Caloric testing in patients with heavy or light cupula of the lateral semicircular canal

OBJECTIVE: To clarify whether the dysfunction of the lateral semicircular canal remain or not in patients with heavy or light cupula. STUDY DESIGN: Prospective case series. METHODS: The subjects were 19 patients with heavy cupula (3 males, 16 females; mean age, 62.8 years) and 14 patients with light cupula (5 males, 9 females; mean age, 63 years). Caloric testing (iced water) was carried out after complete disappearance of positional nystagmus. We measured maximum slow‐phase velocity and calculated asymmetry. RESULTS: In heavy cupula group, no one revealed canal paresis (CP) and 4 patients (21%) showed inverse CP (affected ear response is greater than healthy ear response). In light cupula group, 3 patients (21%) revealed CP. CONCLUSIONS: Dysfunction of the lateral semicircular canal does not always remain in either heavy cupula or light cupula. The caloric response increases in some cases with heavy cupula. We can explain this phenomenon based on the hydrostatic pressure theory involved in ossicles. LEVEL OF EVIDENCE: 4.