Referred Cutaneous Allodynia in a Migraine Patient without Simultaneous Headache

Efficacy of erenumab in chronic migraine patients with and without ictal allodynia

BACKGROUND

Ictal cutaneous allodynia, common in chronic migraine, is associated with reduced responses to acute treatment with triptans. Allodynia's impact on the efficacy of newer preventive treatments such as erenumab is unknown.

METHODS

Post-hoc subgroup analysis of a double-blind, randomized, placebo-controlled 12-week study of erenumab in chronic migraine, contrasting those with no allodynia with those with moderate-severe allodynia assessed with the Allodynia Symptom Checklist-12, was undertaken.

RESULTS

Of 648 randomized individuals with baseline Allodynia Symptom Checklist-12 scores, 386 (59.6%) had no allodynia and 153 (23.6%) had moderate-to-severe allodynia. Mean (standard deviation) baseline monthly migraine days were 17.6 (4.8) and 18.9 (4.3), respectively. Compared to placebo, the erenumab group had greater reductions in monthly migraine days and monthly acute migraine-specific medication days in both no allodynia and allodynia subgroups. Mean (95% confidence interval) treatment differences in change from baseline for monthly migraine days at week 12 were -2.5 (-3.7, -1.4) in the no allodynia subgroup and -3.3 (-5.3, -1.3) in the moderate-severe allodynia subgroup. Change in acute migraine-specific medication days were -3.3 (-4.3, -2.3) and -2.5 (-4.3, -0.8), respectively.

CONCLUSIONS

Erenumab's efficacy in reducing monthly migraine days and acute migraine-specific medication days in chronic migraine was not impacted by the presence of moderate-severe ictal allodynia.Trial registration: ClinicalTrials.gov NCT02066415.

An experimental model of headache-related pain

Migraine patients often demonstrate cutaneous allodynia, defined as a hypersensitivity of the skin to touch or mechanical stimuli that are normally innocuous. The allodynia sometimes begins intracranially and spreads, via unknown mechanisms, to extracranial regions. The goal of the study was to develop and validate a model of cutaneous allodynia triggered by dural inflammation for this aspect of pain associated with headaches. Inflammatory mediators (IM) were applied to the dura of non-anesthetized rats via previously implanted cannulas and sensory thresholds of the face and hindpaws were characterized. IM elicited robust and time-related facial and hindpaw allodynia which peaked after approximately 3 h. These effects were reminiscent of cutaneous allodynia seen in patients with migraine or other primary headache conditions, and were reversed by agents used clinically in the treatment of migraine. Facial and hindpaw allodynia associated with dural stimulation is a useful surrogate of allodynia associated with primary headache including migraine likely reflecting the development of central sensitization and may be exploited mechanistically for the development of novel therapeutic strategies for headache pain.

Acute and interictal allodynia in patients with different headache forms: an Italian pilot study

OBJECTIVE

To investigate allodynia in patients with different primary headaches.

BACKGROUND

Many migraineurs have allodynia during headache attacks; some may have allodynia outside attacks; allodynia may also be associated with other primary headaches.

METHODS

A total of 260 consecutive primary headache patients presenting for the first time at a headache center, and 23 nonheadache controls answered written questions (subsequently repeated verbally) to determine the presence of acute and interictal allodynia.

RESULTS

We divided the patients into: episodic migraine (N = 177), subdivided into only migraine without aura (N = 114) and those sometimes or always reporting migraine with aura (N = 63); episodic tension-type headache (N = 28); chronic headaches (headache > or = 15 days/month, N = 52), including chronic migraine, chronic tension-type headache, and medication-overuse headache; and other headache forms (N = 3). Acute allodynia was present in 132 (50.7%), significantly more often in patients sometimes or always suffering migraine with aura, and those with chronic headache forms, compared to patients with migraine without aura and episodic tension-type headache. Interictal allodynia was present in 63 (24.2%) patients, with significantly higher frequency in those having migraine with aura attacks than controls and common migraine patients.

CONCLUSIONS

Allodynia is not specific to migraine but is frequent in all headache patients: acute allodynia was reported in half those interviewed and in over a third of patients in each headache category; interictal allodynia was reported by nearly 25%.

Identifying cutaneous allodynia in chronic migraine using a practical clinical method

Cutaneous allodynia is common in migraine. In the majority of previous studies on allodynia in migraine, only patients with episodic migraine (EM) were included. Little is known on patterns of allodynia in chronic migraine (CM). Since the presence of allodynia is associated with a poor response to triptans, a clinically practical method to test migraine patients for allodynia would be useful to the clinician. The aim of this study was to assess the prevalence of dynamic mechanical (brush) allodynia (BA) in CM, using a clinically practical method. Eighty-nine CM patients were prospectively recruited. Patients were given a structured questionnaire regarding demographic data and migraine characteristics. Allodynia was tested using a 10 x 10-cm gauze pad to brush various areas of the skin lightly. The prevalence of BA in the entire study population and in different patient subgroups was calculated. BA was present in 42.7% (38/89) of the patients. The presence of allodynia was unrelated to age, disease duration or to the occurrence of an acute headache exacerbation at the time of testing. Allodynia was positively associated with a history of migraine aura. BA was most common in the cephalic area, but was also seen in cervical dermatomes. BA is common in CM and, unlike in EM, is not significantly affected by the occurrence of an acute headache exacerbation. This suggests that central trigeminovascular neurons are chronically sensitized in patients experiencing migraine headache >15 days per month. The testing of BA in the clinical setting is possible using a simple and brief approach. It allows the clinician to determine whether the patient is sensitized, a diagnosis that affects treatment decisions.