387
Journal of Vestibular Research 24 (2014) 387–395 DOI 10.3233/VES-140525 IOS Press
Comorbidities in vestibular migraine Scott D.Z. Eggersa,∗, Brian A. Neffb , Neil T. Shepardc and Jeffrey P. Staabd a
Department of Neurology, Mayo Clinic, Rochester, MN, USA Department of Otorhinolaryngology, Mayo Clinic, Rochester, MN, USA c Division of Audiology, Mayo Clinic, Rochester, MN, USA d Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MN, USA b
Received 31 December 2013 Accepted 8 May 2014
Abstract. A growing body of clinical and epidemiological evidence supports a specific relationship between vestibular symptoms and migraine. Without a biomarker or complete understanding of pathophysiology, diagnosis of vestibular migraine (VM) currently depends upon symptoms in two dimensions: episodic vestibular symptoms temporally related to migraine symptoms. The Bárány Society and the International Headache Society have recently developed consensus diagnostic criteria. However, many issues remain unsettled, including the type, duration, and timing of vestibular symptoms related to headache that should be required for diagnosing VM. This paper focuses on the challenging third dimension of comorbidity, a frequent cause of diagnostic uncertainty that may confound clinical application and research validation of VM criteria. Several other neurotologic conditions occur more frequently in migraineurs than controls, including benign paroxysmal positional vertigo, Ménière’s disease, and motion sickness. Patients with VM also have high rates of chronic subjective dizziness, which may be associated with anxious, introverted temperaments that can affect clinical presentation and treatment response. Broadly inclusive studies of well-characterized patients with other neurotologic and psychiatric comorbidities are needed to fully understand how vestibular symptoms and migraine interact in order to truly validate vestibular migraine, distill its essential features, define its boundaries, and characterize overlapping comorbidities. Keywords: Vestibular migraine, comorbidity, epidemiology, validation, diagnostic criteria
1. Background of vestibular migraine The relationship between vestibular symptoms and migraine has gained increasing clinical recognition and research attention in the last three decades. After initial observations over a century ago [42], clinicians began to describe otherwise healthy children [7,28,37] and adults [58] with recurrent episodes of vertigo that in subsequent studies appeared to have strong personal or familial links to migraine [19,23,35,36,44,50]. While the entity benign recurrent vertigo of childhood was included in the first Classification and Di∗ Corresponding author: Scott D.Z. Eggers, Department of Neurology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA. Tel.: +1 507 284 4037; Fax: +1 507 284 4074; E-mail: eggers.scott@ mayo.edu.
agnostic Criteria for Headache Disorders by the International Headache Society as a childhood periodic syndrome that may be a precursor to migraine [1], no similar diagnosis existed for adults. Basilar migraine [8], recently renamed migraine with brainstem aura in the International Classification of Headache Disorders (ICHD) 3rd edition (beta version) [3], includes vertigo as one of several brainstem symptoms. However, only a small minority of patients who experience vertigo associated with headaches meets its narrow definition requiring vertigo as one of at least two aura symptoms lasting 5–60 minutes accompanied within 60 minutes by headache [21,27]. In 2001, Neuhauser and colleagues proposed diagnostic criteria [47] for migrainous vertigo, now called vestibular migraine (VM), based on their own and others’ investigations of adults with vestibular symptoms and headaches drawn from dizziness and headache
c 2014 – IOS Press and the authors. All rights reserved ISSN 0957-4271/14/$27.50
388
S.D.Z. Eggers et al. / Comorbidities in vestibular migraine
clinics. These criteria were used in virtually every investigation of vestibular symptoms and migraine for the next decade. Subsequent studies have now validated the overall construct and diagnostic stability of VM [27,54] using the Neuhauser criteria. The growing body of increasingly rigorous research has led to collaboration between the Bárány Society and the International Headache Society to publish revised diagnostic criteria for VM [3,41] (Table 1). However, despite strong epidemiologic data [49] supporting a relationship between vestibular symptoms and migraine, some still question the existence of VM [52,69]. Without a biomarker or complete understanding of pathophysiology [30], further clinical studies of the diagnostic criteria are needed to clarify the scope of VM by distilling its core features and defining the boundaries between VM and other vestibular and headache disorders.
2. Vestibular migraine in two dimensions The concept of VM considers two principal dimensions, vestibular symptoms and headache, neither of which has a biomarker. Thus, each dimension requires validation using available definitions and clinical criteria [3,9]. In the headache dimension, the many reasons to start with migraine have been previously elaborated upon [60]. Migraine is the headache type associated with sensorimotor symptoms including photophobia/phonophobia and reversible auras [3]. Clinical studies have found higher rates of vestibular symptoms in patients with migraine than other headache types [35,40] as well as higher rates of migraine among patients with vestibular symptoms than in the general population [19,39,47,57]. In our previously published work [27] examining the headache types in patients with primary vestibular symptoms, headache sufferers were more likely to have a history of migraine than non-migraine headaches, a reversal of the prevalence in the general population. When considering the type of headache occurring during attacks of dizziness or vertigo, migraine was much more likely to be temporally related to vestibular symptoms than was non-migraine headache. The rate of migraine with aura was greater in those with vestibular migraine than in those with migraine unrelated to vestibular symptoms. In the vestibular migraine group, a greater fraction of those with aura than those without aura had vestibular migraine as their only neurotologic diagnosis. In fact, whether patients with episodic vestibular symptoms met criteria for
probable versus definite VM was determined entirely by the headache characteristics (migraine versus nonmigraine) rather than by nature or timing of vestibular symptoms or presences of any comorbidities. All of these findings support a specific association between episodic vestibular symptoms and migraine. However, no symptoms were universally present to clarify which key elements of migraine are critical for VM. In the vestibular dimension, the primary variables include the type, duration, and timing of vestibular symptoms. Studies of the physical examination and vestibular laboratory evaluation both between and during vestibular symptoms in VM have not revealed any consistent diagnostic pattern of central or peripheral vestibular dysfunction [15,16,20,21,35,68,71]. Thus, the vestibular dimension is currently defined by symptoms alone. The type of vestibular symptoms occurring with VM remains unsettled. While spinning vertigo has received the most attention, positional vertigo and internal vertigo sensations of translation, tilt, rocking, and swaying with or without external vertigo or oscillopsia have all been attributed to VM. Neuhauser and colleagues originally excluded non-vertiginous dizziness from their diagnostic criteria [47], though other investigators have reported that non-vertiginous dizziness may be more common than vertigo among patients with migraine [38,56,72]. Using the Bárány Society’s definitions of vestibular symptoms [9], the most recent VM diagnostic criteria include head motion-induced dizziness with nausea as a qualifying episodic vestibular symptom, but not other forms of non-vertiginous dizziness [41]. The duration of vestibular symptoms related to migraine has been reported to range from seconds to weeks [13,16,20,21,34,35,47], suggesting more than one pathophysiologic mechanism. Our data is consistent with this wide variability (most often minutes to hours) and also confirms observations that only a small minority of patients has vestibular symptoms in a temporal pattern that could represent an aura (i.e., 5–60 minutes of sensory disturbance followed by a migrainous headache) [21,27]. Instead, the duration is most commonly similar to the headache, photophobia, or phonophobia in migraineurs without vertigo, suggesting that vestibular symptoms may be an analog to the somatosensory, visual or auditory sensitivity defining migraine. Understanding the timing or intersection between vestibular symptoms and headache in VM remains a challenging and unresolved issue. Such patients may
S.D.Z. Eggers et al. / Comorbidities in vestibular migraine
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Table 1 Diagnostic criteria for vestibular symptoms associated with migraine, past and present Benign paroxysmal vertigo [3] (previously within childhood periodic syndromes) A. At least five attacks fulfilling criteria B and C. B. Vertigo occurring without warning, maximal at onset and resolving spontaneously after minutes to hours without loss of consciousness. C. At least one of the following associated symptoms or signs: nystagmus, ataxia, vomiting, pallor, or fearfulness. D. Normal neurological examination and audiometric and vestibular functions between attacks. E. Not attributed to another disorder. Migraine with brainstem aura [3] (previously basilar artery migraine; basilar migraine; basilar-type migraine) A. At least two attacks fulfilling criteria B-D. B. Aura consisting of visual, sensory and/or speech/language symptoms, each fully reversible, but no motor or retinal symptoms. C. At least two of the following brainstem symptoms: dysarthria, vertigo, tinnitus, hypacusis, diplopia, ataxia, decreased level of consciousness. D. At least two of the following four characteristics: 1. At least one aura symptom spreads gradually over 5 minutes, and/or two or more symptoms occur in succession. 2. Each individual aura symptom lasts 5–60 minutes. 3. At least one aura symptom is unilateral. 4. The aura is accompanied, or followed within 60 minutes, by headache. E. Not better accounted for by another ICHD-3 diagnosis, and transient ischemic attack has been excluded. Definite vestibular migraine (“definite migrainous vertigo”, Neuhauser 2001 [47]) A. Recurrent episodic vestibular symptoms of at least moderate severity. B. Current or previous history of migraine according to the criteria of the International Headache Society. C. One of the following migrainous symptoms during at least two vertiginous attacks: migrainous headache, photophobia, phonophobia, visual or other auras. D. Other causes ruled out by appropriate investigations. Probable vestibular migraine (“probable migrainous vertigo”, Neuhauser 2001 [47], revised 2004 [46]) A. Recurrent episodic vestibular symptoms of at least moderate severity. B. One of the following: 1. Current or previous history of migraine according to the criteria of the International Headache Society. 2. Migrainous symptoms during 2 attacks of vertigo. 3. Migraine precipitants before vertigo in more than 50% of attacks: food triggers, sleep irregularities, hormonal changes. 4. Response to migraine medications in more than 50% of attacks. C. Other causes ruled out by appropriate investigations. Vestibular migraine (ICVD 2012 [41]/ICHD-3beta 2013 [3]) A. At least five episodes fulfilling criteria C and D. B. A current or past history of migraine without aura or migraine with aura. C. Vestibular symptoms* of moderate or severe intensity, lasting between 5 minutes and 72 hours. D. At least 50% of episodes are associated with at least one of the following three migrainous features: 1. Headache with at least two of the following four characteristics: a. Unilateral location. b. Pulsating quality. c. Moderate or severe intensity. d. Aggravation by routine physical activity. 2. Photophobia and phonophobia. 3. Visual aura. E. Not better accounted for by another ICHD-3 diagnosis or by another vestibular disorder. Probable vestibular migraine (ICVD 2012 [41]) A. At least 5 episodes with vestibular symptoms* of moderate or severe intensity, lasting 5 min to 72 hours. B. Only one of the criteria B and C for vestibular migraine is fulfilled (migraine history or migraine features during the episode). C. Not better accounted for by another vestibular or ICHD diagnosis. *Vestibular symptoms may include: a. Spontaneous vertigo: internal vertigo (a false sensation of self- motion) or external vertigo (a false sensation that the visual surround is spinning or flowing). b. Positional vertigo, occurring after a change of head position. c. Visually induced vertigo, triggered by a complex or large moving visual stimulus. d. Head motion-induced vertigo, occurring during head motion. e. Head motion-induced dizziness with nausea (dizziness is characterized by a sensation of disturbed spatial orientation; other forms of dizziness are currently not included in the classification of vestibular migraine). ICHD indicates International Classification of Headache Disorders. ICVD indicates International Classification of Vestibular Disorders.
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symptoms interact either causally or independently beyond the current narrow definition of VM. Such studies are necessary to truly validate VM and define its core features, boundaries and overlapping comorbidities [60]. The goal of such studies would not be to undo the recently achieved international consensus definition of VM, but rather to gather data to support future modifications based on a strong foundation of empirical evidence.
3. Comorbidity: The third dimension Fig. 1. The scope of vestibular migraine in three dimensions. Vestibular migraine (VM) is conceptualized in two dimensions at the intersection of episodic vestibular symptoms and episodic migraine symptoms. Diagnostic criteria for (definite) VM require a clear temporal relationship between these two dimensions in order to optimize specificity. However, the essential core features and the boundaries with chronic dizziness or non-migraine headache are sometimes ambiguous. Likewise, frequent comorbidity with other neurotologic syndromes (particularly Ménière’s disease and benign paroxysmal positional vertigo) and psychiatric conditions creates a third dimension of diagnostic uncertainty and confounds application of VM criteria. Research methods exist to begin clarifying these uncertainties.
have episodic vestibular symptoms that occur during, before, after, between, or in the absence of headache episodes. As discussed above, vestibular symptoms rarely meet criteria for an aura or follow a consistent pattern. Whether or not other prominent migrainous symptoms occur with the vertigo determines the clinician’s ability to infer a causal rather than non-specific relationship between the two dimensions. This point is emphasized in both recent studies validating the concept of VM [27,54]. A common reason for patients to meet criteria only for probable rather than definite VM is that their episodic headaches lack sufficient migraine features or that episodic vestibular symptoms are not accompanied by clearly migrainous symptoms. Up to a third of such patients with probable VM followed longitudinally appear to have a stable episodic vestibular syndrome with headache and without hearing loss that will never become definite VM or anything else. They definitely have probable VM but will probably never have definite VM, despite the fact that their vestibular symptoms are indistinguishable. Our current classification system based around migraine does not adequately characterize this group. While revised criteria for (definite) VM may be appropriately biased toward requiring greater specificity for the temporal relationship between vestibular and migraine symptoms, broader inclusive studies are needed to more fully understand how the two dimensions of headache and vestibular
Our evolving understanding of VM must consider the third dimension of comorbidity, a frequent cause of diagnostic uncertainty that may confound clinical application and research validation of VM criteria (Fig. 1). Though migraine and vertigo are both common in the general population, the largest epidemiologic survey found that they occurred together about three times more often than would be predicted by chance alone [48], an observation supported by previous clinical series [35,57]. However, VM could not account for the entire increase in prevalence, suggesting that many migraineurs had another explanation for their vestibular symptoms. Several other neurotologic conditions occur more frequently in migraineurs than controls [70], particularly benign paroxysmal positional vertigo (BPPV) [32,67], Ménière’s disease (MD) [17,18,51,53], and motion sickness [6,25,26,34, 35,38], though their relationship to migraine is unclear. Our study of 88 consecutive patients with VM referred to a tertiary neurotologic clinic found that 57% had at least one comorbid neurotologic condition causing vestibular symptoms. Patients with neurotologic comorbidities had higher rates of handicap, anxiety, and depression, as well as higher rates of auditory and vestibular abnormalities than those with VM alone, findings that were dictated by the comorbid condition rather than the type of migraine [27]. These findings suggest that future studies of VM must include not only subjects with VM alone, but those with VM plus other neurotologic diagnoses and those with vestibular symptoms and headache where the diagnoses are uncertain. Vestibular migraine is conceptualized as a condition causing episodic vestibular symptoms lasting seconds to days that can be spontaneous or sometimes positional, creating the potential for diagnostic confusion with BPPV and MD. In our series of 42 patients meeting criteria for probable VM (Table 2), four would
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Table 2 Subgroups of probable vestibular migraine in 42 patients Subgroups of pVM Episodic vertigo (with headache)
Episodic vertigo (with migraine)
Episodic unsteadiness or dizziness (with migraine)
Evolving vestibular migraine (Illness
Journal of Vestibular Research 24 (2014) 387–395 DOI 10.3233/VES-140525 IOS Press
Comorbidities in vestibular migraine Scott D.Z. Eggersa,∗, Brian A. Neffb , Neil T. Shepardc and Jeffrey P. Staabd a
Department of Neurology, Mayo Clinic, Rochester, MN, USA Department of Otorhinolaryngology, Mayo Clinic, Rochester, MN, USA c Division of Audiology, Mayo Clinic, Rochester, MN, USA d Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MN, USA b
Received 31 December 2013 Accepted 8 May 2014
Abstract. A growing body of clinical and epidemiological evidence supports a specific relationship between vestibular symptoms and migraine. Without a biomarker or complete understanding of pathophysiology, diagnosis of vestibular migraine (VM) currently depends upon symptoms in two dimensions: episodic vestibular symptoms temporally related to migraine symptoms. The Bárány Society and the International Headache Society have recently developed consensus diagnostic criteria. However, many issues remain unsettled, including the type, duration, and timing of vestibular symptoms related to headache that should be required for diagnosing VM. This paper focuses on the challenging third dimension of comorbidity, a frequent cause of diagnostic uncertainty that may confound clinical application and research validation of VM criteria. Several other neurotologic conditions occur more frequently in migraineurs than controls, including benign paroxysmal positional vertigo, Ménière’s disease, and motion sickness. Patients with VM also have high rates of chronic subjective dizziness, which may be associated with anxious, introverted temperaments that can affect clinical presentation and treatment response. Broadly inclusive studies of well-characterized patients with other neurotologic and psychiatric comorbidities are needed to fully understand how vestibular symptoms and migraine interact in order to truly validate vestibular migraine, distill its essential features, define its boundaries, and characterize overlapping comorbidities. Keywords: Vestibular migraine, comorbidity, epidemiology, validation, diagnostic criteria
1. Background of vestibular migraine The relationship between vestibular symptoms and migraine has gained increasing clinical recognition and research attention in the last three decades. After initial observations over a century ago [42], clinicians began to describe otherwise healthy children [7,28,37] and adults [58] with recurrent episodes of vertigo that in subsequent studies appeared to have strong personal or familial links to migraine [19,23,35,36,44,50]. While the entity benign recurrent vertigo of childhood was included in the first Classification and Di∗ Corresponding author: Scott D.Z. Eggers, Department of Neurology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA. Tel.: +1 507 284 4037; Fax: +1 507 284 4074; E-mail: eggers.scott@ mayo.edu.
agnostic Criteria for Headache Disorders by the International Headache Society as a childhood periodic syndrome that may be a precursor to migraine [1], no similar diagnosis existed for adults. Basilar migraine [8], recently renamed migraine with brainstem aura in the International Classification of Headache Disorders (ICHD) 3rd edition (beta version) [3], includes vertigo as one of several brainstem symptoms. However, only a small minority of patients who experience vertigo associated with headaches meets its narrow definition requiring vertigo as one of at least two aura symptoms lasting 5–60 minutes accompanied within 60 minutes by headache [21,27]. In 2001, Neuhauser and colleagues proposed diagnostic criteria [47] for migrainous vertigo, now called vestibular migraine (VM), based on their own and others’ investigations of adults with vestibular symptoms and headaches drawn from dizziness and headache
c 2014 – IOS Press and the authors. All rights reserved ISSN 0957-4271/14/$27.50
388
S.D.Z. Eggers et al. / Comorbidities in vestibular migraine
clinics. These criteria were used in virtually every investigation of vestibular symptoms and migraine for the next decade. Subsequent studies have now validated the overall construct and diagnostic stability of VM [27,54] using the Neuhauser criteria. The growing body of increasingly rigorous research has led to collaboration between the Bárány Society and the International Headache Society to publish revised diagnostic criteria for VM [3,41] (Table 1). However, despite strong epidemiologic data [49] supporting a relationship between vestibular symptoms and migraine, some still question the existence of VM [52,69]. Without a biomarker or complete understanding of pathophysiology [30], further clinical studies of the diagnostic criteria are needed to clarify the scope of VM by distilling its core features and defining the boundaries between VM and other vestibular and headache disorders.
2. Vestibular migraine in two dimensions The concept of VM considers two principal dimensions, vestibular symptoms and headache, neither of which has a biomarker. Thus, each dimension requires validation using available definitions and clinical criteria [3,9]. In the headache dimension, the many reasons to start with migraine have been previously elaborated upon [60]. Migraine is the headache type associated with sensorimotor symptoms including photophobia/phonophobia and reversible auras [3]. Clinical studies have found higher rates of vestibular symptoms in patients with migraine than other headache types [35,40] as well as higher rates of migraine among patients with vestibular symptoms than in the general population [19,39,47,57]. In our previously published work [27] examining the headache types in patients with primary vestibular symptoms, headache sufferers were more likely to have a history of migraine than non-migraine headaches, a reversal of the prevalence in the general population. When considering the type of headache occurring during attacks of dizziness or vertigo, migraine was much more likely to be temporally related to vestibular symptoms than was non-migraine headache. The rate of migraine with aura was greater in those with vestibular migraine than in those with migraine unrelated to vestibular symptoms. In the vestibular migraine group, a greater fraction of those with aura than those without aura had vestibular migraine as their only neurotologic diagnosis. In fact, whether patients with episodic vestibular symptoms met criteria for
probable versus definite VM was determined entirely by the headache characteristics (migraine versus nonmigraine) rather than by nature or timing of vestibular symptoms or presences of any comorbidities. All of these findings support a specific association between episodic vestibular symptoms and migraine. However, no symptoms were universally present to clarify which key elements of migraine are critical for VM. In the vestibular dimension, the primary variables include the type, duration, and timing of vestibular symptoms. Studies of the physical examination and vestibular laboratory evaluation both between and during vestibular symptoms in VM have not revealed any consistent diagnostic pattern of central or peripheral vestibular dysfunction [15,16,20,21,35,68,71]. Thus, the vestibular dimension is currently defined by symptoms alone. The type of vestibular symptoms occurring with VM remains unsettled. While spinning vertigo has received the most attention, positional vertigo and internal vertigo sensations of translation, tilt, rocking, and swaying with or without external vertigo or oscillopsia have all been attributed to VM. Neuhauser and colleagues originally excluded non-vertiginous dizziness from their diagnostic criteria [47], though other investigators have reported that non-vertiginous dizziness may be more common than vertigo among patients with migraine [38,56,72]. Using the Bárány Society’s definitions of vestibular symptoms [9], the most recent VM diagnostic criteria include head motion-induced dizziness with nausea as a qualifying episodic vestibular symptom, but not other forms of non-vertiginous dizziness [41]. The duration of vestibular symptoms related to migraine has been reported to range from seconds to weeks [13,16,20,21,34,35,47], suggesting more than one pathophysiologic mechanism. Our data is consistent with this wide variability (most often minutes to hours) and also confirms observations that only a small minority of patients has vestibular symptoms in a temporal pattern that could represent an aura (i.e., 5–60 minutes of sensory disturbance followed by a migrainous headache) [21,27]. Instead, the duration is most commonly similar to the headache, photophobia, or phonophobia in migraineurs without vertigo, suggesting that vestibular symptoms may be an analog to the somatosensory, visual or auditory sensitivity defining migraine. Understanding the timing or intersection between vestibular symptoms and headache in VM remains a challenging and unresolved issue. Such patients may
S.D.Z. Eggers et al. / Comorbidities in vestibular migraine
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Table 1 Diagnostic criteria for vestibular symptoms associated with migraine, past and present Benign paroxysmal vertigo [3] (previously within childhood periodic syndromes) A. At least five attacks fulfilling criteria B and C. B. Vertigo occurring without warning, maximal at onset and resolving spontaneously after minutes to hours without loss of consciousness. C. At least one of the following associated symptoms or signs: nystagmus, ataxia, vomiting, pallor, or fearfulness. D. Normal neurological examination and audiometric and vestibular functions between attacks. E. Not attributed to another disorder. Migraine with brainstem aura [3] (previously basilar artery migraine; basilar migraine; basilar-type migraine) A. At least two attacks fulfilling criteria B-D. B. Aura consisting of visual, sensory and/or speech/language symptoms, each fully reversible, but no motor or retinal symptoms. C. At least two of the following brainstem symptoms: dysarthria, vertigo, tinnitus, hypacusis, diplopia, ataxia, decreased level of consciousness. D. At least two of the following four characteristics: 1. At least one aura symptom spreads gradually over 5 minutes, and/or two or more symptoms occur in succession. 2. Each individual aura symptom lasts 5–60 minutes. 3. At least one aura symptom is unilateral. 4. The aura is accompanied, or followed within 60 minutes, by headache. E. Not better accounted for by another ICHD-3 diagnosis, and transient ischemic attack has been excluded. Definite vestibular migraine (“definite migrainous vertigo”, Neuhauser 2001 [47]) A. Recurrent episodic vestibular symptoms of at least moderate severity. B. Current or previous history of migraine according to the criteria of the International Headache Society. C. One of the following migrainous symptoms during at least two vertiginous attacks: migrainous headache, photophobia, phonophobia, visual or other auras. D. Other causes ruled out by appropriate investigations. Probable vestibular migraine (“probable migrainous vertigo”, Neuhauser 2001 [47], revised 2004 [46]) A. Recurrent episodic vestibular symptoms of at least moderate severity. B. One of the following: 1. Current or previous history of migraine according to the criteria of the International Headache Society. 2. Migrainous symptoms during 2 attacks of vertigo. 3. Migraine precipitants before vertigo in more than 50% of attacks: food triggers, sleep irregularities, hormonal changes. 4. Response to migraine medications in more than 50% of attacks. C. Other causes ruled out by appropriate investigations. Vestibular migraine (ICVD 2012 [41]/ICHD-3beta 2013 [3]) A. At least five episodes fulfilling criteria C and D. B. A current or past history of migraine without aura or migraine with aura. C. Vestibular symptoms* of moderate or severe intensity, lasting between 5 minutes and 72 hours. D. At least 50% of episodes are associated with at least one of the following three migrainous features: 1. Headache with at least two of the following four characteristics: a. Unilateral location. b. Pulsating quality. c. Moderate or severe intensity. d. Aggravation by routine physical activity. 2. Photophobia and phonophobia. 3. Visual aura. E. Not better accounted for by another ICHD-3 diagnosis or by another vestibular disorder. Probable vestibular migraine (ICVD 2012 [41]) A. At least 5 episodes with vestibular symptoms* of moderate or severe intensity, lasting 5 min to 72 hours. B. Only one of the criteria B and C for vestibular migraine is fulfilled (migraine history or migraine features during the episode). C. Not better accounted for by another vestibular or ICHD diagnosis. *Vestibular symptoms may include: a. Spontaneous vertigo: internal vertigo (a false sensation of self- motion) or external vertigo (a false sensation that the visual surround is spinning or flowing). b. Positional vertigo, occurring after a change of head position. c. Visually induced vertigo, triggered by a complex or large moving visual stimulus. d. Head motion-induced vertigo, occurring during head motion. e. Head motion-induced dizziness with nausea (dizziness is characterized by a sensation of disturbed spatial orientation; other forms of dizziness are currently not included in the classification of vestibular migraine). ICHD indicates International Classification of Headache Disorders. ICVD indicates International Classification of Vestibular Disorders.
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S.D.Z. Eggers et al. / Comorbidities in vestibular migraine
symptoms interact either causally or independently beyond the current narrow definition of VM. Such studies are necessary to truly validate VM and define its core features, boundaries and overlapping comorbidities [60]. The goal of such studies would not be to undo the recently achieved international consensus definition of VM, but rather to gather data to support future modifications based on a strong foundation of empirical evidence.
3. Comorbidity: The third dimension Fig. 1. The scope of vestibular migraine in three dimensions. Vestibular migraine (VM) is conceptualized in two dimensions at the intersection of episodic vestibular symptoms and episodic migraine symptoms. Diagnostic criteria for (definite) VM require a clear temporal relationship between these two dimensions in order to optimize specificity. However, the essential core features and the boundaries with chronic dizziness or non-migraine headache are sometimes ambiguous. Likewise, frequent comorbidity with other neurotologic syndromes (particularly Ménière’s disease and benign paroxysmal positional vertigo) and psychiatric conditions creates a third dimension of diagnostic uncertainty and confounds application of VM criteria. Research methods exist to begin clarifying these uncertainties.
have episodic vestibular symptoms that occur during, before, after, between, or in the absence of headache episodes. As discussed above, vestibular symptoms rarely meet criteria for an aura or follow a consistent pattern. Whether or not other prominent migrainous symptoms occur with the vertigo determines the clinician’s ability to infer a causal rather than non-specific relationship between the two dimensions. This point is emphasized in both recent studies validating the concept of VM [27,54]. A common reason for patients to meet criteria only for probable rather than definite VM is that their episodic headaches lack sufficient migraine features or that episodic vestibular symptoms are not accompanied by clearly migrainous symptoms. Up to a third of such patients with probable VM followed longitudinally appear to have a stable episodic vestibular syndrome with headache and without hearing loss that will never become definite VM or anything else. They definitely have probable VM but will probably never have definite VM, despite the fact that their vestibular symptoms are indistinguishable. Our current classification system based around migraine does not adequately characterize this group. While revised criteria for (definite) VM may be appropriately biased toward requiring greater specificity for the temporal relationship between vestibular and migraine symptoms, broader inclusive studies are needed to more fully understand how the two dimensions of headache and vestibular
Our evolving understanding of VM must consider the third dimension of comorbidity, a frequent cause of diagnostic uncertainty that may confound clinical application and research validation of VM criteria (Fig. 1). Though migraine and vertigo are both common in the general population, the largest epidemiologic survey found that they occurred together about three times more often than would be predicted by chance alone [48], an observation supported by previous clinical series [35,57]. However, VM could not account for the entire increase in prevalence, suggesting that many migraineurs had another explanation for their vestibular symptoms. Several other neurotologic conditions occur more frequently in migraineurs than controls [70], particularly benign paroxysmal positional vertigo (BPPV) [32,67], Ménière’s disease (MD) [17,18,51,53], and motion sickness [6,25,26,34, 35,38], though their relationship to migraine is unclear. Our study of 88 consecutive patients with VM referred to a tertiary neurotologic clinic found that 57% had at least one comorbid neurotologic condition causing vestibular symptoms. Patients with neurotologic comorbidities had higher rates of handicap, anxiety, and depression, as well as higher rates of auditory and vestibular abnormalities than those with VM alone, findings that were dictated by the comorbid condition rather than the type of migraine [27]. These findings suggest that future studies of VM must include not only subjects with VM alone, but those with VM plus other neurotologic diagnoses and those with vestibular symptoms and headache where the diagnoses are uncertain. Vestibular migraine is conceptualized as a condition causing episodic vestibular symptoms lasting seconds to days that can be spontaneous or sometimes positional, creating the potential for diagnostic confusion with BPPV and MD. In our series of 42 patients meeting criteria for probable VM (Table 2), four would
S.D.Z. Eggers et al. / Comorbidities in vestibular migraine
391
Table 2 Subgroups of probable vestibular migraine in 42 patients Subgroups of pVM Episodic vertigo (with headache)
Episodic vertigo (with migraine)
Episodic unsteadiness or dizziness (with migraine)
Evolving vestibular migraine (Illness
