強力集束超音波による猫脳の限局破壊—特に白質と灰白質の反応の差異に関する実験的研究

AN EXPERIMENTAL STUDY OF FOCUSED ULTRASOUND, WITH SPECIAL REFERENCE TO ITS PARAMETER PRODUCING LOCALIZED LESIONS IN THE WHITE AND GRAY MATTER OF THE CAT BRAIN

I．緒言

　近年，実験用動物，さらには，人間の中枢神経系に強力集束超音波を投射して，脳深部に限局性の組織破壊を行なう方法が多数報告され，神経生理学，神経病理学，そして，治療を目的とした神経外科学方面においても注目を集めてきている。しかし，この超音波を，最終的に人脳に対して自由に応用してゆくためには，まだ数多くの基礎的実験を必要とする。たとえば，次の諸点に関する研究や知見が要求される。すなわち，

　（1）破壊巣の時間的推移による変化およびその最終的な運命

High frequency (1MC) focused ultrasound can produce trackless localized lesions in the white and gray matter of the brain. The length and diameter of the lesion is a linear function of the number of ultrasonic pulses. The log. volume of lesion and log. number of pulses are also related linearly.

The white matter is more susceptible to destruc-tion by ultrasound than the gray matter. Also tissue components in the brain show the following order of susceptibility to focused ultrasound : myelin sheaths, axis cylinders, nerve cells, glia cells and blood vessels. So fiber tracts can be blocked with-out destruction of surrounding gray matter and de-myelination might be produced without histological changes of the axis cylinders.

By using a focused ultrasound under exactly cont-rolled dosages, accurately localized, quantitatively reproducible focal trackless destructive lesions can be produced in the central nervous system.