Results of air caloric and other vestibular tests in patients with chronic otitis media

Abstract

Objectives: Air caloric results are supposed to be influenced by anatomic changes of the middle ear. The aims of our study were to evaluate the incidence and characteristics of abnormal air caloric results in patients with unilateral chronic otitis media and without any history of vertigo, and to compare caloric results with there of other vestibular function tests (VFTs).

Methods: Twenty five patients with unilateral chronic otitis media (COM) who were scheduled for surgery underwent VFTs preoperatively. Hearing was assessed using pure-tone audiometry and vestibular function was assessed using a set of VFTs: air caloric, head-shaking nystagmus (HSN), vibration-induced nystagmus (VIN), and subjective visual vertical (SVV) tests.

Results: Six patients (24%) showed pathologic canal paresis (CP) on COM-sided ears. Two patients showed pathologic CP on the contralateral side. However, both of the two showed inverted nystagmus to warm air stimulation on the COM-side and hyperactive nystagmus to cold air stimulation on the COM-side, which means that the COM-sided ear was stimulated too much. There was pathologic HSN in 12 patients (48%), pathologic VIN in 7 (28%), and pathologic SVV in 5 (20%). Overall, 20 (80%) patients showed abnormal findings through a set of VFTs. Patients with an interaural difference of bone-conduction hearing thresholds >/=10 dB tended to show more abnormal VFT results than those for whom the interaural difference of bone-conduction hearing thresholds was <10 dB.

Conclusion: Our data show that one-fourth of patients with unilateral COM show abnormal caloric results on the COM side. However, subclinical latent vestibular imbalances were found to be common, which might be related to the gradual vestibular involvement in inflammatory processes, regardless of the caloric results. Results of a set of VFTs should be referred to when determining vestibular imbalance in patients with COM.

Keywords: Caloric; Chronic otitis media; Head shaking; Subjective visual vertical; Vibration.

Fig. 1

Paradoxical caloric responses. Inverted nystagmus was observed beating toward the non-stimulated side during warm air stimulation on the left ear (COM-sided) by evaporative cooling, followed by secondary nystagmus beating towards the stimulated side (patient No. 1). This inverted nystagmus and hyperactive responses to the cold air stimulation on the COM-side suggest that the COM-sided ear was hyper-excited. The dots indicate slow-phase eye velocities and a positive value means the direction of the slow-phase eye movement is to the right. SPV: slow-phase eye velocity; COM: chronic otitis media.