Reversal of paradoxical stimulation (false inversion) in perforated tympanic membranes by increasing the time of warm stimulation, evidenced by a physical model

Clinical diagnoses of patients showing caloric inversion

“…In previous studies, caloric inversion by dry warm air irrigation has been reported in chronic otitis media with tympanic membrane perforation, 1 , 2 , 3 , 4 , 5 , 6 , 7 and an evaporative cooling effect on the moist mucous lining of the middle ear cavity was suggested as a possible mechanism. Barber et al supported this mechanism by showing that caloric inversion was not observed when the warm air was saturated with water vapor.…”

“… 1 This idea was further supported by an experiment using physical model components composed of PVC pipe mimicking the external auditory canal, a hood, a thermometer, and a caloric air stimulator, which showed that the temperature of a moist hood was actually decreased by dry, warm air stimulation. 2 Caloric inversion occurs in 37%–40% of patients with tympanic membrane perforation, and the occurrence of caloric inversion is not correlated with the perforation size. 2 , 3 …”

“… 2 Caloric inversion occurs in 37%–40% of patients with tympanic membrane perforation, and the occurrence of caloric inversion is not correlated with the perforation size. 2 , 3 …”

“… 1 In other words, the fast phase of nystagmus moves toward the unstimulated ear when warm air or water flows into the ear and moves toward the stimulated ear when cold air or water flows into the ear. The presence of caloric inversion by warm air irrigation has been demonstrated in chronic otitis media patients with tympanic membrane perforation many times 2 , 3 , 4 , 5 , 6 , 7 , 8 since the first report. 1 This phenomenon is believed to occur due to the evaporative cooling effect that dry warm air irrigation has on the moist mucous membrane in the middle ear cavity.…”

“…Although varying patterns of caloric inversion, such as disconjugate nystagmus elicited by cold air irrigation in patients with tympanic membrane perforation, were demonstrated in the first report, 1 subsequent investigations have focused on caloric inversion by warm air irrigation in patients with tympanic membrane perforation. 2 , 3 , 4 , 5 , 6 , 7 , 8 …”