Similarities and Differences between Vestibular Migraine and Recurrent Vestibular Symptoms-Not Otherwise Specified (RVS-NOS)

Meniere's disease and vestibular migraine (VM) are two common inner ear disorders whose diagnoses are based on clinical history and audiometric exams. In some cases, patients have been reporting different episodes of vertigo for years but not fulfilling the Barany Society criteria for either. These are called Recurrent Vestibular Symptoms-Not Otherwise Specified (RVS-NOS). It is still under debate if this is a single disease entity or a part of the spectrum of already established disorders. The purpose of our work was to establish similarities and differences with VM in terms of clinical history, bedside examination, and family history. We enrolled 28 patients with RVS-NOS who were followed for at least 3 years with stable diagnosis; results were compared with those of 34 subjects having a diagnosis of definite VM. The age of onset of vertigo was lower in VM than in RVS-NOS (31.2 vs. 38.4 years). As for the duration of attacks and symptoms, we detected no differences other than subjects with RVS-NOS reporting milder attacks. Cochlear accompanying symptoms were more frequently reported by VM subjects (one subject reporting tinnitus and another one reported tinnitus and fullness). Motion sickness was equally reported by subjects across two samples (around 50% for both). Bipositional long-lasting, non-paroxysmal nystagmus was the most common finding in the two groups, with no significant difference. Finally, the percentage of familial cases of migrainous headache and episodic vertigo did not differ between the two samples. In conclusion, RVS-NOS shares some common aspects with VM, including the temporal profile of attacks, motion sickness (commonly considered a migraine precursor), bedside examination, and family history. Our results are not inconsistent with the possibility that RVS-NOS may be a heterogeneous disorder, even if some of these subjects may share common pathophysiological mechanisms with VM.