Abstract
Objective:
To systematically review extracranial vasomotor reactions in patients with migraine, and to discuss potential overlaps with rosacea.
Background:
Autonomic manifestations are common in migraine and may reflect trigeminovascular system activation. Flushing during migraine attacks may indicate altered extracranial vasomotor reactivity which resembles that of the facial skin disorder rosacea.
Methods:
PubMed and EMBASE were searched for studies investigating extracranial vascular reactions in migraine and rosacea published until January 2018.
Results:
We uncovered 41 studies investigating extracranial circulation in migraine and 12 studies in rosacea. Skin temperature was generally lower on the forehead, nose and hands of migraine patients compared to controls. The superficial temporal artery (STA) showed greater amplitude variations in migraine patients compared to controls, and compression of either the STA or the common carotid artery during attacks led to transient pain relief in about one-third of the investigated patients. Facial skin blood flow was asymmetrical in migraine patients compared to healthy volunteers.
Conclusion:
Findings on extracranial microcirculation suggest an altered function of the autonomic nervous system in migraine patients. Similar signs of autonomic nervous system dysfunction are reported in rosacea. We suggest an overlap in autonomic and neurovascular pathophysiology in migraine and rosacea.
Introduction
Autonomic manifestations are common in migraine 1 and are thought to reflect activation of the trigeminal parasympathetic pathway during attacks. Research in the area has predominately focused on the cranial autonomic symptoms; conjunctival injection, lacrimation, nasal congestion, rhinorrhoea and eyelid oedema. 1 However, clinical observations have shown that patients may experience facial pallor during the initial stage of migraine attacks, followed by a sense of flushing and sometimes facial oedema. 2 A predisposition to severe flushing of the face, neck and chest following emotional stress has been described in migraine patients, 3 and a ‘red migraine’ comprising flushing and other autonomous symptoms was first described in 1867. 4
A link between migraine and the dermatologic disorder rosacea has been reported in recent studies. The conditions overlap in epidemiology 5 and may also share pathophysiological aspects. 6 Rosacea is a facial skin condition characterized by facial redness and flushing in the centrofacial area along with secondary symptoms such as facial oedema, papules and pustules, ocular symptoms and rhinophyma. Disease activity in rosacea has been connected to release of the neuropeptides calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide and pituitary adenylate cyclase-activating polypeptide, which are also active in migraine. 7 Infusion with CGRP induces flushing in both healthy individuals and migraine patients and interestingly, pretreatment with CGRP receptor antagonist in healthy volunteers blocks flushing in 100% of the participants. 8
Clinical observations have prompted further research in the extracranial vasomotor reactions in migraine patients through facial skin thermography, forehead skin blood flow measurements, pulsation measurements of the superficial arteries and estimation of forehead sweating as markers of autonomic dysfunction. 9 –11 The wide range of investigations and methods have resulted in very different and occasionally conflicting results, complicating direct comparison.
The purpose of this systematic review was to identify and categorise studies that investigated vasomotor reactions in migraine patients and discuss the next steps necessary in further illuminating facial vasomotor mechanisms in migraine. Furthermore, we sought to identify studies in rosacea with the same focus, to reveal potential overlaps in vasomotor reactions between the two disease entities. Investigations of facial blood flow and temperature in rosacea patients are sparse and inconclusive, and we suggest that studying extracranial vasomotor reactions in both rosacea and migraine patients may help in understanding the possible link between the two disorders.
Methods
Systematic review on migraine
A systematic literature search was performed using PubMed with the keywords (Migraine*) AND (facial OR face) AND (flow OR temperature OR circulation OR flushing OR heat). We furthermore searched EMBASE using the following 15 strings: 1:’exp migraine//’; 2:’facial.mp.’; 3:’extracranial.mp.’; 4:’blood flow.mp.’; 5: ’circulation.mp.’; 6: ’temperature.mp.’; 7: ’(review or meta-analysis or metaanalysis).m.titl.’; 8: ’(animal/ or nonhuman/) not human/’; 9: ’flushing.mp.’; 10: ’2 or 3’; 11: ’4 or 5 or 6 or 9’; 12: ’10 and 11’; 13: ’1 and 12’; 14: ’13 not 7’; 15: ’14 not 8’.
Search terms and in-/exclusion criteria were predefined (NW, CEC and MA). The review was conducted in accordance with the PRISMA guidelines (available at: http://www.prisma-statement.org/). The PubMed search was done on 2 March 2017 and the EMBASE search was finished on 19 July 2017. The PubMed search was repeated on 15 January 2018 in order to uncover any new relevant research in the area published in the time since our initial search was performed. Duplicates were extracted from the search and results were reviewed independently by two reviewers (NW and CEC), first by title and abstract for relevance, and then full text to confirm eligibility for this review. Disagreements were resolved through discussion.
Eligible articles were defined as experimental studies in patients with headache or headache-prone subjects, with focus on facial and/or extracranial circulation or temperature. Articles were excluded if they described animal studies or were published in other languages than English. Review articles, meta-analyses, editorials and conference abstracts were also excluded. Reference lists of included papers were also reviewed to uncover potentially missed articles throughout the initial search.
Systematic review on rosacea
A systematic literature search was also performed for rosacea by searching PubMed for references published any time before 9 January 2018 with the following search string: ‘Rosacea AND (flow OR temperature OR circulation OR heat) AND english[language] NOT review[publication type]’. Only human studies were included, and reference lists were screened for additional papers.
Results
Migraine: Search results
The PubMed search on migraine returned 144 articles, and 219 articles were identified through EMBASE. After removing duplicates, we were left with 308 original articles of which 33 were eligible for this article as they examined extracranial vasomotor responses in migraine patients. Eight additional studies were included after reviewing reference lists, resulting in a total of 41 studies eligible for review. The repeated search in January 2018 uncovered five new articles, but all were excluded because they were either animal studies or did not investigate extracranial circulation (Figure 1). The publications included in this review studied extracranial circulation in headache patients. Outcome variables were grouped in the following four categories: facial temperature; measurements of the superficial temporal artery (STA), both during attacks and during stress; compression of the STA or common carotid artery (CCA) during migraine attacks; and facial skin blood flow measurements. Results of the individual studies are depicted in Table 1.

Flow diagram of search and article selection for both migraine and rosacea. Modified from Moher et al. 71
Overview of studies on migraine listed according to topic investigated; facial temperature, measurements in the STA, compression of STA/CCA during migraine attacks and facial skin blood flow.
M: migraine, unspecified; TTH: tension type headache; STA: superficial temporal artery; HC: healthy control; MA: migraine with aura; MO: migraine without aura; BPV: blood pulse volume; CCA: common carotid artery; ECA: external carotid artery; ICA: internal carotid artery; MCA: middle cerebral artery; OA: ophthalmic artery; PCA: posterior ciliary artery; CRA: central retinal artery; VA: vertebral artery; MRM: menstrually related migraine; IHS: International Headache Society.
a Diagnosed according to IHS criteria.
b Study depicted more than once in table.
Rosacea: Search results
The search on rosacea identified 49 publications; 11 of these were relevant for review, investigating temperature and/or blood flow in rosacea. One additional article was found after screening reference lists. Baseline skin temperatures were similar in patients with erythematotelangiectatic rosacea (ETR) 12,13 and papulopustular rosacea (PPR) 12 compared to controls. Blood flow in lesioned skin, however, was higher compared to the blood flow in the skin of healthy controls (HCs). 12,14
Discussion
Migraine
Facial temperature
Facial skin temperature may be used as a measure of facial skin perfusion, with changes in temperature being directly proportional to changes in perfusion. 15 The assessment of facial skin temperature through infrared thermography was first introduced to study cerebrovascular disorders in 1965, 16 and has since evolved into a very accurate method for obtaining absolute skin temperatures. 15 Some studies included in this analysis were made with thermistors, temperature trainers, thermocouplers or older versions of infrared temperature equipment which leaves comparisons susceptible to differences in sensitivity in measurement variability.
A study of 161 healthy volunteers determined facial temperatures according to region from highest temperature (medial palpebral commissure) to the lowest (nasolabial area). Males generally had slightly higher facial skin temperatures than females. 15
Our systematic search yielded 18 distinct studies investigating skin temperatures in migraine patients. The studies comprised 1990 patients with migraine (both migraine with aura (MA) and migraine without aura (MO)), 362 patients with other kinds of headache (tension type, tension-vascular, ‘mixed’ and cluster headache) and 281 HCs amalgamated. Patients were investigated both during and between headache attacks, and also during different physically and psychologically stressful situations. Higher temperatures ipsilateral to the usual side of headache were reported in the forehead 17,18 of interictal patients in two studies. In one of these studies, however, the pain side specificity was confined to only 3 out of 10 subjects. 17 A tendency of slightly higher temperatures in the bilateral forehead and cheeks were reported in headache-free patients compared to during attacks, especially ipsilateral to the side of pain. 19 Two studies comparing ictal and interictal observations found no difference in temperatures during or between attacks. 20,21
One study, comparing patients during spontaneous attacks to controls, reported no temperature difference in the orbits of the majority of patients, but found orbits to be cooler in 30% and warmer in 14% of the patients compared to the non-headache side, 10 which corresponds to the previously reported vasoconstriction of the ophthalmic artery in some and vasodilation in others. 10 Orbit temperatures have been found warmer during headache compared to controls, whereas they were colder during headache-free periods. 11 Different findings in the above-mentioned studies suggest a patient heterogeneity or variability in measurement capabilities between studies. In one study, no temperature difference was found, but after dividing migraine attacks into groups based on response to compression of the STA for pain relief, 32 attacks that were alleviated with compression were associated with significantly warmer foreheads on the headache side. Further compression for several minutes was associated with a decrease in forehead temperature. 11 The authors suggested that pain was associated with higher forehead blood flow and thus temperatures, and that a decrease in blood flow could relieve pain, but it was not reported how many patients these STA-sensitive attacks were spread across. Interestingly, thermal biofeedback in another study resulted in cooling of the temples and headache relief. 22
Hypothermia in the supraorbital area during headache was reported ipsilateral to the pain side, 11,23 and the intensity of pain was positively correlated to a decrease in forehead temperatures, 23 suggesting sympathetic constriction of forehead vessels in response to pain. Two cohort studies 24,25 investigated interictal patients by infrared thermography revealing a characteristic ‘cold patch’ (an area with a temperature that was ≥0.5°C colder than the surrounding skin area) in the forehead of 85.4% of MO, 89.1% MA and 62.5% of patients with vascular headaches (MA, MO and atypical migraines pooled). 25 The ‘cold patch’ was further investigated before and after preventive treatment with beta or calcium channel blockers. 26,27 One study found that the majority of patients experiencing clinical improvement from preventive treatment had smaller ‘cold patches’ compared to the group with no clinical improvement. 27 This finding contradicted an earlier study where some patients demonstrated a larger ‘cold patch’ despite clinical improvement from preventive treatment with beta or calcium channel blockers. 26 A limitation of these studies was that there was no placebo control and investigators were not blinded to clinical improvement. Furthermore, previous studies had shown that if the face was generally cool, the patch would grow larger, suggesting that the ‘cold patch’ may not be a sign of an area with poor circulation, but rather a sign of generally lower forehead temperatures in patients compared to controls, consistent with previous reports. 18,23
In two studies, temperatures in the hands of headache patients were reported to be lower compared to controls. 28,29 One of these studies reported that hand temperatures were inversely related to number of attacks and that patients had colder noses compared to controls, 29 and the other suggested that increasing the hand-to-forehead temperature ratio might provide headache relief. 28 Interestingly, the cold nose and hands were also present in some healthy volunteers, of which 50% presented with a family history of migraine. 30 Sublingual administration of glyceryl trinitrate induced headache in 5 out of 11 healthy volunteers, 4 of whom had a family history of migraine. 30 These volunteers had lower temperatures in the nasal area compared to the participants who did not report headache, suggesting the presence of an autonomic dysfunction in headache-prone subjects, possibly a sympathetic vasoconstriction or a dysfunction of the parasympathetic vasodilatory function. 29 This may also explain the previously reported association between migraine and Raynaud’s phenomenon. 31
Psychological stress experiments (mental arithmetic, IQ test, exams) were applied in five separate studies. One study compared 37 MO to 37 HCs and found foreheads of MO to be warmer during experiments. 32 In two studies, however, patients had cooler foreheads or slightly increased temperature compared to controls, 18,19 suggesting a dysfunction in the response to stress. Hyperoxia in headache patients would increase the temperature in the hand and forehead of 50% of the patients. Interestingly, there was a lower incidence (33%) of temperature increase in the patients who were currently on preventive treatment. 33 An attempt to use biofeedback in the control of STA pulsation would increase the forehead temperature significantly, 34 suggesting inherently low interictal temperatures in migraine patients. However, results should be cautiously inferred as they were not the focus of the study or part of the a priori hypotheses. A head-back tilt test induced ‘red and puffy faces’ in patients, most likely due to a vasoconstrictor reflex. 18
Despite the vast amount of research in the facial skin temperature of migraine patients, results are equivocal, likely reflecting the use of different methods, the heterogeneity of patient populations and the fact that changes may be discrete and difficult to measure. There is a tendency towards lower temperatures in the nose and hands, and slightly higher temperatures in the forehead of headache patients compared to controls, both during and between attacks. Interestingly, the cold nose was also reported in some healthy volunteers, especially in those with a family history of headache. It is plausible to suggest a genetic disposition to an altered vascular response in these individuals, which may or may not result in headaches, depending on susceptibility. The altered temperature pattern in patients has been suggested to be the result of either sympathetic constriction of facial blood vessels or possibly under-responsiveness to vasodilation during stress. 18
When comparing the studies, some limitations should be acknowledged. The majority of the studies were conducted before the introduction of the International Headache Classification 35 and investigated ‘vascular’ headaches which are not quite well-defined. Therefore, interpretation of reported data is difficult. In most studies, temperature measurements were focused on the frontotemporal area, the cheeks and/or the nose. However, some studies failed to differentiate between sides or the facial area in which the temperature was measured. This also complicates direct comparison, as intra-individual differences in the facial temperature have also been reported in HCs. 15 Additionally, the method in the infrared thermography recordings was not clearly described in all studies, and there were discrepancies in the room temperature (range 20–25°C) during investigations, which is a common limitation in facial temperature studies. 36
Measurements of the STA
The STA is one of the terminal branches of the external carotid artery (ECA) which supplies the area near the orbit, along with the muscles and skin of the forehead via the anterior temporal, zygomatic and transverse facial arteries. A change in pulsation of the STA therefore entails a change in the blood flow supplying the orbit and forehead. Pulse amplitude of the STA was investigated in 12 separate studies comprising 520 migraine patients (both MO and MA), 57 patients with other types of headache and 108 HCs. Investigations were made both ictally and interictally in different stressful settings.
One study measured the diameter of the STA in 25 patients during and between migraine attacks. There was no side difference in diameter between attacks, but the STA on the headache side was larger during attacks than on the non-headache side. Further analyses revealed that the headache side was unchanged during attacks and the non-headache side was constricted. This was based on baseline measurements from another day leaving the post hoc analyses vulnerable to day-to-day variations. 37
Pulsation of the STA was found to be increased ipsilateral to usual side of headache both during attacks 10 and interictally. 38 In line with this, exposing patients to psychological stress (mental arithmetic), 18,19,39 light exercise, 40,41 painful stimulation with ice-water on non-dominant hand 42 or stimulation of the ophthalmic division of the trigeminal nerve with a soapy eye drop 43 would increase pulsation in the STA ipsilateral to usual side of headache. This suggests a more readily response to stressful stimulations. Interestingly, one study measured STA pulsation in a large population during a longer period of time and found that asymmetry in pulsation was present both during and between headaches and that variability became more pronounced in the days preceding an onset of headache. 44
The effect of biofeedback sessions on headache was tested in two separate studies. One study found that regular use of a relaxation technique reduced headache frequency, increased pulsation in the finger and decreased frontotemporal pulsation. 45 Another study found unchanged STA pulsation after biofeedback in migraine patients but reported a positive effect on the headache. 20
Collectively, data suggested asymmetrical reactivity in the STA in headache patients with changes in pulsation amplitude related to headache phase. Furthermore, long-term relaxation exercises were reported to have a possible beneficial effect on pulsation asymmetry, also resulting in a decrease in headache pain. A reason for this may be the resemblance of these exercises to meditation, resulting in decreased stress levels and thus less stress-related headaches. This is in line with clinical reports from migraine patients experiencing worsening of their migraine during stressful periods. Interestingly, despite the difference in STA pulsation in migraine patients compared to controls, it seems that cardiac responses are similar to those of HCs 18 and the changes in STA pulsation may thus be seen as local changes in the vessels of the face and scalp as opposed to a general vasomotor instability in migraine patients.
The method for recording pulse amplitude is a well-recognized and sensitive method. 43 A limitation of pulsation measurement is, however, that the amplitude of STA can vary with position and pressure of the transducer, and even small movements can obscure results. In some of the studies, investigators tried to avoid this by placing the Korotkoff sounds microphone in a pressure-adjustable band. 10,18,19
Compression of STA/CCA during migraine attacks
Numerous methods exist for testing vascular distension and compression in the cranial region of migraine patients. The purpose of compression studies is to test whether flow in the arteries modulates migraine pain. The STA originates from the CCA, and alleviation of migraine pain from compression of either STA or the CCA, has been investigated in a total of 243 migraine patients (both MO and MA) and 73 patients with other headaches. 10,11,46,47
One study found that compression of the CCA could alleviate pain in 100% of investigated attacks and that some attacks could even be temporarily abolished. 46 Compression of the STA or the occipital artery, however, would only result in relief in the anterior or the posterior half of the head, respectively. A more recent study found compression of the STA during 202 attacks in 186 patients to be more effective in alleviating head pain than compression of the CCA. 11 Circular compression of the head was tested in one study, 47 resulting in alleviation of pain in 42% of patients, whereas 28% felt a worsening in pain and 24% experienced no effect.
Collectively, compression may result in headache alleviation in up to 33% of patients, with compression of the STA being the most effective. However, inconsistency of results and large inter- and intra-individual differences should be acknowledged as some patients may experience relief by compression of STA in one attack, and relief by compression of CCA, or no relief at all, in another attack. Most studies applied manual compression which may have varied in the intensity of the pressure across studies and studies lacked a reliable placebo/sham treatment option. Results should therefore be cautiously interpreted.
Facial skin blood flow
Provocation experiments in migraine patients using infusion of vasoactive neuropeptides such as pituitary adenylate cyclase-activating polypeptide suggested an association between flushing and immediate headache in up to 100% of patients. 48
Fifteen studies comprising a total of 542 migraine patients, 182 HCs and 12 with tension-type headache investigated facial skin blood flow both during and between attacks. An increased facial skin blood flow was found ipsilateral to headache, 9,49 which was normalized after treatment with ergotamine tartrate. 9 A subcutaneous injection of sumatriptan (3 mg) during spontaneous attacks did not have any effect on blood flow velocity in the ECA. 50 Teeth clenching or chewing resulted in an increased temporal muscle blood flow which was about doubled interictally compared to ictally. 51,52 This indicates that blood flow is already increased during attacks. Provocation with soapy eye drops in interictal patients would increase vasodilation in the forehead, especially ipsilateral to usual headache side, which was particularly prominent in patients who usually had migraines on the left side. 53
Sustained flushing during histamine-induced headache could be partly antagonized by pretreatment with met-enkephalin analogue. 54
Ictal blood flow was increased in four studies 9,49,51,52 compared to the interictal period. In one of these studies, blood flow was increased ipsilateral to headache, 51 two studies reported decreased blood flow velocity during attacks, 55,56 and one study found no difference between ictal and interictal blood flow. 57 Acupuncture has been found to decrease blood flow velocity in the CCA in migraine patients (no sham control), 58 and a decrease in blood flow in response to local capsaicin was also found in patients with menstrually related migraine compared to both HCs and postmenopausal women. 59 Blood flow was only measured interictally and remained unchanged during the whole menstrual cycle.
Taken together, these studies suggested increased blood flow in the large arteries of the face during attacks. This is consistent with findings of an increase in ictal forehead temperature due to vasodilation and supports the hypothesis of temperature being proportionate to blood flow. Using facial thermography, it is possible to investigate the relationship between blood flow velocity in the feeding arteries and microvascular changes in the skin after sumatriptan. It should be noticed that studies on facial skin blood flow included small populations and some conducted before the International Headache Society classification, making it difficult to compare groups across studies. Blood flow is a function of arterial cross-section and intravascular blood flow velocity, and when only one of these variables is measured, it is not possible to conclude whether changes in, for example, blood flow are a result of changes in velocity, arterial dimensions or both. Further studies are needed to investigate blood flow in a standardized manner in larger populations.
Rosacea
The systematic search on rosacea uncovered 12 studies. Rosacea flushing could be induced by ingestion of alcohol 60 –62 and hot beverages, 61 whereas cold beverages (cold coffee, fizzy water and caffeine tablets) failed to induce flushing. The flushing induced by alcohol and hot beverages was accompanied by an increase in temperature which reached a maximum faster for hot beverages 61 than for alcohol. 60 Further, alcohol-induced flushing was shown to be partly inhibited by clonidine, methysergide and indomethacin. 62 Exposure to heat 13,63,64 or cold 64 could also induce facial flushing which was accompanied by a temperature increase that was more rapid in rosacea patients, but otherwise similar to that of controls. 13 No differences in skin temperatures were found in skin affected by erythematotelangiectatic rosacea (ETR) or papulopustular rosacea (PPR) compared to HC. 12
In one study, baseline skin blood flow was statistically equivalent for rosacea patients and controls. Iontophoresis of acetylcholine induced a similar vasodilatory response, however, the surrounding skin area of the iontophoresis reacted with an increase in blood flow in patients, but not in controls. 65 In addition, patients with severe rosacea had a slightly higher blood flow compared to controls. 66 In these patients, physical and psychological stress induced a similar blood flow increase in patients and controls, however, blood flow in patients with severe rosacea remained slightly higher. 66 Skin blood flow assessed by laser Doppler flowmetry was found to be increased 3- to 4-fold in rosacea patients compared to controls in one study. 14 In patients with PPR, blood flow in lesioned skin was higher in comparison to non-lesioned skin. 12 Treatment of rosacea skin with intense pulsed light resulted in an average decrease in blood flow by 30% 67 Angiogenesis, increased microvessel density with oedema and morphological changes were present more often in lesioned skin compared to non-lesioned skin. 68 Interestingly, an age-related decline in cutaneous vasoconstriction has been reported in healthy volunteers, 69 which might contribute to rosacea symptoms in the middle-aged.
Collectively, the studies on rosacea suggest altered blood flow and temperature in patients compared to controls, particularly in lesioned skin. Rosacea flushing can be induced by the ingestion of alcohol and hot beverages, prolonged exposure of the skin to cold or heat and physical and psychological stress. The observation that intake of hot beverages induces a more rapid flushing compared to use of alcohol 61 suggests that the initiation pathway by the two different triggers is somewhat different, and that intraoral heating in itself may initiate flushing, and not the coffee, as caffeine tablets failed to induce flushing.
Interestingly, in one study on migraine patients, intraoral (maxillary) chilling had a beneficial effect on nausea and pain intensity. 70 To our knowledge, this has not been systematically tested as a treatment in rosacea patients.
It seems there is an augmented sympathetic nerve activity found in forehead skin in rosacea patients during stressful tasks which may be a sign of autonomic dysregulation in rosacea. Similar findings of autonomic dysregulation have been reported in migraine. 6 Given that migraine and rosacea are highly associated in epidemiological studies, 5 it is important to investigate shared molecular mechanisms to understand a significant overlap between the two disorders.
Future perspectives and conclusions
In the reviewed articles, an altered temperature pattern was found in migraine patients who generally showed lower temperature in the forehead, nose and hands. STA was shown to be more susceptible to both physiological and psychological changes in migraine patients compared to controls, and compression of either STA or CCA during attacks may lead to transient pain relief. Blood flow was also found to be asymmetrical in migraine patients, which is consistent with the asymmetrical findings in temperature, indicating an altered blood flow in the face of migraine patients. Collectively, the findings suggest that migraine patients may exhibit dysfunction of the autonomic functions of the extracranial circulation. It is, however, not quite clear whether this is due to sympathetic or parasympathetic dysregulation. It has been suggested that both systems are active, but that the greatest variability may lie in the sympathetic nervous system which seems downregulated between attacks and, maybe due to hypersensitivity, upregulated during attacks. 1 The pathophysiology of rosacea is not better understood, but, as in migraine, a genetic component is believed to play a role along with a dysregulation of both immune, vascular and nervous systems. 7 Further studies are needed to investigate pathophysiology in both diseases and may lead towards acknowledging, understanding and possibly treating a somewhat overlooked symptom in migraine.
Clinical implications
Extracranial vasomotor reactivity in the face is altered in migraine and rosacea.
Altered vasomotor reactivity may reflect dysfunction of the autonomic nervous system.
Better understanding of links between migraine and rosacea may encourage future development of novel therapeutic options in both diseases.
Footnotes
Declaration of conflicting interests
The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Dr Wienholtz reports no disclosures relevant to the manuscript. Dr Christensen reports grant from Lundbeck Foundation (R249-2017-1608). Dr Egeberg has received research funding from Pfizer, Eli Lilly, the Danish National Psoriasis Foundation and the Kgl Hofbundtmager Aage Bang Foundation, and honoraria as consultant and/or speaker from Almirall, Leo Pharma, Samsung Bioepis Co., Ltd, Pfizer, Eli Lilly, Novartis, Galderma and Janssen Pharmaceuticals. Dr Thyssen has received a speaker fee from Galderma on two occasions. Dr Ashina is principal investigator for the following clinical trials: Amgen 20120178 (Phase 2), 20120295 (Phase 2), 20130255 (Open label extension), 20120297 (Phase 3), 20150308 (Phase 2), ElectroCore GM-11 gamma-Core-R, TEVATV48125-CNS-30068 (Phase 3), Novartis CAMG334A2301(Phase 3) and Alder PROMISE-2. Dr Ashina has no ownership interest and does not own stocks of any pharmaceutical company. Dr. Ashina reports personal fees from Alder BioPharmaceuticals, Allergan, Amgen, Alder, Eli Lilly, Novartis and Teva. Dr Ashina serves as an associated editor of Cephalalgia and a coeditor of the Journal of Headache and Pain.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was funded by grants from the Novo Nordisk Foundation (NNF17OC0029698), the Augustinus Foundation and the Lundbeck Foundation (R155-2014-171).
