246 J. R. M. INNES AND A. CARSTEN 



vertebral muscles in the direct vicinity of the spinal cord damage, i.e., in 

 the same irradiated area. The specificity of this myodegeneration in that it 

 was caused by the irradiation is undoubted for the lesion is certainly not 

 artifact or traumatic due to handling the rats. The changes are no different 

 in kind or severity from those seen in types of myodegeneration of man, 

 domestic, or laboratory animals, and which can be produced by a multi- 

 plicity of causes, perhaps most characteristically in natural and experimental 

 alpha-tocopherol deficiency (Hadlow, 1961 ). That some of the lesions were 

 old chronic ones was e\ident by the frecjuency of calcareous depositions, and 

 again no changes in the walls of arteries supplying aflfected muscles were 

 seen. Skeletal muscle is regarded as radio-resistant, but there are few obser- 

 \ations on muscle in concurrent studies of any more deep-seated process 

 which follows irradiation of the nervous system. 



The study is being continued using both rats and monkeys, with the 

 ]3articular aim of seeking clues to determination of the early stage of 

 damage to the nervous system and thus to a better understanding of patho- 

 genesis. The clinico-pathologic studies on monkeys along with serial EEG 

 recordings is but part of this study. In rats, groups of animals have also 

 been irradiated in the lumbar enlargements of the spinal cord. Finally, as 

 such experimental work has clear medical radiotherapeutic implications, 

 groups of animals are now being irradiated with the same dose (3500 rads), 

 but in divided doses following patterns used in radiotherapeutic treatment 

 of lumian beings. 



ACKNOWLEDGMRNT.S 



Our thanks are due to Mr. R. F. Smith, Photographic Division, Brook- 

 haven National Laboratory, for the photographs; to Miss Claire M. Lallier, 

 for technical assistance and care of the experimental rats: and to Miss Ruth 

 Wright, for her part in the extensive histological work involved in the 

 pathologic studies on the rats. 



Refp:rences 



Boden, G. 1948. Radiation myelitis of the cervical spinal cord. Brit. J. Radiol. 21. 

 464-469. 



Clementc, C. D., and Hoist, E. A. 1954. Pathological changes in neurons, neuroglia, 

 and blood-brain barrier induced by x-irradiation of heads of monkeys. A.M. A. 

 Arch. Neurol. Psychiat. 71, 66-79. 



DavidofT, L. M., Dyke, C. G., Elsberg, C. A., and Tarlov, I. M. 1938. The eflfect of 

 radiation applied directly to the brain and spinal cord I. Experimental investiga- 

 tions on Macacus rhesus monkeys. Radiology 31, 451-463. 



Dynes, J. B., and Smedal, M. I. 1960. Radiation myelitis, Am. ] . Roentgenol., Radium 

 Therapy Nuclear Med. 83, 78-87. 



