Hand function in workers with hand-arm vibration syndrome

Hand Function in Workers with Hand-Arm Vibration Syndrome Ragnhild Cederlund, OT, MSc Department of Hand Surgery Malmo University Hospital Malmo, Sweden

Ake Isacsson, PhD

Department of Clinical Neuroscience Division of Occupational Therapy Lund, Sweden

Goran Lundborg, MD, PhD Department of Hand Surgery Malmo University Hospital Malmo, Sweden

H condition

and-arm vibration syndrome is a complex with vascular, sensorineural, and musculoskeletal components. Besides circulatory disturbances known as vibration-induced white fingers, sensory and motor disturbancessuch as numbness, reduced sensation and dexterity, clumsiness, inability to manipulate small objects,' and impaired grip strength-are common symptoms. 1- 9 Workers exposed to hand-held vibrating instruments may be at risk for developing hand-arm vibration syndrome. Eleven percent of all manualworking men in Sweden report that they are using vibrating machines 50% or more of their working time during a normal day. Among manual-working women the corresponding proportion is 1 percent. 10 Among workers exposed to vibration, the reported prevalence of neurovascular problems ranges from 6% to 100%, with an average of about 50%.11 The prevalence of vibration-induced white fingers has been reported to be 25% among car mechanics/ 40% among grinders and welders,12 and up to 80% among stone cutters. 13 - 15 Sensory disturbance has been reported in 30% to 80% of vibration-exposed workers in various occupational groupS.16-19 Several reports indicate an increased prevalence of carThis study was supported by grants from the Swedish Council for Worklife Research and Swedish Medical Research Council, project no. 5188. Correspondence to Ragnhild Cederlund, Department of Hand Surgery, Malmo University Hospital, S-205 02 Malmo, Sweden.

16

JOURNAL OF HAND THERAPY

ABSTRACT: Hand-arm vibration syndrome has been specially addressed in the Scandinavian countries in recent years, but the syndrome is still not sufficiently recognized in many countries. The object of this preliminary study was to describe the nature and character of vibration-induced impairment in the hands of exposed workers. Twenty symptomatic male workers (aged 28 to 65 years) subjected to vibration by hand-held tools were interviewed about subjective symptoms and activities of daily living and were assessed with a battery of objective tests for sensibility, dexterity, grip function, and grip strength. The test results were compared with normative data. The majority of patients complained of cold intolerance, numbness, pain, sensory impairment, and difficulties in handling manual tools and in handwriting. The various objective tests showed considerable variation in indications of pathologic outcome, revealing differences in sensitivity to detect impaired hand function. SemmesWeinstein monofilament testing for perception of light touchdeep pressure sensation, the small-object shape identification test, and moving two-point discrimination testing for functional sensibility provided the most indications of pathologic outcomes. The authors conclude that vibration-exposed patients present considerable impairment in hand function. J HAND THER 12:16-24, 1999.

pal tunnel syndrome in vibration-exposed workers. 20 - 28 The most common tools and machines causing hand -arm vibration syndrome are pneumatic tools such as grinders, drills, jackhammers, fettling tools, riveting guns, impact wrenches, and chainsaws. 2 Workers in vibration-exposed professions include forest workers, miners and stoneworkers, welders, iron-plate workers, bricklayers, concrete workers, machine fitters, electricians, and carpenters. lO Dental personnel such as dentists, dental hygienists/9 and dental technicians30 are also exposed to vibration, mostly through high-speed hand-held tools and ultrasonic scalers. When evaluating and assessing hand problems arising from vibration exposure, several factors should be considered. A diagnosis is often based on a typical history by the patient describing subjective symptoms such as cold-induced blanching of fingers and impaired sensibility, dexterity, and grip force. 3 The most frequently used classification system for vibration injury, the Stockholm Workshop scale for vascular 31 and sensorineural32 symptoms, is based exclusively on the patients' subjective complaints. The Stockholm Workshop scale is a result of a consensus conference held in Stockholm in 1986 and represents a revision of the previously used Taylor-Pelmear scale for staging vibration-induced hand problems. The TaylorPelmear scale focused mainly on vasospastic changes in the hands and did not distinguish between vascular and neurologic problems. 33 The new

TABLE 1. Patient 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Sex Male Male Male Male Male Male Male Male Male Male Male Male Male Male Male Male Male Male Male Male

Age 65 58 58 57 56 55 53 53 53 50 48 48 46 44

41 38 36 34 31 28

Patient Characteristics

Dominant Hand Right Left Right Right Right Right Right Right Right Left Right Right Left Right Right Right Right Right Right Right

scale, however, differentiates the vasospastic and neurologic components. For an objective medical assessment, patients with hand -arm vibration syndrome are usually subjected to various laboratory tests of vascular function in the hand and impulse conduction in peripheral nerves. 34,35 However, how vibration-induced disturbances affect hand function is not well understood. Hand function is defined in this study as the overall functioning of the hand, including sensibility, dexterity, grip function, and grip strength. Several specific tests for sensibility, dexterity, grip function, and grip strength are used routinely in hand rehabilitation units. In our department, patients with vibration-induced impairment are usually not assessed by a hand therapist, unless they are referred to the hand surgery department and questioned about the functional capacity of the hands. Studies of vibration-induced impairment a??ress ~ome aspects of hand function 3,29 and specIfIC tORICS, such as the effect on manipulative skills/6 - 38 but no studies provide an overall description of these patients with reference to hand function, functional limitations of the hand and upper extremity, and the effects of impairment on activities of daily living (ADLs). The aim of the present study was to describe the nature and character of vibration-induced impairment of the hands of exposed workers. In the literature the functional consequences of handarm vibration syndrome have been addressed almost exclusively in terms of laboratory (e.g., neurophysiologic and vascularphysiologic) tests. Our hypothesis is that vibration exposure affects hand function.

Exposure Time (years)

45 25 19 15 30 37 34 25 17 35 28 21 25 27 20 18 19 17 13

8

Affected Side Bilateral Bilateral Bilateral Bilateral Bilateral Bilateral Bilateral Bilateral Bilateral Bilateral Bilateral Bilateral Bilateral Bilateral Bilateral Right Bilateral Bilateral Right Left

Occupation Carpenter Mechanic Machine fitter Electrician Construction worker Dental technician Dental technician Machine fitter Truck driver Mechanic Dental technician Building constructor Iron-plate worker Carpenter Iron-plate worker Industrial worker Iron-plate worker Industrial worker Carpenter Machine fitter

MATERIAL AND METHODS Subjects Twenty male workers, consecutively referred to the Department of Hand Surgery at Malmo University Hospital for an investigation of vibration syndrome, agreed to participate in the study (Table 1). The inclusionary criteria were long-term exposure to hand-held vibrating tools combined with sensory problems (numbness) or vascular problems (white fingers) of the hand, or both. 39 The mean age of the patients was 47 years (range, 28 to 65 years). Seventeen patients were right-handed and three w~re ~eft-handed. Seventeen patients presented wIth bIlateral symptoms, and three with unilateral symptoms (two right side and one left). The mean period of vibration exposure was 24 years (range, 8 to 45 years). The patients (exposed group) had several types of manual occupations. Controls were used to obtain data for some objective tests for which normative data are lacking or for which results from a Swedish population were very low in comparison with available normative data. 40 The control (nonexposed) group consisted of 20 men not exposed to vibration. Their mean age was 46 y:ears (range, 25 to 62 years). They matched the patient group for sex, age, and handedness. Hospital staff and students were recruited as controls.

Data Collection The data collection consisted of three main parts: an interview with the patient to establish January-March 1999

17

subjective symptoms, self-report by means of an ADL questionnaire, and an objective assessment. All patients took part in an assessment during a few hours during the same day, starting with a questionnaire for subjective symptoms and ADLs and continuing with a battery of 15 tests. The assessment was conducted by one of the authors (R.c.) in a standardized way. The tactilometry test for perception of vibration was carried out by a laboratory assistant a few weeks prior to the assessment, and classification of using the Stockholm Workshop scale was done by a hand surgeon a few weeks before the assessment. Both hands were affected in 17 patients, and both hands were assessed in this study. We recorded the results for the most severely affected hand. Interview for Subjective Symptoms

All patients were interviewed and their impairments classified according to the Stockholm Workshop scale for vascular3! and sensorineuraP2 symptoms. In addition to the Stockholm Workshop assessment, specific questions were asked regarding eight fundamental symptoms affecting hand function: cold intolerance, white fingers, pain, sensory reduction, muscle cramp, weakness in grip strength, tendency to drop things, and numbness. Cold intolerance is defined as pain and coldness without blanching of the fingers on exposure to a cool environment.3 The subjective symptoms were each scored on a scale based on four alternatives: 1 point, none/minor (mildest); 2 points, moderate; 3 points, disturbing; and 4 points, hinders function (most severe). After the assessment, patients used a Visual Analogue Scale (VAS) stick to score their pain on a scale from 0 to 10 cm. 4! Self-report ADL Questionnaire

All patients answered a questionnaire covering 28 ADLs in categories of personal care, home, and miscellaneous; they could also add activities in the category of work and leisure. 42 The scale is based on four alternatives: 1 point, can do easily (mildest); 2 points, can do with some difficulty; 3 points, can do with great difficulty; and 4 points, cannot do (most severe). Objective Assessment

All patients took part in an objective assessment using a battery of 15 tests for sensibility, dexterity, grip function, and grip strength. The tests and their functions are listed in Table 2. Perception of Light Touch and Deep Pressure. Serrunes-Weinstein monofilament testing was performed in a standardized way, as described by Bell-Krotoski/3 for assessment of perception of light touch-deep pressure. The monofilament minikit was used, with five probes with nylon hairs 18

JOURNAL OF HAND THERAPY

representing each level of functional sensibilitynormal touch, diminished light touch, diminished protective sensation, loss of protective sensation, and deep pressure sensation. 43,44 A sixth classification, "tested with no response," was included. The hand was mapped in 23 segments. A quantification of 0 to 5 was used: 5 for filament 2.83, 4 for filament 3.61, 3 for filament 4.31, 2 for filament 4.56, 1 for filament 6.65, and 0 for "not testable.,,42 A total score was calculated by adding the scores for all the segments of the hand. Reduced light sensation (filament 3.61) in all fingers was accepted as normal because of the manual workers' calloused skin. 43 Thus, a total score greater than 98 was considered normal. Perception of Vibration. Assessment of perception thresholds for vibration within frequencies of 8 to 500 Hz was performed as described by Lundborg et a1. 45 - 48 The index and little fingers of both hands were investigated. The pulps of the index finger (median nerve) and the little finger (ulnar nerve) were resting on a vibrating probe placed on top of a vibration exciter. The frequency of the vibration stimulus was changed automatically in ascending order from 8 Hz to 16, 32.5, 65, 125, 250, and 500 Hz. A vibrogram was obtained, normally with a characteristic shape. The sensibility index (51) was defined as the ratio between the integrated area under the test curve and the area under an age-matched control curve. 48 The 51 was used as a measure of vibration sense. Mean 51 for each hand with both nerves included was calculated for each patient. Functional Sensibility/Tactile Gnosis. Static two-point discrimination (s2PD) was measured as described by Moberg,49 and an s2PD score of 6 mm or less was regarded as normal. 50 Moving two-point discrimination (m2PD) testing was performed as described by Dellon/! and an m2PD score of 3 mm or less was regarded as normal. S! The Mackinnon-:Dellon Disk-Criminator (Disk-Criminator, BaltiTABLE 2.

Objective Assessment Instruments

Test Semmes-Weinstein monofilaments Tactilometry (sensibility index) Static two-point discrimination Moving two-point discrimination Shape identification tests, smalland large-object Moberg pickup tests, with and without vision Crawford small-parts dexterity test Purdue pegboard test Minnesota manual dexterity test Sollerman grip test Jamar dynamometry Pinch gauge, palmar and key

Function Perception of light touch-deep pressure Perception of vibration Functional sensibility / tactile gnosis Functional sensibility / tactile gnosis Functional sensibility / tactile gnosis Functional sensibility / tactile gnosis Dexterity Dexterity Dexterity Grip function Grip strength Pinch strength

more, Maryland) was used as the assessment tool. The shape identification tests 42,52 are fairly new tests that assess the patient's ability to identify the shapes of 24 objects (six shapes) with vision occluded, The objects vary in diameter from 7 to 20 mm in the large-object test and from 2 to 5 mm in the small-object test, The objects are randomly placed on a dumbbell, and identification is performed with two or three fingertips of choice,52 Both the large- and small-object tests were performed, and the number of correct answers was recorded, The Moberg pickup tests were developed in the 1950s to assess patients' ability to grip and manipulate objects with and without vision. 53 Twelve common objects were used, including cotton wool, a safety pin, matchstick, button, small lid, screw, nail, rubber, paper clip, piece of foam, coin, and key. The mean score of three consecutive trials for each hand was calculated for each patient. Dexterity. The Crawford small-parts dexterity test represents a combined assessment of finger dexterity, tool usage, speed, and job simulation, The test has two subtests, the pin test and the screw test. 54 In this study the pin test was used, as it was found to be a good discriminating test of dexterity.40 The time in minutes and seconds was recorded, The Purdue pegboard test measures finger dexterity and speed using small pins, washers, and collars. The test consists of five subtests addressing the right hand, left hand, and both hands, a summary of the results of these subtests, and an assembly test, 55 The right and left subtests were used in this study as recommended in an earlier study.40 The mean score of three consecutive trials for each hand was calculated and used in the analysis. The Minnesota manual dexterity test represents a shortened version of the Minnesota rate of manipulation test that was designed in the 1930s. The shortened version consists of two subteststhe picking test, which is a unilateral test, and the turning test, which is a bilateral test. These tests address gross coordination, dexterity, and speed,56 The picking test was used/o four trials for each hand were performed, and the total time in seconds was recorded. Grip Function. The Sollerman grip test57,58 was used for assessment of grip function. The Sollerman test consists of 20 tasks based on seven of the hand grips most frequently used in ADLs, and it gives a picture of both the ability and the quality of hand function. The test score correlates well with the accepted disability rating scale used by insurance companies in Sweden. 58 Grip Strength. The Jamar dynamometer was used, with subjects in the standardized positioning recommended by the American Society of Hand Therapists59 and using the second handle position for both men and women. 59,6O The mean of three successive trials for each hand was calculated. Pinch Strength. Pinch gauge testing was used for assessment of palmar (three-jaw chuck) pinch and key (lateral) pinch. The subjects used the

standardized positioning recommended by the American Society of Hand Therapists. 59,6Q The mean of three successive trials for each hand was calculated.

DATA ANALYSIS The results of all 15 tests for each patient were compared with normative or control data. For tests with no normative data-such as the small- and large-object shape identification tests and the Moberg pickup tests-results were compared with those for the matched control group, For several other tests-the Purdue pegboard test, Minnesota manual dexterity test, and Crawford small-parts dexterity test-results for a Swedish population were very low in comparison with available normative data,40 and results for the patient group were also compared with results for controls. For tests in which low scores indicate pathologic outcome-the small- and large-object shape identification tests and the Purdue pegboard testresults for the patient group were compared with results for controls and for the fifth percentile. For tests in which high scores indicate pathologic outcome-the Moberg pickup tests with and without vision, the Crawford small-parts dexterity test, and the Minnesota manual dexterity test-results for patients were compared with results for controls and for the 95th percentile. Results of three testsJamar dynamometry and the palmar and key pinch gauge tests-were compared with normative data,61 estimated in a one-sided 95% confidence interval. For five tests-Semmes-Weinstein monofilaments,43 perception of vibration,48 s2PD,so m2PD,51 and the Sollerman grip test58 -results for the patient group were compared with existing cutoff points for normative data.

RESULTS Interview for Subjective Symptoms The results showed that the majority of symptomatic patients With vibration-induced impairment presented with severe disturbances in hand function. The severity of sensorineural and vascular symptoms as classified on the Stockholm Workshop scale are indicated in Tables 3 and 4. In the sensorineural group, nine patients were classified stage 3SN, seven patients stage 2SN, three patients stage lSN, and one patient stage OSN. In the vasospastic group, 11 patients were classified stage 0, five patients stage 2, and four patients stage 3. In addition to classification according to the Stockholm Workshop scale, an assessment of the patients' subjective symptoms was made as described earlier. Results are shown in Table 5. The total number of patients describing their problems as severe and as hindering function showed that cold intolerance was the dominant complaint, followed by numbness, pain, sensory impairment, January-March 1999

19

TABLE 3.

Staging of Sensorineural Symptoms According to the Stockholm Workshop Scale

Stage

Symptoms

OSN lSN

Exposed to vibration but no symptoms Intermittent numbness, with or without tingling Intermittent or persistent numbness, reduced sensory perception Intermittent or persistent numbness, reduced tactile discrimination and/or manipulative dexterity

2SN 3SN

TABLE 4.

Stage 0 1 2

3 4

No. Patients 1 3 7

No. of Patients

Description

No attacks Occasional attacks affecting only the tips of one or more fingers Moderate Occasional attacks affecting distal and middle (and rarely, proximal) phalanges of one or more fingers Severe Frequent attacks affecting all phalanges of most fingers Like stage 3, with trophic skin Very severe changes in the fingertips Mild

11

0

5

4 0

TABLE 5. Subjective Symptoms (n = 20 symptomatic patients)

None! Minor

Disturbing

Severe

Hinders Function

1 1 2 2 3 2 5 9 25

4 4 5 5 5 7 5 5 40

5 13 8 8 8 10 5 6 63

. 10 2 5 5 4 1 5 0 32

Cold intolerance Numbness Pain Sensory impairment Weakness in grip Dropping things Muscle cramp White fingers TOTAL

TABLE 6. Activities of Daily Living (n = 20 symptomatic patients)

TOTAL

20

3

5

5 9 10 32

12 8 9 7 9

45

JOURNAL OF HAND THERAPY

5 7 6 4 1 23

From the questionnaire covering 28 ADLs, we present five activities described as difficult by the majority of the exposed workers: buttoning clothes, handwriting, handling a book or newspaper, handling manual tools, and lifting and carrying (Table 6). Comparison based on the total number of workers who associated each ADL with some or great difficulty showed that handling manual tools was the most difficult activity for patients to perform. Seventeen workers described it as difficult to perform, 12 associating it with some difficulty and 5 with great difficulty. Fifteen workers described handwriting as difficult to perform, 8 associating it with some difficulty and 7 with great difficulty. Fifteen patients described lifting and carrying as a difficult activity, 9 associating it with some difficulty and 6 with great difficulty.

Objective Assessment The scores of each patient on the objective assessment tests are presented in Table 7, with a summary of the results. The various tests showed considerable variations in their indications of pathologic outcome, showing differences in sensitivity to detect impaired hand function. The most discriminating tests (Figure 1) were Semmes.:Weinstein mono filaments, the small-object shape identification test, and the m2PD, showing pathologic outcomes in 18 of 20 patients in the exposed group, These were followed by the Purdue pegboard test, Moberg pickup test without vision, tactilometry (sensibility index), Sollerman grip test, Moberg pickup test with vision, large-object shape identification test, Minnesota manual dexterity test, Crawford small-parts dexterity test, pinch gauge for key pinch, pinch gauge for palmar pinch, and s2PD. The least discriminating was the Jamar dynamometer, showing pathologic outcomes in 4 of 20 patients.

DISCUSSION

CanDo CanDo Can with with Some Great Cannot Do Easily Difficulty Difficulty Do Handling manual tools Handwriting Lifting / carrying Buttoning clothes Handling book or paper

Self-report ADL Questionnaire

9

Staging of Vasospastic Symptoms According to the Stockholm Workshop Scale

Grade

weakness in grip strength, tendency to drop things, muscle cramp, and white fingers. After the assessment, patients assigned a pain score with the aid of a VAS stick. The mean score was VAS 6 (moderate pain), with scores ranging from 0 (no pain) to 8 (severe pain).

o

o o o o

o

The purpose of this study was to describe the nature and character of vibration-induced impairment of the hands of vibration-exposed workers. Among subjective symptoms a striking finding was the high complaint of pain and muscle cramp: 65% of patients described pain and 50% described muscle cramp that was disturbing and hindered their fUll-ction. There are no known quantification scales that include symptoms such as cold intolerance,

I-'

N

\0 \0 \0

~......

~

I

~

J»

C

w

Objective Assessment Test Scores for Each Patient and Summary of Results

77

92 95 76 76

79

108

97

95

30

37

35 25 17 35

20

18

17

l3

8

57

56

55

53 53 52

50

48 48

46

44

41

38

36

34

31

28

4

5

6

8

10

11 12 13

14

15

16+

17

18

19+

19

27 21 25 27 5

6

0.59 0.61

81

77

20

15/20

18/20

20

0.99

0.59

0.62

0.43

0.67

0.02

8 6

5/20 20

6

6

6

6

6

6 5

18/20 20

5

3

3

5

5

9

5

6

1.02 15

5

6

0.42

0.24

5

10

0.63

0.62

5

15 6

9

6

0.05

5

6 5

5

9

5

9

5

5

1.05

6

10

6

15

6

6

0.46

0.34

0.80

0.53

0.78

109

85

76 73 79 68

77

1.06

0.41

24

24

24 20

24

11 / 20 20

24

23

22

21

24

20

23 24 21 24

24

22

23

24

24

22

24

24

23

22

20 21

20

l3 14

20

18/ 20

16

19

16

15

14

8

9

18

17 12

13

7

20 9 9

12/ 20 20 15 14

11

11

10

15

14

29

40

10 13 11

10

15 19 11

8

15

17

11

17

17

14

12

13

11

16

13

15

16 30

22

22

20

36 31

20

16/20

20

20

25

27

49

82

11

15 15

20

11 11

20

17/ 20

11

16

16

13

11

6

11

12

15

31 24 75

10

9

12

11

7

6

12

9

10

12

26

46

27

19 31

35

44

34

40

33

7.26 362

4.47

6.07 20 4.75

6.49

8/20 20

6.03

11/20 20 331 312 20 255 249

293

240 269

4.25

311

326

456

367

5.16

5.09

6.11

11.05

323

293

274 4.44

345 315

288 288

295

354

313

592

307

4.54 5.40 6.40

5.43

8.55

5.16

11.38

8.01

8.07

5.25

6.11

6.20

79

12/ 19 19 78

79

80

80

80

78

75

80 79 79 75

80

MD

75 79

77

77

79

78

78

79

43

4/20 20 40 41

57

57

45

39

48

9

49 39 55 50

54

30

24 39

34

26

44

15

34

8.1 8.5

20

7/20

14

11

10

6

9

1

10 10

9

8

12

5

13

4.5

6

5

10

4

7

8

3

9.2 9.0

20

8/20

13

13

12

8

9

3

2

2

0

0

0

2

0

3

2

0

2

0

0

0

2

0

0

3

0

3

2

2

2

1

3

3

12 2

2

0

3

2

3

1

3

3

1

2

3

3

9

9

10

11

8

13

2.5

7

9

11

6

8.5

10

NOTE: s2PD indicates static two-point discrimination; m2PD, moving two-point discrimination; SN, sensorineural stage; V, vasospastic scale; MD, missing data. For the s2PD test, m2PD test, Moberg pickup test, Crawford small-parts dexterity test, and Minnesota manual dexterity test, lower scores indicate superior results. For all other tests, higher figures indicate superior results. Bold scores indicate pathologic results. "For normal values, see Sollerman and Ejeskar. 58 tFor normal values, see Mathiowetz et a1. 61 +Unilateral vibration injury.

20+ Patients with pathologic outcome: No. of patients: Mean Median No. of controls: Mean Median

9

7

75

18

58

3

54

77

25

2

15

62

45

65

58

1

SemmesCrawWeinstein TactilMoberg Moberg ford MinneStockShape Monofila- ometryl Pickup holm Identifi- Shape Pickup Purdue Smallsota Exposure ments, SensibilTest Test PegParts Manual Workcation, Identifito Whole ity cation, with Without board Dexter- Dexter7-20 Pinch Pinch shop Jamar PaVibraHand Index s2PD m2PD mm 2-5 mm Vision Test ity Test ity Test DynaVision Gauge, Gauge, Scale tion (Normal (Normal (Normal (Normal (Normal (Normal (Normal (Normal (Normal (Normal (Normal Sollerman mometry Palmar Key tient Age No. (Years) (Years) > 98) :$ 6 mm :$ 3 mm) = 24) > 16) < 13) > 14) < 6.24) (kg)t (kg)t (kg)t SN V > 0.8) < 25) < 310) Grip Test"

TABLE 7.

W mono filaments

---

-_. .__.......,..---

--- 1--···------..····,. --

J

hape identity 2-5mm

I

1

1

I

m2PD 1

Purdue pegboard test

I

I

I

Moberg pickup/no vision

J

Tactilometry

FIGURE 1. Sensitivity of objective assessment tests, based on the number of patients whose test results indicated impaired hand function. SW indicates Semmes-Weinstein; shape identity 2-5 mm, the small-object shape identification test; shape identity 7-20 mm, the largeobject shape identification test; m2PD, moving two-poillt discrimination; s2PD, static two-point discrimination.

1

!l

ollennan grip test

E

Moberg pickup/vision

= ...

= .: ~

J

I

I I

hape identity 7-20mm 1

I

Minnesota test

J

Crawford test 1

I

Pinch gauge, key pinch

I

Pinch gauge, palmar pinch

I

s2P D Jamar dynamometer

J 10

20

15

o of patients

pain, muscle cramp, weakness in grip strength, or tendency to drop things. Several ADLs, like handling manual tools and handwriting, were also severely affected. A surprising finding was the outcome of the Purdue pegboard test, which detected reduced hand function in 17 of 20 workers. This test, also called the finger-tip dexterity test, was one of the best tests to detect dexterity despite the simplicity of the task and the shortness of testing time. This test meets all criteria for a standardized test. The shape identification test is a fairly new test that has not been fully evaluated to meet the standardized norms. Further development of this test will be interesting, especially the small-object test with objects 2 to 5 mm in diameter. The test showed pathologic outcomes in 18 of 20 workers. It is apparent that tactile gnosis is reduced in vibration injuries. The Moberg pickup tests with and without vision form an integrated test of sensory and motor function, but the test is not standardized. The difference between indications of pathologic outcome by the two tests-12 of 20 workers in the test with vision and 16 of 20 workers in the test without vision-show that hand function is diminished when sight is excluded. The s2PD test is widely used for tactile gnosis despite the lack of standardization. The test is also difficult for the evaluator to perform. Moberg has stated that the test demands exactness, concentration, and cooperation between patient and examiner. 49 •62 The m2PD test also lacks standardization and is even more difficult to perform. The difficulty 22

JOURNAL OF HAND THERAPY

is the exactness of pressure and depth of pressure points required. Although the m2PD test showed a high pathologic outcome, in 18 of 20 workers, it is not readily accepted in clinical use, because of its difficulty. No standardized tactile gnosis test is available at the moment. While such tests are being standardized, the best available tests should be used. Some of the assessment instruments used in this study were standardized, but not all. A good standardized instrument should provide measures of reliability and validity, instructions for administering the test, a description of the equipment used,

TABLE 8.

Suggestions for a Subjective and Objective Assessment Battery

Test Subjective assessment: Stockholm Workshop scale Subjective symptoms ADL instrument Objective assessment: Semmes-Weinstein monofilaments Shape identification test Purdue pegboard test Tactilometry (sensibility index) Sollerman grip test Pinch gauge tests Jamar dynamometry

Function Sensorineural and vasospastic stages Cold intolerance, pain, muscle cramp Personal care, living, work, leisure Perception of light touchdeep pressure Functional sensibility/tactile gnosis Dexterity Perception of vibration Grip function Grip strength, key pinch, and palmar pinch Grip strength, transversal grip

normative data, instructions for interpretation and scoring, and a bibliography.63.64 Semmes-Weinstein monofilaments, the Purdue pegboard test, Sollerman grip test, Minnesota manual dexterity test, Crawford small-parts dexterity test, tactilometry (sensibility index), Jamar dynamometry, and the pinch gauge are the tests that best meet the standardized criteria. In this study we also demonstrated the efficacy of available assessment tests for sensibility, dexterity, grip function, and grip strength. The results show that these tests can be valuable as diagnostic tools and that they exhibit various degrees of sensitivity in the detection of vibration-induced impaired hand function. For instance, Semmes-Weinstein monofilaments, the small-object (2 to 5 mm) shape identification test, and the m2PD test indicated pathologic outcome in as many as 18 of 20 patients. Closely following on these, other teststhe Purdue pegboard test, Moberg pickup test without vision, and tactilometry (sensibility index)showed pathologic outcomes in 17, 16, and 15 of the 20 patients, respectively. The results indicate that these types of tests of hand function are most valuable and useful for objectively describing hand function following long-term vibration exposure. When hand function in vibration-injured workers is described, questions concerning subjective symptoms, performance of ADLs, and objective assessments need to be addressed. The Stockholm Workshop scale is widely used when describing sensorineural and vasospastic stages. Other symptoms that are described but not included in the Stockholm Workshop scale are cold intolerance, pain, and muscle cramp. Several tests proved useful in the detection and quantification of functional impairment. Such tests represent a useful complement to the routinely used laboratory tests for vascular and neurologic functions. Interesting objective assessment instruments of hand function to be included in further studies are listed in Table 8. They include SemmesWeinstein monofilaments for perception of light touch-deep pressure, the shape identification tests for functional sensibility and tactile gnosis, the Purdue pegboard test for dexterity, tactilometry for perception of vibration, the Sollerman grip test for grip function, Jamar dynamometry, and pinch gauge tests for grip and pinch strength. Our results help explain why vibrationexposed patients often experience substantially decreased quality of life and considerable problems in performing their work and ADLs. This preliminary study indicates that hand-arm vibration syndrome may cause an impairment and a disability that have not previously been sufficiently recognized. Acknowledgment The authors thank Birgitta Rosen, OT, MSc, Department of Hand Surgery, Malmo University Hospital, for constructive criticism, and Jan Ake Nilsson, Department of Statistics and Information Processing, Malmo University Hospital, for expert statistical advice.

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