The investigation purpose is to study the features of chronic brain ischemia in persons subjected to radiation effect.
Materials and methods
An examination of 536 men aged from 39 to 60 years old having taken part in Chernobyl disaster clean-up in the period from 1986 to 1988 (the first group) was carried out. 436 men with burdened radiation induced anamnesis made the control group (CG). Both groups were representative in age, physical co-morbidity, intensity of encephalitic semiotics for April, 1986. The patients´ state evaluation was carried out on one diagnostic algorithm taking into account physical and neurologic state, radiological anamnesis, laboratory-instrumental investigation methods including brain CT, MRT.
The statistical treatment of the material was carried out with the help of the Biostat program. The Student´s criteria were used for pair values; the differences were considered to be authentic at p< 0,05.
Research results
For the accident moment there were no cerebrovascular insufficiency signs registered in the ACL, in 20 persons (4,2%) of the CG there was semiotics of initial signs of cerebrovascular insufficiency (ISCI) observed. A year after the emergency works the clinical picture of cerebral circulation insufficiency became apparent in 108 liquidators, that is 2,2 times as more than in the CG patients (49 persons). Among them the ISCI in the ACL made 9,9% (53 persons), in CG patients - 5,6% (27 persons); clinical implications of dicirculatory encephalopathy (DE) were detected in 10,2% of the ACL and 4,5% of the CG patients accordingly. In the ACL the organic manifestations of encephalitic pathology were represented by the I stage DE (8,9% of the cases) and the II stage DE (1,3% of the cases); in persons having been subjected to the radiation effect - only DE of the I stage (4,5%). For the following 3 years the DE was formed in 16,0% of the ACL: I stage DE - in 9,7% (52 persons), II stage DE - in 6,3% (34 persons); in every third liquidator (35,4%) the ISCI was registered. In patients without radiological anamnesis the DE was detected in 15,6% of the cases (75 persons): I stage DE - in 14,2%, II stage DE - in 1,4%), and the ISCI increase for three years made in them 15,8%.
The five-year-postaccident-period was characterized by the ISCI predominance (2,8 times as much; p<0,01) over the DE frequency both in the ACL (51,9% and 18,7% accordingly) and in the CG patients (ISCI - 37,9% of the cases; DE - 20,6% of the cases) with relatively stable state of cerebral hemodinamics. During the following 5 years (up to 1996) in the ACL the steady progredient course of chronic brain ischemia was registered. Clinical DE manifestations are detected in the majority (84,1%) of the liquidators (I stage DE - in 41,8%, II stage DE - in 37,5%, III stage DE - in 4,8%). Relatively healthy, i.e. having no clinical manifestations of chronic brain ischemia, 5,2% of the ACL (28 persons) remained. Among "unirradiated" persons the DE development dynamics was less expressed. In this group the ISCI (42,5%) and I stage DE (36,6%) patients prevailed.
The key moment of the 100% DE development in the ACL is a 15-year period after the effect of small radiation doses (Table 1).
Table 1. Discircular encephalopathy development dynamics in the examined patients for the period of 15, 20 years after the accident|
Diseases |
1 group (ACL), n=536 |
2 group (control), n=480 |
|||||||
|
2001 |
2006 |
2001 |
2006 |
||||||
|
Abs. |
% |
Abs. |
% |
Abs. |
% |
Abs. |
% |
||
|
ISCI |
0 |
0 |
0 |
0 |
|
36,2 |
71 |
14,8 |
|
|
I stage DE |
138 |
25,7 |
1 |
0,2 |
196 |
40,8 |
201 |
41,9 |
|
|
II stage DE |
350 |
65,3 |
444 |
82,8 |
78 |
16,3 |
169 |
35,2 |
|
|
III stage DE |
48 |
9,0 |
91 |
17,0 |
12 |
2,5 |
32 |
6,7 |
|
|
Total DE patients |
536 |
100 |
536 |
100 |
286 |
59,6 |
402 |
83,8 |
|
By that time the clinical picture of cerebral discirculation in 65,3% of the cases (350 persons) had been in accord with II stage, in 25,7% of the cases (138 persons) - the I stage, in 9,0% of the cases (48 persons) - III stage. The DE development dynamics in the CG persons bore a more gradual, progressive character, making 59,6% (286 persons) with the prevalence of I and II DE stages (40,8% and 16,3% accordingly). The cerebral affection manifestations corresponding to III DE stage were registered only in 12 patients (2,5%), that is 4 times less than in the ACL (p<0,001).
By 2006 (20 years after the accident) the diffuse ischemic cerebral affection clinical picture had been represented by II stage DE in 82,8% ACL, III stage DE - in 17,0%. In most of them there were cognitive disorders of various manifestation degree, which were combined with local neurologic syndromes (discoordinatory 88,6%, pyramidic 77,4%, psychoorganic 71,6%, progressive vegetative insufficiency 96,1%). The development of psychoorganic syndrome of different manifestation degree was registered in 76 participants of the emergency works (14,2%) by 1996, by 2006 their number grew 5,1 times as more (384 persons; p<0,001). In persons of general population these factors were significantly lower - 0,4% and 4,6% accordingly (p<0,001), that again confirms a more favourable type of the DE course in persons without radiation anamnesis. The increased brain epiactivity development has become specific for DE in persons with radiation anamnesis. In 1996 14 such patients (2,6%) were found out, by 2006 their number had increased up to 69 (12,9%; p<0,001). In the CG patients there were no epileptic phenomena registered.
Among the examined second group patients by 2006 the DE had been registered in 83,8% of the persons, almost the half of the patients (41,9%; 201 persons) having I stage DE, 35,2% (169 persons) - II stage DE, that is 2,8 times less than in the ACL. III stage DE was detected in 32 patients (6,7%); 7 patients (1,5%) were relatively healthy, i.e. had no clinical signs of DE.
Thus, the results of 20-year long observation showed that in persons subjected to ionizing radiation the development of chronic cerebral ischemia is characterized by an early and more "malignant" type of course compared to the patients of general population, for whom a gradual onset rate and a less expressed brain affection are definitive.
Conclusions
- Persons subjected to low-intensity ionizing radiation are referred to the high risk group of chronic cerebral ischemia development.
- In liquidators of Chernobyl Nuclear Power Plant breakdown aftereffects the development of chronic cerebral ischemia is characterized by an early and more "malignant" type of course compared to the patients of general population.
- The discirculatory encephalopathy course in accident consequences liquidators in Chernobyl Nuclear Power Plant bears gradual character: from stormy augmenting of cerebral affection symptoms during the first two years after the radiation, relative stability of the disease clinical implications in the following 5-6 years and then intensively - as a progressive diffuse process of encephalitic failure with forwardness of vegetative dysfunction, psychoorganic syndrome and epilepsy.