Subjective and objective responses to caloric stimulation help separate vestibular migraine from other vestibular disorders

Background: Nystagmus generated during bithermal caloric test assesses the horizontal vestibulo-ocular-reflex. Any induced symptoms are considered unwanted side effects rather than diagnostic information.Aim: We hypothesized that nystagmus slow-phase-velocity (SPV) and subjective symptoms during caloric testing would be higher in vestibular migraine (VM) patients compared with peripheral disorders such as Meniere's disease (MD) and non-vestibular dizziness (NVD).Methods: Consecutive patients (n = 1373, 60% female) referred for caloric testing were recruited. During caloric irrigations, patients scored their subjective sensations. We assessed objective-measures, subjective vertigo (SVS), subjective nausea (SNS), and test completion status.Results: Nystagmus SPV for VM, MD (unaffected side), and NVD were 29 +/- 12.8, 30 +/- 15.4, and 28 +/- 14.2 for warm irrigation and 24 +/- 8.9, 22 +/- 10.0, and 25 +/- 12.8 for cold-irrigation. The mean SVS were 2.5 +/- 1.1, 1.5 +/- 1.33, and 1.5 +/- 1.42 for warm irrigation and 2.2 +/- 1.1, 1.1 +/- 1.19, and 1.1 +/- 1.16 for cold-irrigation. Age was significantly correlated with SVS and SNS, (p < 0.001) for both. The SVS and SNS were significantly higher in VM compared with non-VM groups (p < 0.001), and there was no difference in nystagmus SPV. VM patients SVS was significantly different to the SVS of migraineurs in the other diagnostic groups (p < 0.001). Testing was incomplete for 34.4% of VM and 3.2% of MD patients. To separate VM from MD, we computed a composite value representing the caloric data, with 83% sensitivity and 71% specificity. Application of machine learning to these metrics plus patient demographics yielded better separation (96% sensitivity and 85% specificity).Conclusion: Perceptual differences between VM and non-VM patients during caloric stimulation indicate that subjective ratings during caloric testing are meaningful measures. Combining objective and subjective measures could provide optimal separation of VM from MD.

Automated summary

The study found that patients with vestibular migraine have higher nystagmus slow-phase velocity and subjective symptoms during caloric testing compared to patients with other vestibular disorders. Combining objective and subjective measures can provide better differentiation of vestibular migraine from Meniere's disease.