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Abstract: Objective: Based on the hypothesis that the origin of nystagmus is from the posterior canal (PC), the nystagmus in the head hanging and sitting position should be mirror images. To clarify the anatomical origin of positioning nystagmus in BPPV patients, we analyzed the positioning nystagmus of benign paroxysmal positioning vertigo (BPPV) patients three-dimensionally. Methods: Twenty-six patients with BPPV participated in this study. The positioning nystagmus was recorded in complete darkness from the patient''s left eye by means of an infrared CCD camera. We performed three-dimensional analysis of nystagmus using video image analysis system (VIAS). Subsequently, the rotation axis of the 3D eye movements of the positioning nystagmus was calculated. Results: Among the 26 patients tested, 20 patients demonstrated the axes of nystagmus in good or relatively good alignment to the PC axis. However, in 11 of these 20 patients there was poor alignment of the axis of nystagmus in the sitting position to the PC axis. In addition, six patients showed axes of nystagmus with poor alignment to the PC in the head hanging position. Among them, two patients exhibited axes of nystagmus in good alignment with the anterior canal, in spite of diagnosis of these patients as PC BPPV by experienced examiner based on the positioning nystagmus test. Conclusion: These results demonstrated that only one-third of patients who were diagnosed as BPPV, could be diagnosed as true BPPV which originates from a PC pathology. Besides the possibility that the pathology may originate from the AC, it is still unclear which part of the inner ear may be the candidate site of origin of the pathology of BPPV in the other 15 patients. [Copyright &y& Elsevier]

Abstract: In order to record and analyze the rapid eye movement non-invasively in human subjects, a four times high-speed video camera (4TC) with a new computer software was developed and utilized. Nine healthy volunteers and four patients with vestibular dysfunction participated in this study. Caloric stimulation was applied to the healthy subjects and the eye movements were recorded using a standard camera (SC) and a 4TC. In four patients, the positional and/or positioning nystagmus was recorded using SC and 4TC. Analysis of the eye speed of the quick phase of nystagmus was performed manually from the print out of the chart. The quick phase of the caloric nystagmus was adequately analyzed from the data using 4TC. However, using SC the sampling rate was not sufficiently enough for this purpose, as prospected. The adaptability of the 4TC in clinical examination is exactly similar to that of SC, because of the size and weight of the camera. Although the time taken to analyze eye movements using 4TC is about four times longer than that using SC, this system is quite useful and adequate for analyzing the quick eye movements in vestibular nystagmus, in an out-patient clinic set up. [Copyright &y& Elsevier]

Abstract: Objectives:: Presently, the neurotological tests, using visual stimulation, such as optokinetic nystagmus test (OKN), eye-tracking test (ETT) is being widely used for the diagnosis of vertigo or disequilibrium. The problems of these tests are the large size of the visual stimulator and therefore a wide space requirement. Even if a small apparatus is developed, the apparatus itself would be very expensive. In this study, we developed a small visual stimulation test system comprising the virtual visor, which receives an image for visual stimulation from an on-line computer. Methods:: Using smooth pursuit and optokinetic stimulation onto a virtual visor we assessed the ENG recording in 20 normal subjects. Result:: We found the 30°/s OKN, horizontal eye tracking were adequately stimulated by this technique with reliable results. Conclusion:: This new method of smooth pursuit and optokinetic stimulating by a virtual visor is capable of producing reliable results and may be used in the clinical laboratory of vertigo. However, this stimulator also has some limitations, mainly because of the visual angle of the virtual visor stimulator. [Copyright &y& Elsevier]