Migraine and Olfactory Stimuli

The Environment and Headache: a Narrative Review

PURPOSE OF REVIEW

In this narrative review, we summarize the peer-reviewed literature published between 2017 and 2022 that evaluated ambient environmental risk factors for primary headache disorders, which affect more than half of the population globally. Primary headache disorders include migraine, tension-type headache (TTH), and trigeminal and autonomic cephalalgias (TAC).

RECENT FINDINGS

We identified 17 articles that met the inclusion criteria via PubMed or Google Scholar. Seven studies (41%) relied on data from US populations. The remaining studies were conducted in China, Taiwan, Germany, Ghana, Japan, the Netherlands, South Korea, and Turkey. Air pollution was the most frequently assessed environmental risk factor. Most studies were cross-sectional and focused on all-cause or migraine headaches; one study included TTH, and none included TAC. Short-term exposure to fine particulate matter (PM2.5) was not consistently associated with headache endpoints, but long-term exposure to PM2.5 was associated with migraine headache prevalence and severity across multiple studies. Elevated ambient temperature, changes in weather, oil and gas well exposure, and less natural greenspace, but not noise pollution, were also associated with headache. No studies considered water pollution, metal exposure, ultrafine particulate matter, or wildfire smoke exposure. There is a need for ongoing research focused on headache and the environment. Study designs with the greatest explanatory power may include longitudinal studies that capture the episodic nature of headache and case-crossover analysis, which control for time-invariant individual-level confounders by design. There is also a clear need for research that considers comorbid psychiatric illness and socioeconomic position as powerful modifiers of the effect of the environment on headache.

Clinical significance of osmophobia and its effect on quality of life in people with migraine

OBJECTIVES

In this study, we aimed to evaluate the clinical significance of osmophobia and its effect on quality of life in people with migraine.

METHODS

A total of 145 people with migraine were included in this cross-sectional study. Patients were evaluated with the migraine data form, the Migraine 24-Hour Quality of Life Questionnaire (24-HrMQoLQ), the Migraine Disability Assessment Scale (MIDAS), the Patient Health Questionnaire-9 (PHQ-9), the Insomnia Severity Index (ISI), the Generalized Anxiety Disorder-7 (GAD-7), the Allodynia Symptom Checklist (ASC), and the Fatigue Severity Scale (FSS). To evaluate the presence of osmophobia retrospectively, a semi-structured interview was conducted with the patients by the neurologist.

RESULTS

The mean 24-Hr-MQoLQ of patients with osmophobia was significantly lower than those without osmophobia. The decrease in the 24-Hr-MQoLQ was statistically significant in the areas of feeling and concerns and social functionality. The mean of the MIDAS scale was higher significantly in patients with osmophobia than those without osmophobia. In addition, the mean ISI, PHQ-9, FSS and ASC scores of patients with osmophobia were statistically significantly higher than those without osmophobia.

CONCLUSIONS

Both 24-h and 3-month quality of life of people with migraine with osmophobia were more affected than those without osmophobia. At the same manner, insomnia, depression, fatigue and allodynia were observed at higher rates in people with migraine with osmophobia than in migraine without osmophobia. Osmophobia, which is one of the specific symptoms that distinguishes migraine from other headache disorders, deserves further and multifaceted investigation.

Impact of a 12-week olfactory training programme in women with migraine with aura: protocol for a double-blind, randomised, placebo-controlled trial

INTRODUCTION

Migraine is a leading cause of disability and suffering worldwide. However, conventional pharmacological migraine preventive therapies are often challenging and accompanied by adverse effects. Recently, structured odour exposure has shown to successfully increase pain thresholds in patients with chronic back pain. Despite the importance of the olfactory system in migraine, there are no studies investigating the impact of structured odour exposure in patients with migraine.

METHODS AND ANALYSIS

This double-blind randomised placebo-controlled trial will be conducted at the Headache Clinic of the University Pain Center at TU Dresden, Germany and aims at investigating the impact of a 12-week structured exposure to odours in women with migraine. Fifty-four women between 18 and 55 years with migraine with aura will be recruited and randomised to training with odours and odourless training. The primary outcomes are mechanical and electrical pain thresholds. Secondary outcomes comprise olfactory threshold and the number of headache days. Other exploratory measurements are headache associated pain intensity, acute analgesic intake, symptoms of anxiety and depression, and quality of life. Additionally, this protocol assesses neuroanatomical and neurofunctional changes associated with the 12-week olfactory training. Data analysis will be executed on the basis of the general linear model considering repeated measurements.

ETHICS AND DISSEMINATION

Ethical approvals were obtained from the Ethics Board of the TU Dresden (Protocol No. BO-EK-353082020). Participation will only be possible after written informed consent is provided. Findings will be disseminated through peer-reviewed journals and scientific conferences.

TRIAL REGISTRATION NUMBER

DRKS00027399.

Classification of odors associated with migraine attacks: a cross-sectional study

Migraine, a common primary headache disorder, is associated with various factors such as stress, hormones in women, fasting, weather, and sleep disturbance as well as odors. We aimed to categorize odors associated with migraine and explore their relationships with clinical characteristics. A total of 101 migraineurs answered a questionnaire to determine the odors associated with migraine attacks. We performed factor analysis to explore the common factors of the odors and the relationship between these factors and the clinical characteristics. The factor analysis estimated six common factors: factor 1, fetid odor; factor 2, cooking products; factor 3, oil derivatives and others; factor 4, shampoo and conditioner; factor 5, cleaning products; factor 6, perfumes, insecticides, and rose. Factor 5 also included hair styling preparations, laundry detergent, and fabric softener, usually those with floral fragrances, and factor 5 was more likely to be associated with migraine attacks in patients with chronic migraine than in those with episodic migraine (P = 0.037). Our study showed that odors associated with migraine attacks could be categorized into six groups and suggested that some chemicals were more likely associated with migraine attacks in patients with chronic migraine than in those with episodic migraine.

Peripheral and Central Smell Regions in Migraine Patients using Maraş Powder (Smokeless Tobacco): A Magnetic Resonance Imaging Evaluation

Objective In the present study, we investigated the efficacy of Maraş powder (smokeless tobacco) use on smell regions in migraine patients.

Methods The cranial magnetic resonance imaging images of 58 adult patients were included in this retrospective study. Thirty-eight of them were migraine patients (18 of them using Maraş powder and 20 of them not using Maraş powder) and 20 of them were healthy controls. Bilateral peripheral (olfactory bulb [OB] volume and olfactory sulcus depth) and central smell regions (insular gyrus area and corpus amygdala area) as well as nasal septal deviation were evaluated.

Results In migraine patients (using or not using Maraş powder), OB volumes, and in Maraş powder using migraine patients, corpus amygdala areas were lower than those in the control group (p < 0.05). In Maraş powder-using migraine patients, left insular gyrus areas of the females were significantly lower than the males (p < 0.05).

Conclusion We concluded that the peripheral smell region of the OB volume decreased in migraine patients (using or not using Maraş powder). However, the central smell region of corpus amygdala area decreased in Maraş powder using migraine patients. Maraş powder usage may increase vascular shrinkage, and the decrease in OB volume and corpus amygdala area becomes prominent. It can be said that Maraş powder usage may cause a size decrease in the peripheral and central smell regions in migraine patients. Therefore, migraine patients and non-migrainous people should be noticed for the harmful effects of Maraş powder on the vascular system and smell system in the aspects of OB volume and corpus amygdala area decrease.

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.

Cyclic changes of sensory parameters in migraine patients

BACKGROUND

Migraine shows a cyclic pattern with an inter-ictal-, a pre-ictal, an ictal- and a post-ictal phase. We aimed to examine changes in psychophysical parameters during the migraine cycle.

METHODS

The perception of nociceptive and non-nociceptive stimuli and an electrically induced axon-reflex-erythema were assessed in 20 healthy controls and 14 migraine patients on five consecutive days according to different phases of the migraine cycle. Pain was rated three times during a 10-second electrical stimulus. The size of the axon-reflex-erythema was determined using laser-Doppler-imaging. Intensity and hedonic estimates of odours presented by Sniffin' Sticks were rated.

RESULTS

In healthy controls, no significant changes over the test days were observed. In migraine patients pain thresholds at the head decreased with an ictal minimum. Less habituation after five seconds of stimulation at the head was found pre-ictally, whereas reduced habituation to 10-second electrical stimulation was present in all phases. The axon-reflex-erythema size showed an inter-ictal-specific minimum at the head. odours were perceived ictally as more unpleasant and intense.

CONCLUSIONS

Somatosensory functions, pain thresholds and habituation as predominantly central parameters, axon-reflex-erythema as a peripheral function of trigeminal neurons and odour perception as a predominantly extra-thalamic sensation change specifically over the migraine cycle indicating complex variations of neuronal signal processing.

Evaluation of electrophysiological changes in migraine with visual aura

PURPOSE:

The purpose of this study was to evaluate the electrical responses in the retina and cortex of migraine patients with electrophysiological tests and compare with healthy controls.

MATERIALS AND METHODS:

This prospective study included 18 migraine patients with visual aura and 28 healthy controls. Pattern-reversal visual evoked potentials (VEP) and flash electroretinography (fERG) of migraine patients during the headache-free period were compared with healthy controls.

RESULTS:

There were statistically significant differences in VEP results: P100 and N75 amplitudes increased significantly (P = 0.025 and P = 0.007 respectively) and P100 latency decreased significantly in migraine patients (P = 0.022). Furthermore, fERG scotopic combined cone and rod amplitude increased significantly in migraine patients (P = 0.01).

CONCLUSION:

Migraine brain displays abnormal visual evoked responses in between migraine attacks. In migraine eye, scotopic cone and rod response increased. The results of this study support the hyperexcitability of the retina and cortex in patients with migraine.

Olfactory acuity based on Brief Smell Identification Test (BSITⓇ) in migraine patients with and without aura: A cross-sectional, controlled study

OBJECTIVE

The aim of this study was to evaluate olfactory acuity in migraine patients with and without aura (MwA and MwoA) MATERIAL AND METHODS: The study included 30 MwA patients, 30 MwoA patients, and 30 age- and gender-matched controls. Demographic features and odor-related symptoms (osmophobia, odor offensiveness, and odor-triggered attack status) were noted. Olfactory acuity was measured using the Brief Smell Identification Test (BSIT®), a 12-item derivative of the University of Pennsylvania Smell Identification Test (UPSIT®). BSIT® scores were compared between the migraine patients and controls.

RESULTS

The mean BSIT® score did not differ significantly between the MwA patients (8.7 ± 0.9) and MwoA (9.17 ± 0.9) patients (P = 0.094); however, the mean score in the control group was higher (10.4 ± 0.6) than in the MwA and MwoA patients (P < 0.001). The mean BSIT® score did not differ significantly between patients with and without odor-triggered migraine attacks (9 ± 0.9 and 8.8 ± 0.8, respectively) (P = 0.4). Osmophobia and odor-triggered attacks were more common in the MwA patients than in the MwoA patients (odor-triggered attacks: 66% vs. 40% [P = 0.04]; osmophobia: 76.6% vs. 60% [P = 0.16]) CONCLUSION: Olfactory acuity is lower during attack-free periods in migraine patients, as compared to controls. Migraine aura status does not affect olfactory acuity. Odor-triggered attacks, osmophobia, and offensive odors between attacks were more common in the MwA patients than in the MwoA patients.

Olfactory stimulation Inhibits Nociceptive Signal Processing at the Input Stage of the Central Trigeminal System

The spinal trigeminal nucleus caudalis (SpVc) in the mammalian brainstem serves a pivotal function in pain processing. As the main relay center for nociceptive signals, SpVc conducts pain-related signals from various regions of the head toward higher levels of central processing such as the thalamus. SpVc also receives modulatory signals from other brain areas, which can alleviate the perception of headache. We studied the impact of olfactory co-stimulation on pain-related behavior and SpVc neural activity in mice. Using the TRPA1 agonist allyl isothiocyanate (AITC) as noxious stimulus, we quantified the aversive response and the perceived pain intensity by evaluating explorative running and the mouse grimace scale, respectively. We found that the floral odorants phenylethyl alcohol (PEA) and lavender oil mitigated the aversive response to AITC. Consistent with this finding, a newly developed, automated quantification of c-Fos expression in SpVc revealed that co-stimulation with PEA or lavender profoundly reduced network activity in the presence of AITC. These results demonstrated a substantial analgesic potential of odor stimulation in the trigeminal system and provide an explanation for the palliative effect of odors in the treatment of headache.

Development of quality of life assessment questionnaire associated with osmophobia in people with migraine

BACKGROUND

It is important to implement disease-specific precautions to develop quality of life in migraine. The effect of osmophobia, which is one of the specific symptoms of migraine that might help to differentiate migraine from other headache disorders, on quality of life is unknown. The aim of the present study was to develop a practicable and reliable scale that assesses the effect of osmophobia on quality of life in migraine.

METHODS

This cross-sectional study was carried out with 163 patients with migraine and 110 healthy individuals for control group. The scale items were constructed based on after literature review, expert opinions, and preliminary trial stage. A semi-structured interview was conducted with the patients by the Neurologist to evaluate the presence of osmophobia retrospectively. Migraine osmophobia-related quality of life assessment (MORA) consisted of 6 items including personal care, eating or cooking, house cleaning, close relationship, social life and traveling.

RESULTS

The Cronbach's α coefficient was 0.86; and the Guttman split-half coefficient was 0.83. Receiver operating characteristic analysis showed an area under the curve of 0.943 (95%) confidence interval [CI] = 0.902-0.984), a cut off score of > 9.5, a sensitivity of 91.6%, a specificity of 85.7%. Mean scores of the MORA differed between people with migraine (with and without osmophobia) and healthy controls (<0.001).

CONCLUSION

MORA is a valid and reliable self-report questionnaire that assesses the effect of osmophobia on quality of life in migraine. This questionnaire appears to be practicable diagnostic instrument in clinical practice and research.

Osmophobia in primary headache patients: associated symptoms and response to preventive treatments

Background

Osmophobia, is common among primary headaches, with prevalence of migraine.

The study aimed to evaluate prevalence and clinical characteristics of patients with osmophobia in a cohort of primary headache patients selected at a tertiary headache center. The second aim was to verify the possible predicting role of osmophobia in preventive treatment response in a sub cohort of migraine patients.

Methods

This was an observational retrospective cohort study based on data collected in a tertiary headache center.

We selected patients aged 18–65 years, diagnosed as migraine without aura (MO), migraine with aura (MA) or Chronic Migraine (CM), Tension-Type Headache (TTH); and Cluster Headache (CH). We also selected a sub-cohort of migraine patients who were prescribed preventive treatment, according to Italian Guidelines, visited after 3 months follow up.

Patients were considered osmophobic, if reported this symptom in at least the 20% of headache episodes. Other considered variables were: headache frequeny, the migraine disability assessment (MIDAS), Allodynia Symptom Checklist, Self-rating Depression scale, Self-rating Anxiety scale, Pain intensity evaluated by Numerical Rating Scale-NRS- form 0 to 10.

Results

The 37,9% of patients reported osmophobia (444 patients with osmophobia, 726 without osmophobia).

Osmophobia prevailed in patients with the different migraine subtypes, and was absent in patients with episodic tension type headache and cluster headache (chi square 68.7 DF 7 p < 0.0001). Headache patients with osmophobia, presented with longer hedache duration (F 4.91 p 0.027; more severe anxiety (F 7.56 0.007), depression (F 5.3 p 0.019), allodynia (F 6 p 0.014), headache intensity (F 8.67 p 0.003). Tension type headache patients with osmophobia (n° 21), presented with more frequent headache and anxiety. A total of 711 migraine patients was visited after 3 months treatment. The change of main migraine features was similar between patients with and without osmophobia.

Conclusions

While the present study confirmed prevalence of osmophobia in migraine patients, it also indicated its presence among chronic tension type headache cases, marking those with chronic headache and anxiety.

Osmophobia was associated to symptoms of central sensitization, as allodynia. It was not relevant to predict migraine evolution after first line preventive approach.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-021-01327-2.

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.

Impact of dissociative experiences in migraine and its close relationship with osmophobia

OBJECTIVE

Migraine is a complex episodic disease manifested by dysfunction of the sympathetic nervous system along with numerous neuropsychiatric symptoms. The aim of this study was to identify the dissociative symptoms with neurobiological similarities in episodic and chronic migraine patients and to evaluate their correlation with migraine frequency and severity of attacks.

METHODS

The study included 61 episodic, 45 chronic migraine patients diagnosed using the criteria of the International Headache Society and 54 healthy control subjects. Dissociative Experiences Scale, Beck Anxiety Scale and Beck Depression Inventory were filled with the interviews. Demographic, clinical and headache characteristics of the patients were recorded according to migraine types. Results were analyzed by Kruskal-Wallis method and Spearman's correlation tests.

RESULTS

Dissociative symptoms were more common in the patients with chronic migraine, and there was a statistically significant difference between the chronic migraine group and the episodic migraine and control groups (p = 0.001, p < 0.001). Dissociative experiences were correlated with depression and anxiety findings, and in both groups, there was a significant correlation between clinical characteristics of migraine and osmophobia in the controlled partial correlation analysis (p < 0.05).

CONCLUSION

This study revealed that dissociative symptoms are more common especially in patients with chronic migraine and there is a significant association with osmophobia in both migraine groups. According to these data, we think that dissociative symptoms in chronic migraine patients will be questioned and osmophobia may be a guide in this regard.

A prospective study on osmophobia in migraine versus tension-type headache in a large series of attacks

Background

In literature, osmophobia is reported as a specific migrainous symptom with a prevalence of up to 95%. Despite the International Classification of Headache Disorders 2nd edition proposal of including osmophobia among accompanying symptoms, it was no longer mentioned in the ICHD 3rd edition.

Methods

We conducted a prospective study on 193 patients suffering from migraine without aura, migraine with aura, episodic tension-type headache or a combination of these. After a retrospective interview, each patient was asked to describe in detail osmophobia, when present, in the following four headache attacks.

Results

In all, 45.7% of migraine without aura attacks were associated with osmophobia, 67.2% of migraineurs reported osmophobia in at least a quarter of the attacks. No episodic tension-type headache attack was associated with osmophobia. It was associated with photophobia or phonophobia in 4.3% of migraine without aura attacks, and it was the only accompanying symptom in 4.7% of migraine without aura attacks. The inclusion of osmophobia in the ICHD-3 diagnostic criteria would enable a 9.0% increased diagnostic sensitivity.

Conclusion

Osmophobia is a specific clinical marker of migraine, easy to ascertain and able to disentangle the sometimes challenging differential diagnosis between migraine without aura and episodic tension-type headache. We recommend its inclusion among the diagnostic criteria for migraine as it increases sensitivity, showing absolute specificity.

Photoactivation of olfactory sensory neurons does not affect action potential conduction in individual trigeminal sensory axons innervating the rodent nasal cavity

Olfactory and trigeminal chemosensory systems reside in parallel within the mammalian nose. Psychophysical studies in people indicate that these two systems interact at a perceptual level. Trigeminal sensations of pungency mask odour perception, while olfactory stimuli can influence trigeminal signal processing tasks such as odour localization. While imaging studies indicate overlap in limbic and cortical somatosensory areas activated by nasal trigeminal and olfactory stimuli, there is also potential cross-talk at the level of the olfactory epithelium, the olfactory bulb and trigeminal brainstem. Here we explored the influence of olfactory and trigeminal signaling in the nasal cavity. A forced choice water consumption paradigm was used to ascertain whether trigeminal and olfactory stimuli could influence behaviour in mice. Mice avoided water sources surrounded by both volatile TRPV1 (cyclohexanone) and TRPA1 (allyl isothiocyanate) irritants and the aversion to cyclohexanone was mitigated when combined with a pure odorant (rose fragrance, phenylethyl alcohol, PEA). To determine whether olfactory-trigeminal interactions within the nose could potentially account for this behavioural effect we recorded from single trigeminal sensory axons innervating the nasal respiratory and olfactory epithelium using an isolated in vitro preparation. To circumvent non-specific effects of chemical stimuli, optical stimulation was used to excite olfactory sensory neurons in mice expressing channel-rhodopsin (ChR2) under the olfactory marker protein (OMP) promoter. Photoactivation of olfactory sensory neurons produced no modulation of axonal action potential conduction in individual trigeminal axons. Similarly, no evidence was found for collateral branching of trigeminal axon that might serve as a conduit for cross-talk between the olfactory and respiratory epithelium and olfactory dura mater. Using direct assessment of action potential activity in trigeminal axons we observed neither paracrine nor axon reflex mediated cross-talk between olfactory and trigeminal sensory systems in the rodent nasal cavity. Our current results suggest that olfactory sensory neurons exert minimal influence on trigeminal signals within the nasal cavity.

Neurolocalization of taste disorders

Neurolocalization of taste disorders requires a knowledge of the functional anatomy involved in mediating taste information from the peripheral mucosal surfaces through numerous peripheral cranial nerves to complex subcortical and cortical brain regions. Our understanding of this functional anatomy has advanced in recent years. Taste is an experience that is both innate and learned, and the "taste" experience involves the integration of information from other sensory modalities, such as olfaction and somatosensation. Normal taste perception is influenced by different neurophysiologic states, which involve endocrine function, emotions, and even attitudes and expectations toward eating. At its core, the normal effective ability to taste is a reflection of the proper function of many organ systems within the body and may be considered a marker for good health. Clinical taste disorders, on the other hand, involve the dysfunction of the normal neural taste pathways and/or aberrant influences on multisensory integration and cortical taste processing. The number of disease processes, which can adversely affect taste, are numerous and quite varied in their presentation. There may be contributory involvement of other organ systems within the body, and the appropriate management of taste disorders often requires a multidisciplinary approach to fully understand the disorder. Depending on the underlying cause, taste disorders can be effectively managed when identified. Treatments may include correcting underlying metabolic disturbances, eliminating infections, changing offending medications, replenishing nutritional deficiencies, operating on structural impairments, calming autoimmune processes, and even stabilizing electrochemical interactions.

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.

Olfactory Disorder Pattern In Patients With Neurological Diseases Excluding Psychiatric And Traumatic Aetiologies

INTRODUCTION

The most common cause of olfactory ENT disorders are colds and flu, chronic sinusitis, allergies and traumatic brain injury. Rarer aetiologies include certain neurological, psychiatric and metabolic injuries.

TARGET

The aim of this paper was to check the sort of olfactory disorders found in people who have suffered a brain injury, excluding: cranial traumas, psychiatric diseases, epilepsy, Parkinson's and Alzheimer's disease, and synaesthesia.

MATERIAL AND METHODS

A descriptive study based on 61 patients with diagnoses of various neurological injuries, which were tested by BAST-24 olfactometer. The results were compared with those of a control group (n= 120).

RESULTS

The results show major impairment in these patients' olfactory sense. The neurological injury patients were able to detect from 60-77% of the odours, while the control group were able to detect between 98-100%. The neurological patients were able, at best, to identify, 11-32% of the odours correctly, while the control group were able to correctly detect between 59 -75%. The differences between odour detection and correct identification were statistically significant (p<.05).

CONCLUSIONS

We concluded: a) Neurological injury, not caused by traumatic brain injury, psychiatric disorders or ENT diseases, ranged from 68-89% of the olfactory failures. b) We must bear in mind that these sorts of injuries can cause olfactory disorders. c) ENT and Neurologists should collaborate in the treatment of these disorders.

Induction of chronic migraine phenotypes in a rat model after environmental irritant exposure

Air pollution is linked to increased emergency department visits for headache and migraine patients frequently cite chemicals or odors as headache triggers, but the association between air pollutants and headache is not well understood. We previously reported that chronic environmental irritant exposure sensitizes the trigeminovascular system response to nasal administration of environmental irritants. Here, we examine whether chronic environmental irritant exposure induces migraine behavioral phenotypes. Male rats were exposed to acrolein, a transient receptor potential channel ankyrin-1 (TRPA1) agonist, or room air by inhalation for 4 days before meningeal blood flow measurements, periorbital cutaneous sensory testing, or other behavioral testing. Touch-induced c-Fos expression in trigeminal nucleus caudalis was compared in animals exposed to room air or acrolein. Spontaneous behavior and olfactory discrimination was examined in open-field testing. Acrolein inhalation exposure produced long-lasting potentiation of blood flow responses to a subsequent TRPA1 agonist and sensitized cutaneous responses to mechanical stimulation. C-Fos expression in response to touch was increased in trigeminal nucleus caudalis in animals exposed to acrolein compared with room air. Spontaneous activity in an open-field and scent preference behavior was different in acrolein-exposed compared with room air-exposed animals. Sumatriptan, an acute migraine treatment blocked acute blood flow changes in response to TRPA1 or transient receptor potential vanilloid receptor-1 agonists. Pretreatment with valproic acid, a prophylactic migraine treatment, attenuated the enhanced blood flow responses observed after acrolein inhalation exposures. Environmental irritant exposure yields an animal model of chronic migraine in which to study mechanisms for enhanced headache susceptibility after chemical exposure.

The effects of Maras powder use on patients with migraine

BACKGROUND

It is accepted that smoking often triggers migraine. However, studies evaluating the relationship between the use of smokeless tobacco and migraine are limited, and there is no clear consensus on the subject. In this study, it was aimed to evaluate the relationship between migraine and Maras powder, which is the most common smokeless tobacco in Turkey.

SUBJECTS AND METHODS

The study included a total of 600 subjects, consisting of 300 patients (aged >18 years) diagnosed with a migraine according to the International Headache Society (IHS-ICHD-3 Beta) criteria after presenting at Sütçü Imam University Medical Faculty Neurology Policlinic with the complaint of headache between July 2016 and December 2016 and a control group of 300 individuals with similar features of age, gender, and educational level. A questionnaire was administered to each patient to record the status of smoking or using Maras powder.

RESULTS

In the migraine patient group, 16.4% smoked and 9.7% used Maras powder. In the control group, the rate of smoking was 8.5% and the rate of Maras powder use was 11.86%. In males diagnosed with a migraine, the use of Maras powder was found to be at a higher rate than smoking (p<0.001). The Visual Pain Score and the headache frequency values were higher in those who smoked or used Maras powder than in non-users (p<0.001). The Fagerström Test for Nicotine Dependence Smokeless Tobacco results of the patients diagnosed with migraine and who used Maras powder were found to be higher than of those who smoked (Fagerström Test for Nicotine Dependence; p<0.001). When patients were evaluated according to the Migraine Disability Assessment Scale, the majority of migraine patients were seen to be at stages 1 and 2, and one in every three patients who used Maras powder cigarette and one in every two patients who smoked had headaches of a severity which affected their daily activities (p<0.001).

CONCLUSION

Smoking or the use of Maras powder increases the frequency and severity of migraines in a similar way. Therefore, Maras powder must be included in the scope of the fight against tobacco and people should be warned about this issue.

Alcohol Use as a Comorbidity and Precipitant of Primary Headache: Review and Meta-analysis

PURPOSE OF REVIEW

In contrast to well-established relationships between headache and affective disorders, the role of alcohol use in primary headache disorders is less clear. This paper provides a narrative overview of research on alcohol use disorders (AUDs) in primary headache and presents a meta-analysis of the role of alcohol as a trigger (precipitant) of headache.

RECENT FINDINGS

The majority of studies on AUDs in headache have failed to find evidence that migraine or tension-type headache (TTH) is associated with increased risk for AUDs or problematic alcohol use. The meta-analysis indicated that 22% (95% CI: 17-29%) of individuals with primary headache endorsed alcohol as a trigger. No differences were found between individuals with migraine (with or without aura) or TTH. Odds of endorsing red wine as a trigger were over 3 times greater than odds of endorsing beer. An absence of increased risk for AUDs among those with primary headache may be attributable to alcohol's role in precipitating headache attacks for some susceptible individuals. Roughly one fifth of headache sufferers believe alcohol precipitates at least some of their attacks. Considerable study heterogeneity limits fine-grained comparisons across studies and suggests needs for more standardized methods for studying alcohol-headache relationships and rigorous experimental designs.

Migraine: A look down the nose

BACKGROUND

Studies have suggested that contact between opposing mucosal surfaces in the nasal wall and cavity can be a target of the surgical treatment of migraines. Unfortunately, not enough is known about the role of nasal pathology in the pathogenesis of this condition. The co-existence of further rhinological disorders can be an impediment to defining the cause and effect of anatomical variants. The authors compared the MRI scans of migraine- and non-migraine patients (MPs and NMPs, respectively) to determine the prevalence of such mucosal contact points in order to extrapolate whether there is a significant association with migraines.

METHODS

Coronal and axial MRI brain scans of 522 patients (412 migraineurs and 110 non-migraineurs) were analysed for the prevalence of anatomical variations of the nasal cavity, e.g. concha bullosa, septal deviations, mucosal swelling and contact points.

RESULTS

The results showed no significant difference between MPs and NMPs patients for any of the parameters examined. Moreover, 87% MPs and 79% NMPs had at least one contact point. The most frequent contact point was between the middle turbinate and the septum, observed in 54% of MPs and 45% of NMPs.

CONCLUSIONS

Contact points with the nasal mucosa are highly prevalent in both MPs and NMPs. Although a contact point does not cause a migraine in the absence of the disease, the concomitant presence of migraine and contact points can trigger an attack, and therefore, it is necessary to differentiate or exclude a rhinological disorder in these patients.

Associations between Unconventional Natural Gas Development and Nasal and Sinus, Migraine Headache, and Fatigue Symptoms in Pennsylvania

BACKGROUND

Unconventional natural gas development (UNGD) produces environmental contaminants and psychosocial stressors. Despite these concerns, few studies have evaluated the health effects of UNGD.

OBJECTIVES

We investigated associations between UNGD activity and symptoms in a cross-sectional study in Pennsylvania.

METHODS

We mailed a self-administered questionnaire to 23,700 adult patients of the Geisinger Clinic. Using standardized and validated questionnaire items, we identified respondents with chronic rhinosinusitis (CRS), migraine headache, and fatigue symptoms. We created a summary UNGD activity metric that incorporated well phase, location, total depth, daily gas production and inverse distance-squared to patient residences. We used logistic regression, weighted for sampling and response rates, to assess associations between quartiles of UNGD activity and outcomes, both alone and in combination.

RESULTS

The response rate was 33%. Of 7,785 study participants, 1,850 (24%) had current CRS symptoms, 1,765 (23%) had migraine headache, and 1,930 (25%) had higher levels of fatigue. Among individuals who met criteria for two or more outcomes, adjusted odds ratios for the highest quartile of UNGD activity compared with the lowest were [OR (95% CI)] 1.49 (0.78, 2.85) for CRS plus migraine, 1.88 (1.08, 3.25) for CRS plus fatigue, 1.95 (1.18, 3.21) for migraine plus fatigue, and 1.84 (1.08, 3.14) for all three outcomes together. Significant associations were also present in some models of single outcomes.

CONCLUSIONS

This study provides evidence that UNGD is associated with nasal and sinus, migraine headache, and fatigue symptoms in a general population representative sample. Citation: Tustin AW, Hirsch AG, Rasmussen SG, Casey JA, Bandeen-Roche K, Schwartz BS. 2017. Associations between unconventional natural gas development and nasal and sinus, migraine headache, and fatigue symptoms in Pennsylvania. Environ Health Perspect 125:189-197; http://dx.doi.org/10.1289/EHP281.

Possible role of calcitonin gene-related peptide in trigeminal modulation of glomerular microcircuits of the rodent olfactory bulb

Chemosensation in the mammalian nose comprises detection of odorants, irritants and pheromones. While the traditional view assigned one distinct sub-system to each stimulus type, recent research has produced a more complex picture. Odorants are not only detected by olfactory sensory neurons but also by the trigeminal system. Irritants, in turn, may have a distinct odor, and some pheromones are detected by the olfactory epithelium. Moreover, it is well established that irritants change odor perception and vice versa. A wealth of psychophysical evidence on olfactory-trigeminal interactions in humans contrasts with a paucity of structural insight. In particular, it is unclear whether the two systems communicate just by sharing stimuli, or whether neuronal connections mediate cross-modal signaling. One connection could exist in the olfactory bulb that performs the primary processing of olfactory signals and receives trigeminal innervation. In the present study, neuroanatomical tracing of the mouse ethmoid system illustrates how peptidergic fibers enter the glomerular layer of the olfactory bulb, where local microcircuits process and filter the afferent signal. Biochemical assays reveal release of calcitonin gene-related peptide from olfactory bulb slices and attenuation of cAMP signaling by the neuropeptide. In the non-stimulated tissue, the neuropeptide specifically inhibited the basal activity of calbindin-expressing periglomerular interneurons, but did not affect the basal activity of neurons expressing calretinin, parvalbumin, or tyrosine hydroxylase, nor the activity of astrocytes. This study represents a first step towards understanding trigeminal neuromodulation of olfactory-bulb microcircuits and provides a working hypothesis for trigeminal inhibition of olfactory signal processing. This article is protected by copyright. All rights reserved.

A lost track in ICHD 3 beta: A comprehensive review on osmophobia

Background

Osmophobia (Os) has been reported to be much more prevalent in migraine (M) than in other primary headaches, and its high specificity in the differential diagnosis between M and tension-type headache (TTH) has been reported. Os was included in the ICHD II Appendix as a diagnostic criterion of M. It disappeared in ICHD-3 beta. To understand this choice, we reviewed the literature after 2004.

Methods

This was a systematic review. We searched in PubMed, MEDLINE and Cochrane library for “osmophobia”, “odour/odorphobia AND headache”, “odour/odor hypersensitivity AND headache” and “olfactory hypersensitivity AND headache”.

Results

112 papers cited Os as an accompanying symptom of headache; 16 focused on Os in M diagnosis. With the data from 40 articles, we calculated the pooled prevalence of Os in 14,360 patients (2281 pediatric) affected by M (n = 12,496) and TTH (n = 1864). In M, the prevalence was 48.5% (CI 95% 41.4 to 55.8%) in adults and 23.4% (CI 95% 15.7 to 33.4%) in pediatric patients; in TTH, the prevalence was 8.9% (CI 95% 4.6 to 13.5%) in adults and 7.9% (CI 95% 3.3 to 18.1%) in pediatric patients. Ten of these papers allowed us to calculate the sensibility and specificity of Os in differential diagnosis between M and TTH. In adults, the value of specificity was 94.1% (CI 95% 88.9 to 96.9%), and sensitivity was 51.4% (CI 95% 38.4 to 64.2%). In pediatric patients, specificity was 92.0% (CI 95% 81.9 to 96.7%), and sensitivity was 22.1% (CI 95% 10.1 to 41.8%).

Conclusion

The literature endorses the inclusion of Os among M diagnostic criteria. On this ground, the decision to remove Os from ICHD 3 beta appears unjustified and a revision of this choice is recommended.

May headache triggered by odors be regarded as a differentiating factor between migraine and other primary headaches?

Objectives

The objective of this article is to characterize olfactory stimulation as a trigger of headaches attacks and differentiation between migraine and other primary headaches.

Participants and methods

The study was prospective and experimental, with comparison of groups. A total of 158 volunteers (73 men and 85 women) were diagnosed with primary headaches, according to the criteria of the International Classification of Headache Disorders, Third Edition (beta version) (ICHD-3β). The study was conducted by two examiners; one of them was assigned to diagnose the presence and type of primary headache, while the other was responsible for exposing the volunteers to odor and recording the effects of this exposure.

Results

Of the 158 volunteers with headache, there were 72 (45.6%) cases of migraine and 86 (54.4%) with other primary headaches. In both groups, there were differences in headache characteristics (χ2 = 4.132; p = 0.046). Headache attacks (25/72; 34.7%) and nausea (5/72; 6.9%) were triggered by odor only in patients with migraine, corresponding to 19.0% (30/158) of the sample, but in none with other primary headaches (χ2 = 43.78; p < 0.001). Headache occurred more often associated with nausea ( p = 0.146) and bilateral location ( p = 0.002) in migraineurs who had headache triggered by odor. Headache was triggered after 118 ± 24.6 min and nausea after 72.8 ± 84.7 min of exposure to odor.

Conclusions

The odor triggered headache attacks or nausea only in migraineurs. Therefore, headache triggered by odors may be considered a factor of differentiation between migraine and other primary headaches and this trigger seems very specific of migraine.

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.

Clinical features associated with ictal osmophobia in migraine

Olfactory hypersensitivity may occur during migraine attacks and has been found to be very specific for this form of headache. Aim of this study was to investigate if migraineurs with ictal osmophobia have particular clinical features comparing to patients without ictal osmophobia. We recruited 200 consecutive migraineurs. Other primary headaches comorbidity and migraine prophylaxis were exclusion criteria. Each patient was interviewed following a structured questionnaire including general features about migraine, depression and anxiety symptoms. Migraine triggers both spontaneously and selecting from a specific list. Allodynia during the migraine attack was measured using the Allodynia symptoms check-list 12 (ASC-12). Eighty four (42 %) patients are non-osmophobic vs. 116 patients (58 %) who are osmophobic. After a logistic regression analysis, pain intensity (OR 1.391; p = 0.008) and anxiety (OR 1.099; p = 0.047) were significantly higher while aura (OR 0.421; p = 0.028) is less frequent in osmophobic migraineurs. We found significant differences in clinical features of osmophobic patients in respect to non-osmophobic ones. Ictal osmophobia seems being related to a broader sensorial hypersensitivity that could lead to a more florid clinical presentation.

Possible link between Toxoplasma gondii and the anosmia associated with neurodegenerative diseases

Toxoplasma gondii is an intracellular protozoan infecting 30% to 50% of global human population. Recently, it was suggested that chronic latent neuroinflammation caused by the parasite may be responsible for the development of several neurodegenerative diseases manifesting with the loss of smell. Studies in animals inoculated with the parasite revealed cysts in various regions of the brain, including olfactory bulb. Development of behavioral changes was paralleled by the preferential persistence of cysts in defined anatomic structures of the brain, depending on the host, strain of the parasite, its virulence, and route of inoculation. Olfactory dysfunction reported in Alzheimer's disease, multiple sclerosis, and schizophrenia was frequently associated with the significantly increased serum anti-T gondii immunoglobulin G antibody levels. Damage of the olfactory system may be also at least in part responsible for the development of depression because T gondii infection worsened mood in such patients, and the olfactory bulbectomized rat serves as a model of depression.

Olfactory function in migraine both during and between attacks

INTRODUCTION

People with migraine often report being osmophobic, both during and between acute migraine attacks. It is not clear, however, whether such reports are associated with changes in olfaction such as hyperosmia, as measured by psychophysical testing. In this case-control study we quantitatively assessed olfactory identification ability, which correlates with threshold tests of olfactory acuity, in patients with migraine at baseline (no headache), during migraine episodes, and after a treated attack and compared the test scores to those of matched control subjects.

METHODS

Fifty episodic migraine subjects and 50 and sex- and age-matched controls without headache were tested. All completed the University of Pennsylvania Smell Identification Test (UPSIT), a standardized and well-validated olfactory test.

RESULTS

At baseline, the UPSIT scores did not differ significantly between the migraine and control study groups (median paired score difference: -1, p = 0.18). During migraine attacks, a minority of migraine subjects (eight of 42) developed microsmia (i.e. lower test scores by at least four points), suggesting that, as compared to their matched controls, olfactory acuity was somewhat impaired during migraine attacks (p = 0.02). This difference was less pronounced and not statistically significant after a successfully treated attack (p = 0.15).

DISCUSSION

People with episodic migraine were found to have similar olfactory function as age- and sex-matched controls, but a minority exhibit microsmia or hyposmia during acute attacks. The cause of this dysfunction is unknown, but could relate to autonomic symptoms, limbic system activation, or disorders of higher order sensory processing.

The influence of health-risk perception and distress on reactions to low-level chemical exposure

The general aim of the current study was to investigate how perceived health risk of a chemical exposure and self-reported distress are related to perceived odor intensity and odor valence, symptoms, cognitive performance over time as well as reactions to blank exposure. Based on ratings of general distress, 20 participants constituted a relatively low distress group, and 20 other participants a relatively high distress group. Health risk perception was manipulated by providing positively and negatively biased information regarding n-butanol. Participants made repeated ratings of intensity, valence and symptoms and performed cognitive tasks while exposed to 4.7 ppm n-butanol for 60 min (first 10 min were blank exposure) inside an exposure chamber. Ratings by the positive and negative bias groups suggest that the manipulation influenced perceived health risk of the exposure. The high distress group did not habituate to the exposure in terms of intensity when receiving negative information, but did so when receiving positive information. The high distress group, compared with the low distress group, rated the exposure as significantly more unpleasant, reported greater symptoms and performed worse on a cognitively demanding task over time. The positive bias group and high distress group rated blank exposure as more intense. The main findings suggest that relatively distressed individuals are negatively affected by exposures to a greater degree than non-distressed.

Migraine and triggers: post hoc ergo propter hoc?

The influence of environmental factors on the clinical manifestation of migraine has been a matter of extensive debate over the past decades. Migraineurs commonly report foods, alcohol, meteorologic or atmospheric changes, exposure to light, sounds, or odors, as factors that trigger or aggravate their migraine attacks. In the same way, physicians frequently follow this belief in their recommendations in how migraineurs may reduce their attack frequency, especially with regard to the consumption of certain food components. Interestingly, despite being such a common belief, most of the clinical studies have shown conflicting results. The aim of the review is to critically analyze clinical and pathophysiological facts that support or refute a correlation between certain environmental stimuli and the occurrence of migraine attacks. Given the substantial discrepancy between patients' reports and objective clinical data, the methodological difficulties of investigating the link between environmental factors and migraine are highlighted.

Odorant substances that trigger headaches in migraine patients

OBJECTIVES

Our objective was to determine odorants that trigger migraine attacks and the time of onset of headache after exposure.

METHODS

Migraine or tension-type headache patients, diagnosed according to the criteria of the International Classification of Headache Disorders-II, were interviewed about lifetime prevalence of headaches triggered by odors and time of onset of pain, after exposure of the patient to the odor.

RESULTS

We studied 200 migraine patients and 200 tension-type headache patients. There were odor-triggered headaches after 25.5 ± 1.9 minutes of exposure in 70.0% (140/200) of migraine patients and none with tension-type headache, which ran at low sensitivity (70.0%, 95% CI 63.1-76.2) and high specificity (100.0%, 95% CI 97.6-100.0). Odor-triggered headaches are distributed in the following order of frequency: perfumes (106/140, 75.7%), paints (59/140, 42.1%), gasoline (40/140, 28.6%) and bleach (38/140, 27.1%). There was significance in the association of odor-triggered migraine, especially among perfume with cleaning (phi = -0.459), cooking (phi = 0.238), beauty products (phi = -0.213) and foul odors (phi = -0.582).

CONCLUSIONS

Odorants, isolated or in association, especially perfume, may trigger migraine attacks after a few minutes of exposure.

Alliaceous migraines

OBJECTIVE

To report a migraineur with osmophobia and trigger to garlic and onion aroma.

BACKGROUND

While odors serve as a trigger in 70% of migraineurs, alliaceous aromas have been described only rarely. Furthermore, nor has more than one type of alliaceous odor acted as a trigger in the same individual. Neither has migraine with aura been described as precipitated by such aromas. A patient experiencing migraines with aura, triggered almost exclusively by alliaceous aromas, is described.

METHODS

CASE STUDY

32-year-old woman; 5 years previously felt nasal pruritis upon eating a red onion dip. Shortly thereafter, the mere aroma of raw onions caused a sensation of her throat closing along with an associated panic attack. Over the intervening years, upon exposure to onions and garlic aroma she experienced a fortification spectra and visual entopia, followed by a bipareital, crushing level 10/10 headache, burning eyes and nose, lacrimation, perioral paresthesias, generalized pruritis, nausea, fatigue, sore throat, dysarthria, confusion, dyspnea, palpitations, presyncopal sensations, hand spasms, tongue soreness, neck pain, phonophobia, and photophobia. These would persist for 1 hour after leaving the aroma. She was unresponsive to medication and would wear a surgical mask when out. The patient also experienced chemosensory complaints: dysosmias every few months; phantosmias of food or cleaning products every month for a minute of level 5/10 intensity; pallinosmia of onion or garlic odor for 30 minutes after exposure; and metallic pallinugeusia after eating with metal utensils.

RESULTS

Neurological exam normal except for bilateral positive Hoffman reflexes.

CHEMOSENSORY TESTING

Quick Smell Identification Test 3/3 and Brief Smell Identification Test 12/12 were normal. Magnetic resonance imaging and computed tomography with and without contrast normal. Allergy skin test was positive for garlic and onion. Nose plug and counter stimulation with peppermint prevented the onset of headaches and associated symptoms.

CONCLUSION

This is the first report of migraines with aura triggered by more than one alliaceous compound in the same individual. Possible mechanisms include odor induced, emotional change, vasomotor instability, trigeminal-induced neurogenic inflammation, and allergic response. In alliaceous and odor-induced migraines, a trial of counter stimulation and nose plugs is warranted.

Understanding migraine through the lens of maladaptive stress responses: a model disease of allostatic load

The brain and body respond to potential and actual stressful events by activating hormonal and neural mediators and modifying behaviors to adapt. Such responses help maintain physiological stability ("allostasis"). When behavioral or physiological stressors are frequent and/or severe, allostatic responses can become dysregulated and maladaptive ("allostatic load"). Allostatic load may alter brain networks both functionally and structurally. As a result, the brain's responses to continued/subsequent stressors are abnormal, and behavior and systemic physiology are altered in ways that can, in a vicious cycle, lead to further allostatic load. Migraine patients are continually exposed to such stressors, resulting in changes to central and peripheral physiology and function. Here we review how changes in brain states that occur as a result of repeated migraines may be explained by a maladaptive feedforward allostatic cascade model and how understanding migraine within the context of allostatic load model suggests alternative treatments for this often-debilitating disease.

Trigger factors for familial hemiplegic migraine

Objective: The aim was to identify and describe migraine trigger factors in patients with familial hemiplegic migraine (FHM) from a population-based sample.

Methods: 127 FHM patients were sent a questionnaire listing 16 trigger factors. Distinction was made between attacks of hemiplegic migraine (HM) and migraine with aura (MA) or without aura (MO) within each patient.

Results: The response rate was 59% (75/127) of whom 57 (76%) had current HM attacks. Sixty-three per cent (47/75) reported at least one factor triggering HM, and 36% (27/75) reported at least one factor that often or always caused HM. Twenty per cent (15/75) reported only HM, whereas FHM in combinations with MA and MO were reported by 80% (60/75). Stress (with attacks either following or during the stress), bright light, intense emotional influences and sleeping too much or too little were the trigger factors mentioned by most.

Conclusion: Many FHM patients report trigger factors and one-third reported at least one trigger factor often or always triggering FHM. The typical triggers are the same as for MA. Patients should be educated to avoid these factors. The role of trigger factors in the onset of new or first attacks of FHM remains unknown.

Odors as triggering and worsening factors for migraine in men

OBJECTIVE: To assess the role of odors in triggering or worsening migraine in men. METHOD: Ninety-eight male migraineurs from the general population were assessed individually through questionnaires. Environmental factors relating to their migraine were reported, with special focus on the role of odors. RESULTS: Odors were the second most frequent triggering factor for migraine attacks (48%), behind stressful situations (59%). Likewise, odors were the second most frequent worsening factor (73%), just behind excessive light (74%). Thirty-three individuals (33.4%) stated that odors were both triggering and worsening factors for their migraine attacks. Perfume, cigarette smoke and cleaning products were the most frequent migraine-related odors reported by these male migraineurs. CONCLUSION: This was the first study to assess the role of odors in migraine exclusively in men. There was a high degree of odor-related migraine among these men, thus suggesting that patient education could alert such individuals to gender-related factors, since different triggering and worsening factors have been reported by males and females.