The diagnosis of disorders caused by hand-transmitted vibration : Southampton Workshop 2000

The diagnosis of disorders
caused by hand-transmitted
vibration: Southampton
Workshop 2000
Appendix X5B to Final Report
May 2001

Research Network on Detection and Prevention of
Injuries due to Occupational Vibration Exposures
EC Biomed II concerted action BMH4-CT98-3291

MICHAEL J. GRIFFIN, MASSIMO BOVENZI

Content of Report in:
The diagnosis of disorders caused by hand-transmitted vibration: Southampton
Workshop 2000. Int Arch Occup Environ Health, 2001, supplement, in press.

Abstract
Objectives: To identify the current state of knowledge, current uncertainties and
future needs related to the diagnosis of disorders associated with the use of vibratory
hand-held tools.
Method: An international workshop was convened with invited experts, medical
doctors, scientists and engineers familiar with hand-transmitted vibration and the
diagnosis of vascular, neurological and musculoskeletal disorders. This paper
records the general conclusions from four panel discussions.
Results: For the most common vascular disorder (vibration-induced white finger), the
principal symptom and sign involves attacks of well-demarcated finger blanching
(Raynaud's phenomenon); a low finger systolic blood pressure following cooling is

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Vibration Injury Network
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indicative of vibration-induced white finger and a zero finger systolic blood pressure
can confirm an attack of Raynaud's phenomenon. For neurological disorders, some
symptoms can exist without detectable signs and some signs can exist without
symptoms; numbness and tingling are commonly reported but neurological changes
may be present without these symptoms. The pathogenesis of musculoskeletal
disorders in users of vibratory tools is not clear; symptoms may include pain that may
not be associated with abnormal results in objective tests. For both neurological and
musculoskeletal disorders, a thorough neuromuscular and skeletal examination is
required; diagnosis must consider the work history and medical history, the results of
physical examination and any objective tests in addition to other factors (e.g. age,
smoking, alcohol, systemic disorders, medication and neurotoxic agents) that might
have contributed to symptoms, signs and test results.
Conclusions: While vibration-induced white finger is caused by vibration, some
neurological and musculoskeletal disorders are the result of work with vibratory tools
where the separate roles of vibration, repetitive movements, grip and push forces,
non-neutral postures and any other ergonomic stressors are often unclear. Such
disorders may be more easily identified as being caused by the work than by
exposure to hand-transmitted vibration per se. A person found to have developed
disorders induced by either vibration or the work situation should not be returned to
the same vibration exposure or work without any changes expected to lessen the
risks.

Key words Hand-transmitted vibration, symptoms, signs, objective tests, vibration-
induced white finger, hand-arm vibration syndrome
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Introduction
Hand-transmitted vibration may contribute to various disorders of the vascular,
neurological and musculoskeletal systems of the body [1, 7]. These disorders can
result in disability and handicap to the affected person, with loss of work and
impaired quality of life. There are also costs to employers and welfare systems.
The early diagnosis of disorders caused by hand-transmitted vibration may help to
prevent the progression of disorders and serious disability. Sensitive and specific
methods of detecting problems and their progression may assist the affected
individual, help to advance knowledge of the causes of disorders and lead to
improved means of protection from injury.
The purpose of the Southampton Workshop 2000 was to bring together experts in
the diagnosis of disorders caused by hand-transmitted vibration so as to identify the
current state of knowledge, current uncertainties and future needs. Papers presented
at the workshop provided a foundation for four panel discussions. This paper records
the general conclusions from the panel discussions.

Vascular disorders
The principal vascular disorder associated with exposure to hand-transmitted
vibration is vibration-induced white finger, a type of secondary Raynaud's
phenomenon [1, 7, 12]. It was recognised that this may take several different forms
but the nature of the disorder, the symptoms and signs are most commonly as listed
in Table 1.
Objective methods of measuring finger circulation following finger cooling are
considered helpful but currently insufficient to identify the severity of vibration-
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induced white finger. This vascular disorder may vary between fingers so it is
desirable to assess all fingers when performing objective tests of finger circulation.
The diagnosis of vibration-induced white finger must recognise that there exist other
causes of similar symptoms and signs. The diagnosis cannot be made without
knowledge that there has been significant exposure to hand-transmitted vibration.
Although current standards suggest methods of calculating the risk of finger
blanching from exposure to hand-transmitted vibration, the estimates can be only
approximate in a group of exposed persons, not applicable to all tools, and never
sufficient to predict disorder in an individual [2, 8, 10].

Neurological disorders
There is clear evidence that work with vibratory tools can result in a wide variety of
neurological disorders [1, 7, 11], especially those involving sensory mechanisms
(Table 2).
Current experience suggests that symptoms of neurological disorders can exist
without detectable signs, and signs of neurological changes can exist without
symptoms [11]. Numbness and tingling are common but there can be neurological
changes without these symptoms. A thorough neurological and musculoskeletal
examination is required for the interpretation of any objectives tests. Diagnosis must
consider the work history and medical history, the results of physical examination,
objective tests and other factors that might have contributed to symptoms, signs and
test results [11].
Neurological disorders might arise from either the effects of hand-transmitted
vibration or as a result of other aspects of the work. There are currently no
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established means of predicting neurological disorders from the severity of
exposures to hand-transmitted vibration [2, 8].

Musculoskeletal disorders
Although users of vibratory tools may report musculoskeletal symptoms (e.g. ache,
pain, stiffness) in the fingers, hand, wrist, arm and/or shoulder, the pathogenesis of
the disorders affecting the musculoskeletal system can be varied and difficult to
determine [1, 7, 9], (Table 3).
There are no minimal signs of musculoskeletal disorders: symptoms can exist without
signs (i.e. without abnormal results using common objective tests).
There is some evidence that work with hand-held percussive tools producing low
frequency vibration (or repeated shocks) of high magnitude (e.g. chipping hammers,
road breakers, quarry drills) may be associated with abnormal radiological findings in
the wrist and elbow joints (e.g. premature osteoarthrosis, exostoses at the sites of
tendon insertion) [1, 5].
The relative importance of hand-transmitted vibration and other ergonomic and
psychosocial risk factors in the causation of musculoskeletal disorders is often
unclear [9]. Indeed, there is currently no established exposure-response relationship
between the physical characteristics of occupational exposures to hand-transmitted
vibration and the development of any musculoskeletal disorder [2].

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The diagnostic process
The method of obtaining information prior to differential diagnosis can be important.
Table 4 lists the generally preferred approach, although iteration around the
proposed order will often be necessary.
For health screening and health surveillance it may be sufficient to use
questionnaires, often completed by a trained interviewer questioning workers. There
should be some measure of quality control to check the accuracy of responses
obtained when using questionnaires.
For some purposes, and in some countries, medical doctors will be required to
perform some, or all, of the diagnosis, especially when a change of employment or
litigation is under consideration. Currently, the diagnosis of neurological and
musculoskeletal disorders is complex and requires the examination and opinion of a
suitable expert who is in possession of the results of objective test results.
Diagnosis may be performed for several reasons, including deciding on future
employment. Where there is reason to believe that the work caused or contributed to
the onset or development of a vascular, neurological or musculoskeletal disorder, it is
considered inappropriate to allow a worker to return to the same work without
arranging for changes to the work that are likely to lessen the risks.

Discussion
There is a need to improve the methods of reporting symptoms arising from vascular,
neurological and musculoskeletal disorders associated with work involving hand-
transmitted vibration. This includes the interpretation of specific words and affects the
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reporting and application of scientific studies and also the application of current
methods of reporting symptoms.
There is scope for improving scales for reporting the extent of symptoms and signs:
current scales for vibration-induced white finger confound the effects of frequency
and extent of blanching [6, 13], and the so-called ‘sensorineural stages’ of the effects
of hand-transmitted vibration employ terms that have not been defined (e.g. reduced
sensory perception, reduced tactile perception, manipulative dexterity), [4].

Conclusions
By definition, vibration-induced white finger is caused by exposure to hand-
transmitted vibration. A necessary symptom (which is also a sign) of vibration-
induced white finger is an attack of well-demarcated finger blanching. In workers
exposed to hand-transmitted vibration, a low finger systolic blood pressure measured
following provocative cooling is indicative of vibration-induced white finger and a zero
finger systolic blood pressure can confirm an attack of Raynaud's phenomenon [3,
12].
Neurological and musculoskeletal disorders can arise from work with vibratory tools
where the separate roles of vibration, repetitive movements, grip and push forces,
non-neutral postures and any other ergonomic stressors are often unclear [9, 11].
Such disorders may be more easily identified as being caused by the work than by
exposure to hand-transmitted vibration per se.
A person found to have developed a disorder induced by either vibration or the work
situation should not be returned to the same vibration exposure or work without any
changes that can reasonably be expected to lessen the risks of the disorder.
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References
1. Bovenzi M (1998) Hand-transmitted vibration. In: Stellman JM (ed) Encyclopaedia
of Occupational Health and Safety, 4th edn. ILO, Geneva, Vol II, pp 50.7-50.12
2. Bovenzi M (1998) Exposure-response relationship in the hand-arm vibration
syndrome: an overview of current epidemiology research. Int Arch Occup Environ
Health 71: 509-519
3. Bovenzi M (2001) Finger systolic blood pressure indices for the diagnosis of
vibration-induced white finger. Int Arch Occup Environ Health #:##
4. Brammer AJ, Taylor W, Lundborg G (1987) Sensorineural stages of the hand-arm
vibration syndrome. Scand J Work Environ Health 13: 279-283
5. Gemne G, Saraste H (1987) Bone and joint pathology in workers using hand-held
vibrating tools. An overview. Scand J Work Environ Health 13: 290-300
6. Gemne G, Pyykkö I, Taylor W, Pelmear PL (1987) The Stockholm Workshop
scale for the classification of cold-induced Raynaud's phenomenon in the hand-
arm vibration syndrome (revision of the Taylor-Pelmear scale). Scand J Work
Environ Health 13: 275-278
7. Griffin MJ (1990) Handbook of human vibration. Academic Press, London
8. Griffin MJ (1997) Measurement, evaluation, and assessment of occupational
exposures to hand-transmitted vibration. Occup Environ Health 54: 73-89
9. Hagberg M (2001). Clinical assessment of musculoskeletal disorders in workers
exposed to hand-arm vibration. Int Arch Occup Environ Health #:##
10. International Organization for Standardization (1986) Mechanical vibration -
Guidelines for the measurement and the assessment of human exposure to
hand-transmitted vibration. ISO 5349. ISO, Geneva
11. Nilsson T (2001). Neurological diagnosis: aspects on bedside and
electroneurophysiological examinations. Int Arch Occup Environ Health #:##
12. Olsen N (2001). Physiological and diagnostic aspects of vibration-induced white
finger. Int Arch Occup Environ Health #:##
13. Palmer KT, Coggon DN (1997) Deficiencies of the Stockholm vascular grading
scale for hand-arm vibration. Scand J Work Environ Health 23: 435-439
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Table 1. Vibration-induced white finger
The nature of the vibration-induced white finger:
Vibration-induced white finger is a disorder characterised by complete episodic closure
of digital blood vessels. Both central and local pathogenic mechanisms may be
involved. The pathogenesis of vibration-induced white finger is not yet fully understood.
Symptoms of vibration-induced white finger:
A necessary symptom for the diagnosis of vibration-induced white finger is the
occurrence of attacks of well-demarcated finger blanching (Raynaud's phenomenon).
• Attacks of blanching normally commence with blanching in the distal phalanges and
may extend to other more proximal phalanges before receding to the distal phalanges
and recovery.
• Blotchiness (patches of blanching) may occur during onset or recovery from an attack.
• Anaesthesia will occur during an attack of blanching but numbness may not be
noticed.
• There may be a sequence of colour changes in which blanching is followed by
cyanosis and redness, sometimes accompanied by pain.
• Attacks are mainly provoked by exposure to cold conditions (including dampness) but
cold will not necessarily provoke an attack.
• Persons with vibration-induced vascular disorders may feel their fingers to be
abnormally cold, even without a blanching attack.
Signs and objective tests of vascular disorder:
A sufficient sign of vibration-induced white finger is the observation of an attack of well-
demarcated finger blanching.
•Finger systolic blood pressures measured following cooling of the digits to 15°C and
10°C will often be low in persons with vibration-induced white finger; an approximately
zero finger systolic blood pressure can verify an attack of Raynaud’s phenomenon.
•Finger rewarming times following cold exposure may be prolonged.
•Standardisation of cold provocation (rewarming) tests is desirable.
•Tests are recommended on all potentially affected digits on both hands.
•Current objective tests (finger systolic blood pressures and rewarming times following
cold provocation) do not indicate the severity of vibration-induced white finger and are
therefore not required if an attack of finger blanching has been witnessed.
Other considerations:
• Vascular damage caused by hand-transmitted vibration should be distinguished from
primary Raynaud’s phenomenon and other causes of secondary Raynaud’s
phenomenon.
• Effects of age, smoking, medication and vasoactive agents should be taken into
account.
Minimal vibration exposure required for diagnosis:
Regular exposure to vibration known to be capable of causing vibration-induced white
finger.
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Table 2. Neurological disorders caused by work with vibratory tools.
The nature of the neurological disorders:
Neuropathy to peripheral, mainly the sensory but sometimes also the motor, nervous
system, related to work with vibrating machines in which there may be:
• Disorders of end organs
• Nerve fibre dysfunction resembling entrapment neuropathy
• Diffuse or multi-focal neuropathy
• Any of the nerves of the upper limbs may be affected by hand-transmitted vibration.
• The disorder is not necessarily confined to digits but may extend to the palm and the
arms.
• The involvement of the autonomic nervous system has been considered, but this was
not the subject of the workshop
Symptoms of neurological disorders:
There are no minimal symptoms of neurological disorders caused by hand-transmitted
vibration because manifestations of disorder can pass unnoticed by affected persons.
• Numbness and tingling are commonly reported.
• It is desirable to unify the terminology for the description of symptoms in different
languages.
Signs and objective tests of neurological disorders:
There are no minimal signs of neurological disorder: symptoms can exist without signs.
• A thorough neurological and musculoskeletal physical examination is a pre-requisite
for the diagnosis and interpretation of any objective tests.
• Useful objective measures include sensory tests (e.g. thresholds for heat, cold and
vibration and aesthesiometry) and electrodiagnostic testing.
• Standardisation of tests is desirable.
Other considerations:
• Endocrine, metabolic, and immunologic disorders, traumatic injuries, infections,
polyneuropathies, and idiopathic focal neuropathies should be excluded.
• Effects of age, smoking, alcohol, medication and neurotoxic agents should be taken
into account.
Minimal vibration exposure required for diagnosis:
Exposure to vibration known to be capable of causing neurological disorders.
• There is currently no established exposure-response relationship between the physical
characteristics of occupational exposures to hand-transmitted vibration and the
development of neurological disorders.

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