Vertigo and Dizziness Related to Migraine: A Diagnostic Challenge

Dear Sir   Let me first congratulate Drs Neuhauser and Lempert for a very thorough and exhaustive review of a very difficult topic (1). The review follows several original scientific studies published by the same authors in leading journals. The main thesis of the review, and of the previous papers, is that there is a causal relationship between migraine and vertigo and that a specific clinical entity, ‘migrainous vertigo’, can be distinguished. The authors should be praised for having fully understood the system of the International Headache Society (IHS) classification and for having proposed explicit diagnostic criteria for this new entity. One might therefore ask why this entity has not been included in the second edition of the International Headache Classification. In the following I give some of the reasons.

First, if we regard vertiginous symptoms as just one more manifestation of migraine, then it follows logically that no specific subcategory of migraine is needed. Migraine patients have a lot of symptoms that are not included in the diagnostic criteria for migraine. The art of classification dictates that one should use only what is needed in order to develop simple, sensitive and specific diagnostic criteria.

Second, if migrainous vertigo is regarded as a specific subtype of migraine similar to hemiplegic migraine and basilar migraine, then several other considerations are relevant. The main problem is that out of a huge number of migraine patients and dizzy/vertiginous patients, a small group is singled out by the proposed criteria. There is no evidence of familial aggregation of this subform, except perhaps in very few families. The treatment evidence cited is very weak. Response to prophylactic agents is a useless criterion as these drugs have multiple actions that affect other symptoms than migraine. For example, many cause sedation and dizziness. Drug effects may thus contribute to the apparent relation between dizziness and migraine. Response to acute treatment with a specific antimigraine drug would carry some weight, but the only controlled study (by the authors) is negative. This was explained as due to lack of power, which may or may not be the reason. If there is a true causal relationship one might also wonder why not many more migraine patients have vertigo in association with an attack. In population-based migraine studies vertigo is rare (except in basilar and hemiplegic migraine). If we then go through the proposed diagnostic criteria, it is immediately evident that the category of probable migrainous vertigo is meaningless. It only requires recurrent episodic vestibular symptoms plus one of a range of migraine symptoms. For instance, response to one migraine medication in more than 50% of attacks is enough. Flumazine is such a drug, but it is also used for vertigo. Migraine precipitants are reportedly present before vertigo in more than 50% of attacks. However, migraine precipitants are highly unspecific and also occur before attacks of tension-type headache and in people not developing any kind of headache. Migrainous symptoms in attacks of vertigo is also a very mild requirement in patients who may have had 50 attacks or more. If we then examine the criteria for definite migrainous vertigo, they are still not very strict. The request that patients have had migraine, which is not the case for probable migrainous vertigo. The problem is, however, to request only one of the following migrainous symptoms during at least two vertiginous attacks: migrainous headache, photophobia, phonophobia, visual and other auras. Photo- and phonophobia are very non-specific symptoms that occur with a variety of disorders. For that reason, in the criteria for migraine without aura, we have requested that if nausea is not present then both photo- and phonophobia must be present.

What is needed is a straightforward population-based study, where both migrainous symptoms and vertiginous symptoms and their temporal interrelationship are evaluated. In addition, a randomized, double-blind, controlled trial of a triptan in patients diagnosed with a definite migrainous vertigo as defined in Neuhauser's paper should be conducted. In such a study, care should be taken not to treat regular migraine attacks but only vertiginous attacks. Even in the absence of such evidence, the studies of Neuhauser and Lempert will make clinicians place more emphasis on vertiginous symptoms when taking the migraine history.