Background & Objectives: The distance between the utricles is important in vestibular tests like the unilateral centrifugation test for examining the utricular function. In this test, the axis of rotation crosses precisely through one utricle, thus only the opposite utricle is stimulated. The interutricular distance needs to be known in order to stimulate one utricle maximally for this test, and it would be better if the distance could be estimated from surface landmarks like intermastoid distance.
Subjects & Methods: We investigated the correlation between the interutricular distance (IUD) and the intermastoid distance (IMD), measured on magnetic resonance images. Data were collected from 177 subjects (72 men and 105 women), who suffered from dizziness, sensorineural hearing loss and facial nerve disorders.
Results: We found that IUDs were 7.33+/-0.42 cm (6.03-8.75 cm) and the maximum difference of IUDs between the subjects was 2.73 cm. There was a significant correlation between IUD and IMD. The IUDs of men (7.57+/-0.38 cm) and women (7.17+/-0.38 cm) showed the similar correlation with those of IMD. The correlation was not different from that published for Caucasian subjects.
Conclusion: These findings show that there is a significant correlation between IUD and IMD. IMD can be useful for estimating IUD, which enables exact stimulation to be given to the unilateral utricle in the unilateral centrifugation test. Moreover, individual assessment of IUD gives more precise stimulation than using a fixed IUD in the unilateral centrifugation test.
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