNTA reduced the extent of cutaneous allodynia, with a significant reduction in both the ASC-12 (1 vs. 6; p < 0.001) and PI-NRS VAS (1 vs. 5; p < 0.001) to hair brushing median scores at T1, compared to baseline. Reduced MHD rates were significantly associated with a smaller interictal burden at T1. The efficacy of BoNTA, with a significant reduction in MHD and HIT-6 scores at T1 compared to T0, was re-confirmed.

CONCLUSIONS

BoNTA resulted in a statistically significant reduction in the interictal burden and also improved cutaneous allodynia. The reduction in ictal burden was associated with the down-scaling of the interictal burden. Hence, BoNTA improved the full spectrum of migraine impairment by diminishing the clinical expression of central sensitization.

Changes in migraine interictal burden following treatment with galcanezumab: Results from a phase III randomized, placebo-controlled study

OBJECTIVE

To evaluate changes in interictal burden with galcanezumab versus placebo in patients with episodic (EM) or chronic migraine (CM).

BACKGROUND

The disruptive effects of migraine occur both during attacks (ictal period) and between attacks (interictal period), affecting work, school, family, and social life. Migraine clinical trials typically assess ictal burden endpoints, neglecting interictal burden.

METHODS

CONQUER was a 3-month, double-blind study that randomized adult patients with EM or CM who had experienced failure of two to four standard-of-care migraine preventive medication categories to receive monthly galcanezumab (n = 232) or placebo (n = 230), followed by 3 months of open-label galcanezumab. The mean change in interictal burden, a secondary objective, was measured using the four-item Migraine Interictal Burden Scale (MIBS-4). The total score for MIBS-4 can range from zero to 12, with scores ≥5 indicating severe interictal burden. Post hoc analyses evaluated shifts in MIBS-4 severity categories and item-level improvement.

RESULTS

The MIBS-4 total score indicated severe interictal burden at baseline (mean [SD]: all patients, 5.5 [3.5]; EM, 5.0 [3.4]; CM, 6.2 [3.5]). Reductions in the MIBS-4 score were significantly greater with galcanezumab versus placebo at Month 3 (mean [SE]: all patients -1.9 [0.2] vs. -0.8 [0.2], p < 0.0001; EM, -1.8 [0.3] vs. -1.1 [0.3], p = 0.033; CM, -1.8 [0.4] vs. -0.3 [0.4], p < 0.001), with further improvement at Month 6 after all patients had received galcanezumab (mean [SE]: all patients, -2.4 [0.2] vs. -2.0 [0.2]; EM, -2.3 [0.3] vs. -2.2 [0.3]; CM, -2.1 [0.4] vs. -1.5 [0.4]). The percentage of patients with severe interictal burden decreased substantially for the galcanezumab-treated patients, from 59% (137/232) at baseline to 27% (58/217) at Month 6 (EM from 51% [70/137] to 23% [30/131]; CM from 71% [67/95] to 33% [28/86]).

CONCLUSION

In addition to the known efficacy of galcanezumab in the ictal period, these findings suggest treatment with galcanezumab results in a significant reduction in interictal burden.

The not so hidden impact of interictal burden in migraine: A narrative review

Migraine is a highly prevalent neurological disease of varying attack frequency. Headache attacks that are accompanied by a combination of impact on daily activities, photophobia and/or nausea are most commonly migraine. The headache phase of a migraine attack has attracted more research, assessment tools and treatment goals than any other feature, characteristic, or phase of migraine. However, the migraine attack may encompass up to 4 phases: the prodrome, aura, headache phase and postdrome. There is growing recognition that the burden of migraine, including symptoms associated with the headache phase of the attack, may persist between migraine attacks, sometimes referred to as the "interictal phase." These include allodynia, hypersensitivity, photophobia, phonophobia, osmophobia, visual/vestibular disturbances and motion sickness. Subtle interictal clinical manifestations and a patient's trepidation to make plans or commitments due to the unpredictability of migraine attacks may contribute to poorer quality of life. However, there are only a few tools available to assess the interictal burden. Herein, we examine the recent advances in the recognition, description, and assessment of the interictal burden of migraine. We also highlight the value in patients feeling comfortable discussing the symptoms and overall burden of migraine when discussing migraine treatment needs with their provider.

Evaluating migraineurs' preferences for migraine treatment outcomes using a choice experiment

OBJECTIVE

The impact of migraines on patients is commonly divided between the level of impairment associated with headache symptoms (headache phase) and the quality-of-life effects immediately following the headache (post-headache phase). Evaluations of migraineurs' productivity losses and health-related quality of life have provided an understanding of the burden associated with the headache and post-headache symptoms, but do not quantify the relative importance of each phase from a patient perspective. In this study, we evaluated migraineurs' willingness to accept trade-offs among symptom severity in the headache and post-headache phases, symptom duration in the headache and post-headache phases, and symptom-free time within a general-preference theoretic framework.

METHODS

We administered a choice-format, conjoint-analysis survey, also called a discrete-choice experiment, to a sample of migraineurs from a nationally representative online consumer panel. After inclusion and exclusion criteria were applied, 510 eligible subjects completed the survey. The survey elicited choices between pairs of migraine profiles describing symptom durations and symptom-free time for the headache and post-headache phase.

RESULTS

Migraineurs in our study were strongly affected by the pain associated with the headache phase. However, experiencing difficulty with daily social and family activities in the post-headache phase also had a statistically significant impact on migraineurs' perceived level of well-being. Migraineurs reported that hypothetical treatments that limited the duration of headache symptoms without allowing them to resume their daily activities for 16 hours after a headache, on average, were less than half as good as treatments that limited both headache and post-headache symptoms.

CONCLUSION

Our results suggest that treatments that relieve and shorten symptoms during the post-headache phase can offer significant benefits to migraineurs.