Objective: it has been documented in the literature that caloric responses with the lateral semicircular canal in a horizontal position are reduced, but not absent. This paper addresses what contributions to the caloric response, if any are made by the otoliths, and what influences on caloric response might be seen in patients with otolithic pathology.Study design: a prospective case series study.Setting: Tertiary and quaternary care teaching hospital.Patients: two normal subjects underwent "horizontal" calorics to document caloric response with the lateral semicircular canal in the horizontal position. This assessment was also carried out on eight sequential patients who were documented to have otolithic disease (as evidenced by abnormal VEMP assessment).
Interventions:Two sets of caloric tests (standard and horizontal) were carried out on our subjects. Patients underwent identical caloric assessment after CVEMP and OVEMP assessment.
Main outcome measures:VEMPs were scored as either normal or abnormal for each parameter we assess. Calorics were scored using the standard slow phase velocity measurements for each one.Results: Patients with otolithic abnormalities showed different caloric results in the horizontal position than is suggested in the literature and was shown by our two normal subjects.
Conclusion:Caloric responses are modulated and in patients with otolithic pathology, semicircular canal function is modulated, as caloric responses are different in patients than in normals when the lateral orientation to gravity is changed. Our results suggest that the otoliths do in fact mediate caloric responses.