Evaluation of olfaction in patients with migraine using an odour stick identification test

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.

Olfactory function assessment of migraine patients by using the Sniffin' sticks test: A clinical study

OBJECTIVE

This as a cross-sectional controlled clinical study. We hypothesis that the olfactory functions in migraine patients may differ from the healthy controls. In this study, we evaluated the olfactory functions by using a Sniffin' Sticks test battery, which is a reliable and semi quantitative test to evaluate for olfactory dysfunction.

METHODS

Patients above 18 years of age who had migraine received a definitive diagnosis of migraine from experienced headache specialists based on the criteria of The International Classification of Headache Disorders-3 were included. Odor threshold, discrimination, and identification parameters were assessed using the "Sniffin' Sticks" test.

RESULTS

One-hundred and one migraine patients (age [mean ± SD], 36.9 ± 10.4 years; range, 18-60 years) and sixty healthy volunteers (age 34.5 ± 13.2 years, range 18-65 years) participated in our study. The median odor threshold score [percentiles 25th-75th] was 8.3 [6.5-9.8] for the migraine group during attack free period and 4.5[3.6-6.0] for the control group. It was found that the migraine group had a median odor discrimination score of 10.0 [10.0-13.0] and the control group 12.0 [11.0-13.0]. These differences were statistically significant (p < 0.001 and p = 0.032 respectively). The median odor discrimination and identification scores were statistically significant higher for the participants with higher educational level group than in those of lower educational group (p < 0.0001). The median odor discrimination and identification scores of those without allodynia (12.0 [10.0-14.0] and 13.0 [10.0-13.0] respectively) were higher than that of those with allodynia (11.0 [9.0-12.0] and 11.0 [10.0-13.0] respectively) (p = 0.037 and p = 0.034 respectively).

CONCLUSIONS

We found that the odor thresholds, discrimination and identification scores of the migraine group demonstrate differences from those of the healthy group and in relation to allodynia.

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.

Migraine with aura: less control over pain and fragrances?

BACKGROUND

Accumulating data emphasizes the importance of olfaction in migraine pathophysiology. However, there are only a few studies evaluating how the migraine brain processes olfactory stimulation, and virtually no studies comparing patients with and without aura in this context.

METHODS

This cross-sectional study recorded event-related potentials from 64 electrodes during a pure olfactory or pure trigeminal stimulus in females with episodic migraine with aura (n = 13) and without aura (n = 15), to characterize the central nervous processing of these intranasal stimuli. Patients were tested in interictal state only. Data were analyzed in the time domain and in the time-frequency domain. Source reconstruction analysis was also performed.

RESULTS

Patients with aura had higher event-related potentials amplitudes for left-sided trigeminal and left-sided olfactory stimulations, and higher neural activity for right-sided trigeminal stimulation in brain areas related to trigeminal and visual processing. Following olfactory stimulations patients with aura displayed decreased neural activity in secondary olfactory structures compared to patients without aura. Oscillations in the low frequency bands (< 8 Hz) differed between patient groups.

CONCLUSIONS

Altogether this may reflect hypersensitivity to nociceptive stimuli in patients with aura relative to patients without aura. Patients with aura have a bigger deficit in engaging secondary olfactory-related structures, possibly leading to distorted attention and judgements towards odors. The cerebral overlap between trigeminal nociception and olfaction might explain these deficits.

Migraine triggers in Asian countries: a narrative review

Background

Migraine is one of the most common neurological disorders worldwide. Clinical characteristics of migraine may be somewhat different across ethnic groups. Although factors such as stress, lack of sleep, and fasting are known as migraine triggers, the discussion about geographical differences of migraine triggers in Asia is lacking.

Methods

In this study, we performed a narrative review on migraine triggers in Asia. We searched PubMed for relevant papers published between January 2000 and February 2022.

Results

Forty-two papers from 13 Asian countries were included. Stress and sleep are the most frequently reported migraine triggers in Asia. There were some differences in migraine triggers in Asian countries: fatigue and weather common in Eastern Asia and fasting common in Western Asia.

Conclusion

Majority of the common triggers reported by patients with migraine in Asia were stress and sleep, similar to those reported globally, thus showing they are universally important. Some triggers linked to internal homeostasis are influenced by culture (e.g., alcohol, food/eating habit), and triggers related to environmental homeostasis, such as weather, are highly heterogenous between regions.

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.

Exploring the contributing factors to multiple chemical sensitivity in patients with migraine

Objective

Multiple chemical sensitivity (MCS) is a form of chemical intolerance in which various systemic symptoms are triggered by exposure to a variety of chemical substances. Although migraine has been associated with central sensitivity syndrome, the relationship between MCS and migraine has not been studied. We assessed the frequency of MCS and its related factors in patients with migraine.

Methods

We performed a cross‐sectional study that included 95 patients (14 M/81 F; age, 45.4 ± 12.4 years) out of 100 consecutive patients with migraine from our outpatient headache clinic. MCS was defined as having a combination of Q1 ≥ 30, Q3 ≥ 13, and Q5 ≥ 17 on the quick environment exposure sensitivity inventory (QEESI; Japanese version). Central sensitization inventory‐A scores >40 were considered an indication of central sensitization. Headache‐related disability and psychological distress were evaluated with the Migraine Disability Assessment score (MIDAS) and Kessler Psychological Distress Scale (K6), respectively.

Results

MCS was identified in 20% of patients with migraine; however, none had previously been diagnosed with MCS. The MCS‐positive group had higher rates of photophobia, osmophobia, visual aura, sensory aura, and central sensitization and higher MIDAS and K6 scores than the MCS‐negative group. A logistic regression analysis showed that osmophobia, sensory aura, and central sensitization were significant contributors to MCS.

Conclusion

We showed that MCS was observed in 20% of patients with migraine, and our study results may indicate a possible association of MCS with central sensitization and hypersensitivity‐related symptoms in patients with migraine.

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.

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.

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.

Validation of the "My Headache Checker" that includes osmophobia in the diagnosis of migraine

BACKGROUND

Migraine is a common headache disorder, with a 1 year prevalence rate of 6.0 %. However, less than 10% of patients with migraine receive medication in hospital. "My Headache Checker," a brief and self-administered migraine screening tool, which includes osmophobia in addition to the ID-Migraine™ three-item subset, was developed. The objective of this study was to analyze the applicability of "My Headache Checker" in Japanese patients.

METHODS

A total of 238 patients visiting the outpatient department were enrolled in the study. The patients' chief complaint was not headache. "My Headache Checker" was administered to the patients. Subsequently, they were evaluated by a generalist for the diagnosis of headache. The clinical diagnosis of headache was determined based on the International Classification of Headache Disorders Ⅲ.

RESULTS

Twenty (8.4%) patients satisfied the criteria for the diagnosis of migraine. Sensitivity, specificity, positive predictive value, and negative predictive value of "My Headache Checker" were 0.90, 0.83, 0.69, and 0.95, respectively. Sensitivity, specificity, positive predictive value, and negative predictive value of the ID-Migraine™ were 0.90, 0.85, 0.72, and 0.95, respectively.

CONCLUSION

The majority of migraine patients are missed in busy outpatient departments. Our results suggest that "My Headache Checker" is a useful tool in diagnosing unrecognized migraine patients. However, the addition of osmophobia did not contribute to improve the screening power of the ID-Migraine™.

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.

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.

Identification of Everyday Sounds Perceived as Noise by Migraine Patients

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

Constipation is associated with tension type headache in women

ABSTRACT Tension-type headaches (TTH) and irritable bowel syndrome (IBS) are comorbid diseases affecting, especially, women. One of the underlying mechanisms for both is autonomic dysfunction in the brain-gut axis. We aimed to evaluate the factors accompanying TTH and their relation to functional gastrointestinal disorders. Methods: Women diagnosed with TTH were questioned about headache pattern and severity, and accompanying factors, as well as being screened for IBS according to the Rome III criteria. The participants were divided into two groups: constipation-dominant IBS (IBS-C) group and “others”, with a total of 115 individuals included in the study. Results: Of the 115 patients; 48 (41.8%) of the women had IBS-C criteria while 67 (58.2%) described mixed-type IBS or diarrhea-dominant IBS. There were no significant differences in terms of mean age (p = 0.290), body mass index (p = 0.212), visual analog scale (p = 0.965), duration of attacks (p = 0.692), and episodic/chronic type (p = 0.553). Osmophobia was seen in 43.5%; phonophobia in 68.7%, and photophobia in 47.0% of the patients, and only osmophobia was significantly associated in women in the IBS-C group (p = 0.001). Conclusion: In female patients with TTH, a higher level of constipation was detected. The relationship of these two diseases suggests that they may share common mechanisms. This is the first study showing the relationship of osmophobia with constipation.

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.

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.

Olfactory functioning in early multiple sclerosis: Sniffin' Sticks Test study

INTRODUCTION

Previous studies have shown that olfactory functioning is affected by multiple sclerosis (MS). This study assessed the level of the olfactory impairment in early MS by using the Sniffin' Sticks Test.

METHODS

This study included 30 patients with MS and 30 healthy controls. We collected demographic and clinical data from participants and administered the Sniffin' Sticks Test.

RESULTS

We found no differences between the MS and control groups in odor discrimination, odor identification, and threshold discrimination identification scores, but odor threshold (OT) scores were higher in the control group than in the MS group (P=0.49). In addition, we did not find any correlation between MS patients' olfactory test scores and their scores on the Mini-Mental State Examination (MMSE), Expanded Disability Status Scale (EDSS), disease duration, history of optic neuritis, or being on immunomodulatory therapy.

CONCLUSION

In recent studies, odor threshold impairment seemed to be the most striking finding in patients with MS. Although the present study found a mild alteration in odor threshold, olfactory dysfunction appears to be a consequence of neurodegeneration in the higher order olfactory brain regions, which is thought to be a time-dependent process.

Olfactory acuity in chronic migraine: a cross-sectional study

OBJECTIVE/BACKGROUND

This study aims to measure olfactory acuity in chronic migraine subjects, at baseline and on migraine days, and compare to age- and sex-matched controls. Olfactory impairment is common in neurological disorders. While smell hypersensitivity has been established with chronic migraine, olfactory acuity has not been well studied.

METHODS

We recruited 50 subjects with chronic migraine from the Jefferson Headache Center and 50 age- and sex-matched controls. Using the University of Pennsylvania Smell Identification Test (UPSIT), a validated test of olfaction, olfactory acuity was measured at baseline and during a migraine for subjects, and compared to controls at baseline and at home 2 weeks later. All subjects were additionally screened for odor sensitivity and allodynia.

RESULTS

The mean UPSIT score for migraine subjects was 34.5 on non-migraine days and 34.7 on migraine days (mean difference=-0.4, 95% confidence interval [CI; -1.3, 0.6] P=.45). Controls had a mean of 35.9 and 36.1 for each test day (mean difference = -0.1, 95% CI [-0.9, 0.7] P=.87). On average, migraineurs performed worse than their matched control counterparts in both test sittings (test 1: P=.047; test 2: P=.01). The great majority of subjects were allodynic (42/50) compared with only 9 of 50 controls, and the majority of subjects (41/50) found more than one listed odor to be bothersome, compared with only 10/50 controls. On non-migraine days, 18/48 chronic migraine subjects had abnormal olfaction and on migraine days 14/42 had abnormal olfaction, compared with only 9/50 controls who had abnormal olfaction on their first UPSIT.

CONCLUSIONS

While chronic migraine patients do not appear to have a significant change in olfactory acuity between migrainous and non-migrainous periods, they do appear to be more likely to have abnormal olfactory acuity at baseline compared to age- and sex-matched controls.

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.

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.

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.

Clinical correlates and diagnostic utility of osmophobia in migraine

Background: Osmophobia is an under-investigated associated symptom in migraine.

Objective: To evaluate the clinical correlates and diagnostic utility of osmophobia.

Methods: Adult patients with migraine (with or without aura), probable migraine (PM), tension-type headache (TTH), and cluster headache (CH) were recruited retrospectively from our headache registration system. Migraine patients with and without osmophobia were compared. The newly proposed criteria for migraine requiring at least two of photo-, phono-, or osmophobia instead of both photo- and phonophobia were validated.

Results: In total, 2883 patients were included: 1809 migraine, 792 PM, 138 TTH, and 144 CH. Osmophobia was more common in migraine (62.2%) than in PM (33.8%), TTH (14.5%), and CH (31.3%) (all p < 0.001). Migraine patients with osmophobia scored higher on the Hospital Anxiety and Depression Scale (HADS) than those without (15.6 ± 7.6 vs. 13.3 ± 7.8, p < 0.001). The concordance in headache diagnoses between ICHD-2 (International Classification of Headache Disorders, Second Edition) and the newly proposed criteria was “almost perfect” (κ = 0.886, p < 0.001). Additionally, 16.9% of ICHD-2 PM patients were reclassified as migraine using the newly proposed criteria.

Conclusions: Osmophobia was prevalent in migraineurs, and was associated with higher HADS scores. The newly proposed criteria appear comparable to the ICHD-2 criteria, and may increase the diagnostic yield for Asian migraineurs, among whom photophobia was less common.

Migraine diagnosis: screening items, instruments, and scales

Migraine is a common and disabling disorder with a 1-year prevalence of 4.5-6% in men and 14.5-18% in women. The diagnosis of migraine is usually made according to the second edition of the International Classification of Headache Disorders (ICHD-2) criteria; however, not all physicians are familiar with the diagnostic criteria. Underdiagnosis remains a major issue in general practice, resulting in inadequate treatment. Several instruments are designed to improve the diagnosis of migraine, to identify the comorbid psychological disturbances, to measure the burden and disability, and to access any reduction in quality of life (QoL) that occurs due to migraine attacks with good reliability and validity. Furthermore, the disability and QoL measured by certain instruments serve as surrogate targets when treating migraines. In this review, we examine the instruments that are in common use in daily practice and current research on migraines, focusing on the purpose of each instrument, clinical applications, pitfalls in interpretation, and, if any, minimally clinically important difference(s) (MCID). In general, a structured intake form and a headache diary are recommended in approaching patients with headache. In addition, ID-Migraine, a three-item screening test, has been validated in primary care settings as a way to improve the rapid diagnosis of migraine. The Visual Aura Rating Scale (VARS) is helpful for the diagnosis of migraine with aura. In addition, migraine is commonly associated with psychiatric comorbidities, which can be assessed by the Beck Depression Inventory (BDI), 9-item Patient Health Questionnaire (PHQ-9), and Hospital Anxiety and Depression Scale (HADS). To evaluate the impact of migraines, disability can be assessed using the Migraine Disability Assessment Questionnaire (MIDAS). Reduction in QoL can be evaluated using the Migraine-Specific Quality of Life Survey (MSQ 2.1), European Quality of Life-Five Dimensions (EQ-5D), or Short-Form 36 (SF-36). Despite all these instruments, proper selection and interpretation of each instrument remain crucial.

Osmophobia as an early marker of migraine: A follow-up study in juvenile patients

Background: Osmophobia is frequent in children with migraine (20–35%) but can also occur in up to 14% of cases with tension-type headache (TTH). So far, the prognostic role of this symptom in children with primary headaches has never been evaluated.

Methods: A longitudinal prospective study was conducted on 90 young patients with TTH (37 with osmophobia, 53 without osmophobia). We evaluated whether osmophobia could predict the diagnosis transformation from TTH to migraine after a 3-year follow-up.

Results and Discussion: In our cases the rate of diagnosis change was significantly greater in cases with osmophobia (62%) than in those without (23%). Osmophobia persisted at a 3-year follow-up in the majority of our cases (85%) and it was found to be one of the major predictors for the development of migraine; other predictors of evolution to migraine were phonophobia, a probable rather than certain diagnosis of TTH and olfactory triggers (p < 0.05).

Conclusion: Our data confirm that osmophobia has an important diagnostic and prognostic role in children with primary headaches and should be systematically investigated at diagnosis and during follow-up.