v57supp43 48, [ Pobierz całość w formacie PDF ]
//-->Nagoya J. Med. Sci. 57 (Suppl.).43 - 48, 1994HAND-ARM VIBRATION EXPOSURE ANDTHE DEVELOPMENT OF VffiRATION SYNDROMEKAZUHISA MIYASHITA!, KUNIHIKO MIYAMOTO!,MOTOTSUGU KURODAl ,SHINTARO TAKEDAland HIROTOSHI IWATA2IDepartment of Hysiene, Wakayama Medical College, Wakayama 640, Japan2Department of Hygiene, School of Medicine, Gifu University, Gifu 500, JapanABSTRACTTo evaluate the circulatory disturbances, sensory disturbances and damage to muscles and joints by chainsaw vibration exposure, the process of the deterioration of the symptoms with chain saw operating time wasstudied. Subjects were classified into eight groups according to TOT (Total Operating Time): Group 0,46controls; Group A,39operators«2,000hours); Group B,53operators(2,000-4,000hours); Group C,45operators(4,000-6,000hours); Group D,29operators(6,000- 8,000hours); Group E,31operators(8,000-10,000hours); Group F,35operators(10,000-15,000hours); and Group G,34operators(>15,000hours). The subjective symptoms and clinical findings due to operating chain saws were dividedinto three main categories of peripheral circulatory disturbances, sensory disturbances and damage tomuscles and joints. According to the criteria, the total score of each disturbance was calculated per individ-ual in Group 0 and Groups A through G, respectively. The scores for the three (circulatory, sensory, mus-cles and joints) disturbances increased significantly with the increase of TOT. The scores for circulatory dis-turbances increased significantly in Group A and B, as compared with those in its previous Group, respec-tively. The scores for sensory disturbances increased significantly in Groups A, Band F. The scores for dam-age to muscles and joints increased significantly in GroupB.Key Words: Hand-arm vibration, Vibration syndrome, Raynaud's phenomenon, Dose-response relation-shipINTRODUCTIONWorkers occupationally exposed to vibration often complain of symptoms of peripheral cir-culatory disturbances, peripheral nerve disturbances and bone and joint disorders. Many cross-sectional and longitudinal investigations have been performed, and dose-response relationshipshave been derived from epidemiological data.l - S)In some papers, the response has been as-sessed only by the prevalence rate of a symptom or a finding, and Raynaud's phenomenon isoften used as a response. To evaluate vibration syndrome with complex symptoms, a compre-hensive or quantitative evaluation of the symptoms combined with clinical findings is needed. Inthis study, to evaluate circulatory disturbances, sensory disturbances and damage to muscles andjoints by chain saw vibration exposure, a scoring method is introduced and the process of dete-rioration of the symptoms with chain saw operating time was studied.SUBJECTS AND METHODSSubjects were 266 workers professionally exposed to chain saw hand-arm vibration, and 46controls, forestry workers never exposed to vibration. The subjects were all male and in ageCorrespondence: Dr. Kazuhisa Miyashita, Department of Hygiene, Wakayama Medical College, 27 Kyuban-cho, Wakayama640,Japan4344Kazuhisa Miyashitaet al.group40to59years of age to eliminate the effects of sex and age.Inorder to determine the vibration exposure dose for an individual, total operating time(TOT) was calculated from the full occupational history using the following equation: chain sawoperating time/dayXdays/yearXyears. Subjects were classified into eight groups according toTOT as follows: Group 0,46controls never exposed occupational hand-arm vibration; GroupA,39operators with less than2,000hours exposure; Group B,53operators with2,000-4,000hours exposure; Group C,45operators with4,000-6,000hours exposure; Group D,29oper-ators with6,000-8,000hours exposure; Group E,31operators with8,000-10,000hours ex-posure; Group F,35operators with10,000- 15,000hours exposure; and Group G,34oper-ators with over15,000hours exposure. Table1shows the subjects by TOT groups.Subjective symptoms were obtained by clinical interview from all subjects with reference tothe pain and/or numbness or tingling of hands and forearm or upper arms and restriction ofjoint movement. Clinical examinations consisted of peripheral circulatory function tests, sensoryfunction tests and motor function tests combined with cold water immersion tests. Raynaud'sphenomenon was identified by a medical doctor by detailed interview.The subjective symptoms and clinical findings due to operating chain saws were divided intothree main categories of peripheral circulatory disturbances, sensory disturbances and damage tomuscles and joints. Circulatory disturbances included Raynaud's phenomenon, skin tempera-ture, hyperemia time of the nail, tingling or numbness of hand and arm and some subjectivesymptoms. Sensory disturbances included loss of pain and vibratory sense, hypesthesia of touchsense, tingling or numbness of hand and arms and some subjective symptoms. Damage to mus-cles and joints included lowering of grip force and pinch power of finger, restriction of joint mo-bility, muscle pain, joint pain and some subjective symptoms.Subjective symptoms and findings of medical examinations were scored25points in total ineach category according to their severity, as shown in Table 2. According to the criteria, thetotal score of each disturbance was calculated per individual in Group 0 and in Groups Athrough G, respectively, and the mean scores were compared with Group 0 and the operatorsgroups. The correlation coefficients between total operating time and scores of operator groupswere also studied.Significance of scores in each group and correlation coefficients were statistically tested byStudent t-test.Table1.GroupNumber of subjects by the total operating time (TOT)TOTnoABo-20004000600080001000015000------CDEF200040006000800010000150004639534529313534G45VIBRATION EXPOSURE AND VIBRATION SYNDROMETable 2.(a) Circulatory disturbancesSymptoms or examination5Skintemperatul~eCriteria for scoring of symptoms and findingsCri teria for minimum scoreI - 3I - 3measurement before immersion test*re'cQvery rate**measurement before immersion te5t*measurement at:>min after immersion test*bela" 31.5"Cbela" 60.6%Hyperemia timeof the nailover 1.;) secover 2.0 secmorc than 1fingel'Raynaud's phenomenonTingling or numbnessSubjective s;ymptomsin fingers or handsin forearmhypesthesia forHarmand coldstiffness of fingers2 -2 -in either sidein either side(b) Sensory disturbancesPain sensemeasurement before immersion te51*measurement at5min after immersion lest*measurement before immersion test*measurement at:>min after immersion test*in fingersin forearmOJ'- 3- 3- 33over 2gr bj-' Heighted needleover 2gr by "eighted needleover 10 dBover 20 dBin ei thet' sidein ei theI'sideVibratory senseTingl ing or numbnessSubjective symptomshands- 3- 3eachfive subjective symptoms on h:.'pesthesiaof hands and arms(C) Damage to muscles and jointsGrip strengthPinch power~tuscleon dominant sidemeasurement between thumb and forefingeron dominant sidein hand, forearm and upper armin \.;ristIelbow and shouldel' jointswrist and shoulder jointselbow jointI--2eacheachbela" 40 Kgbelo" 5.5 KgpainJoint painRestriction of jointmobilityfluscle atrophy ofhandSubjective symptoms--2each3three subjective symptoms on inability toperform fine tasksI each*Either hand is immersed into 10"C"ater for 10 minutes**Recovery rate is the percent obtained from skin temperature at 10 min after immersion / skintemperature before immersionRESULTSThe mean scores in peripheral circulatory disturbances, sensory disturbances and damage tomuscles and joints were shown for each group (Fig. 1). The scores for circulatory disturbanceswas much, as well as those for sensory disturbances. The scores for damage to muscles andjoints were less than for the other two disturbances. The scores for the three (circulatory, sen-sory, muscles and joints) disturbances increased significantly with the increase of TOT(p<O.Ol). The scores for circulatory disturbances increased significantly in Groups A and B ascompared with those in the previous groups, respectively. The scores for sensory disturbancesincreased significantly in Groups A, BandF.The scores for damage to muscles and joints in-creased significantly in GroupB.Fig. 2 showed the prevalence rates of Raynaud's phenomenon and numbness of hands and46Kazuhisa Miyashitaet at.arms by group. The prevalence rate of Raynaud's phenomenon showed a straight-line elevationwith TOT and significantly increased in Group B as compared with Group 0, and in Group E ascompared with GroupB.The prevalence rate of numbness showed an arch shaped elevationwith TOT and significantly increased in Groups A and B as compared with Groups 0 and A, re-spectively, and showed a slight increase in Groups B through G.SCORE16141210*<>Sensory dis turbancesdis turbances86+Circu 1a tory'"90amage to muscles and joints(Mean±SE)*p<0.0542oFig. 1.IIIIII(o200040006000800°100065000 (TOT)The scores in circulatory disturbances, sensory disturbances and damage to musclesand joints by the groups divided according to TOT.10080<ll.....~60<ll<llCUa.....co><ll40•20oFig. 2.Prevalence rate of Raynaud's phenomenon and numbness of handand arms among chain saw operators.47VIBRATION EXPOSURE AND VIBRATION SYNDROMEDISCUSSIONInour previous studY,I,3) we investigated the vibration exposure time-response relationshipamong chain saw operators by the prevalence rates of various symptoms. In the group with lessthan 2,000 hours exposure, the findings were characteristic of the early stage of the syndromesuch as tingling or numbness, pain in hand and arm. In the group with less than 5,000 hours ex-posure, peripheral circulatory and nerve disturbances were observed from not only subjectivesymptoms but also clinical aspects such as prolonged recovery of finger skin temperature aftercold water immersion or hypesthesia of pain and vibratory sense. Raynaud's phenomenon wasobserved among about 30% of operators. Muscles, bone and joints were affected, and a weak-ness of grip strength appeared. With longer exposure of less than 8,000 hours, there was asteady progression of symptoms. Raynaud's phenomenon occurred more frequently and wasmore severe. Both circulatory and nerve functions were more severely affected, and the pre-valence of muscles disturbance, along with pain in the joints and bones, increased. The majorityof symptoms in this group were considered to be functional changes, although, in some cases,organic changes were involved. In the group with operating time in excess of 8,000 hours or so,the prevalence of Raynaud's phenomenon was 50%, and the area of finger blanching enlarged.Circulatory as well as nerve disturbances progressed, giving rise to a typical pathological condi-tion seen in a severe stage of vibration syndrome. Occasionally, this severe stage was combinedwith damage to bones and joints, evidencing further organic change.In the present study, the scoring method was introduced for the evaluation of the severity ofvibration syndrome. This method involved subjective symptoms and clinical findings for periph-eral circulatory disturbances, sensory disturbances and damage to bones and joints, which werescored according to the criteria. Development of vibration syndrome was quantitatively assessedby the scoring method. According to the criteria, the total score for each disturbance was calcu-lated per individual in Group 0 and in Groups A through G, respectively. The mean score ineach category showed a significant elevation with the increase of TOT. This confirmed the dose-response relationship in vibration syndrome. In the curves of circulatory disturbances and sen-sory disturbances, there was a marked elevation at 0-2,000 hours, 2,000-4,000 hours and8,000-10,000 hours. These were considered to be important points in the development of vi-bration syndrome over time.However, the prevalence rate of Raynaud's phenomenon showed a straight-line elevationwith TOT, and the prevalence rate of numbness showed an arch-shaped elevation with TOT.The former was considered to be the symptom combined with circulatory and sensory disturb-ances, and the latter is associated with manifest circulatory disturbances. Judging from the pre-valence, Raynaud's phenomenon could be a better indication of the dose-response relationshipor the staging in vibration syndrome, as used in some stage classifications or models.6- S)CONCLUSIONAccording to the scoring methods for the symptoms of vibration syndrome, circulatory dis-turbances, sensory disturbances and damage to muscles and joints among chain saw operatorsdeteriorated with total chain saw operating hours. The dose-response relationship in vibrationsyndrome was quantitatively confirmed. [ Pobierz całość w formacie PDF ]