Measurement of ocular countertorsion reflex with fundoscopic camera in normal subjects and in patients with inner ear lesions

Summary

To record the ocular countertorsion reflex (OCR), we devised a new technique using an ophthalmo-fundoscope camera. OCR was measured in twenty two healthy subjects and in eighty three patients with inner ear lesions as benign paroxysmal positional vertigo (BPPV), sudden deafness, Menière's disease, vestibular neuronopathy, acoustic neuroma and cases given ototoxic drugs. The mean values and the standard deviations of OCR for healthy subjects were obtained, but a wide range of the values in each eye in each direction was evident.

Considering the wide range of OCR values, judgement should based not only on OCR value itself, but on differences in OCR values between clockwise (CW) and counter-clockwise (CCW) tilt or on the percentage of OCR values in CW or CCW tilt to the total countertorsion of that eye.

In this report OCR values below 2∘ in either tilt (CW or CCW) were regarded as abnormal and 5∘ differences at 30∘ tilt and 4∘ differences at 45∘ tilt between CW and CCW tilt were regarded as suspicious of otolith dysfunction.

Abnormal OCR values in most unilateral inner ear lesions excluding acoustic neuromas were seen in 14% according to our criteria.

The incidence of abnormal OCR values was high in BPPV with caloric abnormalities, acoustic neuromas and in cases given ototoxic drugs, while it was less in BPPV without caloric abnormalities and vestibular neuronopathy.

From the results obtained by this test, a hypothesis was drawn as to the relation of the tilt to the lesion of the otolith organ.

With the development of the otolith function test, it could be applied to many disorders of the inner ear and internal auditory canals and to reevaluate the hitherto known diagnosis as Meniere's disease, sudden deafness etc.