眼振反応におけるDP現象
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概要
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Directional Preponderance (DP), is a readiness for nystagmus to occur to one side more than to the other.Hallpike et al (1954), found that brain tumors located in the posterior portion of the temporal lobe cause a directional preponderance of caloric induced vestibular nystagmus to the side of the lesion.Hakas and Kornhuber (1959), published their studies of DP in 201 cases of localized cerebral lesions. They found only 31% of the cases had DP of vestibular nystagmus. Of these, 67% were to the side opposite from those of the lesion and 33% toward the lesion. Their conclusions, very different from those of Hallpike et al, were that DP showed no direct relationship to a lesion in a particular part of a particular hemisphere.In answer to Hakas and Kornhubers' paper, Hallpike (1961), stated that this striking disparity between the two results can be attributed to the difference of techniques of physiological conditions of the test procedure employed, namely, the former test were carried out with active optic fixation, and the latter with eyes closed.In view of the conflicting reports of the literature concerning the problem of DP phenomenon, the author has reinvestigated on this problem, from the clinical and experimental observations. Attention was directed to the following points.1) Does a precise localization of the cortical area which influence the vestibular system and produce DP of induced nystagmus, truely exist or not?2) Is DP of induced nystagmus affected significantly according to the difference of test procedures, i.e. test with optic fixation maintained and test with eyes closed?3) Is vestibular test of no value in the localization of cerebral lesions as concluded by Hakas and Kornhuber?In the animal's experiment, the author has employed a new type of method, i.e. focused ultrasonic irradiation to make localized lesions in the brain of rabbits.Results obtained from both the experimental and clinical observations are summarized as follows.1) DP phenomenon shows no direct relationship to a lesion in a particular parts of a particular hemisphere, as reported by Kornhuber and others.2) The region of responsibility for the development of DP will be located in some parts level with the subcortical area or the brain-stem.3) By the use of focus ultrasound irradiation, pronounced DP to the side of the lesion could be observed from the lesions of pontomesencephalic reticlar formation of the rabbits.
- 一般社団法人 日本耳鼻咽喉科学会の論文