A causal link between vertigo and migraine has been suspected, based on epidemiological observations indicating a more than chance association of migraine with vertigo and dizziness. Dizziness and vertigo rank among the most common complaints in the general population and are frequently reported by patients with migraine. The prevalence of migraine has been shown to be increased in patients with dizziness [1] and, in particular, among patients with unclassified recurrent vertigo [2, 3]. Conversely, patients with migraine reported more frequently vertigo than patients with tension-type headache (27 % vs. 8 %) [4]. Vertigo was also more common in migraine patients than in headache-free controls in a case-control study [5]. However, the interrelations of migraine and vertigo are complex as different causes may account for an association. First, since both dizziness/vertigo and migraine are very common in the general population, they may coincide simply by chance. The lifetime prevalence of migraine in industrialized countries has quite consistently been estimated at 13–16 % [6], and dizziness and vertigo affect approximately 20–30 % of the general population [7, 8]. In a large population-based neurotological survey, the lifetime prevalence of dizziness/vertigo was estimated at nearly 30 %. Vertigo of vestibular origin accounted for 7.4 % of all dizziness/vertigo symptoms [9]. Thus, assuming a lifetime prevalence of 14 % for migraine [6] and 7.4 % for vertigo, one can expect a chance coincidence of 1 %. However, the actual prevalence of participants reporting both migraine and vertigo of vestibular origin in the neurotological survey was three times higher (3.2 %), suggesting a more than chance concurrence [9]. In addition, other vestibular disorders such as benign paroxysmal positional vertigo [10, 11] and Menière’s disease [12] show a statistical link with migraine, the basis of this association still remaining uncertain. In an individual patient with dizziness/vertigo and migraine, clinicians must, therefore, determine if vertigo symptoms are causally related to migraine, if they are caused by another vestibular disorder that is statistically associated with migraine or if vertigo and migraine are unrelated.

The interrelations of migraine and Menière’s disease are complex. Vestibular migraine and Menière’s disease share many clinical features [4, 27], and prevalence of migraine is increased in patients with Menière’s disease [12]. Fluctuating hearing loss, tinnitus and aural pressure may occur in vestibular migraine, but hearing loss does not progress to profound levels [17, 27]. Similarly, migraine headaches, photophobia and even migraine auras frequently occur during Menière attacks [12]. An association of Menière’s disease and migraine has already been suggested by Prosper Menière in his first description of the disorder in 1861 [28]. A case-control study in 78 patients with idiopathic unilateral or bilateral Menière’s disease according to the criteria of the American Academy of Otolaryngology [29] found a twofold increased prevalence of migraine according to the ICDH-2 criteria compared to age- and sex-matched controls (56 % vs. 25 %). Nearly half of the Menière patients always experienced at least one migrainous symptom (migrainous headache, photophobia, aura symptoms) along with their Menière attacks, suggesting a pathophysiological link between the two disorders or reflecting an unsolved overlap of clinical symptoms and current diagnostic criteria [12, 30]. Patients with features of both Menière’s disease and vestibular migraine have been repeatedly reported [31]. Migraine, episodic vertigo and Menière’s disease may occur in familial clusters, suggesting genetic inheritance [32]. Comorbidity with migraine was found to be associated with a more severe clinical phenotype of Menière’s disease, with an earlier age of onset and higher incidence of bilateral cochlear involvement [31]. Common pathophysiological mechanisms that may cause a variable phenotype of vertiginous, cochlear and migrainous symptoms include neurotransmitter imbalances [15, 33] or defunct ion channels which are expressed both in the inner ear and brain [34].

In the first few years after onset of symptoms, differentiation of vestibular migraine from Menière’s disease may be challenging, as Menière’s disease can be monosymptomatic with vestibular symptoms only in the early stages of the disease. As a rule, the two disorders can be distinguished when a pronounced sensorineural hearing loss becomes evident in Menière’s disease within a few years, while cochlear impairment in VM, if present, remains mild even at longer follow-up [27].

Recurrent episodes of positionally induced, short-lasting vertigo attacks in VM may closely resemble benign paroxysmal positional vertigo (BPPV) [35]. Although clinically two separate entities, there is clinical evidence for a link between migraine and BPPV. Migraine is three times more common in patients presenting with idiopathic BPPV compared to patients with BPPV secondary to trauma or surgical procedures [10]. Similarly, the prevalence of migraine was two times higher in patients with idiopathic BPPV compared to age- and sex-matched controls [11]. Genetic factors and vascular damage to the labyrinth have been proposed as potential pathophysiological mechanisms linking the two disorders [10].

In a patient with migraine and episodic positional vertigo, the clinician must, therefore, determine if positional vertigo is due to vestibular migraine or if BPPV exists as a comorbid condition. When patients present during the acute episode, BPPV is easily diagnosed by the typical nystagmus beating in the plane of the affected semicircular canal, which is elicited on positional testing [36]. In patients with VM, most often a central-type positional nystagmus can be observed during the acute attack [37, 38]. In the vertigo-free interval, episodic positional vertigo in VM may be distinguished from BPPV by its shorter episode duration and greater episode frequency [35].

Migraineurs are more susceptible to motion sickness (30–50 %) than patients with tension headache or headache-free controls (about 20 %) [4, 5, 21]. Susceptibility to vestibular stimuli may be most marked in patients with VM who were four times more likely to become nauseous during caloric testing compared to patients with other causes of dizziness [39] and showed the highest motion sickness scores among patients with different types of migraine [22].

Conversely, vestibular stimulation by caloric testing induced migraine attacks in half of 39 migraineurs within 24 h, the effect being most pronounced in migraineurs with VM. Interestingly, migraine headaches were also triggered by caloric stimulation in 12 % of non-migraineurs [40]. Migraineurs also report more ‘visual vertigo’ while looking at spinning objects [5]. Headache, scalp tenderness and photophobia could be provoked by optokinetic stimulation in a recent study. Migraineurs were more nauseated and had longer-lasting headache and photophobia than controls [41]. Recently, rizatriptan, a serotonin agonist effective in treatment of migraine headaches, has been shown to reduce vestibular-induced motion sickness in migraineurs [42]. Pathophysiological models explaining the concurrence of headache, vertigo and motion sickness in migraineurs include common neurotransmitters such as serotonin which are active in the inner ear, trigeminal ganglion and brainstem vestibular and trigeminal nuclei and solitary nucleus as well as shared central neuronal circuits for vestibular and nociceptive information processing [43].

Transient loss of consciousness has since long been known as a prominent symptom in basilar migraine as described by Bickerstaff [44]. However, orthostatic hypotension and syncope also frequently occur in other subtypes of migraine. Orthostatic symptoms were more common in patients with migraine than in controls (68 % vs. 8 %) [45]. Among 451 females aged 15–44 years, fainting spells were more frequently reported by women with migrainous headaches (11 %) than by those without migraine (2 %) [46]. In the population-based CAMERA study, migraineurs showed an elevated lifetime prevalence of syncope (43 % vs. 31 %), recurrent syncope (13 % vs. 5 %) and orthostatic intolerance (32 % vs. 12 %) compared to non-migraineurs [24]. Syncope during migraine attacks has been reported to occur in 5 [41] to 10 % [47] of migraineurs. In a series of 248 patients with frequent syncope, a high rate of migraine headaches preceding or following syncopal episodes was reported (30 %), leading to the hypothesis of ‘syncopal migraine’, i.e. recurrent syncopes caused by a primary migrainous mechanism [48].

Case studies on autonomic function in migraine patients have yielded conflicting results, reporting both hypo- and hyperfunction of the sympathetic and parasympathetic systems [24]. However, the CAMERA study, despite the finding of an increased prevalence of syncope and orthostatic hypotension among migraine sufferers, did not reveal clear interictal signs of autonomic nervous system failure in migraineurs [24].

Cerebellar dysfunction causes imbalance, which patients may experience as dizziness. In recent years, several neuronal disorders presenting with a variable phenotype of episodic vertigo, cerebellar ataxia and different subtypes of migraine have been identified to be caused by defect ion channels that are expressed in the cerebellum and other brain structures. Patients with familial hemiplegic migraine (FHM), a rare subtype of migraine, may develop progressive cerebellar ataxia and nystagmus [49]. Mutations in the CACNA1A gene coding for the 1A subunit of a neuronal Ca2+ channel, which is heavily expressed in the cerebellum, have been identified not only in FHM but also in episodic ataxia type 2 (EA-2) [50] and spinocerebellar ataxia type 6. Episodic ataxia (EA-2) is characterized by short attacks of cerebellar ataxia or vertigo and interictal nystagmus. Approximately half of the patients with EA-2 also have migraine [34]. Both FHM and EA-2 may be associated with typical symptoms of basilar migraine [34, 51]. Subtle interictal signs of vestibulocerebellar dysfunction have also been found in 83 % patients with migraine and were more pronounced in patients with migraine with aura [52]. Similarly, up to two thirds of patients with VM show interictal central vestibular and ocular motor deficits indicating mild cerebellar and brainstem dysfunction which tend to somewhat progress with time [16, 27, 53]. However, the search for genetic mutations of ion channels involved in other subtypes of migraine and progressive cerebellar ataxia has been negative in VM so far [54, 55].