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VIBRATION SYNDROME
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believed to do this by interaction with receptor sites the cell surface. An L.A.T.s.-binding protein has been isolated from the thyroid gland, but whether this is identical with the protein of the T.s.H. receptor site has not yet been established. The most attractive current hypothesis is that L.A.T.S. may be an antibody reacting at or near the T.s.H. receptor site on the thyroid cell wall, thereby stimulating the adenylcyclase system in a manner similar to T.S.H. Satisfactory proof that L.A.T.S. causes thyrotoxicosis will probably only be obtained with the introduction of a more sensitive and specific in-vitro assay technique. As yet the bioassay has limited clinical application. It is useful in predicting the likelihood of congenital hyperthyroidism, and a more sensitive assay would be helpful in the diagnosis of thyrotoxicosis and in the assessment of its progress and remission. on
VIBRATION SYNDROME THE Industrial Injuries Advisory Council has again been asked to consider whether disorders induced by exposure to vibration from machinery should be prescribed under the National Insurance (Industrial Injuries) Act, 1965. In the Council’s report1 the majority of its members hold that these disorders should not be prescribed; but two members dissent. It has long been established that the chief abnormality is a state of " white nngers " or " dead hand ", indistinguishable from Raynaud’s phenomenon, and now sensibly called in the report " vibration-induced white fingers" (v.w.F.). There are other possible but less easily defined effects, such as bony cysts, neurological changes, or muscular aches in the hands and arms. Extensive investigations were conducted between 1944 and 1949 by members of the Medical Research Council’s former department for research in industrial medicine at the London Hospital 2-4; and some other surveys have been completed since.5 But little new fundamental knowledge has emerged. There is no doubt at all that a causal link exists between vibration transmitted to the hands and the later appearance of v.w.F. in cold conditions. Moreover, the phenomenon can be demonstrated in most of its victims sooner or later when the weather is right. These facts apart, the question of prescription bristles with difficulties. Firstly, there are myriad sources of vibration, and almost all people could claim to have been subjected to some of them. Secondly, it is not even necessary for a vibrating tool itself to be held in the hands, for grinders of castings against bench-mounted wheels may also have V.W.F.6 It would be impossible, therefore, to specify all the occupations for which prescription ought to give " cover ". Thirdly, Raynaud’s phenomenon is symptomatic of a variety of 1.
2. 3. 4. 5. 6.
Vibration Syndrome. Interim report by the Industrial Injuries Advisory Council. Cmnd. 4430. H.M. Stationery Office. 2s. Hunter, D., McLaughlin, A. I. G., Perry, K. M. A. Br. J. ind. Med. 1945, 2, 10. Agate, J. N., Druett, H. A. ibid. 1946, 3, 159. Agate, J. N. ibid. 1949, 6, 144. Stewart, A. M., Goda, D. F. ibid. 1970, 27, 19. Agate, J. N., Druett, H. A., Tombleson, J. B. L. ibid. 1946, 3, 167.
non-industrial diseases; and an idiopathic form, usually mild, is common among the general population. If be prescribed, the unscrupulous or misguided workmen might abuse the Act’s provisions. Certainly it would be necessary to establish a clear connection between a significant and sufficient duration of industrial exposure and the appearance of V.W.F.— though few people who believe themselves to be an industrially injured party would admit to any earlier v.w.F. were to
symptoms. Other difficulties arise. The disorder may appear some time after cessation of work with vibrating machinery. It is generally agreed that v.w.F. is often, perhaps usually, a minor disability; but it is not always so. Affected men seldom have to leave their work because of V.W.F., but they may do so on medical advice or if they are frightened of possible long-term effects. Some men find themselves at a disadvantage only if they voluntarily change from a warm inside job to an outdoor one. Still others, though they are not prevented from working, are handicapped in their outdoor hobbies or in special manual skills, such as violin-playing. It is easy to sympathise, therefore, with the Council in its continuing dilemma. It has played safe again; but many people will support the minority view and say that if a man suffers from a clearly visible abnormality of the hands as a result of his work, and if he can demonstrate a significant loss of function or capacity to enjoy life, he should be indemnified. This condition has been known for a long time. Is it really beyond the capacity of industrial medicine and the Law to evolve a formula which would allow compensation to the significantly affected but guard against the trivial or questionable claim ? In each case, a judgment would be called for-but there is nothing new in that.
LIGHT ON OBSCURATIONS THE central artery of the retina emerging at the optic disc must be more closely and more frequently scrutinised than any other blood-vessel in the body, and some of its pecularities may provide important diagnostic clues. It supplies only the inner retinal layers, and communication between its vascular territory and the
surrounding choroidal circulation is limited. Its four main branches, formed near the disc, communicate with each other only by way of a capillary network, so there are no effective alternative pathways should the main stem or one of the branches be suddenly occluded. Because these precarious anatomical arrangements exist in a tissue with a high rate of oxidative metabolism and a limited capacity to withstand ischaemia and because visual failure is such an obvious and alarming symptom, the eye is a uniquely sensitive index of vascular insufficiency. In the brain
or
two types. In the
eye, transient ischæmia may be of
first, the period of ischsemia coincides
with obstruction, partial or complete, of the regional artery, and the attack subsides when the vascular calibre returns to normal. In the second type there is no alteration in calibre and the ischaemic episode is due to a breakdown in homoeosiasis, provoked for example by systemic hypotension or by metabolic factors causing redistribution of blood.
believed to do this by interaction with receptor sites the cell surface. An L.A.T.s.-binding protein has been isolated from the thyroid gland, but whether this is identical with the protein of the T.s.H. receptor site has not yet been established. The most attractive current hypothesis is that L.A.T.S. may be an antibody reacting at or near the T.s.H. receptor site on the thyroid cell wall, thereby stimulating the adenylcyclase system in a manner similar to T.S.H. Satisfactory proof that L.A.T.S. causes thyrotoxicosis will probably only be obtained with the introduction of a more sensitive and specific in-vitro assay technique. As yet the bioassay has limited clinical application. It is useful in predicting the likelihood of congenital hyperthyroidism, and a more sensitive assay would be helpful in the diagnosis of thyrotoxicosis and in the assessment of its progress and remission. on
VIBRATION SYNDROME THE Industrial Injuries Advisory Council has again been asked to consider whether disorders induced by exposure to vibration from machinery should be prescribed under the National Insurance (Industrial Injuries) Act, 1965. In the Council’s report1 the majority of its members hold that these disorders should not be prescribed; but two members dissent. It has long been established that the chief abnormality is a state of " white nngers " or " dead hand ", indistinguishable from Raynaud’s phenomenon, and now sensibly called in the report " vibration-induced white fingers" (v.w.F.). There are other possible but less easily defined effects, such as bony cysts, neurological changes, or muscular aches in the hands and arms. Extensive investigations were conducted between 1944 and 1949 by members of the Medical Research Council’s former department for research in industrial medicine at the London Hospital 2-4; and some other surveys have been completed since.5 But little new fundamental knowledge has emerged. There is no doubt at all that a causal link exists between vibration transmitted to the hands and the later appearance of v.w.F. in cold conditions. Moreover, the phenomenon can be demonstrated in most of its victims sooner or later when the weather is right. These facts apart, the question of prescription bristles with difficulties. Firstly, there are myriad sources of vibration, and almost all people could claim to have been subjected to some of them. Secondly, it is not even necessary for a vibrating tool itself to be held in the hands, for grinders of castings against bench-mounted wheels may also have V.W.F.6 It would be impossible, therefore, to specify all the occupations for which prescription ought to give " cover ". Thirdly, Raynaud’s phenomenon is symptomatic of a variety of 1.
2. 3. 4. 5. 6.
Vibration Syndrome. Interim report by the Industrial Injuries Advisory Council. Cmnd. 4430. H.M. Stationery Office. 2s. Hunter, D., McLaughlin, A. I. G., Perry, K. M. A. Br. J. ind. Med. 1945, 2, 10. Agate, J. N., Druett, H. A. ibid. 1946, 3, 159. Agate, J. N. ibid. 1949, 6, 144. Stewart, A. M., Goda, D. F. ibid. 1970, 27, 19. Agate, J. N., Druett, H. A., Tombleson, J. B. L. ibid. 1946, 3, 167.
non-industrial diseases; and an idiopathic form, usually mild, is common among the general population. If be prescribed, the unscrupulous or misguided workmen might abuse the Act’s provisions. Certainly it would be necessary to establish a clear connection between a significant and sufficient duration of industrial exposure and the appearance of V.W.F.— though few people who believe themselves to be an industrially injured party would admit to any earlier v.w.F. were to
symptoms. Other difficulties arise. The disorder may appear some time after cessation of work with vibrating machinery. It is generally agreed that v.w.F. is often, perhaps usually, a minor disability; but it is not always so. Affected men seldom have to leave their work because of V.W.F., but they may do so on medical advice or if they are frightened of possible long-term effects. Some men find themselves at a disadvantage only if they voluntarily change from a warm inside job to an outdoor one. Still others, though they are not prevented from working, are handicapped in their outdoor hobbies or in special manual skills, such as violin-playing. It is easy to sympathise, therefore, with the Council in its continuing dilemma. It has played safe again; but many people will support the minority view and say that if a man suffers from a clearly visible abnormality of the hands as a result of his work, and if he can demonstrate a significant loss of function or capacity to enjoy life, he should be indemnified. This condition has been known for a long time. Is it really beyond the capacity of industrial medicine and the Law to evolve a formula which would allow compensation to the significantly affected but guard against the trivial or questionable claim ? In each case, a judgment would be called for-but there is nothing new in that.
LIGHT ON OBSCURATIONS THE central artery of the retina emerging at the optic disc must be more closely and more frequently scrutinised than any other blood-vessel in the body, and some of its pecularities may provide important diagnostic clues. It supplies only the inner retinal layers, and communication between its vascular territory and the
surrounding choroidal circulation is limited. Its four main branches, formed near the disc, communicate with each other only by way of a capillary network, so there are no effective alternative pathways should the main stem or one of the branches be suddenly occluded. Because these precarious anatomical arrangements exist in a tissue with a high rate of oxidative metabolism and a limited capacity to withstand ischaemia and because visual failure is such an obvious and alarming symptom, the eye is a uniquely sensitive index of vascular insufficiency. In the brain
or
two types. In the
eye, transient ischæmia may be of
first, the period of ischsemia coincides
with obstruction, partial or complete, of the regional artery, and the attack subsides when the vascular calibre returns to normal. In the second type there is no alteration in calibre and the ischaemic episode is due to a breakdown in homoeosiasis, provoked for example by systemic hypotension or by metabolic factors causing redistribution of blood.