Caloric-vHIT Dissociation in Vestibular Migraine: An Observational, Retrospective Case Series Study

Area of Science:

• Neurology
• Otolaryngology
• Vestibular System Disorders

Background:

• Caloric-vHIT dissociation is a hallmark of Ménière's disease (MD).
• Its presence and underlying mechanisms in vestibular migraine (VM) are not well understood.
• This study investigates caloric-vHIT dissociation in VM patients.

Purpose of the Study:

• To characterize the clinical and mechanistic heterogeneity of caloric-vHIT dissociation in definite vestibular migraine (VM).
• To analyze longitudinal data from a retrospective cohort of VM patients with this dissociation.
• To differentiate VM from MD based on vestibular and auditory profiles.

Main Methods:

• Retrospective analysis of 100 patients with MD or VM.
• Identification and longitudinal follow-up (approx. 7 years) of seven VM patients with caloric-vHIT dissociation.
• Classification of dissociation patterns (CalHiT-0, A, B, C) based on caloricパス (CP) and video head impulse test (vHIT) values.

Main Results:

• Caloric-vHIT dissociation occurred in 17.5% of VM patients (A-pattern) and 3.3% of MD patients (B-pattern).
• Case-level analysis revealed mechanistic heterogeneity in VM, including peripheral hypofunction, familial factors, trauma, and central modulation.
• VM patients lacked auditory symptoms and progressive hearing loss, with comparable disability (DHI) to MD despite lower vestibular deficits.

Conclusions:

• Caloric-vHIT dissociation is present in a significant subset of VM patients and is not exclusive to MD.
• The heterogeneity suggests multiple underlying mechanisms beyond endolymphatic hydrops.
• Interpreting this dissociation requires considering auditory and longitudinal profiles, not in isolation.