Cardiovascular responses to lateral semicircular canal stimulation in man

The cardiovascular effects of aural irrigation with water at 37 degrees C (control subjects, n = 6) or 44 degrees C (experimental subjects n = 11) were assessed from measurements of heart rate, brachial arterial blood pressure and forearm blood flow. The occurrence and intensity of vestibular stimulation was assessed from the electronystagmogram. The procedure had no significant effect on cardiovascular variables in control subjects or in subjects who were exposed to vestibular stimulation but who were not nauseated by it (n = 6). Those subjects who felt nauseous (n = 5) showed a tachycardia and forearm vasodilatation. These results provide no evidence that vestibular stimulation contributes to orthostatic reflexes in man.