せき柱側湾症例の視運動系平衡障害　：　頭けい部外傷例でのそれとの比較観察　　Ｐａｒｔ　Ｉ　：　視運動性眼振のＦｏｖｅａｌ‐Ｐａｔｔｅｒｎ，Ｒｅｔｉｎａｌ‐Ｐａｔｔｅｒｎの分布を指標とする分析　Ｐａｒｔ　ＩＩ　：　Ｆｏｖｅａｌ‐Ｐａｔｔｅｒｎ緩除相のＳｔａｂｉｌｉｔｙを指標とする分析

To see the characteristics of ataxia induced by scoliosis we attempted to examine the equilibrium function of scoliotic patients using the tests for optokinetic nystagmus and compared the results obtained with those from patients with head and neck injury. The methods of analysis of optokinetic nystagmus used herein were the following two. One was that in which nystagmic responses were recorded using “the superimposed method” and these were further divided into the following two patterns: foveal and retinal (hereafter termed the method of Nakano et al., 1972). The other was that in which the above-described foveal pattern was adopted and tested in terms of both degrees and patterns of fluctuation of the slow phase (hereafter termed the method of Izumikawa, Futaki et al., 1978).<br>The results from these two methods of analysis of optokinetic nystagmus and our interpretation of these results were as follows.<br>(1) In the patients with scoliosis and those with head and neck injury, malfunction of the oculomotor system was observed and it contributed to abnormal development of both foveal and retinal patterns. Furthermore, in the former group, the system related to the production of the foveal pattern (i. e., the pursuit-movement system) was predominantly disturbed, whereas in the latter, the system related to the production of the retinal pattern (i. e., the saccadic-movement system) was significantly deteriorated.<br>(2) The patients with head and neck injury tended to show an increased retinal pattern when a small dose of adrenaline (0.006mg per kg of body weight) was injected subcutaneously. This indicates that the malfunction of the above-mentioned saccadic-movement system is possibly due to hyperexcitability of the adrenaline-sensitive component in the brain stem reticular formation (Rothballer 1956). Furthermore, in traumatized patients dysfunction of the cerebellum possibly contributes to excessive development of the retinal pattern, in collaboration with the hyperexcitability of the above-mentioned adrenaline-sensitive component. In contrast, the scoliotic patients tended to show a decreased retinal-pattern when the same drug was given. Furthermore, no signs of cerebellar symptom were found in these patients. With reference to these results and those described in item (5), the malfunction of the pursuit-movement system which was mentioned above was possibly induced in relation to the following two factors: abnormal tonic impulses from the truncal proprioceptors (particularly, those from the lumbar region) and congenital dysfunction of the hypothalamo-brain stem system. Thus, we postulate that there are demonstrable differences between the two groups of patients with regard to the development of malfunction of the oculomotor system.<br>(3) Traumatized patients with cerebellar symptoms responded to slow and rapid movements of stripes of an optic cylinder, showing excessive development of overshooting form and slowing of pursuit, respectively.<br>This indicates that the cerebellum probably exerts the following two different actions on the reactivity of the oculomotor system, particularly the brain stem. One is an inhibitory action on the hyperreactivity of the pursuit-movement system in the brain, which is manifested in response to slowly moving objects. The other is an excitatory action on the hyporeactivity of the saccadic-movement system, which is displayed in response to rapidly moving objects. Through the two types of actions of the cerebellum, foveo-retinal coordination is effectively realized in response to various optokinetic stimuli, through which the brain participates in the maintenance of equilibrium of humans.<br>(4) The method of Nakano et al. was found to be useful in detecting dysfunction of the cerebellum, showing excessive development of both overshooting form and slowing of pursuit. The method of Izumikawa, Futaki et al. was noted to be valuable in demonstrating dysfunction of the cerebellum