Migraine-related vertigo: a common and important disorder.

Migraine-related vertigo (MRV) or vestibular migrainehas had a diﬃcult history being understood as a dis-order. But now with better recognition, it may be givenits due in clinical assessments and research. Dizziness isthe second most common neurologic complaint andMRV is of the most common presenting causes ofvertigo in clinics for dizziness [1]. In the most simplisticview, MRV is a syndrome of recurrent vertigo attacksthat occur in people who have the diagnosis of migraineheadache or aura. While it is easy to assert that there isa disease of vertigo attacks on the basis of migraine, it ishard to prove. Migraine headache itself is well-knownto be diﬃcult to precisely specify: even the InternationalHeadache Society criteria are a collection of mix-and-match symptom features that add up to a diagnosis [2].There has been no equivalent consensus on the diag-nosis of MRV, however, Neuhauser [3] has come upwith a reasonable check-list of determining that thevertigo symptoms that are not explained by other ver-tigo-causing disorders and then verifying that thediagnostic criteria for migraine headaches are met.Whilst we appear to be approaching more precisepathophysiologic mechanisms for migraine headaches[4], there is less such convergence for MRV. Indeed,studies of such patients fail in simplest mechanistic levelof neurological disorder description: central or periph-eral? A heroic study by Lempert!s group [5] examinedMRV patients for nystagmus during attacks. Theﬁndings were: some central, some peripheral, someboth. The pathophysiology of migraine headachesseems to localize to the trigeminal nuclear complex inthe brainstem, a region closely apposed to vestibularnuclei. However, there is the scientiﬁcally unfortunateﬁnding of reliably measurable peripheral damage in thevestibular system in MRV patients. Some 20–40% ofthem show attenuated unilateral responses to caloricstimuli [6]. Thus, while there may be some central braincomponent to MRV, these peripheral eﬀects need to beexplained. Perhaps like the vascular phenomena ofmigraine HA, these ﬁndings are epiphenomena [4]. Thiswould explain the inconsistent ﬁnding of peripheralchanges.Further discouragement in the realm of MRV isfound in the search for deﬁnitive treatment and forprophylaxis. There have been a number of studies ofclassical migraine headache treatments used inmanagement of MRV and there is some cross-over ofeﬀectiveness. In my own experience, lifestyle man-agement (diet, sleep and exercise) and traditionalmigraine headache treatments, such as verapamil andpropranolol, work acceptably well. However, thereis much trial-and-error in the regular use of thesemedications.Most frustrating in MRV are patients who havedrastic impairments of their lives and who are resistantto therapy. I believe it is important to publicize thedevastation that MRV can cause patients throughemotional stress and life disruption that result from it.Neuhauser notes a group that I very frequentlyencounter in my vertigo disorders clinic: perimeno-pausal women who had migraine headaches earlier intheir lives [3]. Such patients seem to be particularly re-calcitrant to treatment. The recent recognition thatestrogen and progesterone are very active neuro–hu-moral and neurotransmitter modulators [7,8] re-en-forces the idea that like migraine headache, MRV mayhave a strong brain component that is directly aﬀectedby reproductive hormones. I am optimistic that hor-monal management regimens will be found that willreduce triggering of migraine headaches and MRV.An important clinical experience I have is the resis-tance of patients to the diagnosis that they havemigraines. Perhaps with reason, they do not want to belabeled as having a genetically determined and thus life-long disorder that upsets many lives. The resistance isstrong in patients presenting with vertigo. Many com-plain they don!t really have a problem with headaches,how can they have migraine? In the minority who havemigraine visual aura, which is pathognomonic formigraine,theexplanationis easier.Especiallyin commonmigraine, a useful approach in discussing it withpatients is to do the appropriate medical diagnosticprocedure: rule out other vertigo causing disorders andthen consider migraine.Acceptance by patients and by clinicians of this com-mon disorder will lead to understanding of its life eﬀectsandtorenewedeﬀortstounderstandandtreatthisdisease.