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Benign Paroxysmal positioning vertigo and acoustic tumors are thought to be related to the function of the vertical semicircular canal (VSCC). Therefore, we developed a new test to assess VSCC function by analyzing VSCC-induced nystagmus. We examined 11 healthy subjects, wearing goggles equipped with an infrared CCD camera and sitting on a chair designed to bilaterally stimulate the VSCCs by tilting the head backward during 45° rotation to the right on the sagital plane. The stimuli used were sinusoidal rotation with a maximal angular velocity of 100°/sec at a frequency of 0.033 Hz. The result was that the maximum slow phase eye velocity (MSPEV) of horizontal nystagmus decreased parallel to the head-tilted angle and the MSPEV of the vertical nystagmus was maximal when the head was tilted 60° or 70° backward. From the perspective of VSCC anatomy, the direction of horizontal nystagmus is reversed when head is tilted 60° backward. However, we could not observe the reverse of the direction of horizontal nystagmus even when head tilted 80° backward. We considered that vertical nystagmus was maximal when the head was tilted 60-70° backward because this position applied the optimal stimulation to the VSCC. This finding is in agreement with the position of the vertical VSCC in skull. We concluded that rotational test with respect to the VSCC can be used to analyze VSCC function.

To test vertical semicircular canal function, we developed a new and convenient type of rotation-chair, in which subjects sat with their heads and backs tilting backward 60°and with their heads rolling laterally 45°. A CCD camera and infrared video system was used to record eye movement in the dark. Normal subjects were rotated with an acceleration of 2°/sec2 until the angular velocity reached 60°/sec. The rotation was then stopped with a deceleration of 100°/sec2 after per-rotation nystagmus subsided. The maximal slow phase eye velocity (MSPEV) of vertical components of vertical semicircular canal (VSCC)-induced post-rotatory nystagmus (PRN) were analysed.Subjects were first rotated with laterally rolling head angles of 30°, 45° and 60°to examine the optimal angle for stimulating VSCC.MSPEV of posterior semicircular canal (PSCC)-induced PRN was largest with a head angle of 60°. While MSPEV of anterior semicircular canal (ASCC)-induced PRN did not vary with the laterally rolling head angle. MSPEV of the vertical components of VSCC-induced PRN was then compared with that of the horizontal components of lateral semicircular canal (LSCC)-induced PRN. MSPEV of both PSCC- and ASCC-induced PRN were significantly smaller than that of LSCC-induced PRN.MSPEV of ASCC-induced PRN was slightly smaller than that of PSCC-induced PRN, though individual differences varied widely. However, there were very small leftright differences in MSPEV of both PSCC- and ASCC-induced PRN. Therefore, it is suggested that our PRN function test involving VSCC can diagnose vestibular diseases.

We present a 41-year-old male with vertigo due to orthostatic hypotension caused by diabetic neuropathy. Autonomic function test showed no increase in either plasma noradrenaline or sympathetic activity in response to standing up. During head up tilting, vertebral blood flow measured by Doppler flowmeter decreased with a decrease in blood pressure and asymmetrical vertebral blood flow was evident. Head up tilting also induced nystagmus and vertigo. After the patient was treated for orthostatic hypotension by L-threo-3, 4-dihydroxyphenylserine, a precursor of noradrenaline, neither asymmetrical vertebral blood flow nor nystagmus were observed during head up tilt. It is suggested that asymmetrical vertebral blood flow induced by sympathetic dysfunction causes asymmetrical excitability of the vestibular system, resulting in nystagmus and vertigo.

An equilibrium test battery was performed in 28 patients who had received cochlear implants in our institute in the last 4 years. A total of 13 patients complained of dizziness after the operation. They were divided into three groups according to the time course of dizziness; dizziness occurring immediately after the operation and disappeared within two weeks (immediate type); lasting more than two weeks in 2 patients (prolonged type); in 4 patients it occurred more than one month after the operation (late onset type). Patients who had no dizziness after the operation had a lower response to caloric testing than did those who experienced dizziness. The cause of dizziness was judged to be due to a peripheral lesion in the immediate and prolonged groups, but in only 1 patient of the late onset group.

We developed a new type of rotatory chair system to examine vertical semicircular canal-stimulative postrotatory nystagmus in normal ears. The subjects sat on the rotatory chair with their heads and backs tilting backward 60 from the vertical line, and their heads at 30°, 45°, or 60°to the plane of rotation. The rotation was performed with an initial acceleration of 10°/sec 2 for 10 sec and a terminal acceleration of 100° or 180°/sec 2 following a period of constant velocity for 20 sec in each position with either clockwise or counter-clockwise rotation. In this position, we were able to examine isolated excitatory single canals for all four of the vertical semicircular canals. The postrotatory nystagmus was analyzed with an infrared video recording system. There were no remarkable differences in the maximum slow phase eye velocity and the duration of postrotatory nystagmus between terminal acceleration of 100°/sec 2 and that of 180°/sec 2. Moreover, there were no obvious differences in the balance of nystagmic reactions, after stimulative rotation for the anterior or posterior semicircular canal, between the left and the right sides.However, the degree of postrotatory nystagmic reaction in each posterior semicircular canal was usually much more than that in each anterior semicircular canal in most normal subjects.

β-thromboglobulin (β-TG) and platelet factor 4 (PF-4), which are indexes of intravascular platelet activation, were measured in patients with Meniere's disease. Serum concentrations of p-TG and PF-4 were elevated in 15% of the patients. Ticlopidine, a platelet aggregation inhibitor, decreased the serum levels of β-TG and PF-4, and was effective clinically in 69% of the cases. These findings suggest that platelet aggregation is one of the causes of vertigo in Meniere's disease.