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Vestibular migraine (VM) is a debilitating condition where vestibular symptoms are causally related to migraine (1). As a new vestibular central entity, VM was recently defined as recurrent vertigo episodes in patients with a history of migraine by the International Headache Society (IHS) (2) and the Bárány Society (3). The cause of VM is still a matter of speculation, and all of the proposed mechanisms are derived from the presumed pathophysiology of migraine (4). While it is less common than migraine (which affects 13 - 16 % of the adult population in Croatia and worldwide) (5,6), VM is the most common neurologic cause of vertigo (1,7), with a prevalence between 0,89 - 2.7 % in the adult population (7–9). VM has received increasing interest in the last 2 decades but remains under-recognized (10). The diagnostic challenge of VM perhaps lies in the broad spectrum of its clinical features, the absence of “typical” migraine headaches, and the clinical manifestations which are so varied that some authors speak of “a chameleon among episodic vertiginous syndromes” (11,12). A detailed medical history of migraine and vestibular symptoms, and neuro-otologic examination during the attacks provide the key to diagnosis (3,9,12). The most common vestibular symptoms in an acute (ictal, IC) VM attack are head motion-induced vertigo with photophobia, phonophobia, and nausea, while the most common vestibular symptom in a symptom-free (inter-ictal, II) period of VM is visually induced vertigo (12). There is no specific diagnostic abnormality that can be measured in a VM, neither in the IC nor in the II period (12). Also, the results of the clinical tests in VM patients tend to vary significantly (11,12), so vestibular and radiology testing are helpful to exclude other oto-neurological disorders (13). During the IC phase of VM, some patients have central spontaneous nystagmus, central positional nystagmus, or a combination of the two (14,15). In most VM patients, the general oto-neurologic examination is normal interictally (13). In recent clinical studies, measuring the gain of the vestibular-ocular reflex (VOR) with a video head impulse test (vHIT) (16–18), and the degree of the subjective visual vertical (SVV) (19,20) represent a helpful augmentation of clinical examination in VM patients. To date, no one compared the results of oto-neurologic clinical examination, VOR, and SVV measurements in the IC and II phases in the same VM patients. As a result, this study will analyze the results of VOR and SVV in the IC and II phases of VM patients, in addition to the clinical oto-neurological features. Our study, therefore, will primarily provide a two-dimensional (oto-neurologic) clinical approach to VM patients, and then vestibular-ocular diagnostic peculiarity by vHIT and SVV in an IC and II period of VM patients. |
