Clinical Heterogeneity in Vestibular Migraine Diagnosed Using Bárány Society Criteria: Differences According to Caloric-Test-Based Evidence of Peripheral Vestibular Dysfunction.

BACKGROUND AND PURPOSE: Vestibular migraine (VM) is a common cause of episodic vertigo with heterogeneous presentations. Some VM patients show caloric abnormalities suggestive of peripheral vestibular dysfunction (PVD). This study compared clinical symptoms and vestibulo-ocular function between VM patients with caloric canal paresis (CP) >25% (VM-CP+), which was used as an operational definition of evidence of PVD, and those without caloric CP >25% (VM-CP-). METHODS: We enrolled 181 patients diagnosed with VM according to the Bárány Society criteria: 47 in the VM-CP+ group and 134 in the VM-CP- group. All patients underwent videonystagmography and caloric testing, while the video head impulse test (vHIT), vestibular-evoked myogenic potential (VEMP) measurements, and subjective visual horizontal (SVH) and subjective visual vertical (SVV) assessments were performed in available subsets. RESULTS: Compared with VM-CP- patients, those with VM-CP+ showed higher frequencies of external vertigo, rotational vertigo, spontaneous nystagmus, unidirectional horizontal positional nystagmus, horizontal head-shaking nystagmus, abnormal cervical VEMPs, and abnormal upright SVH/SVV. The vHIT findings were abnormal only in VM-CP+ patients with available data. Conversely, a history of motion sickness and a family history of migraine were more common in VM-CP-. Multivariable regression showed that rotational vertigo, external vertigo, and unidirectional horizontal positional nystagmus were independently associated with VM-CP+, whereas a history of motion sickness and a family history of migraine were negatively associated with VM-CP+. CONCLUSIONS: VM-CP+ and VM-CP- patients showed different clinical and vestibulo-ocular patterns, suggesting the presence of clinical heterogeneity within VM. VM-CP+ patients may show a phenotype related to peripheral vestibular asymmetry. Whether this reflects a comorbid or additive effect of migraine and PVD or a migraine-related functional state should be investigated in future prospective studies.