Photophobia in headache disorders: characteristics and potential mechanisms

Visual snow syndrome in patients with migraine: widening the clinical spectrum of the syndrome with permanent and episodic manifestations

PURPOSE

Migraine is the comorbidity most frequently associated with visual snow syndrome (VSS), but the prevalence of VSS in patients with migraine (PWM) has not been studied. Our objective was to evaluate the frequency of VSS in PWM and to analyze if symptoms of VSS happened in a permanent or episodic manner (eVSS) in this population.

METHODS

We conducted a multicenter observational cross-sectional study. PWM was recruited from headache units, and a survey about the presence of visual snow symptoms was administered. The frequency and characteristics of patients that met current VSS criteria were analyzed. Demographic and clinical features of patients with VSS, eVSS, and PWM with no visual snow were compared.

RESULTS

A total of 217 PWM were included. Seventeen patients (7.8%) met the VSS criteria. VSS patients had visual aura more frequently (58.8% vs. 31%; p = 0.019) and a higher MIDAS score (96.6 vs. 47.7; p = 0.014). Fifty-eight PWM (26.7%) showed visual snow and associated features in an episodic way and were classified as eVSS. Patients with VSS showed a tendency towards a higher frequency of visual symptoms than patients with eVSS (p > 0.05). No statistically significant differences in sociodemographic characteristics and comorbid conditions were found between VSS and eVSS.

CONCLUSION

The prevalence of VSS in PWM may be higher than that described for the general population. Some PWM may present similar visual symptoms to patients with VSS but in an episodic manner. Our study reinforces the observation that the clinical spectrum of visual snow is likely to be broader than previously described.

Photophobia and Visual Triggers in Vestibular Migraine

INTRODUCTION

Vestibular migraine (VM) is a prevalent vestibular disorder characterized by episodic vertigo. However, the relationship between photophobia and visual triggers in VM remains unexplored. We investigated the correlation of photophobia during the VM attack with interictal photosensitivity and visually triggering dizziness in patients with VM.

METHODS

We enrolled patients diagnosed with VM, with or without photophobia, across seven specialized vertigo and headache clinics in China. Healthy individuals were also included as a control group. Using a cross-sectional survey design, we collected data related to light intensity and dizziness frequency triggered by flicker, glare, and eyestrain using the Headache Triggers Sensitivity and Avoidance Questionnaire.

RESULTS

A total of 366 patients were recruited. The photosensitivity and frequency of dizziness induced by flicker, glare, and eyestrain observed in patients with VM and photophobia were significantly elevated compared with those in patients without photophobia and control participants (P < 0.001). A significant positive correlation was observed between photosensitivity levels and dizziness frequency triggered by flicker, glare, and eyestrain in patients with VM and photophobia (P < 0.001).

CONCLUSIONS

This study unequivocally established a positive association of ictal photophobia with interictal photosensitivity and visually triggering dizziness, strongly advocating the need for further research on exposure-based therapies for managing VM.

CLINICAL TRIALS REGISTRATION

ClinicalTrial.gov Identifier, NCT04939922, retrospectively registered, 14th June 2021.

Unveiling the therapeutic potential of Dl-3-n-butylphthalide in NTG-induced migraine mouse: activating the Nrf2 pathway to alleviate oxidative stress and neuroinflammation

BACKGROUND

Migraine stands as a prevalent primary headache disorder, with prior research highlighting the significant involvement of oxidative stress and inflammatory pathways in its pathogenesis and chronicity. Existing evidence indicates the capacity of Dl-3-n-butylphthalide (NBP) to mitigate oxidative stress and inflammation, thereby conferring neuroprotective benefits in many central nervous system diseases. However, the specific therapeutic implications of NBP in the context of migraine remain to be elucidated.

METHODS

We established a C57BL/6 mouse model of chronic migraine (CM) using recurrent intraperitoneal injections of nitroglycerin (NTG, 10 mg/kg), and prophylactic treatment was simulated by administering NBP (30 mg/kg, 60 mg/kg, 120 mg/kg) by gavage prior to each NTG injection. Mechanical threshold was assessed using von Frey fibers, and photophobia and anxious behaviours were assessed using a light/dark box and elevated plus maze. Expression of c-Fos, calcitonin gene-related peptide (CGRP), Nucleus factor erythroid 2-related factor 2 (Nrf2) and related pathway proteins in the spinal trigeminal nucleus caudalis (SP5C) were detected by Western blotting (WB) or immunofluorescence (IF). The expression of IL-1β, IL-6, TNF-α, Superoxide dismutase (SOD) and malondialdehyde (MDA) in SP5C and CGRP in plasma were detected by ELISA. A reactive oxygen species (ROS) probe was used to detect the expression of ROS in the SP5C.

RESULTS

At the end of the modelling period, chronic migraine mice showed significantly reduced mechanical nociceptive thresholds, as well as photophobic and anxious behaviours. Pretreatment with NBP attenuated nociceptive sensitization, photophobia, and anxiety in the model mice, reduced expression levels of c-Fos and CGRP in the SP5C and activated Nrf2 and its downstream proteins HO-1 and NQO-1. By measuring the associated cytokines, we also found that NBP reduced levels of oxidative stress and inflammation. Most importantly, the therapeutic effect of NBP was significantly reduced after the administration of ML385 to inhibit Nrf2.

CONCLUSIONS

Our data suggest that NBP may alleviate migraine by activating the Nrf2 pathway to reduce oxidative stress and inflammation in migraine mouse models, confirming that it may be a potential drug for the treatment of migraine.

Visual snow syndrome and migraine: a review

Visual snow syndrome is a neurological condition characterized by ongoing prominent phenomena described consistently as tiny dots moving across the entire visual field, often associated with complex visual symptoms. These can take the form of afterimages, entoptic phenomena, nyctalopia and light sensitivity. Although some of these symptoms can be benign, they can nonetheless become significantly impactful for many who experience them, particularly in cases that have a sudden and abrupt start. As visual snow syndrome becomes increasingly recognized in clinical practice we begin to learn about its typical presentation and underlying pathophysiology. Treatment of visual snow, however, still proves quite challenging, and efforts need to be focused on unravelling the biological mechanisms of the syndrome. This endeavour has characterized the most recent research on visual snow, mostly involving neuroimaging, neurophysiological and neurobehavioral studies aimed at understanding its underlying neural signature. Another important aspect of the syndrome, which will likely prove critical in deepening our understanding of visual snow, is represented by the intricate biological and historical connexion with migraine. This narrative review focused on visual snow syndrome will explore its clinical, pathophysiological and treatment aspects in detail.

Neuropeptide Y in the medial habenula alleviates migraine-like behaviors through the Y1 receptor

BACKGROUND

Migraine is a highly disabling health burden with multiple symptoms; however, it remains undertreated because of an inadequate understanding of its neural mechanisms. Neuropeptide Y (NPY) has been demonstrated to be involved in the modulation of pain and emotion, and may play a role in migraine pathophysiology. Changes in NPY levels have been found in patients with migraine, but whether and how these changes contribute to migraine is unknown. Therefore, the purpose of this study was to investigate the role of NPY in migraine-like phenotypes.

METHODS

Here, we used intraperitoneal injection of glyceryl trinitrate (GTN, 10 mg/kg) as a migraine mouse model, which was verified by light-aversive test, von Frey test, and elevated plus maze test. We then performed whole-brain imaging with NPY-GFP mice to explore the critical regions where NPY was changed by GTN treatment. Next, we microinjected NPY into the medial habenula (MHb), and further infused Y1 or Y2 receptor agonists into the MHb, respectively, to detect the effects of NPY in GTN-induced migraine-like behaviors.

RESULTS

GTN effectively triggered allodynia, photophobia, and anxiety-like behaviors in mice. After that, we found a decreased level of GFP⁺ cells in the MHb of GTN-treated mice. Microinjection of NPY attenuated GTN-induced allodynia and anxiety without affecting photophobia. Furthermore, we found that activation of Y1-but not Y2-receptors attenuated GTN-induced allodynia and anxiety.

CONCLUSIONS

Taken together, our data support that the NPY signaling in the MHb produces analgesic and anxiolytic effects through the Y1 receptor. These findings may provide new insights into novel therapeutic targets for the treatment of migraine.

Photophobia and migraine outcome during treatment with galcanezumab

Background

Calcitonin gene-related peptide (CGRP) plays a pivotal role in migraine physiology, not only regarding migraine pain but also associated symptoms such as photophobia. The aim of the present study was to assess monoclonal antibodies targeting CGRP efficacy not only in terms of headache and migraine frequency and disability but also in reducing ictal photophobia.

Material and methods

This is a retrospective observational study, conducted at the Headache Center-ASST Spedali Civili Brescia. All patients in monthly treatment with galcanezumab with at least a 6-month follow-up in September 2022 with reported severe photophobia during migraine attacks were included. Data regarding headache frequency, analgesics consumption, and migraine disability were collected quarterly. Moreover, patients were asked the following information regarding photophobia: (1) whether they noticed an improvement in photophobia during migraine attacks since galcanezumab introduction; (2) the degree of photophobia improvement (low, moderate, and high); and (3) timing photophobia improvement.

Results

Forty-seven patients were enrolled in the present study as they met the inclusion criteria. Seventeen patients had a diagnosis of high-frequency episodic migraine and 30 of chronic migraine. From baseline to T3 and T6, a significant improvement in terms of headache days (19.2 ± 7.6 vs. 8.6 ± 6.8 vs. 7.7 ± 5.7; p < 0.0001), migraine days (10.4 ± 6.7 vs. 2.9 ± 4.3 vs. 3.6 ± 2.8; p < 0.0001), analgesics consumption (25.1 ± 28.2 vs. 7.6 ± 7.5 vs. 7.6 ± 8.1; p < 0.0001), MIDAS score (82.1 ± 48.4 vs. 21.6 ± 17.6 vs. 18.1 ± 20.5; p < 0.0001), and HIT-6 score (66.2 ± 6.2 vs. 57.2 ± 8.6 vs. 56.6 ± 7.6; p < 0.0001) was found. Thirty-two patients (68.1%) reported a significant improvement in ictal photophobia, with over half of the patients reporting it within the first month of treatment. Photophobia improvement was more frequent in patients with episodic migraine (p = 0.02) and triptans responders (p = 0.03).

Conclusions

The present study confirms previous reports regarding galcanezumab efficacy beyond migraine frequency. In particular, over 60% of patients, in our cohort, documented a significant improvement also in reducing ictal photophobia. This improvement was, in most patients, moderate to high, and within the first 6 months of treatment, regardless of the clinical response on migraine frequency.

Dialysis headache: A literature review in the last 30 years

Introduction According to the International Classification of Headache Disorders (ICHD-3), dialysis headache has no specific characteristics occurring during and caused by haemodialysis. It resolves spontaneously within 72 hours after the haemodialysis session has ended. Objective To describe the prevalence, clinical features, associated symptoms and risk factors of dialysis headache. Methods Based on a literature search in the major medical databases and using the descriptors“dialysis headache”, “hemodialysis and headache” and “renal dialysis and headache”we included articles published between 1992 and 2022. Of the 492articles found, only 9 met the inclusion criteria and were analyzed. Results We describe 444 patients (53.1% men and 46.9% women) diagnosed with dialysis headache, corresponding to 24.8% of those who underwent hemodialysis.The age ranged from 15 to 75 years. Pain occurred predominantly from the third hour of hemodialysis (65.8%), lasting less than four hours (71.7%), located bilaterally (63.1%), pulsatile (58.5%) and moderate intensity (68.9%).The most frequent associated symptoms were photophobia or phonophobia (71.5%), vertigo (22.3%) and nausea and/or vomiting (16.5%). Conclusion This review showed a high prevalence of dialysis headache in patients undergoing hemodialysis and that the clinical characteristics, treatment and prevention are still poorly studied.

Seasonal Effects on Hospitalizations Due to Mood and Psychotic Disorders: A Nationwide 31-Year Register Study

Purpose

To examine seasonal patterns of hospital admissions due to mood and psychotic disorders and to investigate whether the admission rates show variation according to the seasonal daylength (photoperiods).

Patients and Methods

A retrospective nationwide register-based cohort of all psychiatric admissions (N=978,079) during 1987–2017 in Finland was utilized. The smoothed time-series of adjusted ratio of observed and expected (O/E) daily counts were estimated to examine seasonal variation. The mean O/E with 95% confidence intervals (CI) was used to study the admission rates by photoperiods. The calendar days were classified into the 71-day photoperiods based on the daylength (long/summer, short/winter, equal/spring, equal/fall) and the pace of change in daylength (slowly/rapidly increasing/decreasing daylength).

Results

Manic episodes peaked in summer during the long (mean O/E=1.10, 95% CI=1.06–1.13) and slowly decreasing (1.09, 1.06–1.13) photoperiods and had a nadir in winter during the slowly increasing (0.93, 0.89–0.98) photoperiod. Admissions for unipolar depressive (UPD) episodes peaked in autumn and in spring at the end of the rapidly decreasing (1.03, 1.02–1.04) and increasing (1.03, 1.01–1.04) photoperiod, and dropped in summer during the long and slowly decreasing (0.95, 0.94–0.96) photoperiods. Bipolar depressive (BPD) and mixed episodes signaled excess admissions in autumn and in spring. Admissions for schizophrenia were higher than expected from summer to early-autumn, during the long and slowly decreasing photoperiods (1.02, 1.02–1.03), and lower than expected in other seasons, especially in mid-spring during the rapidly increasing photoperiod (0.98, 0.98–0.99).

Conclusion

The study indicates the seasonality and photoperiodicity of mental disorders, especially for manic episodes. The seasonal pattern is similar between schizophrenia and manic episodes, and between UPD, BPD, and mixed episodes.