68 YAMAZAKI, BENNETT AND CLEMENTE 



thickenino, there invariably was some thickening in the walls of the medium 

 sized and smaller arteries of the pial layers. 



Discussion 



The neurologic findings observed in the rats in this study are similar to 

 the findings of other investigators in their studies on irradiated newborn and 

 young guinea pigs, rabbits, kittens, and dogs (Danysz, 1903: Turner and 

 George. 1910; Brunner, 1920; Nemenov, 1934; Demel 1926; Mogilnitzky 

 and Podljaschuk, 1930). Tremors, clonic twitching, epileptoid seizures, pa- 

 ralysis of extremities, retardation of head and body size, and poor mental 

 performance have been reported. Previously, however, a systematic sequen- 

 tial age-dose relationship during the neonatal period had not been demon- 

 strated. 



The eflfect of radiation on the developing human brain is not as well docu- 

 mented as are the animal studies. The occurrence of microencephaly, mental 

 defectives, hydrocephaly, ossification defects of the cranial bones, eye defects, 

 and skeletal abnormalities in children born after maternal pelvic irradiation 

 has been reported (Murphy, 1929; Goldstein and Murphy, 1929). Intrau- 

 terine exposure of the fetus to atomic radiation in sufficient amount to cause 

 acute radiation eflfects on the mother has resulted in children with signifi- 

 cantly smaller head circumferences than in the control group (Plummer, 

 1952; Yamazaki ct al., 1954). Information concerning irradiation of the 

 head alone in infants and children is scanty. Children irradiated for scalp 

 lesions developed epilation in three weeks, and, after a year or so, hemi- 

 paresis and siezures developed in one patient (Lorey and Schaltenbrand, 

 1932) and a subdural hematoma was reported. In contrast to this, over 

 3,000 persons, many of whom were children, recei\ing epilating doses of ra- 

 diation for treatment of tinea capitis had no evidence of injury to the brain 

 (Mackee and Cipollaro, 1946) . In another report, children over 3 years who 

 received radiation to the head for a similar condition did not develop any 

 abnormal neurologic findings (Macleod, 1909). Children under 3 years were 

 not radiated to avoid any possibility of radiation injury. Periods of somno- 

 lence lasting from 4 to 14 days were noted in 30 out of 1,100 children epi- 

 lated by radiation therapy for ringworm of the scalp (Druckmann, 1929). 

 A similar type of reaction was noted in adult human volunteers who received 

 approximately 150 r to the diencephalic area (Birkner and Trautmann, 

 1953). Disturbances of sleep-wake patterns and changes in gonadal function 

 also were noted. In this regard, radiosensitivity of the hypothalamus and 

 brain stem has been demonstrated in recent studies by Clemente and Hoist 

 (1954) and Arnold and his associates (1954a,b,c). A report on the sur- 

 vivors of the atomic bomb explosions who exhibited no sign of burns. 



