310 N. I. GRASHCHENKOV 



out. Moiseev (1957) detected serious morphologic changes in the hypophysis 

 of guinea pigs after irradiation. 



Shamova (1958) demonstrated the distortion of several vegetative reflexes 

 such as Scherbach's heat reflex, and variation in the sensitivity to ultraviolet 

 radiation, which, with the clinical picture supports the hypothesis that the 

 hypothalamus plays a leading part in onset of the disease. 



These findings are in full agreement with our own morphologic research, 

 which also indicates that exposure to radiation causes pronounced damage 

 to the hypothalamic region. Various authors suggest different systems of 

 classification for the clinical symptoms that have been discovered. 



The early phase is described as moderately pronounced cerebral asthenia 

 which manifests itself as an asthenovegetative syndrome. More pronounced 

 changes are described as an astheno-organic syndrome (encephalopathy). 



There are also a good many dubious descriptions. Khazanov and Korenev- 

 skaya (1958), for example, have described a case of neuritis of the femoral 

 nerve as being due to the eflfect of radiation. 



The number of works devoted to acute radiation sickness is considerably 

 smaller. Pigalev (1954) divides the disease into three phases: acute, sub- 

 acute, and chronic. In cases of severe damage death occurs before the end 

 of the acute phase. 



Kurshakov (1954) subdivides the acute form into four periods: first period, 

 a few hours after exposure; second or latent period, lasting a few days to 

 2 weeks; third period, grave symptoms; fourth period, recovery. 



It follows that ionizing radiation affects the activity of all links in the 

 nervous system (the receptor apparatus, peripheral nerves, the peripheral 

 parts of the vegetative nervous system, spinal cord, different apparatus of the 

 brain stem and hypothalamic-diencephalic region), and it has a direct eff"ect 

 on the cerebral cortex. 



It is difficult to determine which of these many interrelated parts is most 

 affected, since the disturbance of any one leads to deviations from the 

 normal condition in all parts of the nervous system. 



In my view, the most important damage done by ionizing radiation is to 

 the receptor apparatus, the higher vegetative and endocrine centers of the 

 superior parts of the brain stem and the cerebral cortex. 



One of the main effects of ionizing radiation on the receptor structures 

 (resulting either from the direct action of radiation or from the action of the 

 radicals formed in tissues during irradiation) is that the normal transmission 

 of the nervous system's information is disturbed and several reflex responses 

 are distorted. 



As the well known research by Vvedensky and Ukhtomsky has shown, the 

 excessive inflow of impulses favors the development of parabiotic states and 

 pathologic dominants at different levels of the nervous system. 



Functional and organic changes occurring in the hypothalamic and di- 



