Central sensitization in photophobic and non-photophobic migraineurs: possible role of retino nuclear way in the central sensitization process

Associations between the burdens of comorbid sleep problems, central sensitization, and headache-related disability in patients with migraine

Objective

Sleep disturbances are common in migraine patients and affect quality of life. Central sensitization (CS) is likely to play a role in the increased severity and chronicity of migraine. We hypothesized that the number of comorbid sleep problems would affect headache-related disability through the effects of central sensitization (CS).

Methods

We performed a cross-sectional study including 215 consecutive patients with migraine. Insomnia was defined as a Pittsburgh Sleep Quality Index (PSQI) global score greater than 5. Probable REM sleep behavior disorder (pRBD) was defined as an RBD screening score of 5 or greater. Excessive daytime sleepiness (EDS) was defined as an Epworth Sleepiness Scale score of 10 or higher. Suspected sleep apnea (SA) was defined as patients with snoring or sleep apnea witnessed 3 or more nights a week. CS was assessed by the Central Sensitization Inventory (CSI).

Results

Restless legs syndrome, insomnia, EDS, SA and pRBD were observed in 25.6%, 71.6%, 34.4%, 10.2%, and 21.4%, respectively, of the patients. At least one sleep problem was present in 87.0% of the patients. According to the results of the multinomial logistic regression analysis with no sleep problems as a reference, after we corrected for adjustment factors, the Migraine Disability Assessment (MIDAS) score significantly increased when three or more comorbid sleep problems were present. According to our mediation analysis, an increased number of sleep problems had a direct effect on the MIDAS score after we adjusted for other variables, and the CSI score was indirectly involved in this association.

Conclusion

The present study showed an association between migraine-related disability and the burden of multiple sleep problems, which was partially mediated by CS.

Central Sensitization in Migraine: A Narrative Review

Central sensitization (CS) is an increase in the responsiveness of nociceptive neurons in the central nervous system to their normal afferent input. As a result, even minor irritation can induce severe pain, leading to the chronicity and severity of various diseases, such as neurological disorders. CS is associated with migraine, which is a major neurological disorder that inflicts a high disability in daily life. Specifically, CS is thought to be involved in the pathogenesis of cutaneous allodynia as well as chronification of migraine. In this article, we reviewed the association between CS and migraine, including pathophysiological aspects and evidence from clinical studies. We suggest that appropriate screening and management of CS in migraine could further improve the quality of life of migraine patients.

Photophobia in headache disorders: characteristics and potential mechanisms

Photophobia is present in multiple types of headache disorders. The coexistence of photophobia and headache suggested the potential reciprocal interactions between visual and pain pathways. In this review, we summarized the photophobic characteristics in different types of headache disorders in the context of the three diagnostic categories of headache disorders: (1) primary headaches: migraine, tension-type headache, and trigeminal autonomic cephalalgias; (2) secondary headaches: headaches attributed to traumatic brain injury, meningitis, non-traumatic subarachnoid hemorrhage and disorder of the eyes; (3) painful cranial neuropathies: trigeminal neuralgia and painful optic neuritis. We then discussed potential mechanisms for the coexistence of photophobia and headache. In conclusion, the characteristics of photophobia are different among these headache disorders. The coexistence of photophobia and headache is associated with the interactions between visual and pain pathway at retina, midbrain, thalamus, hypothalamus and visual cortex. The communication between these pathways may depend on calcitonin gene-related peptide and pituitary cyclase-activating polypeptide transmission. Moreover, cortical spreading depression, an upstream trigger of headache, also plays an important role in photophobia by increased nociceptive input to the thalamus.

Cutaneous Allodynia in Migraine: A Narrative Review

Objective

In the present work, we conduct a narrative review of the most relevant literature on cutaneous allodynia (CA) in migraine.

Background

CA is regarded as the perception of pain in response to non-noxious skin stimulation. The number of research studies relating to CA and migraine has increased strikingly over the last few decades. Therefore, the clinician treating migraine patients must recognize this common symptom and have up-to-date knowledge of its importance from the pathophysiological, diagnostic, prognostic and therapeutic point of view.

Methods

We performed a comprehensive narrative review to analyze existing literature regarding CA in migraine, with a special focus on epidemiology, pathophysiology, assessment methods, risk for chronification, diagnosis and management. PubMed and the Cochrane databases were used for the literature search.

Results

The prevalence of CA in patients with migraine is approximately 60%. The mechanisms underlying CA in migraine are not completely clarified but include a sensitization phenomenon at different levels of the trigemino-talamo-cortical nociceptive pathway and dysfunction of brainstem and cortical areas that modulate thalamocortical inputs. The gold standard for the assessment of CA is quantitative sensory testing (QST), but the validated Allodynia 12-item questionnaire is preferred in clinical setting. The presence of CA is associated with an increased risk of migraine chronification and has therapeutic implications.

Conclusions

CA is a marker of central sensitization in patients with migraine that has been associated with an increased risk of chronification and may influence therapeutic decisions.

Dim the Lights: A Narrative Review of Photophobia in Migraine

A preference for darkness is one of the main associated features in people with migraine, the cause remaining a mystery until some decades ago. In this article, we describe the epidemiology of photophobia in migraine and explain the pathophysiological mechanisms following an anatomical structure. In addition, we review the current management of migraine and photophobia. Ongoing characterization of patients with photophobia and its different manifestations continues to increase our understanding of the intricate pathophysiology of migraine and vice versa. Detailed phenotyping of the patient with photophobia is encouraged.

Mild traumatic brain injury affects the features of migraine

BACKGROUND

Headache is one of the most common symptoms after concussion, and mild traumatic brain injury (mTBI) is a risk factor for chronic migraine (CM). However, there remains a paucity of data regarding the impact of mTBI on migraine-related symptoms and clinical course.

METHODS

Of 2161 migraine patients who participated in the American Registry for Migraine Research between February 2016 and March 2020, 1098 completed questions assessing history of TBI (50.8%). Forty-four patients reported a history of moderate to severe TBI, 413 patients reported a history of mTBI. Patients' demographics, headache symptoms and triggers, history of physical abuse, allodynia symptoms (ASC-12), migraine disability (MIDAS), depression (PHQ-2), and anxiety (GAD-7) were compared between migraine groups with (n = 413) and without (n = 641) a history of mTBI. Either the chi-square-test or Fisher's exact test, as appropriate, was used for the analyses of categorical variables. The Mann-Whitney test was used for the analyses of continuous variables. Logistic regression models were used to compare variables of interest while adjusting for age, gender, and CM.

RESULTS

A significantly higher proportion of patients with mTBI had CM (74.3% [307/413] vs. 65.8% [422/641], P = 0.004), had never been married or were divorced (36.6% [147/402] vs. 29.4% [187/636], P = 0.007), self-reported a history of physical abuse (24.3% [84/345] vs. 14.3% [70/491], P <  0.001), had mild to severe anxiety (50.5% [205/406] vs. 41.0% [258/630], P = 0.003), had headache-related vertigo (23.0% [95/413] vs. 15.9% [102/640], P = 0.009), and difficulty finding words (43.0% [174/405] vs. 32.9% [208/633], P <  0.001) in more than half their attacks, and headaches triggered by lack of sleep (39.4% [155/393] vs. 32.6% [198/607], P = 0.018) and reading (6.6% [26/393] vs. 3.0% [18/607], P = 0.016), compared to patients without mTBI. Patients with mTBI had significantly greater ASC-12 scores (median [interquartile range]; 5 [1-9] vs. 4 [1-7], P < 0.001), MIDAS scores (42 [18-85] vs. 34.5 [15-72], P = 0.034), and PHQ-2 scores (1 [0-2] vs. 1 [0-2], P = 0.012).

CONCLUSION

Patients with a history of mTBI are more likely to have a self-reported a history of physical abuse, vertigo, and allodynia during headache attacks, headaches triggered by lack of sleep and reading, greater headache burden and headache disability, and symptoms of anxiety and depression. This study suggests that a history of mTBI is associated with the phenotype, burden, clinical course, and associated comorbid diseases in patients with migraine, and highlights the importance of inquiring about a lifetime history of mTBI in patients being evaluated for migraine.

Photophobia: shared pathophysiology underlying dry eye disease, migraine and traumatic brain injury leading to central neuroplasticity of the trigeminothalamic pathway

BACKGROUND

Photophobia is a potentially debilitating symptom often found in dry eye disease (DE), migraine and traumatic brain injury (TBI).

METHODS

We conducted a review of the literature via a PubMed search of English language articles with a focus on how photophobia may relate to a shared pathophysiology across DE, migraine and TBI.

RESULTS

DE, migraine and TBI are common conditions in the general population, are often comorbid, and share photophobia as a symptom. Across the three conditions, neural dysregulation of peripheral and central nervous system components is implicated in photophobia in various animal models and in humans. Enhanced activity of the neuropeptide calcitonin gene-related peptide (CGRP) is closely linked to photophobia. Current therapies for photophobia include glasses which shield the eyes from specific wavelengths, botulinum toxin, and inhibition of CGRP and its receptor. Many individuals have persistent photophobia despite the use of these therapies, and thus, development of new therapies is needed.

CONCLUSIONS

The presence of photophobia in DE, migraine and TBI suggests shared trigeminothalamic pathophysiologic mechanisms, as explained by central neuroplasticity and hypersensitivity mediated by neuropeptide CGRP. Treatment strategies which target neural pathways (ie, oral neuromodulators, transcutaneous nerve stimulation) should be considered in patients with persistent photophobia, specifically in individuals with DE whose symptoms are not controlled with traditional therapies.

Photophobia and allodynia in persistent post-traumatic headache are associated with higher disease burden

OBJECTIVE

To assess photophobia and allodynia in subjects with post-traumatic headache and examine how these sensory hypersensitivities associate with clinical measures of disease burden.

BACKGROUND

Post-traumatic headache is the most frequent and disabling long-term consequence of mild traumatic brain injury. There is evidence of sensory dysfunction in acute post-traumatic headache, and it is known from other headache conditions that sensory amplifications correlate with more severe disease. However, systematic studies in post-traumatic headache are surprisingly scarce.

METHODS

We tested light and tactile sensitivity, along with measures of disease burden, in 30 persistent post-traumatic headache subjects and 35 controls.

RESULTS

In all, 79% of post-traumatic headache subjects exhibited sensory hypersensitivity based on psychophysical assessment. Of those exhibiting hypersensitivity, 54% exhibited both light and tactile sensitivity. Finally, sensory thresholds were correlated across modalities, as well as with headache attack frequency.

CONCLUSIONS

In this study, post-traumatic headache subjects with both light and tactile sensitivity had significantly higher headache frequencies and lower sensitivity thresholds to both modalities, compared to those with single or no sensory hypersensitivity. This pattern suggests that hypersensitivity across multiple modalities may be functionally synergistic, reflect a higher disease burden, and may serve as candidate markers of disease.

Synergistic but separable sensory changes in postural tachycardia syndrome and chronic migraine

PURPOSE

Up to 90% of patients with postural tachycardia syndrome (PoTS) report headaches, and comorbid migraine headaches are common. Given this, pathophysiological interaction is possible, which may reveal key aspects of disease expression and treatment opportunities. We hypothesized that PoTS subjects-both with and without migraine-would show features of central sensitization, including allodynia and photophobia.

METHODS

Eighty participants were evaluated, including 30 PoTS, 30 chronic migraine (CM), and 20 non-headache healthy controls (NH), using tilt table testing, psychophysical assessment of sensory sensitivity thresholds, and an online questionnaire to assess measures of headache burden and associated symptoms. Clinical characteristics and sensory thresholds were compared between disease groups and controls, as well as in a subgroup analysis within the PoTS group, based on headache phenotype.

RESULTS

Sensory sensitivity thresholds were significantly lower and symptom scores were higher in both the PoTS and CM groups compared to controls. However, the patterns of expression differed between PoTS and CM, with pain threshold reductions in the forearm only of PoTS subjects (non-trigeminal sensory sensitization), compared to both periorbital and forearm sites in CM. Unexpectedly, light sensitivity thresholds were significantly lower in PoTS than in both CM and NH.

CONCLUSIONS

These findings reveal an underappreciated aspect of disease burden in PoTS, and suggest network sensitization similar to, but separable from, that of migraine. The presence of both photophobia and allodynia in PoTS is reflective of exteroceptive rather than strictly interoceptive disruption, and expands our fundamental understanding of the disorder.

Contribution of intraganglionic CGRP to migraine-like responses in male and female rats

Objective

To evaluate whether intraganglionic calcitonin gene-related peptide induced differential migraine-like responses in male and female rats.

Methods

Calcitonin gene-related peptide was injected in the trigeminal ganglion of male and female rats followed by assessment of periorbital mechanical allodynia with von Frey hairs. The influence of systemic treatment with sumatriptan or intraganglionic treatment with minocycline and propentofylline was determined on the calcitonin gene-related peptide-induced mechanical allodynia in male and female rats. One additional group was exposed to an aversive light 24 h after calcitonin gene-related peptide priming, followed by evaluation of periorbital mechanical threshold, and another group was tested in the elevated-plus maze.

Results

Intraganglionar calcitonin gene-related peptide-induced periorbital mechanical allodynia in female (0.5 to 6 h) and male rats (0.5 to 4 h). Systemic sumatriptan briefly attenuated the mechanical allodynia, but intraganglionar minocycline or propentofylline injection was effective only in male rats. Calcitonin gene-related peptide induced photic sensitivity in female and male rats (lasting 4 h and 1 h, respectively), as well as anxiety-like behavior.

Conclusions

Intraganglionar calcitonin gene-related peptide may play a major role in migraine-like responses, including periorbital mechanical allodynia, light sensitivity and anxiety like-behavior. Female rats are likely to be more susceptible to calcitonin gene-related peptide effects and a better understanding of the sexual dimorphism in calcitonin gene-related peptide signaling may help to improve migraine therapy.

The role of visual system in migraine

The visual system is involved in different ways in migraine. Visual auras are the most common form of migraine aura. It may consist of positive or negative visual symptoms and cortical spreading depression is felt to be the phenomenon that underlies it. Even in migraine without aura, vision it is not totally excluded given that one of the major criteria for the diagnosis of migraine is photophobia. In persistent visual aura, patients refer symptoms defined as visual snow and television static. In retinal migraine unilateral decreased vision or complete visual loss occurs. Ophthalmoplegic migraine is characterized by palsy of one among the three ocular motor nerves. Migraine visual aura, particularly when occurring without headache, is a diagnosis of exclusion. Imaging studies and laboratory tests should exclude neurologic disease, included seizures and central nervous system tumor, ocular pathologies, carotid or cardiac disease, thrombosis and connective tissue disease.

Photophobia in neurologic disorders

Photophobia is a common symptom seen in many neurologic disorders, however, its pathophysiology remains unclear. Even the term is ambiguous. In this paper, we review the epidemiology and clinical manifestations of photophobia in neurological disorders, including primary headache, blepharospasm, progressive supranuclear palsy, and traumatic brain injury, discuss the definition, etiology and pathogenesis, and summarize practical methods of diagnosis and treatment.

Altered pupillary light response scales with disease severity in migrainous photophobia

Background Autonomic dysfunction and light sensitivity are core features of the migraine attack. Growing evidence also suggests changes in these parameters between attacks. Though sensory and autonomic responses likely interact, they have not been studied together across the spectrum of disease in migraine. Methods We performed digital infrared pupillometry while collecting interictal photophobia thresholds (PPT) in 36 migraineurs (14 episodic; 12 chronic; 10 probable) and 24 age and sex-matched non-headache controls. Quantitative pupillary light reflexes (PLR) were assessed in a subset of subjects, allowing distinction of sympathetic vs parasympathetic pupillary function. A structured questionnaire was used to ascertain migraine diagnosis, headache severity, and affective symptoms. Results Photophobia thresholds were significantly lower in migraineurs than controls, and were lowest in chronic migraine, consistent with a disease-related gradient. Lower PPT correlated with smaller dark-adapted pupil size and larger end pupil size at PPT, which corresponded to a reduced diameter change. On PLR testing, measures of both parasympathetic constriction and sympathetic re-dilation were reduced in migraineurs with clinically severe migraine. Conclusions In summary, we show that severity of photophobia in migraine scales with disease severity, in association with shifts in pupillary light responses. These alterations suggest centrally mediated autonomic adaptations to chronic light sensitivity.

Characterization of Migraineurs Having Allodynia: Results of a Large Population-based Study

OBJECTIVE

Allodynia reflects the clinical correlate of central sensitization, but it is usually neglected in clinical headache management. We aimed to report the prevalence and previously unnoticed associations of allodynia in migraineurs by a nationwide face-to-face questionnaire-based study by physicians.

METHODS

A total of 5323 households were examined for headache according to the diagnostic criteria of International Classification of Headache Disorders-II. Detailed headache features, premonitory signs, demographics, socio-economic status, and hormonal status of female individuals were analyzed with regard to the presence of allodynia in patients with definite migraine.

RESULTS

Allodynia was present in 61.1% of migraineurs in the general population of Turkey. The duration and severity of attacks (P<0.0001), photophobia (P=0.001), phonophobia, and also osmophobia (P<0.0001), as well as premonitory signs (P=0.018), showed significant associations with allodynia. Migraineurs with aura or family history of migraine more often reported allodynia in comparison with those without (P=0.001 and 0.028, respectively). Allodynic migraineurs had a higher rate of physician consults and high levels on the Migraine Disability Assessment questionnaire, reflecting increased burden of headache. Furthermore, migraineurs with allodynia had high probability of attacks close to menses. Migraine improved during pregnancy, but it worsened after menopause or during oral contraceptive use in individuals experiencing allodynia when compared with those without allodynia.

DISCUSSION

The duration, severity, and disability of migraine attacks, photophobia, phonophobia, and osmophobia, as well as premonitory signs, showed significant associations with allodynia in the general population. Moreover, migraineurs with aura or family history of migraine more often reported allodynia, and allodynic migraneurs were more sensitive to hormonal changes. Allodynia, which seems to indicate higher tendency to central sensitization, should be implemented in daily headache practice to predict the prognosis and high levels of migraineous involvement.

Psychosocial and Somatosensory Factors in Women with Chronic Migraine and Painful Temporomandibular Disorders

Introduction. Psychosocial and somatosensory factors are involved in the pathophysiology of chronic migraine (CM) and chronic temporomandibular disorders (TMD). Objective. To compare and assess the relationship between pain catastrophizing and kinesiophobia in patients with CM or chronic TMD. Method. Cross-sectional study of 20 women with CM, 19 with chronic TMD, and 20 healthy volunteers. Pain catastrophizing and kinesiophobia were assessed. The level of education, pain intensity, and magnitude of temporal summation of stimuli in the masseter (STM) and tibialis (STT) muscles were also evaluated. Results. There were significant differences between the CM and chronic TMD groups, compared with the group of asymptomatic subjects, for all variables (p < .05) except kinesiophobia when comparing patients with CM and healthy women. Moderate correlations between kinesiophobia and catastrophizing (r = 0.46; p < .01) were obtained, and the strongest association was between kinesiophobia and magnification (r = 0.52; p < .01). The strongest associations among physical variables were found between the STM on both sides (r = 0.93; p < .01) and between the left and right STT (r = 0.76; p < .01). Conclusion. No differences were observed in pain catastrophizing and kinesiophobia between women with CM and with chronic TMD. Women with CM or chronic TMD showed higher levels of pain catastrophizing than asymptomatic subjects.

Migraine is associated with altered processing of sensory stimuli

Migraine is associated with derangements in perception of multiple sensory modalities including vision, hearing, smell, and somatosensation. Compared to people without migraine, migraineurs have lower discomfort thresholds in response to special sensory stimuli as well as to mechanical and thermal noxious stimuli. Likewise, the environmental triggers of migraine attacks, such as odors and flashing lights, highlight basal abnormalities in sensory processing and integration. These alterations in sensory processing and perception in migraineurs have been investigated via physiological studies and functional brain imaging studies. Investigations have demonstrated that migraineurs during and between migraine attacks have atypical stimulus-induced activations of brainstem, subcortical, and cortical regions that participate in sensory processing. A lack of normal habituation to repetitive stimuli during the interictal state and a tendency towards development of sensitization likely contribute to migraine-related alterations in sensory processing.

Role of phosphorylated extracellular signal-regulated kinase, calcitonin gene-related peptide and cyclooxygenase-2 in experimental rat models of migraine

Although migraine is a common neurological condition, the pathomechanism is not yet fully understood. Activation of the trigeminovascular system (TVS) has an important function in this disorder and neurogenic inflammation and central sensitization are important mechanisms underlying this condition. Nitroglycerin (NTG) infusion in rats closely mimics a universally accepted human model of migraine. Electrical stimulation of the trigeminal ganglion (ESTG) of rats can also activate TVS during a migraine attack. Numerous studies have revealed that phosphorylated extracellular signal-regulated kinase (p-ERK), calcitonin gene-related peptide (CGRP) and cyclooxygenase-2 (COX-2) are involved in pain and nociceptive pathways. However, few studies have examined whether p-ERK, CGRP and COX-2 are involved in neurogenic inflammation and central sensitization. In the present study, the expression of p-ERK, CGRP and COX-2 was detected in the dura mater, trigeminal ganglion (TG) and spinal trigeminal nucleus caudalis in NTG-induced rats and ESTG models by immunohistochemistry. The three areas considered were crucial components of the TVS. The selective COX-2 inhibitor nimesulide was used in ESTG rats to examine the association between p-ERK, CGRP and COX-2. The results demonstrated that p-ERK, CGRP and COX-2 mediated neurogenic inflammation and central sensitization in migraine. In addition, the expression of p-ERK and CGRP was attenuated by the COX-2 inhibitor.