The wavelength of light causing photophobia in migraine and tension-type headache between attacks

Photophobia is associated with lower sleep quality in individuals with migraine: results from the American Registry for Migraine Research (ARMR)

BACKGROUND

Patients with migraine often have poor sleep quality between and during migraine attacks. Furthermore, extensive research has identified photophobia as the most common and most bothersome symptom in individuals with migraine, second only to headache. Seeking the comfort of darkness is a common strategy for managing pain during an attack and preventing its recurrence between episodes. Given the well-established effects of daily light exposure on circadian activity rhythms and sleep quality, this study aimed to investigate the relationship between photophobia symptoms and sleep quality in a cohort of patients with migraine.

METHODS

A cross-sectional observational study was conducted using existing data extracted from the American Registry for Migraine Research (ARMR). Participants with a migraine diagnosis who had completed the baseline questionnaires (Photosensitivity Assessment Questionnaire (PAQ), Generalized Anxiety Disorder-7 (GAD-7), Patient Health Questionnaire-2 (PHQ-2)), and selected questions of the ARMR Sleep questionnaire were included. Models were created to describe the relationship of photophobia and photophilia with various sleep facets, including sleep quality (SQ), sleep disturbance (SDis), sleep onset latency (SOL), sleep-related impairments (SRI), and insomnia. Each model was controlled for age, sex, headache frequency, anxiety, and depression.

RESULTS

A total of 852 patients meeting the inclusion criteria were included in the analysis (mean age (SD) = 49.8 (13.9), 86.6% (n = 738) female). Those with photophobia exhibited significantly poorer sleep quality compared to patients without photophobia (p < 0.001). Photophobia scores were associated with SQ (p < 0.001), SDis (p < 0.001), SOL (p = 0.011), SRI (p = 0.020), and insomnia (p = 0.005) after controlling for age, sex, headache frequency, depression, and anxiety, signifying that higher levels of photophobia were associated with worse sleep-related outcomes. Conversely, photophilia scores were associated with better sleep-related outcomes for SQ (p < 0.007), SOL (p = 0.010), and insomnia (p = 0.014).

CONCLUSION

Results suggest that photophobia is a significant predictor of poor sleep quality and sleep disturbances in migraine. These results underscore the necessity for comprehensive and systematic investigations into the intricate interplay between photophobia and sleep to enhance our understanding and develop tailored solutions for individuals with migraine.

Individualized spectral filters alleviate persistent photophobia, headaches and migraines in active duty military and Veterans following brain trauma

PURPOSE

Consistent with association between photophobia and headache, growing evidence suggests an underlying causal relationship between light sensitivity and central pain. We investigated whether an intervention to regulate light sensitivity by filtering only wavelengths causing difficulties for the specific individual could alleviate headaches/migraines resulting from traumatic brain injury (TBI).

METHODS

Secondary data analysis of a clinical database including N = 392 military personnel (97% men, 3% women), ranging in age from 20 to 51 years, diagnosed with TBI, persistent headaches/migraines, and light sensitivity. The average elapsed time from TBI diagnosis to intervention was 3 years. Headache/migraine severity, frequency, medication use, and difficulties related to daily functioning were assessed pre and 4-12 weeks post-intervention with individualized spectral filters.

RESULTS

Monthly migraine frequency decreased significantly from an average of 14.8 to 1.9, with 74% reporting no migraines post-intervention. Prescription and over-the-counter medication use decreased by more than 70%. Individuals also reported significant improvement in light sensitivity, headaches/migraine severity, and physical and perceptual symptoms.

CONCLUSIONS

Wearing individualized spectral filters was associated with symptom relief, increased subjective quality of reported health and well-being, and decreased objective medication use for TBI-related persistent headaches/migraines. These results support a suggested relationship between dysregulated light sensitivity and central regulation of pain.

Preservation of Intrinsically Photosensitive Retinal Ganglion Cells (ipRGCs) in Late Adult Mice: Implications as a Potential Biomarker for Early Onset Ocular Degenerative Diseases

Purpose

Intrinsically photosensitive retinal ganglion cells (ipRGCs) play a crucial role in non-image-forming visual functions. Given their significant loss observed in various ocular degenerative diseases at early stages, this study aimed to assess changes in both the morphology and associated behavioral functions of ipRGCs in mice between 6 (mature) and 12 (late adult) months old. The findings contribute to understanding the preservation of ipRGCs in late adults and their potential as a biomarker for early ocular degenerative diseases.

Methods

Female and male C57BL/6J mice were used to assess the behavioral consequences of aging to mature and old adults, including pupillary light reflex, light aversion, visual acuity, and contrast sensitivity. Immunohistochemistry on retinal wholemounts from these mice was then conducted to evaluate ipRGC dendritic morphology in the ganglion cell layer (GCL) and inner nuclear layer (INL).

Results

Morphological analysis showed that ipRGC dendritic field complexity was remarkably stable through 12 months old of age. Similarly, the pupillary light reflex, visual acuity, and contrast sensitivity were stable in mature and old adults. Although alterations were observed in ipRGC-independent light aversion distinct from the pupillary light reflex, aged wild-type mice continuously showed enhanced light aversion with dilation. No effect of sex was observed in any tests.

Conclusions

The preservation of both ipRGC morphology and function highlights the potential of ipRGC-mediated function as a valuable biomarker for ocular diseases characterized by early ipRGC loss. The consistent stability of ipRGCs in mature and old adult mice suggests that detected changes in ipRGC-mediated functions could serve as early indicators or diagnostic tools for early-onset conditions such as Alzheimer's disease, Parkinson's disease, and diabetes, where ipRGC loss has been documented.

Topographic localization of migraine triggers and its association with headache frequency and severity

OBJECTIVE

Internal biological rhythm with or without external trigger may precipitate migraine. Classifying exogenous and endogenous triggers to a topographic localization may help in understanding the migraine. We report topographic localization of migraine triggers and its influence on headache frequency and severity.

METHODS

588 migraineurs, aged 16-69 years were included. Various endogenous and exogenous triggers were categorized to topographic localization- hypothalamic, pituitary, auditory, visual, somato-sensory, olfactory and gustatory. The relationship of topographic localization of triggers with episodic versus chronic migraine, and moderate versus severe headache were analyzed using univariate followed by multivariate analysis.

RESULTS

All migraineurs had triggers 584(99.9%) except 4(0.1%) patients. Presence of multiple triggers (99.4%), and combination of both endogenous and exogenous triggers (97.7%) was the rule. On topographic localization, hypothalamic trigger was the commonest (98.1%) followed by visual (84.1%), auditory (82.1%), somatosensory (76.1%), olfactory (26.2%), pituitary (24.1%), and gustatory (6.6%). 98.6% patients had combination of hypothalamic with pituitary triggers. Hypothalamic [Adjusted odds ratio (AOR) 4.50] and auditory triggers (AOR 0.34) independently predicted chronic migraine, and auditory (AOR 0.55) and gustatory (AOR 2.41) triggers predicted severity of headache.

CONCLUSION

Hypothalamic triggers are the commonest suggesting an innate susceptibility of migraine. Auditory trigger may precipitate frequent and severe headache.

Intercritical photophobia in the migrainous patient. Proposal for diagnostic criteria

INTRODUCTION

Photophobia is a symptom of abnormal light intolerance without pain sensation that requires an anamnesis and an examination to diagnose an underlying etiology.

BASIC PROCEDURE

This article focuses on 30 clinical cases with isolated intense photophobia and on the review of the literature.

OBJECTIVE

The purpose of this article is to establish diagnostic criteria for photophobia.

RESULTS

The etiology of photophobia appears to be at the level of the intrinsically photosensitive retinal ganglion cells known as melanopsin cells and at a neurochemical level mediated by calcitonin-related peptide and the pituitary activating peptide cyclase.

CONCLUSION

The treatment of photophobia could consist of monoclonal antibodies against calcitonin-related peptide and/or pituitary activating peptide cyclase.

Post-traumatic headaches and vision: A review

BACKGROUND: Post-traumatic headache is the most common sequela of brain injury and can last months or years after the damaging event. Many headache types are associated with visual concerns also known to stem from concussion. OBJECTIVES: To describe the various headache types seen after head injury and demonstrate how they impact or are impacted by the visual system. METHODS: We will mirror the International Classification of Headache Disorders (ICHD) format to demonstrate the variety of headaches following brain injury and relate correlates to the visual pathways. The PubMed database was searched using terms such as headache, head pain, vision, concussion, traumatic brain injury, glare, visuomotor pathways. RESULTS: Every type of headache described in the International Classification of Headache Disorders Edition III can be initiated or worsened after head trauma. Furthermore, there is very often a direct or indirect impact upon the visual system for each of these headaches. CONCLUSION: Headaches of every described type in the ICHD can be caused by brain injury and all are related in some way to the afferent, efferent or association areas of the visual system.

Is Palinopsia in Migraineurs a Phenomenon of Impaired Habituation of Visual Cortical Neurons?

Palinopsia in migraine has been reported recently, which may be due to the dysexcitability of visual cortical neurons. In this cross-sectional study, we report the correlation of neuronal dysexcitability with palinopsia using pattern shift visual evoked potential (PSVEP) in 91 migraineurs and 25 healthy controls. The presence of palinopsia was evaluated using a novel objective method, and revealed more frequent palinopsia in the migraineurs compared to the controls (53 of 91 [58.2%] vs 3 of 25 [12%]; P < .001). Five consecutive blocks of PSVEP were recorded for the evaluation of sensitization and impaired habituation. Amplitudes of N75 and P100 in block 1 were considered for sensitization. Impaired habituation of N75 and P100 was considered if any amplitudes in blocks 2 to 5 were higher than block 1. Impaired habituation was more frequent in migraineurs compared with the controls, and was more marked in wave N75 (81.3% vs 32%; P < .001) than wave P100 (63.7% vs 44%; P = .12). Impaired habituations of wave N75 (81.7% vs 58.9%; P = .008) and wave P100 (71.7% vs 46.4%; P = .008) were more frequent in those with palinopsia compared with those without. There was a lack of suppression of P100 amplitude in block 3 in the palinopsia group compared to the controls. The duration of palinopsia correlated with the extent of impaired habituation of N75. It can be concluded that the impaired habituation of PSVEP waveforms is a biomarker of palinopsia in migraine.

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.

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.

Migraine and light: A narrative review

OBJECTIVE

In this narrative review, we summarize clinical and experimental data on the effect of light in migraine and discuss future prospects.

BACKGROUND

Effective nonpharmacological treatment of hypersensitivity to light in migraine is an unmet clinical need. Current management strategies primarily consist of seeking a dark room and avoiding light exposure. Advances in the past 2 decades have improved our understanding of the underlying pathophysiology of how migraine is influenced by light. This may provide promising avenues for novel approaches in clinical management.

METHODS

We searched MEDLINE for articles published from database inception up to September 1, 2021. We used the search term "migraine" with the search terms "light," "photophobia," "treatment," "trigger," "circadian rhythm," "environment," and/or "pathophysiology."

RESULTS

Light is commonly reported as a trigger factor of migraine attacks, however, early manifestation of photophobia and false attribution is likely the actual cause based on data deriving from retrospective, prospective, and experimental studies. The most common photophobia symptoms in migraine are exacerbation of headache by light and abnormal sensitivity to light with the underlying neural pathways likely being dependent on ongoing activity in the trigeminovascular system. Clinical studies and experimental models have identified mediators of photophobia and uncovered narrow wavebands of the light spectrum that may reduce pain intensity during a migraine attack. Consequently, novel devices have undergone exploratory clinical trials with promising results.

CONCLUSION

False attribution is likely the reason why light is commonly reported as a trigger factor of migraine attacks, and a prospective confirmation is required to prevent unnecessary avoidance. The observation that individuals with migraine are not equally photophobic to all wavebands of the light spectrum opens the potential for innovative pain management strategies. In this context, using human-centric lighting (also called integrative lighting) to mimic the natural daylight cycle and avoid harmful wavebands through modern technology may prove beneficial. Future research should identify direct and indirect consequences of light and other environmental factors in migraine to fill out knowledge gaps and enable evidence-based care strategies within institutions, work environments, and other settings.

Reflexive Eye Closure in Response to Cone and Melanopsin Stimulation: A Study of Implicit Measures of Light Sensitivity in Migraine

BACKGROUND AND OBJECTIVES

To quantify interictal photophobia in migraine with and without aura using reflexive eye closure as an implicit measure of light sensitivity and to assess the contribution of melanopsin and cone signals to these responses.

METHODS

Participants were screened to meet criteria for 1 of 3 groups: headache-free (HF) controls, migraine without aura (MO), and migraine with visual aura (MA). MO and MA participants were included if they endorsed ictal and interictal photophobia. Exclusion criteria included impaired vision, inability to collect usable pupillometry, and history of either head trauma or seizure. Participants viewed light pulses that selectively targeted melanopsin, the cones, or their combination during recording of orbicularis oculi EMG (OO-EMG) and blinking activity.

RESULTS

We studied 20 participants in each group. MA and MO groups reported increased visual discomfort to light stimuli (discomfort rating, 400% contrast, MA: 4.84 [95% confidence interval 0.33, 9.35]; MO: 5.23 [0.96, 9.50]) as compared to HF controls (2.71 [0, 6.47]). Time course analysis of OO-EMG and blinking activity demonstrated that reflexive eye closure was tightly coupled to the light pulses. The MA group had greater OO-EMG and blinking activity in response to these stimuli (EMG activity, 400% contrast: 42.9%Δ [28.4, 57.4]; blink activity, 400% contrast: 11.2% [8.8, 13.6]) as compared to the MO (EMG activity, 400% contrast: 9.9%Δ [5.8, 14.0]; blink activity, 400% contrast: 4.7% [3.5, 5.9]) and HF control (EMG activity, 400% contrast: 13.2%Δ [7.1, 19.3]; blink activity, 400% contrast: 4.5% [3.1, 5.9]) groups.

DISCUSSION

Our findings suggest that the intrinsically photosensitive retinal ganglion cells (ipRGCs), which integrate melanopsin and cone signals, provide the afferent input for light-induced reflexive eye closure in a photophobic state. Moreover, we find a dissociation between implicit and explicit measures of interictal photophobia depending on a history of visual aura in migraine. This implies distinct pathophysiology in forms of migraine, interacting with separate neural pathways by which the amplification of ipRGC signals elicits implicit and explicit signs of visual discomfort.

Managing Photophobia with the Utilisation of Smart Light Bulbs

Photophobia can affect a person's quality of life. We present a case of idiopathic photophobia that was successfully managed with smart light bulbs that allowed the patient to participate in daily activities. Smart light can complement other treatment options including tinted lenses. In conclusion, smart light is a novel way of treating photophobia and should be considered by clinicians.

Assessing migraine patients with multifocal pupillographic objective perimetry

Background

To establish the effects of stimulating intrinsically-photosensitive retinal ganglion cells (ipRGCs) on migraine severity, and to determine if migraine produces objectively-measured visual field defects.

Methods

A randomized, open labelled, crossover study tested migraineurs and normal controls using multifocal pupillographic objective perimetry (mfPOP) with 44 test-regions/eye. A slow blue protocol (BP) stimulated ipRGCs, and a fast yellow protocol (YP) stimulated luminance channels. Migraine diaries assessed migraine severity. Per-region responses were analyzed according to response amplitude and time-to-peak.

Results

Thirty-eight migraineurs (42.0 ± 16.5 years, 23 females) and 24 normal controls (39.2 ± 15.2 years, 14 females) were tested. The proportion of subjects developing a migraine did not differ after either protocol, either during the 1st day (odds ratio 1.0; 95% confidence interval 0.2–4.4, p = 0.48) or during the first 3 days after testing (odds ratio 0.8; 95% confidence interval 0.3–2.1, p = 0.68). Migraine days/week did not increase following testing with either protocol in comparison to the baseline week (1.4 ± 1.6 pre-testing (mean ± SD), 1.3 ± 1.4 post-BP, and 1.3 ± 1.2 post-YP; p = 0.96), neither did other measures of severity. Migraine occurring up to 2 weeks before testing significantly lowered amplitudes, − 0.64 ± 0.14 dB (mean ± SE), while triptan use increased amplitudes by 0.45 ± 0.10 dB, both at p < 0.001.

Conclusions

Stimulating ipRGCs did not affect migraine occurrence or severity. Pupillary response characteristics were influenced by the occurrence of a recent migraine attack and a history of triptan use.

Interictal Photophobia and Phonophobia Are Related to the Presence of Aura and High Frequency of Attacks in Patients with Migraine

Background: Despite that photophobia and phonophobia are well-known symptoms related to migraine, it is unclear whether they affect daily life activities during the headache-free period. Objective: To evaluate the interictal photophobia/phonophobia intensity during daily activities in migraineurs and non-headache individuals. Methods: Women with migraine without aura (MoA, n = 30), migraine with aura (MA, n = 30), chronic migraine (CM, n = 30) and without headache (CG, n = 30) reported the photophobia and phonophobia intensity during daily activities using a Likert scale ranging from 0 (no discomfort) to 10 (maximum discomfort). Results: The migraine groups reported higher intensity of interictal photophobia and phonophobia than CG during “driving” and “social situations”, respectively (p < 0.05). MA and CM groups presented higher intensity of phonophobia than CG, hearing sounds in everyday situations and listening to conversations in noisy places (p < 0.05). Also, the MA group presented higher interictal phonophobia than the CG to keep concentration in noisy places (p < 0.05). Weak positive correlations were observed between the intensity of both photophobia and phonophobia with migraine intensity, frequency of migraine and frequency of aura (p < 0.05). Conclusion: Interictally, the intensity of photophobia and phonophobia reported during daily activities is higher in patients with migraine, especially those with aura and chronic migraine, than in non-headache subjects.

Visual Evoked Potential Responses after Photostress in Migraine Patients and Their Correlations with Clinical Features

In the past few years, researchers have detected subtle macular vision abnormalities using different psychophysical experimental tasks in patients with migraine. Recording of visual evoked potential (VEP) after photostress (PS) represents an objective way to verify the integrity of the dynamic properties of macular performance after exposure to intense light. VEPs were recorded before and after PS in 51 patients with migraine (19 with aura (MA) and 22 without aura (MO) between attacks, and 10 recorded during an attack (MI)) and 14 healthy volunteers. All study participants were exposed to 30 s of PS through the use of a 200-watt bulb lamp. The P100 implicit time and N75-P100 amplitude of the baseline VEP were compared with those collected every 20 s up to 200 s after PS. VEP parameters recorded at baseline did not differ between groups. In all groups, the VEP recordings exhibited a significant increase in implicit times and a reduction in amplitude at 20 s after the PS. In migraine, the percentage decrease in amplitudes observed at 20 s after photostress was significantly lower than in healthy volunteers, in both MO and MA patients, but not in MI patients. When data for MO and MA patients were combined, the percentage of amplitude change at 20 s was negatively correlated with the number of days that had elapsed since the last migraine attack, and positive correlated with attack frequency. We showed dynamic changes of recovery of VEP after PS depending on the migraine cycle. This finding, in conjunction with those previously attained with other neuromodulatory interventions using VEPs, leads us to argue that migraine-disease-related dysrhythmic thalamocortical activity precludes amplitude suppression by PS.

Intercritical photophobia in the migraineous patient. Proposal for diagnostic criteria

INTRODUCTION

Photophobia is a symptom of abnormal light intolerance without pain sensation that requires an anamnesis and an examination to diagnose an underlying etiology.

BASIC PROCEDURE

This article focuses on 30 clinical cases with isolated intense photophobia and on the review of the literature.

OBJECTIVE

The purpose of this article is to establish diagnostic criteria for photophobia.

RESULTS

The etiology of photophobia appears to be at the level of the intrinsically photosensitive retinal ganglion cells known as melanopsin cells and at a neurochemical level mediated by calcitonin-related peptide and the pituitary activating peptide cyclase.

CONCLUSION

The treatment of photophobia could consist of monoclonal antibodies against calcitonin-related peptide and/or pituitary activating peptide cyclase.

Investigation of light-induced lacrimation and pupillary responses in episodic migraine

The purpose of this pilot study was to investigate the light-induced pupillary and lacrimation responses mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs) in migraine. Ten participants with episodic migraine and normal tear production, as well as eleven visually normal controls participated in this study. Following an initial baseline trial (no light flash), participants received seven incremental and alternating red and blue light flashes. Pupillometry recording of the left eye and a 1-min anesthetized Schirmer’s test of the right eye (using 0.5% proparacaine) were performed simultaneously. Intrinsic and extrinsic ipRGC photoactivities did not differ between migraine participants and controls across all intensities and wavelengths. Migraine participants, however, had significantly lower lacrimation than controls following the highest blue intensity. A positive correlation was found between melanopsin-driven post-illumination pupillary responses and lacrimation following blue stimulation in both groups. Our results show that participants with self-reported photophobia have normal ipRGC-driven responses, suggesting that photophobia and pupillary function may be mediated by distinct ipRGC circuits. The positive correlation between melanopsin-driven pupillary responses and light-induced lacrimation suggests the afferent arm of the light-induced lacrimation reflex is melanopsin-mediated and functions normally in migraine. Lastly, the reduced melanopsin-mediated lacrimation at the highest stimulus suggests the efferent arm of the lacrimation reflex is attenuated under certain conditions, which may be a harbinger of dry eye in migraine.

Melanopsin hypersensitivity dominates interictal photophobia in migraine

PURPOSE

To define the melanopsin and cone luminance retinogeniculate pathway contributions to photophobia in healthy controls and migraineurs.

METHODS

Healthy controls and migraineurs were categorized according to the International Classification of Headache Disorders criteria. Photophobia was measured under full-field illumination using electromyography in response to narrowband lights spanning the melanopsin and cone luminance action spectra. Migraineurs were tested during their interictal headache-free period. Melanopsin-mediated post-illumination pupil responses quantified intrinsically photosensitive Retinal Ganglion Cell (ipRGC) function.

RESULTS

A model combining the melanopsin and cone luminance action spectra best described photophobia thresholds in controls and migraineurs; melanopsin contributions were ∼1.5× greater than cone luminance. In the illumination range causing photophobia, migraineurs had lower photophobia thresholds (∼0.55 log units; p < 0.001) and higher post-illumination pupil response amplitudes (p = 0.03) than controls.

CONCLUSION

Photophobia is driven by melanopsin and cone luminance inputs to the cortex via the retino-thalamocortical pathway. In migraineurs, lower photophobia thresholds reflect hypersensitivity of ipRGC and cone luminance pathways, with the larger and prolonged post-illumination pupil response amplitude indicative of a supranormal melanopsin response. Our findings inform artificial lighting strategies incorporating luminaires with low melanopsin excitation and photopic luminance to limit the lighting conditions leading to photophobia.

Altered lateral geniculate nucleus functional connectivity in migraine without aura: a resting-state functional MRI study

OBJECTIVES

To investigate the structural and functional connectivity changes of lateral geniculate nucleus (LGN) and their relationships with clinical characteristics in patients without aura.

METHODS

Conventional MRI, 3D structure images and resting state functional MRI were performed in 30 migraine patients without aura (MwoA) and 22 healthy controls (HC). The lateral geniculate nucleus volumes and the functional connectivity (FC) of bilateral lateral geniculate nucleus were computed and compared between groups.

RESULTS

The lateral geniculate nucleus volumes in patient groups did not differ from the controls. The brain regions with increased FC of the left LGN mainly located in the left cerebellum and right lingual gyrus in MwoA compared with HC. The increased FC of right LGN located in left inferior frontal gyrus in MwoA compared with HC. The correlation analysis showed a positive correlation between VLSQ-8 score and the increased FC of left cerebellum and right lingual gyrus.

CONCLUSIONS

Photophobia in MwoA could be mediated by abnormal resting state functional connectivity in visual processing regions, the pain perception regulatory network and emotion regulation network. This result is valuable to further understanding about the clinical manifestation and pathogenesis of migraine.

The relationship between exposure to hot/cold weather and the clinical features of headaches in patients with migraine and tension-type headaches

Background and purpose: This study investigates the relationship between exposure to hot/cold weather and the characteristic clinical features of headaches in patients with migraine and tension-type headaches.Methods: This cross-sectional study was conducted with the participation of 190 patients with migraine, and 140 patients with tension-type headaches. The patients were evaluated using a form that collected data on their sociodemographic profile, the clinical features of their headaches, any accompanying symptoms and their relationships with changes in the weather (hot/cold). The headaches of all the participants in the study were thought to be triggered by exposure to hot/cold weather.Results: In the patients with migraine, the exposure to hot/cold weather as a trigger was not found to have a significant relationship with age, body mass index or the characteristic clinical features of headaches (p > 0.05). In patients with tension-type headaches, exposure to hot/cold weather as a trigger was found to have a significant relationship with body mass index (p = 0.019), but not with age or the characteristic clinical features of headaches (p > 0.05).Conclusions: In obese patients with tension-type headache, it was found that hot weather triggered headache more than cold weather. In patients with migraine and tension-type headaches, no relationship was found between exposure to hot/cold weather as a trigger and the clinical features of headaches. The accurate identification of the factors precipitating headaches by both clinicians and patients can help lower the frequency of headaches.

Hemodynamic responses related to intrinsically photosensitive retinal ganglion cells in migraine

To clarify whether photoreception of intrinsically photosensitive retinal ganglion cells (ipRGCs) is related to migraine, we investigated the relationship between hemodynamic responses related to neural activity and visual stimulation of ipRGCs. It has been established that photoreception in ipRGCs is associated with photophobia in migraine. However, the relationship between visual stimulation of ipRGCs and hemodynamic responses in the visual cortex has not been clarified. Hemodynamic responses in the visual cortex were measured using functional near-infrared spectroscopy (fNIRS) as signals reflecting changes in oxygenated and deoxygenated hemoglobin concentrations. Different types of visual stimulation generated by a metamerism method were applied to the peripheral field of the eye of patients with migraine (N = 20) and healthy participants (N = 21). The stimulation intensity on the retina was controlled using an artificial pupil. In the primary visual cortex of patients with migraine, statistically significant changes in fNIRS signals dependent on visual stimulation intensity applied to ipRGCs were observed (p < 0.01), while no such changes were observed in healthy participants. These results reveal that visual stimulation of ipRGCs projecting to the primary visual cortex is involved in hemodynamic responses in patients with migraine, suggesting that ipRGCs, in addition to photometric values related to cones, are associated with migraine.

A reanalysis of a randomized trial on meditation for migraine headaches: Distraction is not enough but meditation takes time

OBJECTIVE

Migraine headaches affect about approximately 15% of the population and some notable efforts have been made to develop meditation interventions to address pain and mood among this population. However, key active ingredients and the necessary duration of meditation interventions to produce an effect are still unknown. The purpose of this study is to assess key meditation ingredients that positively impact mood and headache factors across different meditation techniques and to establish an initial time or" dose" needed to reach proactive treatment efficacy.

METHOD

In this longitudinal study, three active management forms of meditation were compared to a cognitive distraction meditation to assess the effects on migraine headaches and emotions over a 30 day period when practiced 20 min per day.

RESULTS

The active group showed significant decreases in anger (p = .005) and migraine pain (p = .002) over time. Further analysis showed that the bulk of the change for the active management group occurred in the final 10 days, after 20 days of practice of the technique (p < .05).

CONCLUSION

This suggests that cognitively active forms of meditation are more effective in reducing migraine headache pain and negative mood than distraction techniques. However, individuals engaging in these strategies need to consistently practice these techniques for approximately 20 days to proactively reduce migraine headache pain and negative mood.

Visual input drives increased occipital responsiveness and harmonized oscillations in multiple cortical areas in migraineurs

Migraineurs are hypersensitive for most sensory domains like visual, auditory or somatosensory processing even outside of attacks. This behavioral peculiarity is mirrored by findings of cortical hyper-responsivity already in the interictal state. Using repetitive visual stimulation to elicit steady state visually evoked potentials (SSVEP) in 30 interictal episodic migraineurs and 30 controls we show hyper-responsivity of the visual cortex in the migraineurs. Additionally, the occipital regions were remarkably stronger coupled to the temporal, premotor and the anterior cingulate cortex than in headache free controls. These data suggest harmonized oscillations of different cortical areas as a response to visual input which might be driven by the cuneus. Furthermore, the increased coupling is modulated by the current state of the migraine cycle as the coupling was significantly stronger in patients with longer interictal periods.

•

Migraineurs visual cortex compared to controls is hyper-responsiveness in response to repetitive visual stimulation.

•

The hyper-responsiveness is stronger coupled to temporal, premotor and anterior cingulate cortex than in controls.

•

This increased coupling is modulated by the current state of the migraine cycle.

•

Our data suggest that visual input in migraineurs leads to harmonized oscillations of multiple cortical areas.

Neurobiology of Photophobia

BACKGROUND

Photophobia is commonly associated with migraine, meningitis, concussion, and a variety of ocular diseases. Advances in our ability to trace multiple brain pathways through which light information is processed have paved the way to a better understanding of the neurobiology of photophobia and the complexity of the symptoms triggered by light.

PURPOSE

The purpose of this review is to summarize recent anatomical and physiological studies on the neurobiology of photophobia with emphasis on migraine.

RECENT FINDINGS

Observations made in blind and seeing migraine patients, and in a variety of animal models, have led to the discovery of a novel retino-thalamo-cortical pathway that carries photic signal from melanopsinergic and nonmelanopsinergic retinal ganglion cells (RGCs) to thalamic neurons. Activity of these neurons is driven by migraine and their axonal projections convey signals about headache and light to multiple cortical areas involved in the generation of common migraine symptoms. Novel projections of RGCs into previously unidentified hypothalamic neurons that regulate parasympathetic and sympathetic functions have also been discovered. Finally, recent work has led to a novel understanding of color preference in migraine-type photophobia and of the roles played by the retina, thalamus, and cortex.

SUMMARY

The findings provide a neural substrate for understanding the complexity of aversion to light in patients with migraine and neuro-ophthalmologic other disorders.

Automated instrument designed to determine visual photosensitivity thresholds

The Ocular Photosensitivity Analyzer (OPA), a new automated instrument to quantify the visual photosensitivity thresholds (VPT) in healthy and light sensitive subjects, is described. The OPA generates light stimuli of varying intensities utilizing unequal ascending and descending steps to yield the VPT. The performance of the OPA was evaluated in healthy subjects, as well as light sensitive subjects with achromatopsia or traumatic brain injury (TBI). VPT in healthy, achromatopsia, and TBI subjects were 3.2 ± 0.6 log lux, 0.5 ± 0.5 log lux, and 0.4 ± 0.6 log lux, respectively. Light sensitive subjects manifested significantly lower VPT compared to healthy subjects. Longitudinal analysis revealed that the OPA reliably measured VPT in healthy subjects.

Effects of color lenses on visual evoked magnetic fields following bright light

Photophobia is a common condition in which bright light causes an unpleasant feeling due to increased sensitivity to light. In addition to discomfort, photophobia may be accompanied by visual dysfunction. The present study was conducted in order to examine whether visual evoked cortical responses contribute to the assessment of visual dysfunction due to bright light. Visual evoked magnetic fields (VEFs) following the presentation of a uniform bright light of 200–3700 cd/m² in the lower visual field were recorded in 10 healthy volunteers and the effects of five color lenses: yellow, blue, gray, green, and colorless, were examined. VEFs were subjected to a multi-dipole analysis that resulted in the separation of several source activities, including the retina, V1, V2, V6, and fusiform gyrus. Source activity in the retina corresponding to the ERG b-wave exhibited a reduced amplitude and elongated peak latency with the yellow lens. Its latency strongly correlated with transmittance at 450 nm. On the other hand, cortical activities in V1 and the fusiform gyrus were stronger with the yellow lens than with the other color and colorless lenses. Only blue-light blocking showed significant effects. The result showing that the yellow lens enhanced V1 and fusiform activities indicated that processing in these areas was improved when subjects used this lens. The combination of delayed retinal activity and increased visual cortex activity may be an objective indicator of the effects of a color lens on visual function.

Current understanding of photophobia, visual networks and headaches

OBJECTIVE

To review clinical and pre-clinical evidence supporting the role of visual pathways, from the eye to the cortex, in the development of photophobia in headache disorders.

BACKGROUND

Photophobia is a poorly understood light-induced phenomenon that emerges in a variety of neurological and ophthalmological conditions. Over the years, multiple mechanisms have been proposed to explain its causes; however, scarce research and lack of systematic assessment of photophobia in patients has made the search for answers quite challenging. In the field of headaches, significant progress has been made recently on how specific visual networks contribute to photophobia features such as light-induced intensification of headache, increased perception of brightness and visual discomfort, which are frequently experienced by migraineurs. Such progress improved our understanding of the phenomenon and points to abnormal processing of light by both cone/rod-mediated image-forming and melanopsin-mediated non-image-forming visual pathways, and the consequential transfer of photic signals to multiple brain regions involved in sensory, autonomic and emotional regulation.

CONCLUSION

Photophobia phenotype is diverse, and the relative contribution of visual, trigeminal and autonomic systems may depend on the disease it emerges from. In migraine, photophobia could result from photic activation of retina-driven pathways involved in the regulation of homeostasis, making its association with headache more complex than previously thought.

Effect of exposure to short-wavelength light on susceptibility to motion sickness

This randomized cross-over study tested the hypothesis that exposure to short-wavelength light induces symptoms of motion sickness (MS). The study participants were 28 healthy adults (14 women; mean age±SD, 25.96±3.11 years). Two stimuli oscillating within a range of 0.4-0.6 Hz were used to induce MS: a blue wave stimulus with short-wavelength light (460 nm) and a green wave stimulus with middle-wavelength light (555 nm). All participants were exposed to both stimuli throughout two separate periods. After a baseline period, participants were exposed to each stimulus three times for 4 min. The Simulator Sickness Questionnaire, a self-report checklist composed of three subscales (Oculomotor, Disorientation, and Nausea), heart rate variability, and electrogastrography were used to measure the degree of symptoms related to MS. A linear mixed-effects model was used for statistical analysis. The results showed significant main effects for Period (P<0.01), Color (P<0.01), and Time Point (P<0.01) scores on the Simulator Sickness Questionnaire Nausea subscale. A post-hoc test indicated that scores on the Nausea subscale were significantly higher after the third exposure to blue light than after the first and second exposures. The linear mixed-effects model showed significant main effects for Color (P<0.01) with respect to the normogastria/tachygastria ratio. These findings suggest that short-wavelength light induces symptoms of MS, especially gastrointestinal symptoms.

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.

A Quantitative and Qualitative Exploration of Photoaversion in Achromatopsia

Purpose

Photoaversion (PA) is a disabling and ubiquitous feature of achromatopsia (ACHM). We aimed to help define the characteristics of this important symptom, and present the first published assessment of its impact on patients' lives, as well as quantitative and qualitative PA assessments.

Methods

Molecularly confirmed ACHM subjects were assessed for PA using four tasks: structured survey of patient experience, novel quantitative subjective measurement of PA, visual acuities in differing ambient lighting, and objective palpebral aperture-related PA testing.

Results

Photoaversion in ACHM was found to be the most significant symptom for a substantial proportion (38%) of patients. A novel subjective PA measurement technique was developed and demonstrated fidelity with more invasive paradigms without exposing often very photosensitive patients to brighter light intensities used elsewhere. An objective PA measurement was also refined for use in trials, indicating that higher light intensities than previously published are likely to be needed. Monocular testing, as required for trials, was also validated for the first time.

Conclusions

This study offers new insights into PA in ACHM. It provides the first structured evidence of the great significance of this symptom to patients, suggesting that PA should be considered as an additional outcome measure in therapeutic trials. It also offers new insights into the characteristics of PA in ACHM, and describes both subjective and objective measures of PA that could be employed in clinical trials.

Is palinopsia in migraineurs an enhanced physiological phenomenon?

Background

We report the occurrence of palinopsia in patients with migraine and its correlation with migraine characteristics, triggers and allodynia.

Methods

This study included 153 consecutive patients with migraine and recorded their clinical details, including allodynia and migraine triggers and characteristics. Palinopsia was evaluated in migraineurs and 101 controls by using a questionnaire and a novel method.

Results

According to the questionnaire assessment, 9.8% migraineurs had palinopsia. According to the novel method, 57.5% of migraineurs and 12% of controls had palinopsia. Migraineurs most frequently had palinopsia to red color (51.6%), followed by yellow (49.7%), blue (47.7%), green (46.4%) and the least to white (30.7%). A similar pattern with a lesser frequency was noted in controls. The duration of palinopsia was longer in migraineurs than in controls (32.68 ± 20.24 vs. 5.92 ± 4.55 seconds; p < 0.001). Migraineurs with palinopsia differed from those without in terms of noise as a migraine trigger ( p < 0.001) and allodynia as a migraine-associated phenomenon ( p = 0.03). In multivariable analysis, predictors of palinopsia were the frequency ( p = 0.003) and severity ( p = 0.04) of headache and the presence of headache during examination ( p = 0.0001).

Conclusion

Migraineurs had a pattern of palinopsia to different colors that was similar to the controls, but the palinopsia of migraineurs was more frequent and of longer duration, especially during headaches.

Visual processing in migraine

Background

Migraine is a common neurological condition that often involves differences in visual processing. These sensory processing differences provide important information about the underlying causes of the condition, and for the development of treatments.

Review of psychophysical literature

Psychophysical experiments have shown consistent impairments in contrast sensitivity, orientation acuity, and the perception of global form and motion. They have also established that the addition of task-irrelevant visual noise has a greater effect, and that surround suppression, masking and adaptation are all stronger in migraine.

Theoretical signal processing model

We propose utilising an established model of visual processing, based on signal processing theory, to account for the behavioural differences seen in migraine. This has the advantage of precision and clarity, and generating clear, falsifiable predictions.

Conclusion

Increased effects of noise and differences in excitation and inhibition can account for the differences in migraine visual perception. Consolidating existing research and creating a unified, defined theoretical account is needed to better understand the disorder.

Colour Vision in Migraine: Selective Deficits for S-Cone Discriminations

Three studies are reported that explore colour perception in migraine. In each, sensitivity for colours detected selectively by the S-cones and the L- and M-cones was assessed separately. The first study assessed the discrimination of small colour differences using the Farnsworth-Munsell 100-hue test. The second assessed threshold detection for purple, yellow, red and green targets on five equiluminant background colours. The third examined supra-threshold colour scaling using two colour series, purple-yellow and red-green. Each study indicated that differences in colour perception between migraine and control groups were restricted to colours detected by the S-cones, there were no differences in performance for colours detected by the L- and M-cones. The results are discussed in terms of possible pathologies in the early visual pathways.

Migraine photophobia originating in cone-driven retinal pathways

Migraine headache is uniquely exacerbated by light. Using psychophysical assessments in patients with normal eyesight we found that green light exacerbates migraine headache significantly less than white, blue, amber or red lights. To delineate mechanisms, we used electroretinography and visual evoked potential recording in patients, and multi-unit recording of dura- and light-sensitive thalamic neurons in rats to show that green activates cone-driven retinal pathways to a lesser extent than white, blue and red; that thalamic neurons are most responsive to blue and least responsive to green; and that cortical responses to green are significantly smaller than those generated by blue, amber and red lights. These findings suggest that patients' experience with colour and migraine photophobia could originate in cone-driven retinal pathways, fine-tuned in relay thalamic neurons outside the main visual pathway, and preserved by the cortex. Additionally, the findings provide substrate for the soothing effects of green light.

Increased prevalence of depression and anxiety in patients with migraine and interictal photophobia

BACKGROUND

Most patients with migraine report photophobia associated with headache; a subset report interictal photophobia. These patients are light sensitive even during headache-free periods. The objective of this case-control study was to assess the prevalence of symptoms of anxiety and depression in migraine patients with and without interictal photophobia.

METHODS

We recruited 16 subjects with migraine and interictal photophobia, 16 age- and gender-matched migraine subjects without interictal photophobia, and 16 age- and gender- matched controls. Migraine subjects met International Headache Society classification criteria. Participants completed a photophobia questionnaire, Beck Depression Inventory (BDI-II), and Beck Anxiety Inventory (BAI). Chi-square analyses and two-tailed Wilcoxon rank sum tests were used for the analyses.

RESULTS

Subjects with interictal photophobia had significantly higher scores on the photophobia questionnaire compared to subjects without interictal photophobia. Subjects with interictal photophobia had significantly higher scores on the BDI-II and BAI compared to subjects without interictal photophobia.

CONCLUSIONS

Migraine patients with interictal photophobia are more likely to manifest symptoms of depression and anxiety compared to migraine patients without interictal photophobia. Care providers should be aware of increased prevalence of these symptoms in this population and consider appropriate referrals. Future research could assess whether treatment of photophobia leads to improvements in symptoms of depression and anxiety in migraine patients.

Measurement of visual sensitivity in migraine: Validation of two scales and correlation with visual cortex activation

Objective

The objectives of this article are to compare interictal and ictal visual sensitivity between migraine and controls using two published questionnaires, and to correlate responses with a physiologic measure of visual cortex activation.

Methods

Migraine with (MWA, n = 51) and without (MwoA, n = 45) aura and control individuals ( n = 45) were enrolled and underwent BOLD fMRI with a visual stimulus. The visual discomfort score (VDS) assessed interictal and the migraine photophobia score (MPS) assessed ictal visual sensitivity.

Result

VDS was significantly higher both in MWA and MwoA vs controls (both p < 0.0001). MPS was greater in MWA vs MwoA ( p = 0.008). Ictal and interictal visual sensitivity strongly correlated in MWA ( p = 0.004) but not MwoA patients ( p = 0.12). BOLD activation in visual cortex was greater in MWA vs controls (2.7% vs 2.3%, p = 0.003) but similar between MwoA and controls. Increasing VDS was associated with greater BOLD signal change in MWA ( p = 0.03) but not MwoA ( p = 0.65) or controls ( p = 0.53). MPS did not correlate with BOLD activation in either group.

Conclusion

Increased interictal visual sensitivity is present both in MWA and MwoA. However, the correlation with ictal visual sensitivity and with cortical hyper-responsivity varies between MWA and MwoA, suggesting underlying differences between groups.

Multisensory integration in migraine

PURPOSE OF REVIEW

Migraine attacks consist of head pain and hypersensitivities to somatosensory, visual, auditory, and olfactory stimuli. Investigating how the migraine brain simultaneously processes and responds to multiple incoming stimuli may yield insights into migraine pathophysiology and migraine symptoms.

RECENT FINDINGS

The presence and intensity of hypersensitivity to one stimulus type are positively associated with the presence and intensity of hypersensitivities to other stimuli and to headache intensity. Furthermore, exposure to visual, auditory, and olfactory stimuli can trigger migraine attacks. These relationships suggest a role for multisensory integration in migraine.

SUMMARY

Multisensory integration of somatosensory, visual, auditory, and olfactory stimuli by the migraine brain may be an important concept for understanding migraine.

Glare's causes, consequences, and clinical challenges after a century of ophthalmic study

PURPOSE

To provide a multidisciplinary synthesis of scientific information on disability, discomfort, dazzling, and scotomatic (photostress) glare.

DESIGN

Perspective.

METHODS

Analysis and integration of relevant historical and contemporary publications on glare in ophthalmology, illumination engineering, neurology, and other relevant disciplines.

RESULTS

Disability glare is caused by scattered intraocular light (straylight) not useful for vision. Straylight casts a veiling luminance on the retina, reducing image contrast and impairing vision. In common environments, glare and target illumination sources have the same or similar spectra. Colored spectacle or intraocular lens filters reduce both proportionately, so they do not increase retinal image contrast or decrease disability glare. Discomfort glare is caused by situational illumination too intense or variable. Dazzling glare occurs when high illuminances are spread across the retina. Neurophysiological research is clarifying how discomfort and dazzling glare depend on different retinal photoreceptors and nociceptive brain pathways involving the trigeminal ganglion and thalamus. Photostress is caused by excessive local retinal photopigment bleaching uncommon in ordinary situations. Optical glare countermeasures are available for daytime driving but not oncoming automobile headlights at night. Filters that decrease daytime discomfort or dazzling glare also reduce nighttime mesopic and scotopic sensitivity.

CONCLUSIONS

Glare is problematic for patients and clinicians despite a century of scientific research. Advances in understanding glare have been hampered by its complex, multidisciplinary nature and limited interdisciplinary communication. We provide one pathway through the forest of glare nomenclature and mechanisms. Improved diagnostic and therapeutic methodologies await continuing progress in understanding glare.

Shedding light on photophobia

Photophobia is a common yet debilitating symptom seen in many ophthalmic and neurologic disorders. Despite its prevalence, it is poorly understood and difficult to treat. However, the past few years have seen significant advances in our understanding of this symptom. We review the clinical characteristics and disorders associated with photophobia, discuss the anatomy and physiology of this phenomenon, and conclude with a practical approach to diagnosis and treatment.

Advances in understanding the mechanisms of migraine-type photophobia

PURPOSE OF REVIEW

Historically, photophobia was studied in patients and attempts to explain the underlying mechanisms have been speculative. Efforts to understand better the neural substrate of photophobia paved a way to the development of different animal models and the publication of several articles (all in 2010) on the mechanism by which light exacerbates migraine headache.

RECENT FINDINGS

Observations made in blind migraine patients devoid of any visual perception and blind migraine patients capable of detecting light have led to the discovery of a novel retino-thalamo-cortical pathway that carries photic signal from the retina to thalamic trigeminovascular neurons believed to play a critical role in the perception of headache intensity during migraine. Evidence for modulation of the trigeminovascular pathway by light and identification of the pathway through which photic signals converge on the nociceptive pathway that mediates migraine headache provide first set of scientific data on the mechanism by which light intensifies migraine headache.

SUMMARY

The findings provide a neural substrate for migraine-type photophobia. This may lead to identification and development of molecular targets for selective prevention of photophobia during migraine.

Psychogenic non-epileptic seizures: a model of their pathogenic mechanism

Psychogenic non-epileptic seizures (PNES) consist of paroxystic events facilitated by a dysfunction in emotion processing. Models explaining the pathogenic mechanisms leading to these seizure-like episodes are limited. In this article, evidence that supports dysfunction at the level of arousal tolerance, cognitive-emotional information processing and volitional control is reviewed. A hypothetical pathophysiological mechanism is discussed based on functional neuroimaging evidence from PNES-related conditions and traits. This pathophysiological model suggests an alteration in the influence and connection of brain areas involved in emotion processing onto other brain areas responsible for sensorimotor and cognitive processes. Integrating this information, PNES are conceptualized as brief episodes facilitated by an unstable cognitive-emotional attention system. During the episodes, sensorimotor and cognitive processes are modified or not properly integrated, allowing the deployment of autonomous prewired behavioral tendencies. Finally, I elaborate on how therapeutic applications could be modified based on the proposed hypothetical model, potentially improving clinical outcomes.