Ictal and interictal phonophobia in migraine-a quantitative controlled study

Impact of Migraine and Vestibular Migraine on Audiometric Profiles and Quality of Life in Patients With Tinnitus

OBJECTIVE

To investigate the clinical manifestations and complete auditory function in primary tinnitus patients with and without migraine or vestibular migraine.

DESIGN

Retrospective case-control study.

SETTING

A tertiary referral center.

PARTICIPANTS

This study enrolled 298 patients from the Kaohsiung Veterans General Hospital. All patients were diagnosed with primary tinnitus by a neurotologist between April 2020 and August 2021. Patients were excluded if they had histories of chronic otitis media, idiopathic sudden sensorineural hearing loss, Ménière's disease, skull base neoplasm, or temporal bone trauma.

INTERVENTIONS

Twenty-five-item Tinnitus Handicap Inventory (THI), speech audiometry including speech recognition threshold, most comfortable level, uncomfortable loudness levels, dynamic range, and pure-tone audiometry.

MAIN OUTCOMES MEASURES

Objective hearing loss is defined as a mean threshold greater than 25 dB. Extremely elevated THI is defined as a score greater than 1 standard deviation above the mean THI.

RESULTS

Among the 298 patients with tinnitus, 149 were women and 149 were men, with a mean age of 57.06 (range, 19.22-94.58) years.A total of 125 patients completed the THI questionnaire during their initial visit. The median THI score was 32 (95% confidence interval: 13.98-56.00), and the mean score was 34.99 with a standard deviation of 21.01. The sole contributing factor significantly associated with higher total THI score was the diagnosis of migraine or vestibular migraine (p < 0.001, odds ratio = 19.41).Tinnitus patients with migraine or vestibular migraine exhibited significantly lower mean pure-tone auditory thresholds (right 22.2 versus 29.5, p = 0.002; left 22.5 versus 30.4, p < 0.001), speech recognition threshold (right 20.0 versus 25.2, p = 0.016; left 20.2 versus 25.5, p = 0.019), and most comfortable levels values (right 46.1 versus 51.4, p = 0.007; left 46.9 versus 51.4, p = 0.021) compared with the tinnitus patients without migraine.

CONCLUSIONS

In this population-based study, patients with primary tinnitus experienced significantly higher THI scores and exhibited concurrent symptoms, including dizziness/vertigo, cervicalgia, and migraine or vestibular migraine. Among these parameters, the diagnosis of migraine or vestibular migraine was the sole contributor to significant higher THI score.

Quantifying sensory thresholds along the migraine cycle: An exploratory longitudinal study

BACKGROUND

To date, a number of studies on migraine have cross-sectionally evaluated sensory sensitivity with aversion thresholds/scores along the migraine cycle, reporting a decreased tolerance to sensory stimuli in different sensory modalities. Our hypothesis was that patients with migraine would exhibit heightened sensitivity to sound, light, touch and smell on days where they reported greater headache intensity.

METHODS

This is an exploratory, longitudinal study, carried out over the course of 27 days. Aversion thresholds or scores to sound, light, touch and smell were quantified in six patients with migraine (11.33 ± 6.53 headache days/month).

RESULTS

Patients reported an increased sensitivity to light (padj = 0.0297), touch (padj = 0.0077), and smell (padj = 0.0201) on days with higher headache intensity. However, a greater sensitivity to sound on days with higher headache intensity was only reported when anxiety levels were high (padj = 1.4e-06). Interestingly, variable levels of tolerance to bothersome light over time can also influence the correlation between light sensitivity and headache intensity (padj = 1.4e-06).

CONCLUSIONS

Based on the present findings, future longitudinal studies evaluating sensory threshold changes along the migraine cycle in patients with migraine should account for the increased tolerance to bothersome light over time as well as the effect of anxiety on auditory sensitivity.

Increased presynaptic excitability in a migraine with aura mutation

Migraine is a common and disabling neurological disorder. The headache and sensory amplifications of migraine are attributed to hyperexcitable sensory circuits, but a detailed understanding remains elusive. A mutation in casein kinase 1 delta (CK1δ) was identified in non-hemiplegic familial migraine with aura and advanced sleep phase syndrome. Mice carrying the CK1δT44A mutation were more susceptible to spreading depolarization (the phenomenon that underlies migraine aura), but mechanisms underlying this migraine-relevant phenotype were not known. We used a combination of whole-cell electrophysiology and multiphoton imaging, in vivo and in brain slices, to compare CK1δT44A mice (adult males) to their wild-type littermates. We found that despite comparable synaptic activity at rest, CK1δT44A neurons were more excitable upon repetitive stimulation than wild-type, with a reduction in presynaptic adaptation at excitatory but not inhibitory synapses. The mechanism of this adaptation deficit was a calcium-dependent enhancement of the size of the readily releasable pool of synaptic vesicles, and a resultant increase in glutamate release, in CK1δT44A compared to wild-type synapses. Consistent with this mechanism, CK1δT44A neurons showed an increase in the cumulative amplitude of excitatory post-synaptic currents, and a higher excitation-to-inhibition ratio during sustained activity compared to wild-type. At a local circuit level, action potential bursts elicited in CK1δT44A neurons triggered an increase in recurrent excitation compared to wild-type, and at a network level, CK1δT44A mice showed a longer duration of 'up state' activity, which is dependent on recurrent excitation. Finally, we demonstrated that the spreading depolarization susceptibility of CK1δT44A mice could be returned to wild-type levels with the same intervention (reduced extracellular calcium) that normalized presynaptic adaptation. Taken together, these findings show a stimulus-dependent presynaptic gain of function at glutamatergic synapses in a genetic model of migraine, that accounts for the increased spreading depolarization susceptibility and may also explain the sensory amplifications that are associated with the disease.

Investigation of Frequency-Specific Loudness Discomfort Levels in Listeners With Migraine: A Case-Control Study

OBJECTIVES

Hypersensitivity to auditory stimuli is a commonly reported symptom in listeners with migraine, yet it remains relatively unexplored in research. This study aims to investigate loudness discomfort levels in listeners with migraine, while identifying the frequencies most affected by the phenomenon.

DESIGN

To achieve this, the study compared just audible level and loudness discomfort level ranges between participants with and without migraine from the United Kingdom, Greece as well as the participant recruitment platform Prolific, across 13 frequencies from 100 to 12,000 Hz, through an online listening test.

RESULTS

Fifty-five participants with migraine and 49 participants without migraine from both countries and Prolific were included in the analysis, where threshold ranges between just audible and mildly uncomfortable levels were compared in 13 frequencies. Migraineur group participants presented significantly smaller ranges between just audible and mildly uncomfortable level, due to lower thresholds of mild discomfort in 12 of the 13 frequencies when compared with the nonmigraineur group participants. Participants taking the test during their migraine attack or aura presented a tendency for smaller ranges. In addition, participants with self-reported higher severity migraine exhibited bigger ranges compared with participants with low severity migraine within the migraineur group. No relationship between ranges and medication or migraine attack frequency within the migraineur group was observed.

CONCLUSIONS

Results from the study demonstrate a tendency for the migraineur group to present lower thresholds of mild discomfort compared with the nonmigraineur group, aligning with previous studies while extending the phenomenon to more frequencies than those previously examined. Though the present study presented no relationship between ranges and medication or attack frequency, further research is required to investigate a potential link between these factors.

Exploring sensory sensitivity, cortical excitability, and habituation in episodic migraine, as a function of age and disease severity, using the pattern-reversal task

BACKGROUND

Migraine is a cyclic, neurosensory disorder characterized by recurrent headaches and altered sensory processing. The latter is manifested in hypersensitivity to visual stimuli, measured with questionnaires and sensory thresholds, as well as in abnormal cortical excitability and a lack of habituation, assessed with visual evoked potentials elicited by pattern-reversal stimulation. Here, the goal was to determine whether factors such as age and/or disease severity may exert a modulatory influence on sensory sensitivity, cortical excitability, and habituation.

METHODS

Two similar experiments were carried out, the first comparing 24 young, episodic migraine patients and 28 healthy age- and gender-matched controls and the second 36 middle-aged, episodic migraine patients and 30 healthy age- and gender-matched controls. A neurologist confirmed the diagnoses. Migraine phases were obtained using eDiaries. Sensory sensitivity was assessed with the Sensory Perception Quotient and group comparisons were carried out. We obtained pattern-reversal visual evoked potentials and calculated the N1-P1 Peak-to-Peak amplitude. Two linear mixed-effects models were fitted to these data. The first model had Block (first block, last block) and Group (patients, controls) as fixed factors, whereas the second model had Trial (all trials) and Group as fixed factors. Participant was included as a random factor in both. N1-P1 first block amplitude was used to assess cortical excitability and habituation was defined as a decrease of N1-P1 amplitude across Blocks/Trials. Both experiments were performed interictally.

RESULTS

The final samples consisted of 18 patients with episodic migraine and 27 headache-free controls (first experiment) and 19 patients and 29 controls (second experiment). In both experiments, patients reported increased visual hypersensitivity on the Sensory Perception Quotient as compared to controls. Regarding N1-P1 peak-to-peak data, there was no main effect of Group, indicating no differences in cortical excitability between groups. Finally, significant main effects of both Block and Trial were found indicating habituation in both groups, regardless of age and headache frequency.

CONCLUSIONS

The results of this study yielded evidence for significant hypersensitivity in patients but no significant differences in either habituation or cortical excitability, as compared to headache-free controls. Although the alterations in patients may be less pronounced than originally anticipated they demonstrate the need for the definition and standardization of optimal methodological parameters.

Migraine Disability Improvement during Treatment with Galcanezumab in Patients with Chronic and High Frequency Episodic Migraine

BACKGROUND

The aim of the present study was to assess the migraine outcome, in particular migraine disability, in chronic (CM) and high frequency episodic migraine (HFEM) patients in treatment with galcanezumab.

METHODS

The present study was conducted at the Headache Centre of Spedali Civili of Brescia. Patients were treated with galcanezumab 120 mg monthly. Clinical and demographical information were collected at the baseline (T0). Data about outcome, analgesics consumption and disability (MIDAS and HIT-6 scores) were collected quarterly.

RESULTS

Fifty-four consecutive patients were enrolled. Thirty-seven patients had a diagnosis of CM, 17 of HFEM. During treatment, patients reported a significant reduction in terms of mean headache/migraine days (p < 0.001), the attacks' pain intensity (p = 0.001) and monthly consumed analgesics (p < 0.001). The MIDAS and HIT-6 scores also documented a significant improvement (p < 0.001). At the baseline, all patients documented a severe degree of disability (MIDAS score ≥ 21). Following six months of treatment, only 29.2% of patients still documented a MIDAS score ≥ 21, with one third of patients documenting little or no disability. A > 50% MIDAS reduction, compared to baseline, was observed in up to 94.6% of patients, following the first three months of treatment. A similar outcome was found for HIT-6 scores. A significant positive correlation was found between headache days and MIDAS at T3 and T6 (T6 > T3), but not baseline.

DISCUSSION

Monthly prophylactic treatment with galcanezumab was found to be effective in both CM and HFEM, especially in reducing migraine burden and disability.

Migraine without aura

Migraine without aura is the commonest form of migraine in both children and adults. The diagnosis is made by applying the International Classification of Headache Disorders Third Edition subsection for migraine without aura (ICHD-3 subsection 1.1). Attacks in patients with migraine without aura are characterized by their polyphasic presentation (prodrome, headache phase, postdromal phase). The symptomatology of attacks is diverse and heterogeneous, with most common symptoms being photophobia, phonophobia, nausea, vomiting, and aggravation of pain by movement. The clinician and researcher who wants to learn about migraine without aura needs to be able to apply the ICHD-3 criteria with its specific symptomatology to make a correct diagnosis, but also needs to be aware about the plethora of symptoms patients may experience. In this chapter, the reader will explore the clinical phenotypical features of migraine without aura.

The not so hidden impact of interictal burden in migraine: A narrative review

Migraine is a highly prevalent neurological disease of varying attack frequency. Headache attacks that are accompanied by a combination of impact on daily activities, photophobia and/or nausea are most commonly migraine. The headache phase of a migraine attack has attracted more research, assessment tools and treatment goals than any other feature, characteristic, or phase of migraine. However, the migraine attack may encompass up to 4 phases: the prodrome, aura, headache phase and postdrome. There is growing recognition that the burden of migraine, including symptoms associated with the headache phase of the attack, may persist between migraine attacks, sometimes referred to as the "interictal phase." These include allodynia, hypersensitivity, photophobia, phonophobia, osmophobia, visual/vestibular disturbances and motion sickness. Subtle interictal clinical manifestations and a patient's trepidation to make plans or commitments due to the unpredictability of migraine attacks may contribute to poorer quality of life. However, there are only a few tools available to assess the interictal burden. Herein, we examine the recent advances in the recognition, description, and assessment of the interictal burden of migraine. We also highlight the value in patients feeling comfortable discussing the symptoms and overall burden of migraine when discussing migraine treatment needs with their provider.

Involvement of the cerebellum in migraine

Migraine is a disabling neurological disease characterized by moderate or severe headaches and accompanied by sensory abnormalities, e.g., photophobia, allodynia, and vertigo. It affects approximately 15% of people worldwide. Despite advancements in current migraine therapeutics, mechanisms underlying migraine remain elusive. Within the central nervous system, studies have hinted that the cerebellum may play an important sensory integrative role in migraine. More specifically, the cerebellum has been proposed to modulate pain processing, and imaging studies have revealed cerebellar alterations in migraine patients. This review aims to summarize the clinical and preclinical studies that link the cerebellum to migraine. We will first discuss cerebellar roles in pain modulation, including cerebellar neuronal connections with pain-related brain regions. Next, we will review cerebellar symptoms and cerebellar imaging data in migraine patients. Lastly, we will highlight the possible roles of the neuropeptide calcitonin gene-related peptide (CGRP) in migraine symptoms, including preclinical cerebellar studies in animal models of migraine.

Pathophysiology and Therapy of Associated Features of Migraine

Migraine is a complex and debilitating disorder that is broadly recognised by its characteristic headache. However, given the wide array of clinical presentations in migraineurs, the headache might not represent the main troublesome symptom and it can even go unnoticed. Understanding migraines exclusively as a pain process is simplistic and certainly hinders management. We describe the mechanisms behind some of the most disabling associated symptoms of migraine, including the relationship between the central and peripheral processes that take part in nausea, osmophobia, phonophobia, vertigo and allodynia. The rationale for the efficacy of the current therapeutic arsenal is also depicted in this article. The associated symptoms to migraine, apart from the painful component, are frequent, under-recognised and can be more deleterious than the headache itself. The clinical anamnesis of a headache patient should enquire about the associated symptoms, and treatment should be considered and individualised. Acknowledging the associated symptoms as a fundamental part of migraine has permitted a deeper and more coherent comprehension of the pathophysiology of migraine.

Avoidance behaviour modulates but does not condition phonophobia in migraine

Background

Past studies do not account for avoidance behaviour in migraine as a potential confounder of phonophobia.

Objective

To analyse whether phonophobia is partially driven by avoidance behaviour when using the classic methodology (method of limits).

Methods

This is a case-control study where we tested phonophobia in a cohort of high-frequency/chronic migraine patients (15.5 ± 0.74 headache days/month) and non-headache controls. Auditory stimuli, delivered in both ears, were presented using three different paradigms: the method of limits, the method of constant stimuli, and the adaptive method. Participants were asked to report how bothersome each tone was until a sound aversion threshold was estimated for each method.

Results

In this study, we successfully replicate previously reported reduction in sound aversion threshold using three different methods in a group of 35 patients and 25 controls (p < 0.0001). Avoidance behaviour in migraine reduced sound aversion threshold in the method of limits (p = 0.0002) and the adaptive method (p < 0.0001) when compared to the method of constant stimuli. While thresholds in controls remained the same across methods (method of limits, p = 0.9877 and adaptive method, p = 1).

Conclusion

Avoidance behaviour can exacerbate phonophobia. The current methodology to measure phonophobia needs to be revised.

Cycling multisensory changes in migraine: more than a headache

PURPOSE OF REVIEW

Research on migraine usually focuses on the headache; however, accumulating evidence suggests that migraine not only changes the somatosensory system for nociception (pain), but also the other modalities of perception, such as visual, auditory or tactile sense. More importantly, the multisensory changes exist beyond the headache (ictal) phase of migraine and show cyclic changes, suggesting a central generator driving the multiple sensory changes across different migraine phases. This review summarizes the latest studies that explored the cyclic sensory changes of migraine.

RECENT FINDINGS

Considerable evidence from recent neurophysiological and functional imaging studies suggests that alterations in brain activation start at least 48 h before the migraine headache and outlast the pain itself for 24 h. Several sensory modalities are involved with cyclic changes in sensitivity that peak during the ictal phase.

SUMMARY

In many ways, migraine represents more than just vascular-mediated headaches. Migraine alters the propagation of sensory information long before the headache attack starts.

Bimodal sensory integration in migraine: A study of the effect of visual stimulation on somatosensory evoked cortical responses

BACKGROUND

Merging of sensory information is a crucial process for adapting the behaviour to the environment in all species. It is not known if this multisensory integration might be dysfunctioning interictally in migraine without aura, where sensory stimuli of various modalities are processed abnormally when delivered separately. To investigate this question, we compared the effects of a concomitant visual stimulation on conventional low-frequency somatosensory evoked potentials and embedded high-frequency oscillations between migraine patients and healthy volunteers.

METHODS

We recorded somatosensory evoked potentials in 19 healthy volunteers and in 19 interictal migraine without aura patients before, during, and 5 min after (T2) simultaneous synchronous pattern-reversal visual stimulation. At each time point, we measured amplitude and habituation of the N20-P25 low-frequency-somatosensory evoked potentials component and maximal peak-to-peak amplitude of early and late bursts of high-frequency oscillations.

RESULTS

In healthy volunteers, the bimodal stimulation significantly reduced low-frequency-somatosensory evoked potentials habituation and tended to reduce early high-frequency oscillations that reflect thalamocortical activity. By contrast, in migraine without aura patients, bimodal stimulation significantly increased low-frequency-somatosensory evoked potentials habituation and early high-frequency oscillations. At T2, all visual stimulation-induced changes of somatosensory processing had vanished.

CONCLUSION

These results suggest a malfunctioning multisensory integration process, which could be favoured by an abnormal excitability level of thalamo-cortical loops.

Gait control of migraine patients with increasing light and sound levels

BACKGROUND

Under a typical light and sound environment context, individuals with migraine showed balance control deficits on a series of functional activities, which helps to explain why migraineurs report more falls. it isn't established, the effects of intensity light and sound in migraineurs during functional tasks.

RESEARCH QUESTION

Based on the hypersensitivity to light and sound in migraineurs, not only during the attack but also in the interictal period, does the exposure to bright light and loud sound impact motor control in this population?

METHODS

This cross-sectional study consisted of 51 women with migraine and 22 healthy women. They performed three walking tasks: crossing an obstacle, stepping-up and stepping-down a curb, in a control situation with ambient lighting (≅350 lux), bright light (≅1200 lux), and loud sound (≅90 dBa). For statistical analysis, a t-test, a Spearman correlation test, and a repeated measures mixed ANOVA were applied.

RESULTS

Migraineurs presented higher discomfort induced by light (p ≤ 0.0001) and sound (p = 0.001). In the obstacle task, migraineurs had greater step width than controls in the ambient light condition (p = 0.038) and participants of both groups placed their leading foot farther away from the obstacle in the light (p = 0.033) than in the ambient light condition. For the step-up task, this distance increased for both groups and limbs in the light (leading limb: p = 0.015; trailing limb: p = 0.002) and sound (leading limb: p = 0.010; trailing limb: p ≤ 0.0001) conditions compared to the ambient light condition. Step speed increased for light and sound conditions compared to ambient light condition, except for the sound condition in the step-down task.

SIGNIFICANCE

Despite the higher discomfort induced by light and sound in the migraineurs, the effects of these sensory manipulations were similar for both migraineurs and controls, except for step width. Light and sound manipulation induced a less conservative strategy to deal with uneven terrain in both groups.

Patient-identified most bothersome symptom in preventive migraine treatment with eptinezumab: A novel patient-centered outcome

OBJECTIVES

To describe the methodology and implications of the patient-identified most bothersome symptom (PI-MBS) measure used in the phase 3, multicenter, randomized, double-blind, placebo-controlled, and parallel-group PROMISE-2 trial and to evaluate the contribution of this measure to the assessment of the preventive migraine benefits of treatment.

BACKGROUND

Although freedom from MBS is a coprimary endpoint in acute migraine treatment trials, its evaluation in preventive migraine trials is limited. The PROMISE-2 study assessed a unique PI-MBS measure as a secondary endpoint.

METHODS

This was a secondary analysis of data from the PROMISE-2 study. Adults with chronic migraine (CM) were randomized to receive intravenous (IV) eptinezumab 100 mg, eptinezumab 300 mg, or placebo, administered on day 0 and every 12 weeks. At the screening visit, patients were asked to verbally describe the MBS associated with their CM; the question format was open ended. At subsequent visits, patients were asked to rate the overall change in severity of their MBS from study inception to that time point, using a 7-point ordinal scale ranging from "very much worse" (-3) to "very much improved" (+3). Patients completed the Patient Global Impression of Change (PGIC) assessment during the same visits, using an identical rating scale and recall period. Endpoints were summarized descriptively; post hoc correlations using the methodologies of Pearson and Spearman were calculated to evaluate relationships between PGIC and PI-MBS and between PGIC and mean monthly migraine days (MMDs; primary efficacy endpoint in PROMISE-2).

RESULTS

Altogether, 1072 patients received treatment (eptinezumab 100 mg, n = 356; eptinezumab 300 mg, n = 350; placebo, n = 366) and were included in the analysis. There were 23 unique MBS identified; those reported by ≥10 patients included light sensitivity (18.7%), nausea/vomiting (15.1%), pain with activity (13.7%), pain (12.4%), headache (11.2%), sound sensitivity (7.3%), throbbing/pulsating pain (4.7%), cognitive disruption (4.1%), fatigue (2.4%), mood changes (1.5%), and sensitivity to smell (0.9%). Four weeks after the first dose (week 4), the rates of much or very much improvement in PI-MBS were higher with eptinezumab 100 mg (45%) and 300 mg (57%) than with placebo (29%). Four weeks after the second dose (week 16), the proportions with much or very much improvement in PI-MBS had increased to 58%, 65%, and 36%, respectively. At each time point, the percentages of patients with PGIC ratings of much or very much improved were similar to those for patient-reported improvement in PI-MBS. Patient ratings of changes in PI-MBS and PGIC correlated strongly across time points (Pearson, r range, 0.83-0.88; Spearman, r range, 0.83-0.89); the absolute value of the correlations was greater than the correlation among changes in MMDs and PGIC (Pearson, r range, -0.49 to -0.52; Spearman, r range, -0.49 to -0.52).

CONCLUSIONS

Among patients with CM in the PROMISE-2 study, a broad range of PI-MBS was reported at baseline. Throughout the study, patients treated with eptinezumab reported greater improvement in their PI-MBS severity compared with placebo recipients, and this improvement correlated strongly with PGIC findings. Collectively, these results indicate that PI-MBS is a promising and novel outcome measure for preventive trials of CM and thus may provide a unique patient-centered approach for identifying and measuring the burden of migraine symptoms that matter most to each patient, as well as the benefits of treatment.

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.

A review of decreased sound tolerance in autism: Definitions, phenomenology, and potential mechanisms

Atypical behavioral responses to environmental sounds are common in autistic children and adults, with 50-70 % of this population exhibiting decreased sound tolerance (DST) at some point in their lives. This symptom is a source of significant distress and impairment across the lifespan, contributing to anxiety, challenging behaviors, reduced community participation, and school/workplace difficulties. However, relatively little is known about its phenomenology or neurocognitive underpinnings. The present article synthesizes a large body of literature on the phenomenology and pathophysiology of DST-related conditions to generate a comprehensive theoretical account of DST in autism. Notably, we argue against conceptualizing DST as a unified construct, suggesting that it be separated into three phenomenologically distinct conditions: hyperacusis (the perception of everyday sounds as excessively loud or painful), misophonia (an acquired aversive reaction to specific sounds), and phonophobia (a specific phobia of sound), each responsible for a portion of observed DST behaviors. We further elaborate our framework by proposing preliminary neurocognitive models of hyperacusis, misophonia, and phonophobia that incorporate neurophysiologic findings from studies of autism.

Aberrant activity within auditory network is associated with psychiatric comorbidities in interictal migraineurs without aura

The present study aimed to explore associations between brain activity in the auditory cortex and clinical and psychiatric characteristics in patients with migraine without aura (MwoA) during interictal periods. Resting-state data were acquired from patients with episodic MwoA (n = 34) and healthy controls (n = 30). Independent component analysis was used to extract and calculate the resting-state auditory network. Subsequently, we analyzed the correlations between spontaneous activity in the auditory cortex and clinical and psychiatric features in interictal MwoA. Compared with healthy controls, patients with MwoA showed increased activity in the left superior temporal gyrus (STG), postcentral gyrus (PoCG) and insula. Brain activity in the left STG was positively correlated with anxiety scores, and activity in the left PoCG was negatively correlated with anxiety and depression scores. No significant differences were found in intracranial volume between the two groups. This study indicated that functional impairment and altered integration linked to the auditory cortex existed in patients with MwoA in the interictal period, suggesting that auditory-associated cortex disruption as a biomarker may be implemented for the early diagnosis and prediction of neuropsychiatric impairment in interictal MwoA patients.

Migraine understood as a sensory threshold disease

Migraine encompasses a broader spectrum of sensory symptoms than just headache. These "other" symptoms, eg, sensory phobias, cognitive and mood changes, allodynia, and many others indicate an altered sensitivity to sensory input which can be measured, in principle, by quantifying sensory threshold changes longitudinally over time. Photophobia, for example, can be quantified by investigating the discomfort thresholds towards the luminance of light. The aim of this review is to look into how thresholds change in patients with migraine. We performed a PubMed search up to June 2018 targeting all peer-reviewed articles evaluating the changes in threshold, sensory phobia, or sensitivity in patients with migraine. Migraineurs, in general, exhibit lower sensory thresholds compared with healthy controls. These threshold changes seem to follow the different phases during a migraine cycle. In general, thresholds reach a nadir when the headache starts (the ictal phase), rise after the headache ends, and then gradually descend towards the next attack. The sensory modality of measurement-mechanical, thermal, or nociceptive-and the location of measurement-trigeminal vs somatic dermatome-also influence the sensory threshold. Functional imaging studies provide evidence that the hypothalamo-thalamo-brainstem network may be the driving force behind the periodic threshold changes. In summary, there is evidence in the literature that migraine could be understood as a periodic sensory dysregulation originating from the brain. Nevertheless, the interstudy discrepancy is still high due to different study designs and a lack of focus on distinct migraine phases. Further well-designed and harmonized studies with an emphasis on the cyclic changes still need to be conducted.

Cognition and Cognitive Impairment in Migraine

BACKGROUND

Migraine is a complex neurological disorder that affects a significant percentage of the human species, from all geographic areas and cultures. Cognitive symptoms and dysfunctions are interim and disabling components of this disorder and may be related to the brain processes underlying the pathophysiology. Yet they are often undervalued by clinicians. In this review, we present the different types of cognitive dysfunctions associated with migraine and the mechanisms that are potentially causing them.

FINDINGS

While reversible attack-related cognitive dysfunction seems extremely consistent and likely related to functional cortical and subcortical brain changes occurring during attacks, interictal cognitive dysfunction is less consistent and might become more relevant as attack frequency and disease complexity increase. Migraine traits do not seem a predisposition to long-term cognitive decline. Cognitive dysfunction is a frequent manifestation of migraine attacks and may be specific to this disorder; it is important to understand if it could be useful in migraine diagnosis. Attack-related cognitive dysfunction is clinically relevant and contributes to disability, so it should be perceived as a therapeutic target. While there is no evidence to support that migraine increases the risk of long-term or persistent cognitive dysfunction, the fact that it occurs during the attacks and may persist in subjects with frequent or complicated attacks should prompt the understanding of the mechanisms related to its pathophysiology for it may also clarify the processes underlying migraine.

Identification of Everyday Sounds Perceived as Noise by Migraine Patients

Objective Sound hypersensitivity is highly comorbid with migraine headaches. To elucidate the pathogenic mechanism of migraine attacks, we must first identify the types of everyday environmental sounds they perceive as unpleasant and clarify the acoustic properties of such sounds. This study aimed to clarify the true nature of "noise," i.e. everyday sounds perceived as unpleasant by migraineurs, by evaluating their subjective comfort/discomfort in response to several sounds commonly heard in everyday life. Methods Participants were presented with 20 environmental sounds they would likely hear daily. Subjects rated the pleasantness/unpleasantness of each stimulus using a nine-step scale. Patients We recruited 50 adults with migraine headaches (46 women, 4 men) and 50 healthy controls (35 women, 15 men). Results Migraineurs provided statistically significantly lower (more unpleasant) ratings to ambulance sirens, police car sirens, and railroad crossing bells than did controls. Our analysis also investigated the acoustic characteristics associated with higher rating gaps between the two groups. Greater divergence in ratings for the same stimulus was associated with less power (smaller amplitude envelope) and slower temporal variation in signals in the 400-Hz band. Conclusion We identified specific signal components associated with different subjective (un) pleasantness scores between migraineurs and healthy adults, which may lead to the elucidation of the pathogenic mechanism underlying migraine attacks triggered by sound.

Abnormal thalamocortical network dynamics in migraine

OBJECTIVE

To investigate the dynamic functional connectivity of thalamocortical networks in interictal migraine patients and whether clinical features are associated with abnormal connectivity.

METHODS

We investigated dynamic functional network connectivity (dFNC) of the migraine brain in 89 interictal migraine patients and 70 healthy controls. We focused on the temporal properties of thalamocortical connectivity using sliding window cross-correlation, clustering state analysis, and graph-theory methods. Relationships between clinical symptoms and abnormal dFNC were evaluated using a multivariate linear regression model.

RESULTS

Five dFNC brain states were identified to characterize and compare dynamic functional connectivity patterns. We demonstrated that migraineurs spent more time in a strongly interconnected between-network state, but they spent less time in a sparsely connected state. Interestingly, we found that abnormal posterior thalamus (pulvinar nucleus) dFNC with the visual cortex and the precuneus were significantly correlated with headache frequency of migraine. Further topologic measures revealed that migraineurs had significantly lower efficiency of information transfer in both global and local dFNC.

CONCLUSION

Our results demonstrated a transient pathologic state with atypical thalamocortical connectivity in migraineurs and extended current findings regarding abnormal thalamocortical networks and dysrhythmia in migraine.

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.

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

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

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

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

Restless legs syndrome is associated with headache-related disabilities in patients with migraine: a prospective 7-year follow-up study

BACKGROUND AND PURPOSE

No prospective study has evaluated the impact of restless legs syndrome (RLS) on clinical factors in patients with migraine. We planned a prospective study to assess the impact of RLS comorbid status on clinical factors in patients with migraine.

METHODS

A total of 101 patients with migraine who were evaluated for RLS twice at 7-year intervals in a university hospital setting were included in this study. The RLS group was defined as positive for RLS at either baseline or follow-up and the non-RLS group was defined as negative for RLS at both baseline and follow-up. The Migraine Disability Assessment (MIDAS) questionnaire, Beck Depression Inventory-II (BDI-II), Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale were administered to all patients.

RESULTS

The RLS prevalence was 16.8% at baseline and 20.8% at follow-up. Compared with the non-RLS group (n = 27), the RLS group (n = 74) showed a significantly higher rate of smoking and higher MIDAS and BDI-II scores at 7-year follow-up. A significant reduction in MIDAS and BDI-II scores at 7-year follow-up compared with those at baseline was observed in the non-RLS group, but not in the RLS group. The non-RLS group showed a significantly lower MIDAS score at 7-year follow-up than the RLS group after adjusting for confounding variables such as age, gender, smoking status, Epworth Sleepiness Scale and PSQI scores using analysis of covariance. The persistent RLS group (n = 11) (positive for RLS at both baseline and follow-up) showed a significantly higher rate of smoking and increased MIDAS, BDI-II and PSQI scores compared with the non-RLS group (n = 74) at 7-year follow-up.

CONCLUSION

Our prospective study showed that RLS had a significant impact on headache-related disability in patients with migraine.

Electrophysiological Characteristics of the Migraine Brain: Current Knowledge and Perspectives

BACKGROUND

Despite pain being its most prominent feature, migraine is primarily a disorder of sensory processing. Electrophysiology-based research in the field has consistently developed over the last fifty years.

OBJECTIVE

To summarize the current knowledge on the electrophysiological characteristics of the migraine brain, and discuss perspectives.

METHODS

We critically reviewed the literature on the topic to present and discuss articles selected on the basis of their significance and/or novelty.

RESULTS

Physiologic fluctuations within time, between-subject differences, and methodological issues account as major limitations of electrophysiological research in migraine. Nonetheless, several abnormalities revealed through different approaches have been described in the literature. Altogether, these results are compatible with an abnormal state of sensory processing.

PERSPECTIVES

The greatest contribution of electrophysiological testing in the future will most probably be the characterization of sub-groups of migraine patients sharing specific electrophysiological traits. This should serve as strategy towards personalized migraine treatment. Incorporation of novel methods of analysis would be worthwhile.

Altered Brain Functional Connectome in Migraine with and without Restless Legs Syndrome: A Resting-State Functional MRI Study

Background

Migraine is frequently comorbid with restless legs syndrome (RLS), both displaying functional connectivity (FC) alterations in multiple brain networks, although the neurological basis of this association is unknown.

Methods

We performed resting-state functional magnetic resonance imaging and network-wise analysis of FC in migraine patients with and without RLS and healthy controls (CRL). Network-based statistics (NBS) and composite FC matrix analyses were performed to identify the patterns of FC changes. Correlation analyses were performed to identify associations between alterations in FC and clinical profiles.

Results

NBS results revealed that both migraine patients with and without RLS exhibited lower FC than CRL in the dorsal attention, salience, default mode, cingulo-opercular, visual, frontoparietal, auditory, and sensory/somatomotor networks. Further composite FC matrix analyses revealed differences in FC of the salience, default mode to subcortical and frontoparietal, auditory to salience, and memory retrieval networks between migraine patients with and without RLS. There was a trend toward a negative association between RLS severity and cross-network abnormalities in the default mode to subcortical network.

Discussion

Migraine patients with and without RLS exhibit disruptions of brain FC. Such findings suggest that these disorders are associated with differential neuropathological mechanisms and may aid in the future development of neuroimaging-driven biomarkers for these conditions.

Structural alterations of the brainstem in migraine

Atypical brainstem modulation of pain might contribute to changes in sensory processing typical of migraine. The study objective was to investigate whether migraine is associated with brainstem structural alterations that correlate with this altered pain processing.

MRI T1-weighted images of 55 migraine patients and 58 healthy controls were used to: (1) create deformable mesh models of the brainstem that allow for shape analyses; (2) calculate volumes of the midbrain, pons, medulla and the superior cerebellar peduncles; (3) interrogate correlations between regional brainstem volumes, cutaneous heat pain thresholds, and allodynia symptoms.

Migraineurs had smaller midbrain volumes (healthy controls = 61.28 mm³, SD = 5.89; migraineurs = 58.80 mm³, SD = 6.64; p = 0.038), and significant (p < 0.05) inward deformations in the ventral midbrain and pons, and outward deformations in the lateral medulla and dorsolateral pons relative to healthy controls. Migraineurs had a negative correlation between ASC-12 allodynia symptom severity with midbrain volume (r = − 0.32; p = 0.019) and a positive correlation between cutaneous heat pain thresholds with medulla (r = 0.337; p = 0.012) and cerebellar peduncle volumes (r = 0.435; p = 0.001).

Migraineurs with greater symptoms of allodynia have smaller midbrain volumes and migraineurs with lower heat pain thresholds have smaller medulla and cerebellar peduncles. The brainstem likely plays a role in altered sensory processing in migraine and brainstem structure might reflect severity of allodynia and hypersensitivity to pain in migraine.

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Migraineurs have less volume in midbrain regions and show morphologic shape indentations in ventral pons and midbrain as well as right and left outward deformations in the lateral aspects of the pons and medulla.

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Migraineurs with more severe allodynia have less midbrain volume and migraineurs with lower heat pain thresholds have less volume in the cerebellar peduncles and medulla.

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Brainstem morphological alterations might reflect dysfunctional pain modulation in migraine.

Increased Functional Activation of Limbic Brain Regions during Negative Emotional Processing in Migraine

Pain is both an unpleasant sensory and emotional experience. This is highly relevant in migraine where cortical hyperexcitability in response to sensory stimuli (including pain, light, and sound) has been extensively reported. However, migraine may feature a more general enhanced response to aversive stimuli rather than being sensory-specific. To this end we used functional magnetic resonance imaging to assess neural activation in migraineurs interictaly in response to emotional visual stimuli from the International Affective Picture System. Migraineurs, compared to healthy controls, demonstrated increased neural activity in response to negative emotional stimuli. Most notably in regions overlapping in their involvement in both nociceptive and emotional processing including the posterior cingulate, caudate, amygdala, and thalamus (cluster corrected, p < 0.01). In contrast, migraineurs and healthy controls displayed no and minimal differences in response to positive and neutral emotional stimuli, respectively. These findings support the notion that migraine may feature more generalized altered cerebral processing of aversive/negative stimuli, rather than exclusively to sensory stimuli. A generalized hypersensitivity to aversive stimuli may be an inherent feature of migraine, or a consequential alteration developed over the duration of the disease. This proposed cortical-limbic hypersensitivity may form an important part of the migraine pathophysiology, including psychological comorbidity, and may represent an innate sensitivity to aversive stimuli that underpins attack triggers, attack persistence and (potentially) gradual headache chronification.

Functional imaging and migraine: new connections?

PURPOSE OF REVIEW

Over the last several years, a growing number of brain functional imaging studies have provided insights into mechanisms underlying migraine. This article reviews the recent migraine functional neuroimaging literature and provides recommendations for future studies that will help fill knowledge gaps.

RECENT FINDINGS

PET and functional MRI studies have identified brain regions that might be responsible for mediating the onset of a migraine attack and those associated with migraine symptoms. Enhanced activation of brain regions that facilitate processing of sensory stimuli suggests a mechanism by which migraineurs are hypersensitive to visual, olfactory, and cutaneous stimuli. Resting state functional connectivity MRI studies have identified numerous brain regions and functional networks with atypical functional connectivity in migraineurs, suggesting that migraine is associated with aberrant brain functional organization.

SUMMARY

Functional MRI and PET studies that have identified brain regions and brain networks that are atypical in migraine have helped to describe the neurofunctional basis for migraine symptoms. Future studies should compare functional imaging findings in migraine to other headache and pain disorders and should explore the utility of functional imaging data as biomarkers for diagnostic and treatment purposes.

Low heat pain thresholds in migraineurs between attacks

BACKGROUND/OBJECTIVE

Between attacks, migraine is associated with hypersensitivities to sensory stimuli. The objective of this study was to investigate hypersensitivity to pain in migraineurs between attacks.

METHODS

Cutaneous heat pain thresholds were measured in 112 migraineurs, migraine free for ≥ 48 hours, and 75 healthy controls. Pain thresholds at the head and at the arm were compared between migraineurs and controls using two-tailed t-tests. Among migraineurs, correlations between heat pain thresholds and headache frequency, allodynia symptom severity, and time interval until next headache were calculated.

RESULTS

Migraineurs had lower pain thresholds than controls at the head (43.9 ℃ ± 3.2 ℃ vs. 45.1 ℃ ± 3.0 ℃, p = 0.015) and arm (43.2 ℃ ± 3.4 ℃ vs. 44.8 ℃ ± 3.3 ℃, p < 0.001). There were not significant correlations between pain thresholds and headache frequency or allodynia symptom severity. For the 41 migraineurs for whom time to next headache was known, there were positive correlations between time to next headache and pain thresholds at the head (r = 0.352, p = 0.024) and arm (r = 0.312, p = 0.047).

CONCLUSIONS

This study provides evidence that migraineurs have low heat pain thresholds between migraine attacks. Mechanisms underlying these lower pain thresholds could also predispose migraineurs to their next migraine attack, a hypothesis supported by finding positive correlations between pain thresholds and time to next migraine attack.

Elevated audiovisual temporal interaction in patients with migraine without aura

BACKGROUND

Photophobia and phonophobia are the most prominent symptoms in patients with migraine without aura. Hypersensitivity to visual stimuli can lead to greater hypersensitivity to auditory stimuli, which suggests that the interaction between visual and auditory stimuli may play an important role in the pathogenesis of migraine. However, audiovisual temporal interactions in migraine have not been well studied. Therefore, our aim was to examine auditory and visual interactions in migraine.

METHODS

In this study, visual, auditory, and audiovisual stimuli with different temporal intervals between the visual and auditory stimuli were randomly presented to the left or right hemispace. During this time, the participants were asked to respond promptly to target stimuli. We used cumulative distribution functions to analyze the response times as a measure of audiovisual integration.

RESULTS

Our results showed that audiovisual integration was significantly elevated in the migraineurs compared with the normal controls (p < 0.05); however, audiovisual suppression was weaker in the migraineurs compared with the normal controls (p < 0.05).

CONCLUSIONS

Our findings further objectively support the notion that migraineurs without aura are hypersensitive to external visual and auditory stimuli. Our study offers a new quantitative and objective method to evaluate hypersensitivity to audio-visual stimuli in patients with migraine.

Correlations between brain cortical thickness and cutaneous pain thresholds are atypical in adults with migraine

BACKGROUND/OBJECTIVE

Migraineurs have atypical pain processing, increased expectations for pain, and hypervigilance for pain. Recent studies identified correlations between brain structure and pain sensation in healthy adults. The objective of this study was to compare cortical thickness-to-pain threshold correlations in migraineurs to healthy controls. We hypothesized that migraineurs would have aberrant relationships between the anatomical neurocorrelates of pain processing and pain thresholds.

METHODS

Pain thresholds to cutaneously applied heat were determined for 31 adult migraineurs and 32 healthy controls. Cortical thickness was determined from magnetic resonance imaging T1-weighted sequences. Regional cortical thickness-to-pain threshold correlations were determined for migraineurs and controls separately using a general linear model whole brain vertex-wise analysis. A pain threshold-by-group interaction analysis was then conducted to estimate regions where migraineurs show alterations in the pain threshold-to-cortical thickness correlations relative to healthy controls.

RESULTS

Controls had negative correlations (p<0.01 uncorrected) between pain thresholds and cortical thickness in left posterior cingulate/precuneus, right superior temporal, right inferior parietal, and left inferior temporal regions, and a negative correlation (p<0.01 Monte Carlo corrected) with a left superior temporal/inferior parietal region. Migraineurs had positive correlations (p<0.01 uncorrected) between pain thresholds and cortical thickness in left superior temporal/inferior parietal, right precuneus, right superior temporal/inferior parietal, and left inferior parietal regions. Cortical thickness-to-pain threshold correlations differed between migraine and control groups (p<0.01 uncorrected) for right superior temporal/inferior parietal, right precentral, left posterior cingulate/precuneus, and right inferior parietal regions and (p<0.01 Monte Carlo corrected) for a left superior temporal/inferior parietal region.

CONCLUSIONS

Unlike healthy control subjects who have a significant negative correlation between cortical thickness in a superior temporal/inferior parietal region with pain thresholds, migraineurs have a non-significant positive correlation between cortical thickness in a superior temporal/inferior parietal region with pain thresholds. Since this region participates in orienting and attention to painful stimuli, absence of the normal correlation might represent a migraineurs inability to inhibit pain sensation via shifting attention away from the painful stimulus.

Field testing the alternative criteria for tension-type headache proposed in the third beta edition of the international classification of headache disorders: results from the Korean headache-sleep study

Background

According to the third beta edition of the International Classification of Headache Disorder (ICHD-3 beta), the diagnostic criteria for tension-type headache (TTH) might lead to the inclusion of individuals with headaches showing migrainous features. To better define TTH, the alternative diagnostic criteria were proposed in the appendix of ICHD-3 beta. This study attempted to test the alternative criteria for diagnosis of TTH proposed in ICHD-3 beta in a population-based sample from Korea.

Methods

We selected participants from the Korean population aged 19–69 years using stratified random sampling and evaluated them by interview using a questionnaire designed to identify headache type, headache characteristics, and psychiatric comorbidities.

Results

Of the 2,762 participants, 586 (21.3%) were diagnosed as having TTH using the standard criteria. Among these, 238 (40.6%) were also classified as having TTH using the alternative criteria. All 238 TTH subjects first diagnosed as having TTH by the alternative criteria were also classified as having TTH by the standard criteria. If the standard criteria were not applied, the remaining 348 patients were subclassified as having probable migraine (115, 19.6%) and unclassified headache (233, 39.7%). Compared with subjects diagnosed with TTH using the standard criteria, those diagnosed using the alternative criteria were less likely to demonstrate unilateral, pulsating headache, which is aggravated by movement, photophobia, phonophobia, and osmophobia.

Conclusion

Using the alternative criteria, less than half of the subjects with TTH according to the standard criteria were classified as having TTH. All the subjects with TTH by the alternative criteria were classified as having TTH by the standard criteria. This study also demonstrated that subjects diagnosed with TTH using the standard criteria could include people with headaches showing migrainous features.

Is the migrainous brain normal outside of acute attacks? Lessons learned from psychophysical, neurochemical and functional neuroimaging studies

Migraine is a largely inherited disorder of the brain with recurrent head pain attacks. There is an increasing awareness, however, that the manifestation of migrainous biology is not restricted to such acute head pain attacks, but that migraine is rather a disorder with a continuous complex and broad sensory processing dysfunction in which normal sensory stimuli (somatosensory, visual, auditory and olfactory) are misinterpreted by the brain. This dysfunction is most prominent during attacks, but there are more and more evidences that the processing and perception of stimuli is abnormal also outside of attacks to a varying degree. In this topical review, we will summarize and discuss the current clinical, neurochemical and functional neuroimaging literature on this paradigm shift from a strictly episodic head pain disorder to migraine as a more general dysfunction of sensory processing.

Altered brainstem auditory evoked potentials in a rat central sensitization model are similar to those in migraine

Migraine symptoms often include auditory discomfort. Nitroglycerin (NTG)-triggered central sensitization (CS) provides a rodent model of migraine, but auditory brainstem pathways have not yet been studied in this example. Our objective was to examine brainstem auditory evoked potentials (BAEPs) in rat CS as a measure of possible auditory abnormalities. We used four subdermal electrodes to record horizontal (h) and vertical (v) dipole channel BAEPs before and after injection of NTG or saline. We measured the peak latencies (PLs), interpeak latencies (IPLs), and amplitudes for detectable waveforms evoked by 8, 16, or 32 kHz auditory stimulation. At 8 kHz stimulation, vertical channel positive PLs of waves 4, 5, and 6 (vP4, vP5, and vP6), and related IPLs from earlier negative or positive peaks (vN1-vP4, vN1-vP5, vN1-vP6; vP3-vP4, vP3-vP6) increased significantly 2h after NTG injection compared to the saline group. However, BAEP peak amplitudes at all frequencies, PLs and IPLs from the horizontal channel at all frequencies, and the vertical channel stimulated at 16 and 32 kHz showed no significant/consistent change. For the first time in the rat CS model, we show that BAEP PLs and IPLs ranging from putative bilateral medial superior olivary nuclei (P4) to the more rostral structures such as the medial geniculate body (P6) were prolonged 2h after NTG administration. These BAEP alterations could reflect changes in neurotransmitters and/or hypoperfusion in the midbrain. The similarity of our results with previous human studies further validates the rodent CS model for future migraine research.

Enhanced pain-induced activity of pain-processing regions in a case-control study of episodic migraine

OBJECTIVE

The objective of this study was to identify brain regions having aberrant pain-induced activation in migraineurs, thereby gaining insight into particular aspects of pain processing that are atypical in migraineurs.

METHODS

Functional magnetic resonance imaging assessed whole brain responses to painful heat in 24 adult episodic migraineurs who were at least 48 hours pain free and 27 healthy controls. Regions differentially activated in migraineurs compared to controls were identified. Activation intensities in these regions were correlated with headache frequency, number of migraine years, and time to next migraine attack.

RESULTS

Migraineurs had greater pain-induced activation of lentiform nucleus, fusiform gyrus, subthalamic nucleus, hippocampus, middle cingulate cortex, premotor cortex, somatosensory cortex, and dorsolateral prefrontal cortex, and less activation in precentral gyrus and superior temporal gyrus. There were significant correlations between activation strength and headache frequency for middle cingulate (r = 0.627, p = 0.001), right dorsolateral prefrontal cortex (r = 0.568, p = 0.004), left fusiform gyrus (r = 0.487, p = 0.016), left precentral gyrus (r = 0.415, p = 0.044), and left hippocampus (r = 0.404, p = 0.050) and with number of migraine years for left fusiform gyrus (r = 0.425, p = 0.038). There were no significant correlations between activation strength and time to next migraine attack.

CONCLUSIONS

The majority of regions with enhanced pain-induced activation in headache-free migraineurs participate in cognitive aspects of pain perception such as attending to pain and pain memory. Enhanced cognitive pain processing by migraineurs might reflect cerebral hypersensitivity related to high expectations and hypervigilance for pain.

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.

Atypical resting-state functional connectivity of affective pain regions in chronic migraine

OBJECTIVE

Chronic migraineurs (CM) have painful intolerances to somatosensory, visual, olfactory, and auditory stimuli during and between migraine attacks. These intolerances are suggestive of atypical affective responses to potentially noxious stimuli. We hypothesized that atypical resting-state functional connectivity (rs-fc) of affective pain-processing brain regions may associate with these intolerances. This study compared rs-fc of affective pain-processing regions in CM with controls.

METHODS

Twelve minutes of resting-state blood oxygenation level-dependent data were collected from 20 interictal adult CM and 20 controls. Rs-fc between 5 affective regions (anterior cingulate cortex, right/left anterior insula, and right/left amygdala) with the rest of the brain was determined. Functional connections consistently differing between CM and controls were identified using summary analyses. Correlations between number of migraine years and the strengths of functional connections that consistently differed between CM and controls were calculated.

RESULTS

Functional connections with affective pain regions that differed in CM and controls included regions in anterior insula, amygdala, pulvinar, mediodorsal thalamus, middle temporal cortex, and periaqueductal gray. There were significant correlations between the number of years with CM and functional connectivity strength between the anterior insula with mediodorsal thalamus and anterior insula with periaqueductal gray.

CONCLUSION

CM is associated with interictal atypical rs-fc of affective pain regions with pain-facilitating and pain-inhibiting regions that participate in sensory-discriminative, cognitive, and integrative domains of the pain experience. Atypical rs-fc with affective pain regions may relate to aberrant affective pain processing and atypical affective responses to painful stimuli characteristic of CM.

Spontaneous trigeminal allodynia in rats: a model of primary headache

Animal models are essential for studying the pathophysiology of headache disorders and as a screening tool for new therapies. Most animal models modify a normal animal in an attempt to mimic migraine symptoms. They require manipulation to activate the trigeminal nerve or dural nociceptors. At best, they are models of secondary headache. No existing model can address the fundamental question: How is a primary headache spontaneously initiated? In the process of obtaining baseline periorbital von Frey thresholds in a wild-type Sprague-Dawley rat, we discovered a rat with spontaneous episodic trigeminal allodynia (manifested by episodically changing periorbital pain threshold). Subsequent mating showed that the trait is inherited. Animals with spontaneous trigeminal allodynia allow us to study the pathophysiology of primary recurrent headache disorders. To validate this as a model for migraine, we tested the effects of clinically proven acute and preventive migraine treatments on spontaneous changes in rat periorbital sensitivity. Sumatriptan, ketorolac, and dihydroergotamine temporarily reversed the low periorbital pain thresholds. Thirty days of chronic valproic acid treatment prevented spontaneous changes in trigeminal allodynia. After discontinuation, the rats returned to their baseline of spontaneous episodic threshold changes. We also tested the effects of known chemical human migraine triggers. On days when the rats did not have allodynia and showed normal periorbital von Frey thresholds, glycerol trinitrate and calcitonin gene related peptide induced significant decreases in the periorbital pain threshold. This model can be used as a predictive model for drug development and for studies of putative biomarkers for headache diagnosis and treatment.

Concurrent functional and structural cortical alterations in migraine

AIM

Various animal and human studies have contributed to the idea of cortical structural-functional alterations in migraine. Defining concurrent cortical alterations may provide specific insights into the unfolding adaptive or maladaptive changes taking place in cortex in migraine.

METHODS

From a group of 60 episodic migraineurs, 20 were recruited to the study. Using high-resolution magnetic resonance imaging, structural and functional cortical measures were compared in migraineurs who experienced increased frequency of attacks (HF; 8-14 days/month; n = 10), to those who experienced less frequent migraine attacks (LF; < 2 days/month; n = 10), and to healthy controls (HC; n = 20).

RESULTS

Parallel structural and functional differences were found as follows: (i) HF patients showed higher thickness in the area representing the face in the post-central gyrus, which correlated with the observed stronger functional activation, suggesting adaptation to repeated sensory drive; (ii) smaller cortical volume was observed in the cingulate cortex that correlated with lower activation in the HF group; and (iii) similarly significant structural and functional differences (HF > LF) were observed in the insula that may reflect potential alteration in affective processing.

CONCLUSION

These results suggest differential response patterns in the sensory vs. affective processing regions in the brain that may be an adaptive response to repeated migraine attacks.

The biological basis of headache

This article covers the remarkable recent decades as clinicians and scientists have grappled with understanding headache. It is a challenge to understand how a 'normal' brain can become dysfunctional, incapacitating an individual, and then become 'normal' again. Does the answer lie in the anatomy, electrical pathways, the chemistry or a combination? How do the pieces fit together? The components are analyzed in this article. Animal models have provided potential answers. However, these processes have never been proven in man. The dynamic imaging of pain and headache is rapidly evolving and providing new insights and directions of research.

Visual and auditory perceptual rivalry in migraine

INTRODUCTION

Recent evidence demonstrates that perceptual rivalry rate can be modulated by perturbation of the serotonergic system. Specifically, pharmacologically lowering the availability of serotonin results in slower rivalry rates. As it has been suggested that brain serotonin is low during the interictal phase of migraine, we hypothesized that perceptual rivalry rates would be reduced in individuals with migraine.

METHODS

Visual and auditory perceptual rivalry measures were obtained for a group of 30 participants with migraine (15 migraine with aura, 15 migraine without aura) and 20 non-headache control individuals.

RESULTS

Our experiments reveal fewer perceptual rivalry switches within both visual and auditory domains for our migraine without aura group, while the with-aura group performed similarly to non-headache controls. Dividing the data by headache frequency rather than headache subtype classification revealed fewer perceptual switches in those with more frequent headaches.

CONCLUSIONS

Our data provides further support for interictal differences in brain sensory reactivity in migraine, with the observed effects being in the same direction as those caused by pharmacologically reducing brain availability of serotonin in normal observers.

Acetate causes alcohol hangover headache in rats

BACKGROUND

The mechanism of veisalgia cephalgia or hangover headache is unknown. Despite a lack of mechanistic studies, there are a number of theories positing congeners, dehydration, or the ethanol metabolite acetaldehyde as causes of hangover headache.

METHODS

We used a chronic headache model to examine how pure ethanol produces increased sensitivity for nociceptive behaviors in normally hydrated rats.

RESULTS

Ethanol initially decreased sensitivity to mechanical stimuli on the face (analgesia), followed 4 to 6 hours later by inflammatory pain. Inhibiting alcohol dehydrogenase extended the analgesia whereas inhibiting aldehyde dehydrogenase decreased analgesia. Neither treatment had nociceptive effects. Direct administration of acetate increased nociceptive behaviors suggesting that acetate, not acetaldehyde, accumulation results in hangover-like hypersensitivity in our model. Since adenosine accumulation is a result of acetate formation, we administered an adenosine antagonist that blocked hypersensitivity.

DISCUSSION

Our study shows that acetate contributes to hangover headache. These findings provide insight into the mechanism of hangover headache and the mechanism of headache induction.

Is phonophobia associated with cutaneous allodynia in migraine?

OBJECTIVE

To determine whether phonophobia and dynamic mechanical (brush) allodynia are associated in episodic migraine (EM).

METHODS

Adult patients with EM were prospectively recruited. A structured questionnaire was used to obtain demographic and migraine related data. Phonophobia was tested quantitatively using a real time sound processor and psychoacoustic software. Sound stimuli were pure tones at frequencies of 1000 Hz, 4000 Hz and 8000 Hz, delivered to both ears at increasing intensities, until an aversive level was reached. Allodynia was assessed by brushing the patient's skin with a gauze pad at different areas. Patients were tested both between and during acute attacks. Sound aversion thresholds (SATs) in allodynic and non-allodynic patients were compared.

RESULTS

Between attacks, SATs were lower in allodynic compared with non-allodynic patients, with an average difference of -5.7 dB (p=0.04). During acute attacks, the corresponding average SAT difference (allodynic-non-allodynic) was -15.7 dB (p=0.0008). There was a significant negative correlation between allodynia scores and SATs, both within and between attacks.

CONCLUSIONS

The results support an association between phonophobia and cutaneous allodynia in migraine.