Serotonin-Induced Plasma Extravasation in the Murine Inner Ear: Possible Mechanism of Migraine-Associated Inner ear Dysfunction

Assessment of Sacculocollic and Vestibulomasseteric Reflex Pathways in Individuals With Migraine and Vestibular Migraine

PURPOSE

The study's objective was to evaluate the functioning of sacculocollic and vestibulomasseteric reflex pathways in individuals with vestibular migraine and migraine.

METHOD

Seventy-five participants aged 18-50 years were selected for the study. Participants were divided into three groups. Group 1 consisted of 25 healthy individuals, Group 2 consisted of 25 migraine individuals, and Group 3 consisted of 25 individuals with vestibular migraine. Cervical vestibular-evoked myogenic potential (cVEMP) and masseter vestibular-evoked myogenic potential (mVEMP) were recorded using a 500-Hz tone burst stimulus presented at 125 dB peSPL for all participants.

RESULTS

The cVEMP test results showed a delayed p13 and n23 latency for both migraine and vestibular migraine individuals when compared to healthy individuals. Also, the amplitude of the p13-n23 peak was reduced compared to healthy individuals in both migraine and vestibular migraine. Similarly, the mVEMP test results showed a delayed p11 and n21 latency for both migraine and vestibular migraine individuals. No difference was observed in the amplitude of the p11-n21 peak complex between the three groups. Spearman's rho correlation revealed no significant (p > .05) correlation between cervical and masseter VEMP latency and amplitude parameters between healthy, migraine, and vestibular migraine individuals.

CONCLUSIONS

The results of the study are suggestive of the pathology of the sacullocollic and vestibulomasseteric reflex pathways in individuals with migraine and vestibular migraine. Individuals with migraine and vestibular migraine should undergo a detailed vestibular evaluation.

Case Series: Vestibular Migraines in Fragile X Premutation Carriers

BACKGROUND

Vestibular migraine (VM) is one of the most common causes of recurrent vertigo and presents with a history of spontaneous or positional vertigo with a history of migraine headaches. While research has identified a high prevalence of migraine headaches and vestibular deficits among fragile X premutation carriers, there has been no discussion about VM within this population.

OBJECTIVE

This case series and review seeks to describe the clinical characteristics and pathophysiology of VM among individuals with the fragile X premutation. We also seek to discuss treatment and future steps in addressing VM in this population.

METHODS

A review of the literature regarding vestibular migraine and presentation of migraine headaches and vestibular deficits among premutation carriers was performed. A detailed clinical history of migraine headaches and vertigo was obtained from three patients with the fragile X premutation seen by the senior author (RJH).

RESULTS

All three cases first developed symptoms of migraine headaches earlier in life, with the development of VM near menopause. Two of the three cases developed progressive balance issues following the development of VM. All three cases found that their VM episodes were improved or resolved with pharmacological and/or lifestyle interventions.

CONCLUSIONS

It is important to recognize VM among premutation carriers because beneficial treatments are available. Future studies are needed regarding the prevalence of VM and the relationship to subsequent FXTAS. The pathophysiology of VM remains uncertain but possibilities include mitochondrial abnormalities, cranial nerve VIII toxicity secondary to neurotoxic protein accumulation, and calcitonin gene-related peptide (CGRP) signaling dysfunction due to altered levels of fragile X messenger ribonucleoprotein (FMRP).

Characteristics of Benign Paroxysmal Positional Vertigo in Young Children

OBJECTIVES

This study aimed to determine the clinical characteristics of benign paroxysmal positional vertigo (BPPV) in young children.

STUDY DESIGN

Retrospective case review.

METHODS

All children <10 years old that have been diagnosed with BPPV at our pediatric vestibular program between December 2012-July 2021 were selected. Clinical features were identified by medical record review, including demographics, comorbidities, canal involvement, response to treatment, and incidence of recurrence.

RESULTS

A total of 34 children were diagnosed with BPPV with a mean age of 7.9 years old (SD ± 1/7; range 5-9) at the time of diagnosis and a male:female ratio of 1:1. Involved semicircular canals included posterior in 82% (n = 28), horizontal in 41% (n = 14), and superior in 24% (n = 8) of patients, respectively. Comorbid diagnoses included migraine (n = 14), concussion (n = 10), acute vestibular syndrome (n = 4), and persistent postural perceptual dizziness (n = 6). Recurrence with initially confirmed resolution occurred in 10 patients (29%) with a mean of 2.5 recurrences per patient (SD: 2.2; range 1-8). A family history of vertigo or migraine was identified in 11 and 17 patients, respectively.

CONCLUSIONS

BPPV is a cause of vertigo in children that may be overlooked. A relatively high proportion of patients demonstrated horizontal or superior canal involvement, recurrence, and additional comorbid causes of dizziness. Thus, providers evaluating young children with dizziness should perform diagnostic maneuvers to evaluate BPPV of all semicircular canals and continue to monitor children after successful treatment for recurrence.

LEVEL OF EVIDENCE

4, Case Series Laryngoscope, 133:694-699, 2023.

Diagnosis of comorbid migraine without aura in patients with idiopathic/genetic epilepsy based on the gray zone approach to the International Classification of Headache Disorders 3 criteria

Background

Migraine without aura (MwoA) is a very frequent and remarkable comorbidity in patients with idiopathic/genetic epilepsy (I/GE). Frequently in clinical practice, diagnosis of MwoA may be challenging despite the guidance of current diagnostic criteria of the International Classification of Headache Disorders 3 (ICHD-3). In this study, we aimed to disclose the diagnostic gaps in the diagnosis of comorbid MwoA, using a zone concept, in patients with I/GEs with headaches who were diagnosed by an experienced headache expert.

Methods

In this multicenter study including 809 consecutive patients with a diagnosis of I/GE with or without headache, 163 patients who were diagnosed by an experienced headache expert as having a comorbid MwoA were reevaluated. Eligible patients were divided into three subgroups, namely, full diagnosis, zone I, and zone II according to their status of fulfilling the ICHD-3 criteria. A Classification and Regression Tree (CART) analysis was performed to bring out the meaningful predictors when evaluating patients with I/GEs for MwoA comorbidity, using the variables that were significant in the univariate analysis.

Results

Longer headache duration (<4 h) followed by throbbing pain, higher visual analog scale (VAS) scores, increase of pain by physical activity, nausea/vomiting, and photophobia and/or phonophobia are the main distinguishing clinical characteristics of comorbid MwoA in patients with I/GE, for being classified in the full diagnosis group. Despite being not a part of the main ICHD-3 criteria, the presence of associated symptoms mainly osmophobia and also vertigo/dizziness had the distinguishing capability of being classified into zone subgroups. The most common epilepsy syndromes fulfilling full diagnosis criteria (n = 62) in the CART analysis were 48.39% Juvenile myoclonic epilepsy followed by 25.81% epilepsy with generalized tonic-clonic seizures alone.

Conclusion

Longer headache duration, throbbing pain, increase of pain by physical activity, photophobia and/or phonophobia, presence of vertigo/dizziness, osmophobia, and higher VAS scores are the main supportive associated factors when applying the ICHD-3 criteria for the comorbid MwoA diagnosis in patients with I/GEs. Evaluating these characteristics could be helpful to close the diagnostic gaps in everyday clinical practice and fasten the diagnostic process of comorbid MwoA in patients with I/GEs.

Early detection and monitoring of hearing loss in vestibular migraine: Extended high-frequency hearing

Background

Vestibular migraine (VM) presents mainly with recurrent vestibular symptoms and migraine. A great number of patients with VM have cochlea symptoms such as tinnitus, hearing loss.

Methods

A cross-sectional study was conducted on patients with definite VM (dVM) and probable VM (pVM) who met the diagnostic criteria. Auditory-vestibular tests and psychological assessments were performed. Logistic regression was used to evaluate the predictive effect of EHF pure tone audiometry (PTA) for standard frequency (SF) hearing loss.

Results

Fifteen patients with pVM and 22 patients with dVM were recruited. Overall, the two most vertigo types were vestibulo-visual symptoms (83.78%) and internal vertigo (54.05%). A vertigo attack persisted for <5 min in approximately 57% of patients, compared with 5 min to 72 h in 43%, and lasted longer than 72 h in 8%. Approximately 87% of patients had psychological disorders. Most patients with VM (92%) suffered from some degree of EHF hearing impairment, and 68% had SF hearing loss, which is substantially higher than their complaints (43%). Moreover, the mean EHF hearing threshold cutoff value (57 dB HL) worked well in predicting SF hearing loss (area under curve, AUC, 0.827), outperforming distortion product optoacoustic emission (AUC, 0.748).

Conclusion

VM has a wide range of clinical manifestations. Hearing loss had a considerably higher rate compared to actual complaints. Moreover, patients with VM tended to have bilateral EHF and high-frequency hearing loss. The effectiveness of the mean EHF hearing threshold cutoff value in predicting hearing loss supported its use in the early detection of hearing loss and monitoring disease progression.

Pathophysiology and Therapy of Associated Features of Migraine

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

A preliminary trial of botulinum toxin type A in patients with vestibular migraine: A longitudinal fMRI study

Objective

This study aims to investigate the efficacy of botulinum toxin type A (BTX-A) in the prophylactic management of vestibular migraine (VM) and to determine whether this treatment modulates intrinsic functional brain network.

Methods

Vestibular migraine patients (n = 20, mean age 45.4 years) who were resistant to conventional prophylactic therapies had BTX-A injection and rs-fMRI before and 2 months after the injection. We also measured the changes in the frequency of vertigo and migraine attacks, symptomatic functional disability scores, and neuropsychiatric inventories.

Results

After BTX-A injection, the mean monthly frequencies of migraine and vertigo episodes decreased significantly compared with the baseline (p < 0.01, paired t-test). The Headache Impact Test-6 score and the Migraine Disability Assessment, and the vertigo parameters, measured by the Dizziness Handicap Inventory and the Vertigo Symptom Scale, showed an improvement, as did the anxiety and depression scores 2 months after BTX-A treatment. The low-frequency fluctuation analysis of the rs-fMRI data found significant changes in the functional connectivity of the right superior temporal gyrus. Adoption of this cluster as the seed region increased the functional connectivity with the left post-central gyrus, right supramarginal gyrus, and right middle temporal gyrus after BTX-A treatment.

Conclusion

This prospective study suggests that BTX-A treatment is effective at ameliorating migraine and vertigo symptoms in VM patients who were resistant to conventional therapies. Along with symptomatic improvements, changes in the functional connectivity within the multisensory vestibular and pain networks suggest a dysmodulation of multimodal sensory integration and abnormal cortical processing of the vestibular and pain signals in VM patients.

Positive Relationship Between Paroxysmal Vertigo and Right-to-Left Shunt: A Large Observational Study

Background

The association between paroxysmal vertigo and right-to-left shunt (RLS) is rarely reported. This study investigates the prevalence and correlation of RLS in patients with different paroxysmal vertigo diseases.

Methods

Patients with paroxysmal vertigo from seven hospitals in China were included in this observational study between 2017 and 2021. Migraine patients within the same period were included for comparison. Demographic data and medical history were collected; contrast transthoracic echocardiography was performed; and the clinical features, Dizziness Handicap Inventory, and incidence of RLS in each group were recorded.

Results

A total of 2,751 patients were enrolled. This study's results demonstrated that the proportion of RLS in patients with benign recurrent vertigo (BRV) and vestibular migraine (VM) was significantly higher than that in patients with benign paroxysmal positional vertigo, Meniere's disease, and vestibular paroxysmia (P < 0.05). No statistical difference was shown between the frequency of RLS in patients with BRV and those with migraine and VM. A positive correlation was shown between the RLS grade and Dizziness Handicap Inventory scores of patients with VM and BRV (P < 0.01) after effectively controlleding the effect of confounding variables.

Conclusions

RLS was significantly associated with BRV and VM. RLS may be involved in the pathogeneses of BRV and VM and may serve as a differential reference index for the paroxysmal vertigo.

Trial Registration

CHRS, NCT04939922, registered 14 June 2021- retrospectively registered, https://register.clinicaltrials.gov.

Evaluation of video head impulse test during vertiginous attack in vestibular migraine

Objective

The aim of this study is to evaluate vestibular functions with video head impulse test (VHIT) and to understand the value of VHIT in differential diagnosis in patients with vestibular migraine (VM) during dizziness attack.

Materials and methods

Two groups were enrolled in this study. The first consisted of 84 vestibular migraine patients, and second group of 74 healthy subjects. VHIT was applied to patients with VM during vertigo attack and the results were compared with the VHIT values applied to subjects in the control group.

Results

The mean vestibulo-ocular reflex (VOR) in all semicircular canals in the VM group was lower than healthy individuals, but the results were not statistically significant. Refixation saccades were found in 52.3% of VM patients and in 10.2% of healthy individuals.

Conclusions

When patients with VM were evaluated with VHIT during vertiginous attack, VOR gain values were not different from healthy individuals, but the number of catch-up saccades were higher in VM patients, which indicates peripheral vestibular involvement. For differential diagnosis in patients with VM, vestibular tests should be performed during the vertigo attack. When evaluating VHIT results, the presence of refixation saccades should also be evaluated.

Non-contrast MRI of Inner Ear Detected Differences of Endolymphatic Drainage System Between Vestibular Migraine and Unilateral Ménière's Disease

Objective

We aimed to evaluate the diagnostic performance of some anatomical variables with regard to endolymphatic sac (ES) and duct (ED), measured by non-contrast three-dimensional sampling perfection with application-optimized contrasts using different flip angle evolutions (3D-SPACE) magnetic resonance imaging (MRI), in differentiating vestibular migraine (VM) from unilateral Ménière's disease (MD).

Methods

In this study, 81 patients with VM, 97 patients with unilateral MD, and 50 control subjects were enrolled. The MRI-visualized parameters, such as the distance between the vertical part of the posterior semicircular canal and the posterior fossa (MRI-PP distance) and visibility of vestibular aqueduct (MRI-VA), were measured bilaterally. The diagnostic value of the MRI-PP distance and MRI-VA visibility for differentiating VM from unilateral MD was examined.

Results

(1) Compared with the VM patients, patients with unilateral MD exhibited shorter MRI-PP distance and poorer MRI-VA visibility. No differences in the MRI-PP distance and MRI-VA visibility were detected between patients with VM and control subjects. (2) No significant interaural difference in the MRI-PP distance and MRI-VA visibility was observed in patients with VM and those with unilateral MD, respectively. (3) Area under the curve (AUC) showed a low diagnostic value for the MRI-PP distance and MRI-VA visibility, respectively, in differentiating between the VM and unilateral MD.

Conclusions

Based on non-enhanced MRI-visualized measurement, anatomical variables with regard to the endolymphatic drainage system differed significantly between the patients with VM and those with unilateral MD. Further investigations are needed to improve the diagnostic value of these indices in differentiating VM from unilateral MD.

Exploring Vestibular Assessment in Patients with Headache and Dizziness

Patients often report symptoms of headache and dizziness concomitantly. Symptoms of dizziness can be explored with a comprehensive vestibular assessment, allowing for the investigation of central and peripheral vestibular system contributions to symptoms of dizziness. Patients who report both symptoms of headache and dizziness demonstrate abnormalities of the vestibular system which can be measured quantitatively. Completion of comprehensive vestibular testing can help to guide diagnosis and strategies for intervention.

Skull Vibration-Induced Nystagmus Test (SVINT) in Vestibular Migraine and Menière's Disease

BACKGROUND

Vestibular migraine (VM) and Menière's disease (MD) are the two most frequent episodic vertigo apart from Benign Paroxysmal Positional Vertigo (BPPV) differential diagnosis for them may be troublesome in the early stages. SVINT is a newly proposed vestibular test, which demonstrated to be fast and reliable in diagnoses above all of peripheral vestibular deficits.

METHODS

We retrieved clinical data from two groups of subjects (200 VM and 605 MD), enrolled between 2010 and 2020. Among others, these subjects were included when performing a SVINT. The purpose of the study is to assess if SVINT can be useful to differentiate the two episodic disorders.

RESULTS

59.2% of MD subjects presented as positive with SVINT while only 6% did so with VM; among other tests, only video HIT demonstrated a different frequency in the two groups (13.1% and 0.5%, respectively), but the low sensitivity in these subjects makes the test unaffordable for diagnostic purposes.

CONCLUSIONS

Since SVINT demonstrated to be positive in a peripheral vestibular deficit in previous works, we think that our data are consistent with the hypothesis that, in the pathophysiology of VM attacks, the central vestibular pathways are mainly involved.

5-hydroxytryptamine in migraine: The puzzling role of ionotropic 5-HT3 receptor in the context of established therapeutic effect of metabotropic 5-HT1 subtypes

5-hydroxytryptamine (5-HT; serotonin) is traditionally considered as a key mediator implicated in migraine. Multiple 5-HT receptor subtypes contribute to a variety of region-specific functional effects. The raphé nuclei control nociceptive inputs by releasing 5-HT in the brainstem, whereas dural mast cells provide the humoral source of 5-HT in the meninges. Triptans (5-HT_1B/D agonists) and ditans (5-HT_1F agonists) are the best established 5-HT anti-migraine agents. However, activation of meningeal afferents via ionotropic 5-HT₃ receptors results in long-lasting excitatory drive suggesting a pro-nociceptive role for these receptors in migraine. Nevertheless, clinical data do not clearly support the applicability of currently available 5-HT₃ antagonists to migraine treatment. The reasons for this might be the presence of 5-HT₃ receptors on inhibitory interneurons dampening the excitatory drive, a lack of 5-HT₃ A-E subunit-selective antagonists and gender/age-dependent effects. This review is focusing on the controversial role of 5-HT₃ receptors in migraine pathology and related pharmacological perspectives of 5-HT ligands.

The Value of Subjective Visual Vertical in Diagnosis of Vestibular Migraine

OBJECTIVE

To study the value of the subjective visual vertical (SVV) in the diagnosis of vestibular migraine (VM).

METHODS

This study recruited 128 VM patients and 64 age-matched normal subjects. We detected the SVV during the interval between attacks in both groups, in sitting upright, and the head tilted at 45° to the left or right. We then examined the correlation between the SVV results with the vestibular evoked myogenic potential (VEMP) and canal paresis (CP).

RESULTS

It was found there was a significant difference in SVV at the upright position between VM patients and normal controls (P=0.006) and no significant difference was found at the tilts of 45° to the left or right between the two groups. The SVV results at the upright position were significantly correlated with cervical VEMP (P=0.042) whereas not significantly correlated with CP and VEMP. There existed no significant difference in the conformity to the Müller effect (M effect) between the two groups. ROC analysis exhibited that the sensitivity, specificity of SVVs at the upright were 67.200% and 62.500% respectively. The diagnostic value of SVV at the upright position was significantly higher than that at tilts of 45° to the left and right (P=0.006). Nonetheless the diagnostic accuracy was relatively low.

CONCLUSION

Abnormality in SVV possibly stems from the lasting functional disorder of cerebellar or high-level cortical centers in VM patients or is linked to the vestibular compensation. The SVV is of low diagnostic value for VM and the value of SVV in VM warrants further study.

Vestibular Migraine and Its Comorbidities

Vestibular migraine (VM) is one of the most common neurologic causes of vertigo. Symptoms and International Classification of Headache Disorders criteria are used to diagnose VM because no objective tests, imaging or audiologic, have been shown to reliably diagnose this condition. Central auditory, peripheral, and central vestibular pathway involvement has been associated with VM. Although the interaction between migraine and other vestibular disorders can be a challenging scenario for diagnosis and treatment, there are data to show that vestibular rehabilitation and a variety of pharmacologic agents improve reported symptoms and vertigo frequency.

Serotonin-induced vascular permeability is mediated by transient receptor potential vanilloid 4 in the airways and upper gastrointestinal tract of mice

Endothelial and epithelial cells form physical barriers that modulate the exchange of fluid and molecules. The integrity of these barriers can be influenced by signaling through G protein-coupled receptors (GPCRs) and ion channels. Serotonin (5-HT) is an important vasoactive mediator of tissue edema and inflammation. However, the mechanisms that drive 5-HT-induced plasma extravasation are poorly defined. The Transient Receptor Potential Vanilloid 4 (TRPV4) ion channel is an established enhancer of signaling by GPCRs that promote inflammation and endothelial barrier disruption. Here, we investigated the role of TRPV4 in 5-HT-induced plasma extravasation using pharmacological and genetic approaches. Activation of either TRPV4 or 5-HT receptors promoted significant plasma extravasation in the airway and upper gastrointestinal tract of mice. 5-HT-mediated extravasation was significantly reduced by pharmacological inhibition of the 5-HT2A receptor subtype, or with antagonism or deletion of TRPV4, consistent with functional interaction between 5-HT receptors and TRPV4. Inhibition of receptors for the neuropeptides substance P (SP) or calcitonin gene-related peptide (CGRP) diminished 5-HT-induced plasma extravasation. Supporting studies assessing treatment of HUVEC with 5-HT, CGRP, or SP was associated with ERK phosphorylation. Exposure to the TRPV4 activator GSK1016790A, but not 5-HT, increased intracellular Ca2+ in these cells. However, 5-HT pre-treatment enhanced GSK1016790A-mediated Ca2+ signaling, consistent with sensitization of TRPV4. The functional interaction was further characterized in HEK293 cells expressing 5-HT2A to reveal that TRPV4 enhances the duration of 5-HT-evoked Ca2+ signaling through a PLA2 and PKC-dependent mechanism. In summary, this study demonstrates that TRPV4 contributes to 5-HT2A-induced plasma extravasation in the airways and upper GI tract, with evidence supporting a mechanism of action involving SP and CGRP release.

Comparison of Electrocochleography and Video Head Impulse Test findings in Vestibular Migraine and Ménière Disease: A Preliminary Study

OBJECTIVES

To evaluate electrophysiological findings among patients with vestibular migraine (VM) and to compare them with those of patients suffering from definite Ménière disease (MD) without migraine.

MATERIALS AND METHODS

Twenty-one consecutive patients suffering from VM were enrolled; all subjects were selected according to the criteria proposed by the Bàràny Society for Neuro-otology. Each patient underwent a careful otological and neurotological examination. After completing a questionnaire regarding migraine and vertigo complaints, they were assessed by audiometric testing, video head impulse test (vHIT), and electrocochleography (EcochG). Data were compared with those of 21 patients who fulfilled the criteria for definite MD.

RESULTS

52.38% of the patients with VM suffered from at least two episodes of migraine per week, with 42.85% of the subjects complaining of migraines lasting ≥24 hours. 57.14% of the patients reported at least four episodes of vertigo per month, whereas 61.9% suffered from symptoms of chronic unsteadiness. No significant difference (p=0.76) resulted from the comparison of vHIT gain between patients with VM and MD. Eleven out of 21 patients (52.38%) with definite MD presented at least one ear with SP/AP >0.4, differently from patients with VM who exhibited SP/AP values suggestive of endolymphatic hydrops (EH) in only three cases (14.28%).

CONCLUSION

The present study found a higher proportion of abnormal EcochG in MD than in VM (p=0.02) without any significant difference in the vHIT gain. On the basis of our findings, the identification of EH in some patients with VM cannot be definitely related to the same pathway that triggers MD symptoms. Future research may help in better understanding whether abnormal EcochG findings can predict the occurrence of MD among patients with VM.

Vestibular migraine: the chameleon in vestibular disease

Vestibular migraine (VM) has been recently receiving increasing attention as an independent disease concept. It is a common cause of dizziness or headache; however, it was not clearly defined until 2018. Its diagnosis mainly relies on clinical history, including vertigo and migraine, as indicated by the appendix of the 3^rd edition of the International Classification Diagnostic Criteria for Headache Diseases. There is often an overlap of vertigo and migraine across vestibular diseases; therefore, VM often imitates various vestibular diseases. Additionally, VM lacks specific laboratory biomarkers; therefore, it has high misdiagnosis and missed diagnosis rates. Therefore, numerous clinical patients could have inaccurate diagnoses and improper treatment. Therefore, there is a need for further basic research to further clarify the pathogenesis. Moreover, there is a need for clinical trials focusing on specific laboratory biomarkers, including serological, radiological, and electrophysiological examinations, to develop more detailed and complete diagnostic criteria.

Recurrent vestibulopathy: are cVEMP, oVEMP and inner ear MRI useful to distinguish patients with Menière's disease and vestibular migraine?

PURPOSE

The aim of this study was to assess the rate of endolymphatic hydrops (EH) on MRI and the rate of otolithic dysfunction with cVEMP and oVEMP, in patients with recurrent vertigo such as Menière's disease (MD), vestibular migraine (VM) and vestibular Menière's disease (vMD).

METHODS

In this retrospective study, we performed 3D-FLAIR sequences with delayed acquisition in 20 MD, 20 VM and 20 vMD patients. Each subject was then assessed for the presence of EH on MRI. All patients underwent pure-tone audiometry, cVEMP and oVEMP.

RESULTS

In MD patients, EH was observed in 18 (90%) out of 20 patients while EH was observed in only 1 MV (5%) and 1 vMD (5%) patients. We found significant differences between groups for the presence of EH on MRI (p = 0.001). MD patients had significant higher PTA level (p < 0.001) and oVEMP impairment than MV and vMD (p = 0.08 and p = 0.06, respectively). However, no significant differences were observed for cVEMP impairment, either asymmetric ratio (p = 0.36) and 1000/500 ratio (p = 0.20).

CONCLUSIONS

Concerning cVEMP, we observed no significant differences between VM, vMD and MD. However, we observed higher oVEMP impairment, PTA level and EH on MRI in MD patients. We believe that MRI could be used to differentiate MD from VM patients with cochlear symptoms. However, in cases of migraine associated with recurrent vertigo and without cochlear symptoms, we believe that MRI is not a useful tool to differentiate between VM and vMD.

Multifactorial Characteristics of Pediatric Dizziness and Imbalance

OBJECTIVES

To examine the relative prevalence of individual diagnoses in children and adolescents presenting with dizziness and/or imbalance, and to assess the proportion of patients assigned multiple contributing diagnoses.

STUDY DESIGN

Retrospective cohort study.

METHODS

We retrospectively reviewed our internal database of all patients seen at our pediatric vestibular program between January 2012 and March 2019 to determine the incidence of common diagnoses and groups of diagnoses for patients ages 21 or younger.

RESULTS

One thousand twenty-one patients were included with a mean age of 12.5 ± 4.9 years (range: 9 months-21 years). Of this total, 624 patients were female and 397 were male. Common diagnoses included vestibular migraine (VM; 35.0%), benign paroxysmal positional vertigo (BPPV; 21.6%), primary dysautonomia (15.7%), anxiety disorder (13.5%), and persistent postural perceptual dizziness (PPPD; 11.2%). A high proportion of patients (44.4%) received multiple contributing diagnoses. VM was frequently diagnosed with BPPV or PPPD, and 22 patients were diagnosed with all three concurrently.

CONCLUSION

The causes of dizziness and imbalance in the pediatric population are diverse, and many patients have multiple diagnoses that are often interrelated. It is important that providers recognize that the causes of vestibular symptoms in children and adolescents may be multifactorial and may span across multiple specialties.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E1308-E1314, 2021.

Calcitonin gene-related peptide facilitates sensitization of the vestibular nucleus in a rat model of chronic migraine

Background

Vestibular migraine has recently been recognized as a novel subtype of migraine. However, the mechanism that relate vestibular symptoms to migraine had not been well elucidated. Thus, the present study investigated vestibular dysfunction in a rat model of chronic migraine (CM), and to dissect potential mechanisms between migraine and vertigo.

Methods

Rats subjected to recurrent intermittent administration of nitroglycerin (NTG) were used as the CM model. Migraine- and vestibular-related behaviors were analyzed. Immunofluorescent analyses and quantitative real-time polymerase chain reaction were employed to detect expressions of c-fos and calcitonin gene-related peptide (CGRP) in the trigeminal nucleus caudalis (TNC) and vestibular nucleus (VN). Morphological changes of vestibular afferent terminals was determined under transmission electron microscopy. FluoroGold (FG) and CTB-555 were selected as retrograde tracers and injected into the VN and TNC, respectively. Lentiviral vectors comprising CGRP short hairpin RNA (LV-CGRP) was injected into the trigeminal ganglion.

Results

CM led to persistent thermal hyperalgesia, spontaneous facial pain, and prominent vestibular dysfunction, accompanied by the upregulation of c-fos labeling neurons and CGRP immunoreactivity in the TNC (c-fos: vehicle vs. CM = 2.9 ± 0.6 vs. 45.5 ± 3.4; CGRP OD: vehicle vs. CM = 0.1 ± 0.0 vs. 0.2 ± 0.0) and VN (c-fos: vehicle vs. CM = 2.3 ± 0.8 vs. 54.0 ± 2.1; CGRP mRNA: vehicle vs. CM = 1.0 ± 0.1 vs. 2.4 ± 0.1). Furthermore, FG-positive neurons was accumulated in the superficial layer of the TNC, and the number of c-fos+/FG+ neurons were significantly increased in rats with CM compared to the vehicle group (vehicle vs. CM = 25.3 ± 2.2 vs. 83.9 ± 3.0). Meanwhile, CTB-555+ neurons dispersed throughout the VN. The structure of vestibular afferent terminals was less pronounced after CM compared with the peripheral vestibular dysfunction model. In vivo knockdown of CGRP in the trigeminal ganglion significantly reduced the number of c-fos labeling neurons (LV-CGRP vs. LV-NC = 9.9 ± 3.0 vs. 60.0 ± 4.5) and CGRP mRNA (LV-CGRP vs. LV-NC = 1.0 ± 0.1 vs. 2.1 ± 0.2) in the VN, further attenuating vestibular dysfunction after CM.

Conclusions

These data demonstrates the possibility of sensitization of vestibular nucleus neurons to impair vestibular function after CM, and anti-CGRP treatment to restore vestibular dysfunction in patients with CM.

Lasmiditan mechanism of action - review of a selective 5-HT1F agonist

Migraine is a leading cause of disability worldwide, but it is still underdiagnosed and undertreated. Research on the pathophysiology of this neurological disease led to the discovery that calcitonin gene-related peptide (CGRP) is a key neuropeptide involved in pain signaling during a migraine attack. CGRP-mediated neuronal sensitization and glutamate-based second- and third-order neuronal signaling may be an important component involved in migraine pain. The activation of several serotonergic receptor subtypes can block the release of CGRP, other neuropeptides, and neurotransmitters, and can relieve the symptoms of migraine. Triptans were the first therapeutics developed for the treatment of migraine, working through serotonin 5-HT1B/1D receptors. The discovery that the serotonin 1F (5-HT1F) receptor was expressed in the human trigeminal ganglion suggested that this receptor subtype may have a role in the treatment of migraine. The 5-HT1F receptor is found on terminals and cell bodies of trigeminal ganglion neurons and can modulate the release of CGRP from these nerves. Unlike 5-HT1B receptors, the activation of 5-HT1F receptors does not cause vasoconstriction.The potency of different serotonergic agonists towards 5-HT1F was correlated in an animal model of migraine (dural plasma protein extravasation model) leading to the development of lasmiditan. Lasmiditan is a newly approved acute treatment for migraine in the United States and is a lipophilic, highly selective 5-HT1F agonist that can cross the blood-brain barrier and act at peripheral nervous system (PNS) and central nervous system (CNS) sites.Lasmiditan activation of CNS-located 5-HT1F receptors (e.g., in the trigeminal nucleus caudalis) could potentially block the release of CGRP and the neurotransmitter glutamate, thus preventing and possibly reversing the development of central sensitization. Activation of 5-HT1F receptors in the thalamus can block secondary central sensitization of this region, which is associated with progression of migraine and extracephalic cutaneous allodynia. The 5-HT1F receptors are also elements of descending pain modulation, presenting another site where lasmiditan may alleviate migraine. There is emerging evidence that mitochondrial dysfunction might be implicated in the pathophysiology of migraine, and that 5-HT1F receptors can promote mitochondrial biogenesis. While the exact mechanism is unknown, evidence suggests that lasmiditan can alleviate migraine through 5-HT1F agonist activity that leads to inhibition of neuropeptide and neurotransmitter release and inhibition of PNS trigeminovascular and CNS pain signaling pathways.

Research on the Relationship Between Vestibular Migraine With/Without Cognitive Impairment and Brainstem Auditory Evoked Potential

Background: Vestibular migraine (VM) is the most common cause of spontaneous vertigo with no specific physical and laboratory examinations, and is an under-recognized entity with substantial burden for the individual and the society. In this study, by observing the brainstem auditory evoked potential (BAEP) and cognitive function of VM patients, the possible laboratory diagnostic indicators of VM and the influence of disease on cognitive function were discussed. Method: The study included 78 VM patients, 76 migraine patients, and 79 healthy individuals. The age, gender, and other clinical history of the three groups matched. All participants underwent BAEP examinations, in which patients in the migraine group and outpatients of the VM group were in the interictal period, and inpatients in the VM group were examined during episodes, while all patients tested for the Addenbrooke's cognitive examination-revised (ACE-R) scale were in the interictal period. The differences in BAEP and ACE-R scores between the three groups of members and their relationship with the clinical features of VM patients were analyzed. Result: The peak latency of I, III, and V wave in the BAEP of the VM group was longer than that of the migraine group and the control group (p < 0.05). The peak latency of V wave in the BAEP of the migraine group was longer than that of the control group (p < 0.05). The ACE-R of the VM group scored lower than the migraine group in terms of language fluency and language (p < 0.05), and lower than the control group in terms of total score, language fluency, language, and visuospatial (p < 0.05); and the ACE-R of the migraine group scored lower than the control group in the total score and visuospatial (p < 0.05). Conclusion: Migraine patients have brainstem dysfunction, and VM patients have more severe brainstem dysfunction than migraine patients, suggesting that VM patients have both central nervous system damage and peripheral nerve damage. Migraine patients have cognitive impairment, while cognitive impairment in VM patients is more severe than in migraine patients.

Serotonin–norepinephrine reuptake inhibitors for the prevention of migraine and vestibular migraine: a systematic review and meta-analysis

Background and objectives

The role of serotonin–norepinephrine reuptake inhibitors (SNRIs) in migraine prophylaxis has not been completely established. Current treatments for vestibular migraine (VM) are based on scarce evidence. We aimed to perform an updated review focusing on the efficacy and tolerability of SNRIs for migraine and VM prevention.

Methods

We searched the PubMed, Web of Science, and Cochrane Library databases for relevant studies. The primary outcome was migraine frequency. In the case of VM, the Dizziness Handicap Inventory (DHI) scores and Vertigo Severity Scores (VSSs) were extracted.

Results

Six randomized controlled trials involving 418 patients were analyzed. Patients receiving SNRIs had fewer migraine days than those receiving a placebo (standardized mean difference −0.38, 95% CI −0.76 to −0.01, p=0.04). The effects of SNRIs and other active drugs were comparable. In patients with VM, venlafaxine had a significant advantage over other active drugs in decreasing the VSS (weighted mean difference (MD) −1.45, 95% CI −2.11 to −0.78, p<0.0001) and the emotional domain score of the DHI (MD −2.64, 95% CI −4.97 to −0.31, p=0.03). We found no significant difference in the rate of withdrawals due to any reason or withdrawals due to side effects between SNRIs and active drugs and between SNRIs and a placebo.

Conclusions

SNRIs were clinically safe and effective for migraine and VM prophylaxis, were better than a placebo, and not inferior to other active drugs. SNRIs may be a preferable choice for patients with VM with psychiatric disorders.

Self-motion perception is sensitized in vestibular migraine: pathophysiologic and clinical implications

Vestibular migraine (VM) is the most common cause of spontaneous vertigo but remains poorly understood. We investigated the hypothesis that central vestibular pathways are sensitized in VM by measuring self-motion perceptual thresholds in patients and control subjects and by characterizing the vestibulo-ocular reflex (VOR) and vestibular and headache symptom severity. VM patients were abnormally sensitive to roll tilt, which co-modulates semicircular canal and otolith organ activity, but not to motions that activate the canals or otolith organs in isolation, implying sensitization of canal-otolith integration. When tilt thresholds were considered together with vestibular symptom severity or VOR dynamics, VM patients segregated into two clusters. Thresholds in one cluster correlated positively with symptoms and with the VOR time constant; thresholds in the second cluster were uniformly low and independent of symptoms and the time constant. The VM threshold abnormality showed a frequency-dependence that paralleled the brain stem velocity storage mechanism. These results support a pathogenic model where vestibular symptoms emanate from the vestibular nuclei, which are sensitized by migraine-related brainstem regions and simultaneously suppressed by inhibitory feedback from the cerebellar nodulus and uvula, the site of canal-otolith integration. This conceptual framework elucidates VM pathophysiology and could potentially facilitate its diagnosis and treatment.

Benign Paroxysmal Positional Vertigo (BPPV) in Children and Adolescents: Clinical Features and Response to Therapy in 110 Pediatric Patients

OBJECTIVE

This study aimed to characterize the clinical features and outcomes of benign paroxysmal positional vertigo (BPPV) in the pediatric population.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary care center.

PATIENTS

One hundred ten patients, aged 5 to 19 years old, diagnosed with BPPV.

MAIN OUTCOME MEASURES

Patient demographics, comorbidities, canal involvement, response to treatment, and incidence of recurrence.

RESULTS

BPPV was diagnosed in 19.8% of patients seen for dizziness during the study period. Patient age ranged 5 to 19 years old (mean =13.4 ± 3.4 yr). Female:male ratio was 3:2. The most prevalent comorbidities were concussion (n = 42, 38.2%) and migraine disorders (n = 33, 30.0%). Average time to diagnosis from symptom onset was 178.2 ± 190.8 days. The posterior canal was most frequently affected (n = 80, 72.7%), followed by the lateral canal (n = 37, 33.6%) and superior canal (n = 21, 19.1%), and 36.4% (n = 40) of patients had multiple canals affected. Treatment requiring more than or equal to five maneuvers to achieve resolution was observed in 11.8% of cases (n = 13). Recurrence was observed in 18.2% of cases. A logistic regression analysis demonstrated that patients with vestibular migraine or benign paroxysmal vertigo of childhood had five times higher odds of recurrence of BPPV, p = 0.003, 95% [1.735, 15.342], than those who did not have either.

CONCLUSIONS

BPPV is a relatively common cause of dizziness in the pediatric population. Children and adolescents with BPPV can be successfully treated with repositioning maneuvers but may be at risk for treatment resistance and recurrence. Increased awareness of BPPV in pediatric patients may reduce delays in identification and treatment.

Vestibular Migraine

The term vestibular migraine designates recurrent vertigo that is caused by migraine. Vestibular migraine presents with episodes of spontaneous or positional vertigo lasting seconds to days that are accompanied by migraine symptoms. Because headache is often absent during acute attacks, other migraine features have to be identified by thorough history taking. In contrast, vestibular testing serves mainly for the exclusion of other diagnoses. Treatment still lacks solid evidence. It is targeted at the underlying migraine and comprises explanation and reassurance, lifestyle modifications, and drugs.

Vestibular migraine: An update on current understanding and future directions

BACKGROUND

Vestibular migraine is among the most common causes of recurrent vertigo in the general population. Despite its prevalence and high impact on healthcare cost and utilization, it has remained an under-recognized condition with largely unknown pathophysiology. In the present article, we aim to provide an overview of the current understanding of vestibular migraine.

METHODS

We undertook a narrative literature review on the epidemiology, presentations, clinical and laboratory findings, pathophysiology, and treatments of vestibular migraine.

RESULTS

Currently, the diagnosis of vestibular migraine relies solely on clinical symptoms since clinical tests of vestibular function are typically normal, or difficult to interpret based on inconsistent results reported in earlier studies. The challenges related to diagnosis of vestibular migraine lie in its relatively broad spectrum of manifestations, the absence of typical migraine headaches with vestibular symptoms, and its very recent definition as a distinct entity. Here, we highlight these challenges, discuss common vestibular symptoms and clinical presentations in vestibular migraine, and review the current aspects of its clinical diagnosis and evaluation. The concepts related to the pathophysiology and treatment of vestibular migraine are also discussed.

CONCLUSION

Vestibular migraine is still underdiagnosed clinically. Future studies are needed to address the pathophysiological mechanisms and investigate effective treatment regimens.

Capturing acute vertigo

Objective

To facilitate the diagnosis of vestibular disorders by patient-initiated capture of ictal nystagmus.

Methods

Adults from an Australian neurology outpatient clinic reporting recurrent vertigo were recruited prospectively and taught to self-record spontaneous and positional nystagmus at home while symptomatic, using miniature video-oculography goggles. Consenting patients with ictal videorecordings and a final unblinded clinical diagnosis of Ménière disease (MD), vestibular migraine (VM), or benign paroxysmal positional vertigo (BPPV) were included.

Results

Ictal eye videos of 117 patients were analyzed. Of 43 patients with MD, 40 showed high-velocity spontaneous horizontal nystagmus (median slow-phase velocity [SPV] 39.7°/s; 21 showed horizontal nystagmus reversing direction within 12 hours [24 on separate days]). In 44 of 67 patients with VM, spontaneous horizontal (n = 28, 4.9°/s), upbeating (n = 6, 15.5°/s), or downbeating nystagmus (n = 10, 5.1°/s) was observed; 16 showed positional nystagmus only, and 7 had no nystagmus. Spontaneous horizontal nystagmus with SPV >12.05°/s had a sensitivity and specificity of 95.3% and 82.1% for MD (95% confidence interval [CI] 0.84–0.99, 0.71–0.90). Nystagmus direction change within 12 hours was highly specific (95.7%) for MD (95% CI 0.85–0.99). Spontaneous vertical nystagmus was highly specific (93.0%) for VM (95% CI 0.81–0.99). In the 7 patients with BPPV, spontaneous nystagmus was absent or <3°/s. Lying affected-ear down, patients with BPPV demonstrated paroxysmal positional nystagmus. Median time for peak SPV to halve (T50) was 19.0 seconds. Patients with VM and patients with MD demonstrated persistent positional nystagmus (median T50; 93.1 seconds, 213.2 seconds). T50s <47.3 seconds had a sensitivity and specificity of 100% and 77.8% for BPPV (95% CI 0.54–1.00, 0.64–0.88).

Conclusion

Patient-initiated vestibular event monitoring is feasible and could facilitate rapid and accurate diagnosis of episodic vestibular disorders.

Clinical significance of spontaneous nystagmus in pediatric patients

OBJECTIVE

To analyze spontaneous nystagmus recorded in pediatric patients and determine its diagnostic value.

MATERIALS AND METHODS

Retrospective review of 86 patients (mean age = 13.9 ± 4.7 years) with definitive spontaneous nystagmus recorded by videonystagmography (VNG). Spontaneous nystagmus was categorized and analyzed based on its characteristics. Correlations between spontaneous nystagmus and established clinical diagnoses were explored.

RESULTS

Among the patients seen in a period of three years at our pediatric vestibular clinic, 15.4% (86 out of 560) were found to have spontaneous nystagmus and half of them had horizontal nystagmus with a fixed-direction. The majority of cases with spontaneous nystagmus (77%, 66/86) were present without fixation only, while the presence of spontaneous nystagmus with and without fixation was found in 16 patients (19%). Most patients with spontaneous nystagmus without fixation only (68%) were diagnosed with a peripheral vestibular disorder (e.g., vestibular neuritis) or vestibular migraine. In contrast, vertical nystagmus was found in 15 patients, most of whom had central vestibular disorders. Other rare forms of nystagmus or abnormal eye movements, such as pendular nystagmus, ocular oscillation or flutter were recorded in only four patients.

CONCLUSIONS

Spontaneous nystagmus in children and young adults with possible vestibular impairments may vary in clinical presentation. Identification of its characteristics may help to make an accurate clinical diagnosis. While spontaneous nystagmus associated with peripheral vestibular disorders can be readily recognized, spontaneous nystagmus in pediatric patients with vestibular migraine appears to be more complex and variable in form.

Disorders of the inner-ear balance organs and their pathways

Disorders of the inner-ear balance organs can be grouped by their manner of presentation into acute, episodic, or chronic vestibular syndromes. A sudden unilateral vestibular injury produces severe vertigo, nausea, and imbalance lasting days, known as the acute vestibular syndrome (AVS). A bedside head impulse and oculomotor examination helps separate vestibular neuritis, the more common and innocuous cause of AVS, from stroke. Benign positional vertigo, a common cause of episodic positional vertigo, occurs when otoconia overlying the otolith membrane falls into the semicircular canals, producing brief spells of spinning vertigo triggered by head movement. Benign positional vertigo is diagnosed by a positional test, which triggers paroxysmal positional nystagmus in the plane of the affected semicircular canal. Episodic spontaneous vertigo caused by vestibular migraine and Ménière's disease can sometimes prove hard to separate. Typically, Ménière's disease is associated with spinning vertigo lasting hours, aural fullness, tinnitus, and fluctuating hearing loss while VM can produce spinning, rocking, or tilting sensations and light-headedness lasting minutes to days, sometimes but not always associated with migraine headaches or photophobia. Injury to both vestibular end-organs results in ataxia and oscillopsia rather than vertigo. Head impulse testing, dynamic visual acuity, and matted Romberg tests are abnormal while conventional neurologic assessments are normal. A defect in the bony roof overlying the superior semicircular canal produces vertigo and oscillopsia provoked by loud sound and pressure (when coughing or sneezing). Three-dimensional temporal bone computed tomography scan and vestibular evoked myogenic potential testing help confirm the diagnosis of superior canal dehiscence. Collectively, these clinical syndromes account for a large proportion of dizzy and unbalanced patients.

Serotonergic mechanisms of trigeminal meningeal nociception: Implications for migraine pain

Serotonergic mechanisms play a central role in migraine pathology. However, the region-specific effects of serotonin (5-HT) mediated via multiple types of receptors in the nociceptive system are poorly understood. Using extracellular and patch-clamp recordings, we studied the action of 5-HT on the excitability of peripheral and central terminals of trigeminal afferents. 5-HT evoked long-lasting TTX-sensitive firing in the peripheral terminals of meningeal afferents, the origin site of migraine pain. Cluster analysis revealed that in majority of nociceptive fibers 5-HT induced either transient or persistent spiking activity with prevailing delta and theta rhythms. The 5-HT3-receptor antagonist MDL-72222 or 5-HT1B/D-receptor antagonist GR127935 largely reduced, but their combination completely prevented the excitatory pro-nociceptive action of 5-HT. The 5-HT3 agonist mCPBG activated spikes in MDL-72222-dependent manner but the 5HT-1 receptor agonist sumatriptan did not affect the nociceptive firing. 5-HT also triggered peripheral CGRP release in meninges, which was blocked by MDL-72222.5-HT evoked fast membrane currents and Ca²⁺ transients in a fraction of trigeminal neurons. Immunohistochemistry showed expression of 5-HT3A receptors in fibers innervating meninges. Endogenous release of 5-HT from degranulated mast cells increased nociceptive firing. Low pH but not histamine strongly activated firing. 5-HT reduced monosynaptic inputs from trigeminal Aδ- and C-afferents to the upper cervical lamina I neurons and this effect was blocked by MDL-72222. Consistent with central inhibitory effect, 5-HT reduced CGRP release in the brainstem slices. In conclusion, 5-HT evokes powerful pro-nociceptive peripheral and anti-nociceptive central effects in trigeminal system transmitting migraine pain.

Vestibular Migraine: Clinical Challenges and Opportunities for Multidisciplinarity

Migraine and vertigo are two very prevalent conditions in general population. The coexistence of both in the same subject is a significant clinical challenge, since it is not always possible to understand whether they are causally related or associated by chance, requiring different diagnostic and therapeutic approaches. In this review we analyze and summarize the actual knowledge about vestibular migraine (VM), focusing on the new concepts proposed by the International Classification of Headache Disorders 3-beta and by the Bárány Society and also addressing the former concepts, which are still present in clinical practice. We conclude that clinical studies using a multidisciplinary approach are crucial in this field, since different specialists observe the same pathology with different eyes. Clinical presentation of VM is variable in what concerns vestibular symptoms temporal relation with migraine headache, as well as in their accompanying manifestations. Biomarkers, either genomics or functional, and molecular imaging techniques will be helpful to clarify many aspects of the complexity of this entity, helping to define to what extent can VM be considered a separate and independent clinical entity.

Recent Advances in the Understanding of Vestibular Migraine

Approximately 1% of the general population and 10% of patients with migraine suffer from vestibular migraine (VM). However, this condition remains relatively unknown; therefore, it is often underdiagnosed despite the recent adoption of international diagnostic criteria for VM. The diagnosis of VM is based on the symptoms, degree, frequency, and duration of the vestibular episodes, a history of migraine, the temporal association of migraine symptoms with vestibular episodes in at least 50% of cases, and the exclusion of other causes. Physical examination and laboratory findings are usually normal in patients with VM but can be used to rule out other vestibular disorders with similar symptoms. The pathophysiology of VM remains incompletely understood; however, several mechanisms link the trigeminal system, which is activated during migraine attacks, and the vestibular system. Because few controlled trials have specifically investigated VM, the treatment options for this order are largely the same as those for migraine and include antiemetics for severe acute attacks, pharmacological migraine prophylaxis, and lifestyle changes.

Distribution of 5-HT1F Receptors in Monkey Vestibular and Trigeminal Ganglion Cells

Background

Evidence of serotonergic involvement in vestibular pathway contributions to migraine and balance disorders is compelling. Serotonergic 5-HT_1B and 5-HT_1D receptors are expressed extensively in inner ear ganglia of monkeys and rats. The serotonergic 5-HT_1F receptor is also a target of triptans. This study describes its distribution in vestibular and trigeminal ganglia of monkeys.

Methods

Using primary polyclonal antibodies raised against oligopeptides specific for the human 5-HT_1F receptor, neuronal somatic area and intensity of immunoreactive vestibular and trigeminal ganglia were quantified.

Results and Discussion

Virtually all vestibular and considerable trigeminal ganglia showed positive 5-HT_1F receptor immunoreactivity. Inferior and superior vestibular ganglia staining appeared confined to distinct cell regions, varying considerably among cells of different sizes: more intense in small, punctate in some medium and regionally polarized in some large cells. Analyses of average somatic vestibular neuronal immunoreactive intensity identified mainly medium sized cells with high standard deviation of intensity corresponding to punctately stained cells. Less variability occurred in somatic intensity staining and cellular distribution among 5-HT_1F receptor immunopositive trigeminal ganglia. Most exhibited similar punctate staining patterns, higher mean somatic immunoreactive intensity and larger neuronal somatic size proportions per size distribution subpopulation compared to vestibular ganglia size distribution populations. Centrally directed vestibular ganglion neuronal processes, cochlear inner hair cells, vestibular hair cells and blood vessels in vestibular maculae and cristae were immunoreactive. The 5-HT_1F receptor expression in vestibular ganglia shows complex variable staining intensity patterns associated with cell size of immunopositive neurons, not seen in immunopositive trigeminal ganglia and not previously evident with 5-HT_1B and 5-HT_1D receptor subtype immunoreactivity in vestibular ganglia. These data motivate exploration of 5-HT₁ receptor oligomerization and ligand functional selectivity in differential serotonergic involvement in co-morbidity of migraine and balance disorders. Similar findings in cochlear inner hair cell afferents are applicable to migraine-related tinnitus or hypercusis (phonophobia).

The Vestibulo-Collic Reflex is Abnormal in Migraine

Interictal evoked central nervous system responses are characterized in migraineurs by a deficit of habituation, at both cortical and subcortical levels. The click-evoked vestibulo-collic reflex (VCR) allows the assessment of otolith function and an oligosynaptic pathway linking receptors in the saccular macula to motoneurons of neck muscles. Three blocks of 75 averaged responses to monaural 95-dB normal hearing level 3-Hz clicks were recorded over the contracted ipsilateral sternocleidomastoid muscle in 25 migraineurs between attacks and 20 healthy subjects, without vestibular symptoms. Amplitudes, raw and corrected for baseline electromyography, were significantly smaller in migraine patients. Whereas in healthy volunteers the VCR habituated during stimulus repetition (-4.96% ± 14.3), potentiation was found in migraineurs (4.34% ± 15.3; P = 0.04). The combination with a reduced mean amplitude does not favour vestibular hyperexcitability as an explanation for the habituation deficit in migraine, but rather an abnormal processing of repeated stimuli in the reflex circuit.

Vestibular migraine: the most frequent entity of episodic vertigo

Vestibular migraine (VM) is the most common cause of episodic vertigo in adults as well as in children. The diagnostic criteria of the consensus document of the International Bárány Society for Neuro-Otology and the International Headache Society (2012) combine the typical signs and symptoms of migraine with the vestibular symptoms lasting 5 min to 72 h and exclusion criteria. Although VM accounts for 7% of patients seen in dizziness clinics and 9% of patients seen in headache clinics it is still underdiagnosed. This review provides an actual overview on the pathophysiology, the clinical characteristics to establish the diagnosis, the differential diagnosis, and the treatment of VM.

Evaluation and management of vestibular migraine in children: Experience from a pediatric vestibular clinic

OBJECTIVE

Epidemiologic studies have shown Vestibular migraine (VM) to be the most common cause of vertigo in children, but little is known about the typical presentation and response to treatment of this disorder in the pediatric population. The aim of this study was to evaluate the diagnostic features and response to therapy of VM in children managed at a pediatric vestibular clinic.

METHODS

Twenty-eight patients ≤18 years old with a diagnosis of VM were identified from 208 patients seen at the Balance and Vestibular Program at Boston Children's Hospital from July 2012-July 2014, after excluding 12 patients with a history of major otologic or neurologic surgery, recent concussion, or additional vestibular disorders. Patients' electronic medical records and testing results were retrospectively reviewed.

RESULTS

Patients ranged in age from 9 to 18 years old (mean 14.48). All included patients met criteria for definite (n = 25) or probable (n = 3) VM as defined by the International Classification of Headache Disorders. Rotary chair (n = 17), caloric (n = 8), cervical vestibular evoked myogenic potential (n = 16), and video head impulse (n = 3) tests were normal. Medications effectively reduced reported vestibular symptoms in 88% of those treated with tricyclics (n = 8), 86% of those treated with cyprohepatadine (n = 7), 80% of those treated with topiramate (n = 5), 80% of those treated with triptans (n = 10), and 25% of those treated with gabapentin (n = 4).

CONCLUSIONS

Vestibular migraine is a common cause of vertigo in the pediatric population that is frequently responsive to medical therapy.

Vestibular migraine

During the last decades a new vestibular syndrome has emerged that is now termed vestibular migraine (VM). The main body of evidence for VM is provided by epidemiologic data demonstrating a strong association between migraine and vestibular symptoms. Today, VM is recognized as one of the most common causes of episodic vertigo. The clinical presentation of VM is heterogeneous in terms of vestibular symptoms, duration of episodes, and association with migrainous accompaniments. Similar to migraine, there is no clinical or laboratory confirmation for VM and the diagnosis relies on the history and the exclusion of other disorders. Recently, diagnostic criteria for VM have been elaborated jointly by the International Headache Society and the Bárány Society. Clinical examination of patients with acute VM has clarified that the vast majority of patients with VM suffer from central vestibular dysfunction. Findings in the interval may yield mild signs of damage to both the central vestibular and ocular motor system and to the inner ear. These interictal clinical signs are not specific to VM but can be also observed in migraineurs without a history of vestibular symptoms. How migraine affects the vestibular system is still a matter of speculation. In the absence of high-quality therapeutic trials, treatment is targeted at the underlying migraine.

Neurotransmitters in the vestibular system

Neuronal networks that are linked to the peripheral vestibular system contribute to gravitoinertial sensation, balance control, eye movement control, and autonomic function. Ascending connections to the limbic system and cerebral cortex are also important for motion perception and threat recognition, and play a role in comorbid balance and anxiety disorders. The vestibular system also shows remarkable plasticity, termed vestibular compensation. Activity in these networks is regulated by an interaction between: (1) intrinsic neurotransmitters of the inner ear, vestibular nerve, and vestibular nuclei; (2) neurotransmitters associated with thalamocortical and limbic pathways that receive projections originating in the vestibular nuclei; and (3) locus coeruleus and raphe (serotonergic and nonserotonergic) projections that influence the latter components. Because the ascending vestibular interoceptive and thalamocortical pathways include networks that influence a broad range of stress responses (endocrine and autonomic), memory consolidation, and cognitive functions, common transmitter substrates provide a basis for understanding features of acute and chronic vestibular disorders.

New insights into pathophysiology of vestibular migraine

Vestibular migraine (VM) is a common disorder in which genetic, epigenetic, and environmental factors probably contribute to its development. The pathophysiology of VM is unknown; nevertheless in the last few years, several studies are contributing to understand the neurophysiological pathways involved in VM. The current hypotheses are mostly based on the knowledge of migraine itself. The evidence of trigeminal innervation of the labyrinth vessels and the localization of vasoactive neuropeptides in the perivascular afferent terminals of these trigeminal fibers support the involvement of the trigemino-vascular system. The neurogenic inflammation triggered by activation of the trigeminal-vestibulocochlear reflex, with the subsequent inner ear plasma protein extravasation and the release of inflammatory mediators, can contribute to a sustained activation and sensitization of the trigeminal primary afferent neurons explaining VM symptoms. The reciprocal connections between brainstem vestibular nuclei and the structures that modulate trigeminal nociceptive inputs (rostral ventromedial medulla, ventrolateral periaqueductal gray, locus coeruleus, and nucleus raphe magnus) are critical to understand the pathophysiology of VM. Although cortical spreading depression can affect cortical areas involved in processing vestibular information, functional neuroimaging techniques suggest a dysmodulation in the multimodal sensory integration and processing of vestibular and nociceptive information, resulting from a vestibulo-thalamo-cortical dysfunction, as the pathogenic mechanism underlying VM. The elevated prevalence of VM suggests that multiple functional variants may confer a genetic susceptibility leading to a dysregulation of excitatory–inhibitory balance in brain structures involved in the processing of sensory information, vestibular inputs, and pain. The interactions among several functional and structural neural networks could explain the pathogenic mechanisms of VM.

Caloric stimulation and video-head impulse testing in Ménière's disease and vestibular migraine

CONCLUSION

Both the bithermal caloric test and the video-head impulse test (vHIT) were more often abnormal in Ménière's disease (MD) than in vestibular migraine (VM). Horizontal vestibulo-ocular reflex (hVOR) evaluation with caloric test (low-frequency test) was significantly more often abnormal than vHIT (high-frequency test). Therefore, both tests can be used in a complementary way for frequency-selective testing of peripheral vestibular function.

OBJECTIVES

To compare the results of caloric testing and vHIT in MD and VM and to determine which test is more sensitive to uncover peripheral vestibular hypofunction.

METHODS

Patients with MD (n=30) or VM (n=23) were examined with the caloric test and vHIT. The parameters analyzed were the canal paresis factor for the caloric test and the hVOR gain on both sides in vHIT.

RESULTS

The caloric test was abnormal in 67% of patients with MD and in 22% with VM (p=0.002), while the vHIT showed an hVOR deficit in 37% in MD and 9% in VM (p=0.025). In all, 28% of patients with an abnormal caloric test had a normal vHIT, whereas 6% of those with an abnormal vHIT had a normal caloric test. The sensitivity of vHIT compared with caloric testing was 55% for MD and 40% for VM. Neither the caloric test nor vHIT could detect significant differences between early (<5 years) or advanced stages (>5 years) of MD or VM.

Impairment of habituation of the auditory brain stem response in migrainous vertigo

OBJECTIVES

We evaluated the auditory brain stem response (ABR) in migrainous vertigo (MV).

METHODS

Four subjects who met clinical criteria for definite MV and 4 subjects with non-vertiginous migraine (NVM) underwent ABR testing while asymptomatic and within 16 hours of a symptomatic episode. Four control subjects were also tested. A set of 4 consecutive 750-click series was administered at 50-, 60-, and 70-dB intensities. We compared the groups in terms of habituation of the amplitude of wave IV-V (habituation of IV-V) from the first through fourth series for each set.

RESULTS

The habituation of IV-V amplitude to 50-dB stimuli was significantly less (p = 0.047) in the symptomatic MV group (5.08% +/- 22.32%) than in the symptomatic NVM group (-21.44% +/- 13.50%) or the control group (-26.06% +/- 9.76%). The habituation of IV-V amplitude to 70-dB stimuli in the MV group was significantly less (p = 0.031) during symptomatic testing (-3.43% +/- 8.89%) than during asymptomatic testing (-21.23% +/- 6.41%).

CONCLUSIONS

The habituation of IV-V amplitude is reduced during MV attacks. This finding suggests impaired brain stem inhibition at the level of the inferior colliculus, which shares serotonergic connections with the dorsal raphe nucleus, an area hyperactive in migraine.