A genome-wide linkage scan of familial benign recurrent vertigo: linkage to 22q12 with evidence of heterogeneity

A genome-wide association study identifies novel loci of vertigo in an Asian population-based cohort

The contributing genetic factors of vertigo remain poorly characterized, particularly in individuals of non-European ancestries. Here we show the genetic landscape of vertigo in an Asian population-based cohort. In a two-stage genome-wide association study (Ncase = 6199; Ncontrol = 54,587), we identify vertigo-associated genomic loci in DROSHA and ZNF91/LINC01224, with the latter replicating the findings in European ancestries. Gene-based association testing corroborates these findings. Interestingly, both genes are enriched in cerebellum, a key structure receiving sensory input from the vestibular system. Subjects carrying risk alleles from lead SNPs of DROSHA and ZNF91 incur a 1.74-fold risk of vertigo than those without. Moreover, composite clinical-polygenic risk scores allow differentiation between patients and controls, yielding an area under receiver operating characteristic curve of 0.69. This study identified novel genomic loci for vertigo in an Asian population-based cohort, which may help identifying high risk subjects and provide mechanistic insight in understanding the pathogenesis of vertigo.

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).

Vestibular migraine treatment: a comprehensive practical review

Vestibular migraine is an underdiagnosed but increasingly recognised neurological condition that causes episodic vertigo associated with other features of migraine. It is now thought to be the most common cause of spontaneous (non-positional) episodic vertigo, affecting up to 1% of the population. A meta-analysis of preventative treatments for vestibular migraine was published in 2021 but the authors were unable to establish a preferred treatment strategy due to low quality of evidence and heterogeneity of study design and outcome reporting. There remains therefore a clinical need for pragmatic management guidelines specific to vestibular migraine using the available evidence. Here we provide a practical review utilising a systematic qualitative assessment of the evidence for abortive and preventative interventions in adults. The overall evidence base for vestibular migraine treatment is of low quality. Nevertheless, we provide practical treatment recommendations based on the available evidence and our experience to help guide clinicians treating patients with vestibular migraine. We also discuss how future clinical trials could be designed to improve the quality of evidence in this condition.

Patient Experience of Flunarizine for Vestibular Migraine: Single Centre Observational Study

Vestibular migraine (VM) is a leading cause of episodic vertigo, affecting up to 1% of the general population. Despite established diagnostic criteria, there is currently no evidence-based approach for acute treatment of VM, with treatment recommendations generally extrapolated from studies on classical migraine headache. Several small-scale studies have identified flunarizine as a potentially effective prophylactic medication in VM. We conducted a single-centre observational service evaluation study exploring patient experiences of preventative medications over a 28-month period, including flunarizine, for control of VM symptoms. To compare patient experience of flunarizine with other medications, data from patients taking flunarizine were separately analysed. A total of 90% of VM patients taking flunarizine reported symptomatic improvement, compared to only 32% of patients on other medications. Whilst 50% of patients on flunarizine reported side effects. these were not deemed to outweigh the clinical benefits, with most patients deciding to continue treatment. Our data supports the use of flunarizine in VM.

Identification of a genetic variant underlying familial cases of recurrent benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo in humans, yet the molecular etiology is currently unknown. Evidence suggests that genetic factors may play an important role in some cases of idiopathic BPPV, particularly in familial cases, but the responsible genetic variants have not been identified. In this study, we performed whole exome sequencing [including untranslated regions (UTRs)] of 12 families and Sanger sequencing of additional 30 families with recurrent BPPV in Caucasians from the United States (US) Midwest region, to identify the genetic variants responsible for heightened susceptibility to BPPV. Fifty non-BPPV families were included as controls. In silico and experimental analyses of candidate variants show that an insertion variant rs113784532 (frameshift causing truncation) in the neural cadherin gene PCDHGA10 (protocadherin-gamma A10) is an exceedingly strong candidate (p = 1.80x10-4 vs. sample controls; p = 5.85x10-19 vs. ExAC data; p = 4.9x10-3 vs. NHLBI exome data). The mutant protein forms large aggregates in BPPV samples even at young ages, and affected subjects carrying this variant have an earlier onset of the condition than those without [average 44.0±14.0 (n = 16) versus 54.4±16.1 (n = 36) years old, p = 0.054]. In both human and mouse inner ear tissues, PCDHGA10 is expressed in ganglia, hair cells and vestibular transitional epithelia. Fluorescent RNA in situ hybridization using mouse inner ear tissues shows that expression increases with age. In summary, our data show that a variant in the PCDHGA10 gene may be involved in causing or aggravating some familial cases of recurrent idiopathic BPPV.

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.

Genetics and the Individualized Therapy of Vestibular Disorders

Background: Vestibular disorders (VDs) are a clinically divergent group of conditions that stem from pathology at the level of the inner ear, vestibulocochlear nerve, or central vestibular pathway. No etiology can be identified in the majority of patients with VDs. Relatively few families have been reported with VD, and so far, no causative genes have been identified despite the fact that more than 100 genes have been identified for inherited hearing loss. Inherited VDs, similar to deafness, are genetically heterogeneous and follow Mendelian inheritance patterns with all modes of transmission, as well as multifactorial inheritance. With advances in genetic sequencing, evidence of familial clustering in VD has begun to highlight the genetic causes of these disorders, potentially opening up new avenues of treatment, particularly in Meniere's disease and disorders with comorbid hearing loss, such as Usher syndrome. In this review, we aim to present recent findings on the genetics of VDs, review the role of genetic sequencing tools, and explore the potential for individualized medicine in the treatment of these disorders.

Methods: A search of the PubMed database was performed for English language studies relevant to the genetic basis of and therapies for vestibular disorders, using search terms including but not limited to: “genetics,” “genomics,” “vestibular disorders,” “hearing loss with vestibular dysfunction,” “individualized medicine,” “genome-wide association studies,” “precision medicine,” and “Meniere's syndrome.”

Results: Increasing numbers of studies on vestibular disorder genetics have been published in recent years. Next-generation sequencing and new genetic tools are being utilized to unearth the significance of the genomic findings in terms of understanding disease etiology and clinical utility, with growing research interest being shown for individualized gene therapy for some disorders.

Conclusions: The genetic knowledge base for vestibular disorders is still in its infancy. Identifying the genetic causes of balance problems is imperative in our understanding of the biology of normal function of the vestibule and the disease etiology and process. There is an increasing effort to use new and efficient genetic sequencing tools to discover the genetic causes for these diseases, leading to the hope for precise and personalized treatment for these patients.

TRPM7 as a Candidate Gene for Vestibular Migraine

Objectives: Vestibular migraine (VM) is a common vestibular disorder, and familial aggregation of VM with autosomal-dominant inheritance has been described, which supports a genetic background. This study aimed to describe the clinical phenotype of a family with VM, and identify a candidate gene for VM.

Methods: We recruited six individuals (four affected and two unaffected) from three consecutive generations of a Korean family with VM, and performed whole-exome sequencing to search for candidate genes.

Results: All affected individuals presented with recurrent vertigo, headache, and nausea/vomiting that fulfilled the diagnostic criteria of VM. Two individuals also experienced transient hemiparesis or dysarthria during the episodes. The symptoms were triggered by physical or emotional stress. Interictal examinations showed uni- or bi-directional horizontal gaze-evoked nystagmus in three of the individuals. They had no causative mutations in genes causing familial hemiplegic migraine or episodic ataxia. Through whole-exome sequencing from three affected individuals, we identified a nonsense mutation c.3526C>T in TRPM7 that encodes a cation channel selective to Ca²⁺ and Mg²⁺.

Conclusions: Alterations in intracellular Ca²⁺ and Mg²⁺ homeostasis by TRPM7 mutation may contribute to the development of the VM phenotype. Our result suggest that TRPM7 is a novel candidate gene for VM.

Systematic Review of Prevalence Studies and Familial Aggregation in Vestibular Migraine

Background: Vestibular migraine (VM) is complex disorder consisting of episodes of migraine and vertigo with an estimated prevalence of 1–3%. As migraine, it is considered that VM has genetic predisposition; however, evidence to support a genetic contribution has not been critically appraised.

Objective: The aim of this systematic review is to assess available evidence in scientific publications to determine the role of inheritance in VM.

Methods: After performing the quality assessment of the retrieved records, 31 studies were included (24 epidemiological reports and 7 genetic association studies in families or case-control in candidate genes). We gathered data about prevalence of VM in different populations and in families, and also about the genetic findings reported. In addition, other variables were considered to assess the heritability of VM, such as the ancestry, the age of onset or the familial history of vertigo and migraine.

Results: The estimated prevalence of VM was different between black (3.13%), white (2.64%) and Asian (1.07%) ethnicities. The reported prevalence of VM in migraine patients is higher in European countries (21%) than in Asian countries (10%). Moreover, the prevalence of the migraine-vertigo association in families is 4–10 times higher than the prevalence reported in the general population (sibling recurrence risk ratio λ_s = 4.31–10.42). We also found that the age of onset is lower in patients with simultaneous onset of symptoms and in those who have familial history for migraine and/or vertigo, suggesting anticipation. Although some genetic studies have reported few allelic variants associated to MV, replication studies are needed to validate these results.

Conclusions: The available evidence to support heritability in VM is limited. Variability in prevalence depending on ethnicity and geographic location suggests a combined genetic and environmental contribution to VM. However, the familial aggregation observed in VM support genetic and shared familial environmental effects that remarks the necessity of twins and adoptees-based epidemiological studies to estimate its heritability.

A novel genetic variant associated with benign paroxysmal positional vertigo within the LOXL1

Background

Benign paroxysmal positional vertigo (BPPV) is a common, self‐limited, and favorable prognostic peripheral vestibular disorder. BPPV is transmitted in an autosomal dominant fashion, but most cases occur sporadically. Little research has been reported regarding the mutation spectrum of sporadic BPPV in a large cohort. This study attempted to identify the causative candidate variants associated with BPPV in VDR, LOXL1, and LOXL1‐AS1.

Methods

An amplicon‐targeted next‐generation sequencing (NGS) method for VDR, LOXL1, and LOXL1‐AS1, was completed in 726 BPPV patients and 502 normal controls. A total of 30 variants (20 variants from VDR, nine variants from LOXL1, seven variants from LOXL1‐AS1) were identified in these two groups.

Results

Three of 30 variants were nonsynonymous mutations, but no significant difference was found between the BPPV group and the control group via association analysis. A single nucleotide variant (SNV), rs1078967, was identified that is located in intron 1 of LOXL1. The allelic frequency distribution differed significantly between the BPPV group and the control group (p = 0.002). Genotypic frequency was also significantly different (p = 0.006), as determined by gene‐based analyses.

Conclusion

This report is the first to analyze the variant spectrum of BPPV in a large Chinese population.

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.

Genes important for otoneurological diagnostic purposes - current status and future prospects

SUMMARY

This review focuses on the current knowledge of the genes responsible for non-syndromic hearing loss that can be useful for otoneurological diagnostic purposes. From among a large number of genes that have been associated with non-syndromic hearing impairment, we selected several best-known genes, including the COCH gene, GJB2, GJB6 and SLC26A4, and we describe their role and effects of mutations and prevalence of mutations in various populations. Next, we focus on genes associated with tinnitus. Important areas for further research include assessment of genes potentially involved in pathophysiology of tinnitus and vertigo, which have traditionally been considered as being of otological aetiology, while advances in neuroimaging techniques have increasingly shifted studies toward neurological correlations.

Genetics of presbycusis and presbystasis

Presbycusis and presbystasis represent relevant problems of aging, caused by the increase in life expectancy in developed countries. As such, it is advantageous to better understand the physiopathological mechanisms of these age-related inner ear diseases. The hypothesis that presbycusis and presbystasis have a genetic background was proposed some years ago. Several studies (in humans and animals) are available in the literature, and possible genes involved in the physiopathology of both diseases have been identified. The aim of this paper is to present an overview of the information available in the current medical literature on presbycusis and presbystasis.

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.

Pediatric migraine variants: a review of epidemiology, diagnosis, treatment, and outcome

Pediatric migraine variants, previously known as childhood periodic syndromes, migraine equivalents, or migraine precursors, are a group of periodic or paroxysmal disorders occurring in patients who also have migraine with or without aura, or who have an increased likelihood of developing migraine. They have common key clinical features including periodic or paroxysmal character, normal neurological examination between attacks, family history of migraine, and clinical evolution to classic types of migraine. This article aims to review the pathophysiology, evaluation, and management of the pediatric migraine variants including abdominal migraine, benign paroxysmal vertigo, cyclic vomiting syndrome, and benign paroxysmal torticollis as well as the episodic syndromes that may lead to migraine, infantile colic, alternating hemiplegia of childhood, and vestibular migraine.

Vestibular migraine: diagnosis challenges and need for targeted treatment

ABSTRACT Approximately 1% of the general population suffers from vestibular migraine. Despite the recently published diagnostic criteria, it is still underdiagnosed condition. The exact neural mechanisms of vestibular migraine are still unclear, but the variability of symptoms and clinical findings both during and between attacks suggests an important interaction between trigeminal and vestibular systems. Vestibular migraine often begins several years after typical migraine and has a variable clinical presentation. In vestibular migraine patients, the neurological and neurotological examination is mostly normal and the diagnosis will be based in the patient clinical history. Treatment trials that specialize on vestibular migraine are scarce and therapeutic recommendations are based on migraine guidelines. Controlled studies on the efficacy of pharmacologic interventions in the treatment of vestibular migraine should be performed.

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.

Vestibular migraine

Vestibular migraine is now considered a distinct diagnostic entity by both the Barany Society and the International Headache Society. The recognition of vestibular migraine as a diagnostic entity required decades and was presaged by several reports indicating that a large proportion of patients with migraine headaches have vestibular symptoms and that a large proportion of patients with undiagnosed episodic vestibular symptoms have migraine headache. Despite the availability of diagnostic criteria for vestibular migraine, challenges to diagnosis include variability in terms of the character of dizziness, the presence or absence of clearly defined attacks, the duration of attacks, and the temporal association between headache or other migrainous features and vestibular symptoms. Also, symptoms of vestibular migraine often overlap with symptoms of other causes of dizziness, especially Ménière's disease and benign paroxysmal positional vertigo (BPPV). This article will discuss the demographics, epidemiology, clinical manifestations, physical examination findings, laboratory testing, comorbidities, treatment options, and pathophysiology of vestibular migraine. Future research in the field of vestibular migraine should include both clinical and basic science efforts to better understand the pathophysiology of this condition. Controlled treatment trials for vestibular migraine are desperately needed.

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.

Genetics of dizziness: cerebellar and vestibular disorders

PURPOSE OF REVIEW

Recent advances in next generation sequencing techniques (NGS) are increasing the number of novel genes associated with cerebellar and vestibular disorders. We have summarized clinical and molecular genetics findings in neuro-otolology during the last 2 years.

RECENT FINDINGS

Whole-exome and targeted sequencing have defined the genetic basis of dizziness including new genes causing ataxia: GBA2, TGM6, ANO10 and SYT14. Novel mutations in KCNA1 and CACNA1A genes are associated with episodic ataxia type 1 and type 2, respectively. Moreover, new variants in genes such as COCH, MYO7A and POU4F3 are associated with nonsyndromic deafness and vestibular dysfunction. Several susceptibility loci have been linked to familial vestibular migraine, suggesting genetic heterogeneity, but no specific gene has been identified. Finally, loci for complex and heterogeneous diseases such as bilateral vestibular hypofunction or familial Ménière disease have not been identified yet, despite their strong familial aggregation.

SUMMARY

Cerebellar and vestibular disorders leading to dizziness or episodic vertigo may show overlapping clinical features. A deep phenotyping including a complete familial history is a key step in performing a reliable molecular genetic diagnosis using NGS. Personalized molecular medicine will be essential to understand disease mechanisms as well as to improve their diagnosis and treatment.

Genetics of vestibulopathy and migraine

PURPOSE OF REVIEW

Our understanding of the genetics of vestibular loss lags far behind advances in the genetics of hearing loss, in large part because a basic awareness of hearing is a universal human experience, in those without congenital deafness, whereas public awareness of vestibular function is virtually nonexistent. This review highlights the challenges brought on by this disparity and recent advances in genetics, which provide hope for improved diagnosis and treatment of vestibular loss.

RECENT FINDINGS

Linkage analysis has resulted in mapping of genetic loci for familial vestibulopathies with normal hearing and migraine. Targeted gene therapy provides hope for those with permanent vestibular loss.

SUMMARY

Recent discoveries emphasize the need for better ascertainment of vestibular loss in general clinical practice.

Migraine-associated vertigo: diagnosis and treatment

Migraine-associated vertigo has become a well-recognized disease entity diagnosed based on a clinical history of recurrent vertigo attacks unexplained by other central or peripheral otologic abnormalities, which occurs in the patient with a history of migraine headaches. There is no international agreement on what spectrum of symptoms should be covered under this diagnosis, or what terminology should be used. The headaches and vestibular symptoms of migraine-associated vertigo may not be temporally associated, which often obscures the association. Diagnostic tests usually show nonspecific abnormalities that are also seen in patients with migraine who do not experience vestibular symptoms. Management generally follows the recommended treatment of migraine headaches, and includes dietary and lifestyle modifications and medical treatment with beta blockers, calcium channel blockers, and tricyclic amines. Small case series show that acetazolamide and lamotrigine appear to be more effective for the vertigo attacks than headaches. Vestibular rehabilitation has also been shown to be helpful in several studies. In this review, the epidemiologic and clinical features of the disorder, as well as the current state of knowledge on pathophysiology, diagnostic testing, and treatment are described.

Vestibular migraine

Vestibular migraine is a chameleon among the episodic vertigo syndromes because considerable variation characterizes its clinical manifestation. The attacks may last from seconds to days. About one-third of patients presents with monosymptomatic attacks of vertigo or dizziness without headache or other migrainous symptoms. During attacks most patients show spontaneous or positional nystagmus and in the attack-free interval minor ocular motor and vestibular deficits. Women are significantly more often affected than men. Symptoms may begin at any time in life, with the highest prevalence in young adults and between the ages of 60 and 70. Over the last 10 years vestibular migraine has evolved into a medical entity in dizziness units. It is the most common cause of spontaneous recurrent episodic vertigo and accounts for approximately 10% of patients with vertigo and dizziness. Its broad spectrum poses a diagnostic problem of how to rule out Menière's disease or vestibular paroxysmia. Vestibular migraine should be included in the International Headache Classification of Headache Disorders (ICHD) as a subcategory of migraine. It should, however, be kept separate and distinct from basilar-type migraine and benign paroxysmal vertigo of childhood. We prefer the term "vestibular migraine" to "migrainous vertigo," because the latter may also refer to various vestibular and non-vestibular symptoms. Antimigrainous medication to treat the single attack and to prevent recurring attacks appears to be effective, but the published evidence is weak. A randomized, double-blind, placebo-controlled study is required to evaluate medical treatment of this condition.

Locus for familial migrainous vertigo disease maps to chromosome 5q35

OBJECTIVES

Migrainous vertigo (episodic vertigo associated with migraine) is sometimes inherited as an autosomal dominant trait. However, neither disease genes nor loci that might be responsible have been reported. We sought to map the genetic locus for familial migrainous vertigo in a 4-generation family and to define the progression of disease in this family.

METHODS

We studied 23 members in a family in whom migrainous vertigo was inherited as an autosomal dominant trait. Clinical information obtained included case histories and results of otolaryngological, neurologic, audiometric, and imaging evaluations. Genome-wide linkage analysis was performed with Affymetrix Genechip Human Mapping 10K microarrays. Genotyping of family members' DNA with microsatellite markers was used to further assess candidate loci identified from the whole-genome scan.

RESULTS

Of 23 family members, 10 suffered from migrainous vertigo beginning after 35 years of age. Migraine headaches usually preceded the onset of vertigo by 15 to 20 years. Longitudinal audiometric studies over 12 years showed stable, high-frequency sensorineural hearing loss consistent with presbycusis. Low-frequency or fluctuating hearing loss was not observed. The results of vestibular testing and imaging studies were unremarkable. Genetic analysis defined a 12.0 MB interval on chromosome 5q35 between loci rs244895 and D5S2073 that contained the disease gene (logarithm of odds score, 4.21).

CONCLUSIONS

We report the first locus for familial migrainous vertigo, which mapped to 5q35.

Identification of EpCAM as the gene for congenital tufting enteropathy

BACKGROUND & AIMS

Congenital tufting enteropathy (CTE) is a rare autosomal recessive diarrheal disorder presenting in the neonatal period. CTE is characterized by intestinal epithelial cell dysplasia leading to severe malabsorption and significant morbidity and mortality. The pathogenesis and genetics of this disorder are not well understood. The objective of this study was to identify the gene responsible for CTE.

METHODS

A family with 2 children affected with CTE was identified. The affected children are double second cousins providing significant statistical power for linkage. Using Affymetrix 50K single nucleotide polymorphism (SNP) chips, genotyping was performed on only 2 patients and 1 unaffected sibling. Direct DNA sequencing of candidate genes, reverse-transcription polymerase chain reaction, immunohistochemistry, and Western blotting were performed on specimens from patients and controls.

RESULTS

SNP homozygosity mapping identified a unique 6.5-Mbp haplotype of homozygous SNPs on chromosome 2p21 where approximately 40 genes are located. Direct sequencing of genes in this region revealed homozygous G>A substitution at the donor splice site of exon 4 in epithelial cell adhesion molecule (EpCAM) of affected patients. Reverse-transcription polymerase chain reaction of duodenal tissue demonstrated a novel alternative splice form with deletion of exon 4 in affected patients. Immunohistochemistry and Western blot of patient intestinal tissue revealed decreased expression of EpCAM. Direct sequencing of EpCAM from 2 additional unrelated patients revealed novel mutations in the gene.

CONCLUSIONS

Mutations in the gene for EpCAM are responsible for CTE. This information will be used to gain further insight into the molecular mechanisms of this disease.

Familial clustering of migraine, episodic vertigo, and Ménière's disease

OBJECTIVE

To evaluate the association between migraine, episodic vertigo, and Ménière's disease in families.

STUDY DESIGN

Clinical report.

SETTING

University Neurotology Clinic.

PATIENTS

Index patients identified with Ménière's disease and migraine and their family members.

INTERVENTION

Structured interview to assess a diagnosis of migraine, episodic vertigo, and Ménière's disease in 6 families. Genotyping was performed on 3 sets of twins to analyze monozygosity or dizygosity.

MAIN OUTCOME MEASURES

Clinical history of migraine, episodic vertigo, and Ménière's disease.

RESULTS

Six index patients and 57 family members were interviewed either by a senior neurologist in person or over the phone by a trained study coordinator. An additional 6 family members completed questionnaires by mail. All 6 index patients had Ménière's disease and migraine. Twenty-six (41%) of the 63 relatives met International Classification of Headache Disorders II criteria for migraine headaches. Thirteen (50%) of these 26 experienced migraine with aura. Three others experienced typical aura without headache. Seventeen (27%) of 63 family members experienced recurrent spells of spontaneous episodic vertigo. There was one twin pair in each of 3 families; 2 pairs were monozygotic and one was dizygotic. In each twin pair, one twin had migraine and Ménière's disease, whereas the other experienced migraine and episodic vertigo without auditory symptoms.

CONCLUSION

The frequent association of episodic vertigo, migraine, and Ménière's disease in closely related individuals, including identical twins supports the heritability of a migraine-Ménière's syndrome, with variable expression of the individual features of hearing loss, episodic vertigo, and migraine headaches.

Migraine associated vertigo

The interrelations of migraine and vertigo are complex, eluding a simple localization either centrally or peripherally. Spontaneous episodic vertigo, benign paroxysmal positional vertigo, and Meniere's disease all occur more frequently in patients with migraine than in those without. Family studies support a hereditary predisposition to migraine associated vertigo. In this review, we discuss definitions, epidemiology, associated syndromes, neurootological abnormalities, genetics and treatment for patients with migraine and vertigo.