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.