Rating of Olfactory Judgements in Migraine Patients

Evaluating the Frequency of Osmophobia in Tension-Type Headache: A Comparative Study on Migraine

Introduction Osmophobia is hypersensitivity to certain odors. Although osmophobia is a symptom related to migraine, it is also reported in tension-type headache (TTH). Osmophobia is recommended for inclusion in the migraine diagnostic criteria because it increases sensitivity and shows absolute specificity. However, there is no evidence of the association between TTH and osmophobia. This study aimed to evaluate the prevalence and clinical characteristics of osmophobia in a cohort of migraine and TTH patients. Methods For the current analysis, patients who met the inclusion criteria among patients diagnosed with migraine and TTH according to the International Classification of Headache Disorders III criteria in the neurology outpatient clinics of Ankara City Hospital and Akyazı State Hospital were selected retrospectively. A total of 214 patients (129 with migraine and 85 with TTH) were included in the study. Patients' characteristics, visual analog scale (VAS) pain scores, and Migraine Disability Assessment Scale (MIDAS) scores were recorded. Osmophobia characteristics in migraine and TTH patients were compared along with clinical parameters between the groups and within the groups. Results Osmophobia was found in 68% of migraine patients. The most common type of smell that migraine patients experienced was the scent of perfume. A total of 31.3% of the patients with TTH had osmophobia. While the most irritating odorant in migraine patients was perfume (32%), in TTH patients, it was the smell of food (10.5%). There were no significant differences between osmophobia, and age, education level, disease duration, pain frequency, attack duration, or VAS score in both migraine patients and TTH patients. There was also no significant difference between migraine patients with (2.42) and without (2.33) osmophobia in terms of the MIDAS score. Discussion Our study indicates that osmophobia observed in migraine is valuable in differential diagnosis. However, it can be significantly identified in TTH patients. It should be used together with other supporting criteria in differential diagnosis. It would also be useful to question the characteristics of osmophobia in more detail in the anamnesis.

Multisensory hallucinations and other unusual sensory experiences in the context of migraine: a systematic review

OBJECTIVE AND BACKGROUND

Visual auras in migraine have been extensively studied, but less is known about multisensory hallucinations or other unusual sensory experiences, including whether these should be diagnostically considered as part of aura symptoms. The current study aimed to conduct a systematic review and synthesis to bring together existing empirical evidence on these non-visual perceptual experiences, focusing on their phenomenological descriptions and clinical correlates.

METHODS

Forty-eight relevant studies were included based on a systematic search across PsycINFO APA and Web of Science, for peer-reviewed publications in the English language, from 1980 to the present. These comprised a mix of case reports/series (n = 19) and group design studies (n = 29).

RESULTS

Reports of complex multisensory hallucinations, beyond typical established aura symptoms, were numerous and varied in nature. Yet there were limited data on how this related to patient distress and functional interference. Other sensory distortions or hypersensitivities across non-visual domains were also evident, and generally more common in those with established aura symptoms.

CONCLUSION

Our findings provide preliminary evidence that multisensory hallucinations and other unusual perceptual experiences in migraine are likely more common than previously believed. Further investigations are needed to appropriately account for these symptoms within current nosological systems. Increased clinician-patient awareness is important for managing distress (where necessary), and potentially for offering a holistic therapeutic approach to migraine management.

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.

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.

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.

Interictal osmophobia is associated with longer migraine disease duration

Background

Sensitization to sensory stimuli is an essential feature of migraine attacks. The relationship between the clinical course of migraine and increased sensitivity to olfactory stimuli has been little studied so far.

Methods

We analyzed the frequency and quality of osmophobia depending on the phase of migraine in patients with episodic and chronic migraine treated in an tertiary headache center with regard to gender, age, medical history and migraine disability assessment score (MIDAS). Standardized diagnostic questions were used for the assessment of osmophobia.

Results

In our cross-sectional investigation (n = 113), 38.1% of the patients showed an increased preictal hypersensitivity to odors, whereas 61.9% described ictal and 31.9% interictal hypersensitivity to odors, odor-triggered migraine was described in 30.1%. Median migraine disease duration has been statistically significantly longer in patients who suffered from interictal hypersensitivity to odors (28.5 years vs. 20 years; p = 0.012). There was a significant correlation between interictal hypersensitivity and higher age (54.50 vs. 45; p = 0.015). Patients with higher migraine disability in MIDAS experienced more frequently preictal and interictal olfactory sensitization and odor triggered migraine attacks.

Conclusions

In patients with longer migraine disease duration and higher migraine-related impairment, osmophobia was more frequently observed. These results might support the hypothesis of increasing sensitization with increasing burden 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.

International consensus statement on allergy and rhinology: Olfaction

BACKGROUND

The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O).

METHODS

Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus.

RESULTS

The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies.

CONCLUSION

This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.

Exploring alterations in sensory pathways in migraine

Background

Migraine is a neurological disorder characterized by intense, debilitating headaches, often coupled with nausea, vomiting and sensitivity to light and sound. Whilst changes in sensory processes during a migraine attack have been well-described, there is growing evidence that even between migraine attacks, sensory abilities are disrupted in migraine. Brain imaging studies have investigated altered coupling between areas of the descending pain modulatory pathway but coupling between somatosensory processing regions between migraine attacks has not been properly studied. The aim of this study was to determine if ongoing functional connectivity between visual, auditory, olfactory, gustatory and somatosensory cortices are altered during the interictal phase of migraine.

Methods

To explore the neural mechanisms underpinning interictal changes in sensory processing, we used functional magnetic resonance imaging to compare resting brain activity patterns and connectivity in migraineurs between migraine attacks (n = 32) and in healthy controls (n = 71). Significant differences between groups were determined using two-sample random effects procedures (p < 0.05, corrected for multiple comparisons, minimum cluster size 10 contiguous voxels, age and gender included as nuisance variables).

Results

In the migraine group, increases in infra-slow oscillatory activity were detected in the right primary visual cortex (V1), secondary visual cortex (V2) and third visual complex (V3), and left V3. In addition, resting connectivity analysis revealed that migraineurs displayed significantly enhanced connectivity between V1 and V2 with other sensory cortices including the auditory, gustatory, motor and somatosensory cortices.

Conclusions

These data provide evidence for a dysfunctional sensory network in pain-free migraine patients which may be underlying altered sensory processing between migraine attacks.

Investigating the relationships between the burden of multiple sensory hypersensitivity symptoms and headache-related disability in patents with migraine

Objective

Sensory hypersensitivities such as photophobia, phonophobia, and osmophobia are common in patients with migraine. We investigated the burden of these multiple sensory hypersensitivities in migraine.

Methods

In this cross-sectional study, 187 consecutive patients with migraine (26 men/161 women; age, 45.9 ± 13.2 years) were included. Sensory hypersensitivity symptoms such as photo−/phono−/osmophobia and accompanying symptoms were determined by neurologists in interviews. The Migraine Disability Assessment (MIDAS) was used to assess headache-related disability. The Kessler Psychological Distress Scale (K6) was also administered.

Results

Photophobia, phonophobia and osmophobia were observed in 75.4%, 76.5% and 55.1% of the patients with migraine, respectively. A significant overlap in sensory hypersensitivities (photo−/phono−/osmophobia) was found; the proportions of patients with 2 and 3 coexisting sensory hypersensitivities were 33.2% and 41.7%, respectively. The MIDAS score was higher in those with 3 sensory hypersensitivity symptoms than in those with 0 to 2 sensory hypersensitivity symptoms. A generalized linear model with ordinal logistic regression analysis revealed that multiple sensory hypersensitivities, younger age, more migraine days per month, and a higher K6 score were significantly related to the higher MIDAS score.

Conclusion

Our study showed that sensory hypersensitivities commonly occur and overlap in patients with migraine and that multiple sensory hypersensitivity symptoms have a significant impact on headache-related disability.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-021-01294-8.

Headache and Osmophobia in Gas Station Workers Exposed to Gasoline Odor

INTRODUCTION

Headache attacks may be triggered by several factors, among them odors, especially in migraine patients.

OBJECTIVES

The aim of this study wasto determine the association between gasoline odor and headache attacks in patients with migraine or tension-type headache (TTH).

SUBJECTS AND METHODS

The study was prospective, cross-sectional, with comparison of groups, using nonrandom sample and convenience. Fifty-two gas station workers diagnosed with migraine or TTH according to ICHD-3 criteria were interviewed on the relationship between gasoline odor and headache.

RESULTS

Of the 52 gas station workers with headaches, there were 39 (75%) with migraine without aura and 13 (25%) with TTH. The age ranged from 19 to 50 years, with a mean of 29.5 ± 7.2 years. Osmophobia during headache attacks predominated in workers with migraine (29/39; 74.4%). The onset of headache due to odor exposure occurred in 23/39 (60%) of the workers with migraine and in 2/13 (15.4%) in TTH. These differences were statistically significant (χ2 = 7.4; p = 0.016). Osmophobia in the absence of pain (period between attacks) predominated in workers with migraine (17/39, 43.6%), but with no statistical value.

CONCLUSIONS

Gas station workers diagnosed with migraine or TTH may experience osmophobia and headache triggered by the odor of gasoline.

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.

Self-perceived attention difficulties are associated with sensory hypersensitivity in migraine

BACKGROUND

Attention is the process which enables to preferentially select salient or relevant stimuli and to attenuate the response to irrelevant incoming stimuli. Migraine is characterized by both attentional alterations and an abnormal sensory processing to external stimulations. The aim of the study was to investigate potential interactions between self-perceived attentional difficulties and sensory hypersensitivity in migraine patients.

METHODS

Forty-six episodic migraineurs without aura and 46 healthy controls filled out questionnaires on self-perceived attention difficulties and self-reported sensitivity to visual, auditory and olfactory stimulations.

RESULTS

Compared to controls, migraineurs reported significantly higher levels of attention difficulty and sensory sensitivity. Sensory hypersensitivity correlated significantly with self-perceived attentional difficulties in migraineurs (P=0.002), but not with migraine disability or levels of anxiety or depression. Ictal and interictal sensory sensitivities were significantly correlated in migraineurs within visual (P<0.001), auditory (P<0.001) and olfactory (P=0.001) modalities.

CONCLUSION

This study shows for the first time an association between self-reported attentional difficulties and multimodal sensory hypersensitivity. Studies combining behavioral and physiological measures of sensory processing and attention processes are necessary to further understand the peculiar vulnerability of migraineurs to sensory stimuli.

Brain functional connectivity in headache disorders: A narrative review of MRI investigations

Resting-state functional magnetic resonance imaging (rs-fMRI) is used to interrogate the functional connectivity and network organization amongst brain regions. Functional connectivity is determined by measuring the extent of synchronization in the spontaneous fluctuations of blood oxygenation level dependent (BOLD) signal. Here, we review current rs-fMRI studies in headache disorders including migraine, trigeminal autonomic cephalalgias, and medication overuse headache. We discuss (1) brain network alterations that are shared amongst the different headache disorders and (2) network abnormalities distinct to each headache disorder. In order to focus the section on migraine, the headache disorder that has been most extensively studied, we chose to include articles that interrogated functional connectivity: (i) during the attack phase; (ii) in migraine patients with aura compared to migraine patients without aura; and (iii) of regions within limbic, sensory, motor, executive and default mode networks and those which participate in multisensory integration. The results of this review show that headache disorders are associated with atypical functional connectivity of regions associated with pain processing as well as atypical functional connectivity of multiple core resting state networks such as the salience, sensorimotor, executive, attention, limbic, visual, and default mode networks.

Nosographic analysis of osmophobia and field testing of diagnostic criteria including osmophobia

INTRODUCTION

Osmophobia has been suggested as an additional symptom of migraine without aura, and a high prevalence of osmophobia of up to 50% has been reported in the literature. We conducted a nosographic study of osmophobia in all migraineurs and tension-type headache patients and a field testing of suggested diagnostic criteria of osmophobia, presented in the appendix of the second edition of The International Classification of Headache Disorders and suggested by Silva-Néto et al. and Wang et al ., in migraine without aura and tension-type headache patients (n = 1934).

MATERIALS AND METHODS

Each patient received a validated semi-structured interview. All subjects fulfilled the diagnostic criteria of the second edition of The International Classification of Headache Disorders for migraine or tension-type headache. Statistical analyses were performed using statistical software R. The statistical R package "Caret" was used to construct a confusion matrix and retrieve sensitivity, which is defined as the suggested criteria's ability to correctly diagnose migraine without aura patients, and specificity, defined as the suggested criteria's ability to not wrongly diagnose tension-type headache patients.

RESULTS

Osmophobia was present in 33.5% of patients with migraine with aura, in 36.0% of patients with migraine without aura, and in 1.2% of patients with tension-type headache. All migraineurs with osmophobia also fulfilled the current criteria for migraine by having nausea or photophobia and phonophobia. The appendix criteria had a sensitivity of 0.96 and a specificity of 0.99 for migraine without aura, and a sensitivity of 0.65 and a specificity of 0.99 for probable migraine without aura. Both the criteria by Silva-Néto et al. and Wang et al. had a sensitivity of 0.98 and a specificity of 0.99 for migraine without aura, and a sensitivity of 0.66 and a specificity of 0.99 for probable migraine without aura.

DISCUSSION

This study demonstrates the remarkable specificity of osmophobia. The criteria by Silva-Néto et al. and Wang et al. both had a higher sensitivity than the appendix criteria for migraine without aura; all three criteria had a low sensitivity for probable migraine without aura. However, neither the appendix criteria nor the criteria by Silva-Néto et al. or Wang et al. added any extra patients that would not have been diagnosed by the current diagnostic criteria for migraine. Osmophobia is a valuable symptom that may be useful to differentiate between migraine without aura and tension-type headache in difficult clinical cases.

CONCLUSION

Our results do not suggest that alterations of the current diagnostic criteria for migraine without aura are needed.

The Prevalence of Osmophobia in Migranous and Episodic Tension Type Headaches

Background:

Migraines are a neurological disease, of which the most common symptom is an intense and disabling episodic headache. Many persons experience sensory hyper excitability manifested by photophobia, phonophobia and osmophobia. This study was planned to investigate the prevalence of osmophobia in migranous and episodic tension type headache (ETTH).

Materials and Methods:

A semi-structured questionnaire was administered to all patients to evaluate the eventual presence of osmophobia during a headache attack and different characteristics of osmophobia were determined.

Results:

Osmophobia reported in 84% with migranous headache with aura, 74% of migranous patients without aura and in 43.3% of those with ETTH. In 50% of patients, osmophobia was present in all of their headache attacks, 11.7% had osmophobia in more than half of their attacks (from 10 attacks they reported osmophobia in 5-9 ones) and others had this sign in less than half of their attacks (from 10 attacks they reported osmophobia in less than 5 ones). Most frequently the offending odors were scents (88%), foods (54.2%) and cigarette smoke (62.5%). Osmophobia starts 30 min before the headache starts in 22.7% of patients.

Conclusion:

Osmophobia appears structurally integrated into the migraine history of the patient; however, for differential diagnosis with ETTH, other criteria are necessary.

Multisensory Integration in Migraine: Recent Developments

There are well-documented unimodal sensory differences in migraine compared to control groups both during, and between migraine attacks. There is also some evidence of multisensory integration differences in migraine groups compared to control groups, however the literature on this topic is more limited. There are interesting avenues in the area of visual–vestibular integration, which might have practical implications, e.g., motion sickness and nausea in migraine. Recent work has been investigating the possibility of visual–auditory integration in migraine, and found possible differences in the susceptibility to the sound-induced flash illusion in particular, which could give insights into relative excitability of different areas of the cortex, and also into mechanisms for the illusions themselves. This review updates the most recent literature and also highlights potentially fruitful areas of research to understand one of the most common neurological disorders.

Osmophobia in Migraine and Tension-Type Headache and Its Clinical Features in Patients With Migraine

Intolerance to smell is often reported by migraine patients. This study evaluates osmophobia in connection with the diagnosis of migraine and episodic tension-type headache (ETTH). The characteristics of this symptom are also investigated. We recruited from our Headache Centre 1005 patients (772 female, 233 male; age 37 ± 11 years), of whom 677 were migraine without aura (MoA), 130 migraine with aura (MA) and 198 TTH. Patients with two or more forms of primary headache were excluded. Among migraine patients, 43.9% with MoA and 38.5% with MA reported osmophobia during the attacks; none of the 198 TTH patients suffered this symptom. Most frequently offending odours were scents (63.9%), food (55.2%) and cigarette smoke (54.8%). Osmophobia appears structurally integrated into the migraine history of the patient. It seems to be a peculiar symptom favouring the diagnosis of migraine (MoA and MA) in the differential diagnosis with ETTH.

The Insula: A "Hub of Activity" in Migraine

The insula, a "cortical hub" buried within the lateral sulcus, is involved in a number of processes including goal-directed cognition, conscious awareness, autonomic regulation, interoception, and somatosensation. While some of these processes are well known in the clinical presentation of migraine (i.e., autonomic and somatosensory alterations), other more complex behaviors in migraine, such as conscious awareness and error detection, are less well described. Since the insula processes and relays afferent inputs from brain areas involved in these functions to areas involved in higher cortical function such as frontal, temporal, and parietal regions, it may be implicated as a brain region that translates the signals of altered internal milieu in migraine, along with other chronic pain conditions, through the insula into complex behaviors. Here we review how the insula function and structure is altered in migraine. As a brain region of a number of brain functions, it may serve as a model to study new potential clinical perspectives for migraine treatment.

Osmophobia and olfactory functions in patients with migraine

Olfactory dysfunction and migraine has been associated for a long time. In this study, we planned to compare olfactory functions in patients with migraine and osmophobia with patients having migraine but no osmophobia, in addition with a normal control group using "Sniffin' Sticks" test. The main distinction of this study is that all qualitative and quantitative properties of olfactory functions; threshold, discrimination and identification, are evaluated separately and jointly. Thirty healthy person aged between 16 and 56 (18 women, 12 men) and 60 migraine patients aged between 15 and 54 (39 women, 21 man) were included in the study. All patients have been inquired about osmophobia and have been assessed with Hedonic tone assessment. Osmophobia has been tested for perfume, cigarette smoke, leather, stale food, soy sauce, fish, spices and coffee smells. Olfactory functions has been assessed with "Sniffin' Sticks" smell test. Thresholds, discrimination and identification have been determined for each patient. In migraine patients with osmophobia, threshold was 7.75 ± 2.3, in migraine patients without osmophobia threshold was 8.25 ± 1.5 and threshold was 10.75 ± 1.3 for the control group. Discrimination score was 6 ± 1.2 in migraine patients with osmophobia, 9 ± 0.8 in patients without osmophobia and was 12 ± 1.4 in the control group. In migraine patient with or without osmophobia Threshold/Discrimination/Identification (TDI) scores were lower than the control group. The most important parameter in our study is that discrimination scores were especially lower in patients with osmophobia. We believe that this decrease in discrimination in migraine patients with osmophobia; who claim that they smell everything and they are sensitive to all smells, is significant. Further studies about smell discrimination will help better understand some conditions; especially anosmia and hyposmia after upper respiratory tract infections and parosmia.

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.

Biochemistry of primary headaches: role of tyrosine and tryptophan metabolism

The pathogenesis of migraine as well as cluster headache (CH) is yet a debated question. In this review, we discuss the possible role of the of tyrosine and tryptophan metabolism in the pathogenesis of these primary headaches. These include the abnormalities in the synthesis of neurotransmitters: high level of DA, low level of NE and very elevated levels of octopamine and synephrine (neuromodulators) in plasma of episodic migraine without aura and CH patients. We hypothesize that the imbalance between the levels of neurotransmitters and elusive amines synthesis is due to a metabolic shift directing tyrosine toward an increased decarboxylase and reduced hydroxylase enzyme activities. The metabolic shift of the tyrosine is favored by a state of neuronal hyperexcitability and a reduced mitochondrial activity present in migraine. In addition we present biochemical studies performed in chronic migraine and chronic tension-type headache patients to verify if the same anomalies of the tyrosine and tryptophan metabolism are present in these primary headaches and, if so, their possible role in the chronicity process of CM and CTTH. The results show that important abnormalities of tyrosine metabolism are present only in CM patients (very high plasma levels of DA, NE and tryptamine). Tryptamine plasma levels were found significantly lower in both CM and CTTH patients. In view of this, we propose that migraine and, possibly, CH attacks derive from neurotransmitter and neuromodulator metabolic abnormalities in a hyperexcitable and hypoenergetic brain that spread from the frontal lobe, downstream, resulting in abnormally activated nuclei of the pain matrix. The low tryptamine plasma levels found in CM and CTTH patients suggest that these two primary chronic headaches are characterized by a common insufficient serotoninergic control of the pain threshold.

Olfactory processing in adults with autism spectrum disorders

Background

As evidenced in the DSM-V, autism spectrum disorders (ASD) are often characterized by atypical sensory behavior (hyper- or hypo-reactivity), but very few studies have evaluated olfactory abilities in individuals with ASD.

Methods

Fifteen adults with ASD and 15 typically developing participants underwent olfactory tests focused on superficial (suprathreshold detection task), perceptual (intensity and pleasantness judgment tasks), and semantic (identification task) odor processing.

Results

In terms of suprathreshold detection performance, decreased discrimination scores and increased bias scores were observed in the ASD group. Furthermore, the participants with ASD exhibited increased intensity judgment scores and impaired scores for pleasantness judgments of unpleasant odorants. Decreased identification performance was also observed in the participants with ASD compared with the typically developing participants. This decrease was partly attributed to a higher number of near misses (a category close to veridical labels) among the participants with ASD than was observed among the typically developing participants.

Conclusions

The changes in discrimination and bias scores were the result of a high number of false alarms among the participants with ASD, which suggests the adoption of a liberal attitude in their responses. Atypical intensity and pleasantness ratings were associated with hyperresponsiveness and flattened emotional reactions, respectively, which are typical of participants with ASD. The high number of near misses as non-veridical labels suggested that categorical processing is functional in individuals with ASD and could be explained by attention-deficit/hyperactivity disorder. These findings are discussed in terms of dysfunction of the olfactory system.

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.

Central Nervous System Underpinnings of Sensory Hypersensitivity in Migraine: Insights from Neuroimaging and Electrophysiological Studies

Whereas considerable data have been generated about the pathophysiology of pain processing during migraine attacks, relatively little is known about the neural basis of sensory hypersensitivity. In migraine, the term "hypersensitivity" encompasses different and probably distinct pathophysiological aspects of sensory sensitivity. During attacks, many patients have enhanced sensitivity to visual, auditory and/or olfactory stimuli, which can enhance headache while interictally, migraineurs often report abnormal sensitivity to environmental stimuli that can cause nonpainful discomfort. In addition, sensorial stimuli can influence and trigger the onset of migraine attacks. The pathophysiological mechanisms and the origin of such sensitivity (individual predisposition to develop migraine disease or consequence of repeated migraine attacks) are ill understood. Functional neuroimaging and electrophysiological studies allow for noninvasive measures of neuronal responses to external stimuli and have contributed to our understanding of mechanisms underlying sensory hypersensitivity in migraine. The purpose of this review is to present pivotal neuroimaging and neurophysiological studies that explored the basal state of brain responsiveness to sensory stimuli in migraineurs, the alterations in habituation and attention to sensory inputs, the fluctuations of responsiveness to sensory stimuli before and during migraine attacks, and the relations between sensory hypersensitivity and clinical sensory complaints.

Migraine is associated with altered processing of sensory stimuli

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

Functional MRI of migraine

Migraine is a disabling neurological condition manifesting with attacks of headache, hypersensitivities to visual, auditory, olfactory and somatosensory stimuli, nausea, and vomiting. Exposure to sensory stimuli, such as odours, visual stimuli, and sounds, commonly triggers migraine attacks, and hypersensitivities to sensory stimuli are prominent during migraine attacks, but can persist with less magnitude between attacks. Functional MRI (fMRI) has been used to investigate the mechanisms that lead to migraine sensory hypersensitivities by measuring brain responses to visual, olfactory, and painful cutaneous stimulation, and functional connectivity analyses have investigated the functional organisation of specific brain regions and networks responsible for sensory processing. These studies have consistently shown atypical brain responses to sensory stimuli, absence of the normal habituating response between attacks, and atypical functional connectivity of sensory processing regions. Identification of the mechanisms that lead to migraine sensory hypersensitivities and that trigger migraine attacks in response to sensory stimuli might help to better understand neural dysfunction in migraine and provide new targets for migraine prevention, and could provide fMRI biomarkers that indicate early responses to preventive therapy.

A review of hyperacusis and future directions: part I. Definitions and manifestations

PURPOSE

Hyperacusis can be extremely debilitating, and at present, there is no cure. We provide an overview of the field, and possible related areas, in the hope of facilitating future research.

METHOD

We review and reference literature on hyperacusis and related areas. We have divided the review into 2 articles. In Part I, we discuss definitions, epidemiology, different etiologies and subgroups, and how hyperacusis affects people. In Part II, we review measurements, models, mechanisms, and treatments, and we finish with some suggestions for further research.

RESULTS

Hyperacusis encompasses a wide range of reactions to sound, which can be grouped into the categories of excessive loudness, annoyance, fear, and pain. Many different causes have been proposed, and it will be important to appreciate and quantify different subgroups. Reasonable approaches to assessing the different forms of hyperacusis are emerging, including psychoacoustical measures, questionnaires, and brain imaging.

CONCLUSIONS

Hyperacusis can make life difficult for many, forcing sufferers to dramatically alter their work and social habits. We believe this is an opportune time to explore approaches to better understand and treat hyperacusis.

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.

Migraine with aura is associated with impaired colour vision: Results from the cross-sectional German DMKG headache study

BACKGROUND

Hypersensitivity to light, noise and odour are pivotal clinical characteristics of migraine associated with enhanced cortical excitability and dysfunctional habituation. However, little is known about the integrity of basic sensory functioning in migraine on a population-based level.

METHODS

A total of 129 participants with migraine (105 without aura, MwoA, 24 with aura, MA) and 522 healthy controls without headache 12 months prior to baseline were included from a sample of the DMKG study and underwent standardised clinical sensory testing of smell, taste, hearing and vision.

RESULTS

After adjustment for age, sex, smoking status and history of head injuries, the chance of impaired colour perception was significantly higher in MA compared to controls (odds ratio, OR=3.20; 95% CI=1.20-8.53) and MwoA (OR=3.62; 95% CI=1.31-9.97). Compared to MwoA, MA also had an increased chance of smell (OR=3.20; 95% CI=0.98-10.42) and taste (OR=2.58; 95% CI=0.90-7.40) impairment.

CONCLUSIONS

In this cross-sectional, population-based study on sensory functioning in migraine participants, colour vision was impaired interictally in MA compared to MwoA and controls.

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 hypothalamic functional connectivity with autonomic circuits and the locus coeruleus in migraine

The hypothalamus has been implicated in migraine based on the manifestation of autonomic symptoms with the disease, as well as neuroimaging evidence of hypothalamic activation during attacks. Our objective was to determine functional connectivity (FC) changes between the hypothalamus and the rest of the brain in migraine patients vs. control subjects. This study uses fMRI (functional magnetic resonance imaging) to acquire resting state scans in 12 interictal migraine patients and 12 healthy matched controls. Hypothalamic connectivity seeds were anatomically defined based on high-resolution structural scans, and FC was assessed in the resting state scans. Migraine patients had increased hypothalamic FC with a number of brain regions involved in regulation of autonomic functions, including the locus coeruleus, caudate, parahippocampal gyrus, cerebellum, and the temporal pole. Stronger functional connections between the hypothalamus and brain areas that regulate sympathetic and parasympathetic functions may explain some of the hypothalamic-mediated autonomic symptoms that accompany or precede migraine attacks.

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.

Pregnancy and olfaction: a review

Many women report a heightened sense of smell during pregnancy. Accounts of these anecdotes have existed for over 100 years, but scientific evidence has been sparse and inconclusive. In this review, I examine the literature on olfactory perception during pregnancy including measures of self-report, olfactory thresholds, odor identification, intensity and hedonic ratings, and disgust. Support for a general decrease in olfactory thresholds (increase in sensitivity) is generally lacking. There is limited evidence that some suprathreshold measures of olfactory perception, such as hedonic ratings of odors, are affected by pregnancy, but these effects are idiosyncratic. In this review, I explore the hypotheses that have been put forth to explain changes in olfactory perception during pregnancy and provide suggestions for further research.

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.

Functional neuroimaging of migraine

This review summarizes the history of migraine imaging and key findings of studies on functional neuroimaging in migraine and describes how these data have changed our view of the disorder. Functional neuroimaging during migraine attacks and also interictally has initiated the description of "the migraine brain". These studies have led to the demonstration of cortical spreading depression in migraine with aura, the crucial role for the brainstem during migraine attacks, and cortical hypersensitivity in migraineurs modulated by the trigeminal pathway, explaining sensory sensitization such as photophobia and osmophobia.

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.