When a patient presents with dizziness or other apparent vestibular symptoms, one should first determine if these symptoms are indeed vestibular related [25]. The answers are often found in reviewing the patient’s history that needs to be comprehensive and detailed. The presenting symptoms are questioned from all possible aspects in order to understand their possible vestibular relevance and values in localization and diagnosis. For example, a vestibular relevance is strongly suggested when the symptoms include directional spinning and a sensation of self-motion or unsteadiness with directional pulsion. In contrast, the vestibular relevance is likely poor if the dizziness is reported as feeling lightheaded and fainting.

When the vestibular symptoms have been verified in reference to the recommended definitions and classifications [10], the patient should be further questioned regarding a few other symptoms that are frequently associated with vestibular disorders, such as gait disturbance, visual disturbance, nausea, tinnitus, hearing loss, earache, etc. These symptoms can be important for the differential diagnosis. Questions should cover the entire course of progression for each symptom starting from its onset.

Once the presenting vestibular symptoms and their related conditions are understood, the possibly involved neural structures need to be localized and a list of possible diagnoses formulated. For example, recurrent episodic vertigo, which is characterized as brief intense spinning attacks and only associated with head turning toward a certain side in supine position, is indicative of positional irritation of the ipsilateral posterior semicircular canal and is most likely related to canalithiasis or cupulolithiasis, i.e., benign paroxysmal positional vertigo. The concurrence of recurrent episodic spinning-type vertigo and unsteadiness with directional pulsion and ipsilateral ear fullness, loud tinnitus, and hearing loss suggests the involvement of ipsilateral peripheral vestibular and auditory components. In this case, Menière’s disease or acoustic neuroma should be considered. Meanwhile, the migraine-related vestibular symptoms are often poorly localized or grossly localized to the brainstem or cerebellum. As a matter of fact, when a relevant focal lesion is clearly indicated, migraine will unlikely be the diagnosis. However, migraine should be highly suspected when the dizziness is correlated with episodic headache attacks, sensitivity to light and/or noise, nausea, and poor tolerance to head motion. Such a possibility needs to be also considered when episodic headaches and other migraine-like symptoms are identified even when these symptoms may not coincide with the current dizziness.

When the vestibular systems are confirmed, the patient should be asked for a possible previous or current history of headaches. If such a history does exist, detailed headache features should be inquired by means of the same approaches toward vestibular symptoms as previously discussed. Efforts are also made to explore headache-associated symptoms, such as visual aura, nausea, photophobia, and phonophobia. If these symptoms fulfill the ICHD-II criteria for diagnosing migraine with or without aura and alternative diagnosis can be excluded, the existence of migraine is recognized [18]. All the patients with migraine headache should be asked for any vestibular symptoms and those symptoms, if present, should be further assessed for their vestibular relevance with the previously discussed criteria. Since sometimes a history of migraine can be difficult to clearly diagnose, a systemic approach following the clinician’s persistent efforts to identify and localize neurological symptoms and to formulate and refine the diagnostic hypothesis is again the key for uncovering the critical elements for migraine diagnosis.

After recognizing the coexistence of both vestibular symptoms and a history of migraine, the clinician should attempt to find out whether this coexistence is related to the same underlying etiology or is merely a coincidence. The diagnosis of vestibular migraine requires the recognition of a temporal correlation between vestibular symptoms and migraine [8]. Once again, a careful review of all the relevant information from the entire history and physiological examination is essential to determine the relationship between these clinical symptoms. For example, a migraine patient may also suffer from vertigo related to a compressive meningioma at the cerebellopontine angle region on one side. In a case like this, both headache and vertigo can happen together at times.

The final step in diagnosing vestibular migraine is to determine whether or not migraine is the only or the best explanation for the correlation between the identified vestibular symptoms and the migraine diagnosis. If the vestibular symptoms are clearly caused by, or are better related to, a recognized vestibular disorder, the diagnosis of vestibular migraine should be questioned. To do so, a careful differential diagnosis is needed and is usually not a significant challenge to an experienced clinician. However, difficulties are often encountered when a possible correlation between the vestibular symptoms and migraine cannot be completely rejected. For example, some migraine patients may also have vestibular symptoms that are clearly or reasonably believed to be not related to migraine. These vestibular symptoms may occur either by coincidence or due to aggravation during or between migraine attacks. In many cases, the underlying cause of vestibular symptoms can be a minor vestibular, visual, or cerebellar dysfunction that is normally asymptomatic but becomes unmasked or exacerbated during migraine attacks. In other words, despite independent mechanisms, vestibular symptoms and migraine may still interact and reciprocally influence each other. Further, a few neurological disorders in the spectrum of migraine can present with prominent vertiginous symptoms. Those disorders can be distinguished from vestibular migraine based on some of their unique clinical features. These conditions will be discussed later in differential diagnosis.

Having made all the above efforts, the gathered findings are examined against the recommended diagnostic criteria for vestibular migraine. A final diagnosis of vestibular migraine can be made if all the requirements are fulfilled [8].

A few important clinical aspects need to be further discussed. First, the inquiry of medical history should always include asking questions about all the medical conditions that can be relevant to vestibular function, such as cardiac and pulmonary functions, psychiatric and psychological status, childhood development, and, if any, previous diseases that involved peripheral and central nervous systems especially the vestibular system. Women should also be evaluated for their history of menstruation and possible complications with it. Patients should also be routinely asked for current or previous neurological and otological disorders such as motion sickness, gait and balance disorders, visual discomfort, eye misalignment, impaired control of ocular movement, auditory symptoms, head trauma, infection of brain or ear, etc. Relevant social history, such as previous and current medication and substance abuse, and family history, especially about migraine, vertigo, and unsteadiness, should be routinely obtained.

Second, one should keep it in mind that the diagnosis of vestibular migraine is entirely based on the subjective features of relevant clinical symptoms [8]. In other words, the patients with vestibular migraine are not expected to have any significant finding on their physical examination. Although the physical examination is typically normal or unremarkable for the majority of those patients, subtle physical findings, such as brief episodic nystagmus and saccadic tracking, can be recognized during or between attacks of vestibular migraine [26, 27]. These findings are usually considered as benign and can be directly related to migraine. However, investigations are often made in order to prove that they are indeed not attributed to another disorder.

Finally, supplemental investigations in addition to history taking and physical examination are performed in some patients because of their individual conditions. Those clinical investigations include radiology (such as CT and MRI), vestibular laboratory (such as nystagmogram, vestibular evoked myogenic potentials, rotary chair, and posturography), and audiology laboratory (such as audiometry, auditory evoked potentials, and electrocochleogram). When used appropriately, these clinical tests may provide critical information to help with the differential diagnosis.

When typical vestibular symptoms and migraine history are both identified and their temporal correlations confirmed in an otherwise healthy person with normal physical examination, the diagnosis of vestibular migraine may be not difficult. A diagnosis of vestibular migraine will be questioned if the identified vestibular symptoms can be explained by an alternative cause better than migraine. Meanwhile, ambiguous presentations or variations are often encountered. For example, an individual who presents with clear vestibular symptoms may have never experienced a headache despite having a typical migraine aura and associated phobia and nausea. In situations such as this, the judgment may heavily depend on the clinician’s knowledge and experience. In this section, a few vestibular disorders in which the clinical presentations can significantly overlap with vestibular migraine will be discussed.