めまい疾患とモデル実験--脳循環障害によるめまい

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Three types of model experiments, including a hemodynamic simulation model and otoneurological animal models, were used to study circulatory dynamics and the pathogenesis of dizziness due to cerebrovascular disorders.1. A glass-tube model experiment for the vertebrobasilar arterial system.In a parallel conduit model the velocity in the narrow tube was slower than that in the wide one unlike the situation in direct conduit model. Moreover, the higher the viscosity of fluid in the circuit, and the lower the rate of pumping, the slower was the flow velocity in the wide tube in comparison with that in the narrow one.The difference, however, in the flow velocity between the wide and narrow tube became less when a branch tube was added to the parallel conduit.2. Vestibular function tests in rabbits with a unilateral ligated or stenotic vertebral artery.Rabbits with a unilateral ligated vertebral artery had more positional and headshaking afternystagmus than did those with a unilateral stenotic vertebral artery and more peripheral labyrinthine impairment in the pendular rotation test.3. Vestibular function tests in animals with acute and chronic hypertension and microscopic histological findings in the inner ears.Vestibular function tests rarely revealed abnormalities in guinea pigs with acute hypertension caused by a drug, and the histological findings in the inner ears were almost normal. Positional nystagmus was observed in vestibular function tests in rabbits with chronic hypertension caused by unilateral stenosis of a renal artery and bilateral resection of the vasomotor nerves, but the other vestibular function tests hardly showed any peripheral labyrinthine impairment, and the inner ears were histologically almost normal.4. The above findings suggest that circulatory disturbances of either the right or the left vertebral artery, and those of branches of AICA or PICA have a great influence on the circulatory dynamics of the vertebrobasilar system, a parallel conduit. Circulatory disturbances such as stenosis of vertebral arteries appear to make a dynamic difference between the right and the left vertebral artery, a parallel conduit, causing imbalance of the blood flow to the right or the left vestibular system, and to cause dizziness. Hypertension alone can cause only a little irreversible impairment of the peripheral labyrinths, and model experiments for hypertension and dizziness seem to need the addition of other factors.
耳鼻咽喉科臨床学会の論文

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松永喬
奈良県立医科大学

めまい疾患とモデル実験--脳循環障害によるめまい

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