Digital vibrogram: a new diagnostic tool for sensory testing in compression neuropathy

Exposure-response relationship between hand-arm vibration exposure and vibrotactile thresholds among rock drill operators: a 4-year cohort study

OBJECTIVES

The risk of developing hand-arm vibration syndrome (HAVS) from occupational hand-arm vibration (HAV) exposure is traditionally determined by the onset of vascular symptoms (white fingers). However, changes in tactile sensibility at the fingertips is a clinical sign of HAVS which in most cases precedes vascular signs. We aimed to assess relationships between occupational HAV exposure and HAVS-related signs including vibration perception thresholds (VPT) and pegboard score on an individual level, using a longitudinal study design with follow-up tests.

METHODS

We followed-up 148 workers exposed to different HAV levels for 4 years, with health examinations including VPT tests and pegboard tests carried out at baseline, 2 years and 4 years. VPT testing included seven frequencies, from 8 to 500 Hz. Second and fifth finger on both hands were tested, thus a total of 28 tests on each subject. We investigated associations using linear mixed models and significance level at p≤0.05.

RESULTS

There was a significant exposure-response relationship on an individual level between HAV exposure from rock drills and VPT for 16 of 28 test frequencies. The highest rise (worsening) in VPT was found at the 500 Hz test frequency with 1.54 dB increased VPT per 10-fold increase in cumulative exposure. We found no deterioration in pegboard performance associated with HAV exposure among the participants.

CONCLUSIONS

Risk predictions of HAVS may be based on exposure-response relationships between HAV exposure and VPT. The 500 Hz test frequency should be included in the VPT test protocols for early detection of signs related to reduced tactile sensibility.

Vibrotactile sense 5 years after carpal tunnel release in people with diabetes: A prospective study with matched controls

AIM

To compare vibrotactile sense, 5 years after carpal tunnel release in people with and without diabetes.

METHODS

Out of 35 people with diabetes and carpal tunnel syndrome, age- and gender-matched with 31 people without diabetes but with idiopathic carpal tunnel syndrome, 27 and 30 people, respectively, participated in this prolonged follow-up. Vibration perception threshold of the index and little finger (median and ulnar nerve, respectively), 5 years after surgery, was measured at seven different frequencies (8, 16, 32, 64, 125, 250 and 500 Hz).

RESULTS

Significant improvement of vibration perception threshold from 1 to 5 years after carpal tunnel release was found at 64 Hz for people with diabetes, while improvement for people without diabetes was demonstrated at several frequencies (64-250 Hz). However, both groups demonstrated a significant decrease in vibration perception threshold for the low frequencies (8-16 Hz). At 5 years, people with diabetes had significantly impaired vibration perception threshold at the index finger for high frequencies (125-500 Hz), and for nearly all frequencies (16 Hz, 64-500 Hz) at the little finger, compared to people without diabetes.

CONCLUSION

After carpal tunnel release, significant mid-term improvement of vibrotactile sense appears limited for people with diabetes, compared to a continuous improvement for people without diabetes. In addition, a decline in low-frequency vibrotactile sense occurs for the median as well as the ulnar nerve innervated fingers. Clinical Trial Registration NCT01201109.

Normative values of the vibration perception thresholds at finger pulps and metatarsal heads in healthy adults

Aims

To establish normative values of vibration perception thresholds (VPTs), using multi-frequency vibrometry at finger pulps and at metatarsal heads of the foot in healthy adults. We also aimed to investigate factors that could potentially affect VPTs such as age, sex, height, weight, foot- or handedness and skin temperature.

Methods

VPTs were examined in 924 healthy and randomly selected subjects in the southern Sweden (mean 46 years; 628 women and 296 men). Inclusion criterias were adult subjects (>18 years) in considerable health without diabetes mellitus or other nerve affecting disorders. VPTs were measured at the finger pulps of index and little finger, as well as the first and fifth metatarsal heads of the foot, through multi-frequency vibrometry using the VibroSense Meter® I device. Patient characteristics were recorded and skin temperature was measured before assessment of VPTs.

Results

We present normative values of VPTs for a large population of both male and female subjects in various ages. VPTs detoriated as age increased (0.09–0.59 dB per year; p<0.001), i.e. progressing with normal aging. Increasing skin temperature affected VPTs in finger pulps, but not at metatarsal heads, with -0.2 to -1.6 dB, i.e. vibration perception improved with higher temperatures. Height was only found to affect the VPTs of metatarsal heads (250 Hz: 0.42 dB per cm). Sex, weight and handedness did not affect the VPTs.

Conclusion

We investigated the normative values of VPTs and presented affecting factors as age, skin temperature and height. With these results, VPT testing through multi-frequency vibrometry is enabled to be used in a clinical practice as a diagnostic tool when investigating neuropathy and other neurological disorders.

Dose-response relationship between hand-arm vibration exposure and vibrotactile thresholds among roadworkers

BACKGROUND

Testing of vibration perception threshold (VPT) at the fingertips as a quantitative measure of tactile sensitivity is a commonly used tool in diagnosing hand-arm vibration syndrome. There is limited research on dose-response relationships between hand-arm vibration (HAV) exposure and VPT on an individual level.

AIMS

Assess possible dose-response relationships on an individual level between HAV exposure and VPT at the fingertips.

METHODS

We assessed average daily vibration exposure (m/s²A8) and cumulative lifetime HAV exposure for 104 participants from different departments in a road maintenance company based on vibration measurements and questionnaires. VPT was measured based on the technical method described in ISO 13091-1:2005 using octave frequencies 8-500 Hz. We investigated associations using linear regression models with significance level p≤0.05.

RESULTS

The participants were either exposed to rock drills (n=33), impact wrenches (n=52) or none of these tools (n=19). Exposure to rock drills and impact wrenches was associated with elevated VPT for all seven test frequencies in the second and fifth fingers of both hands. A dose-response with the daily exposure measure m/s²(A8) was found based on 1.2 m/s²(A8) for impact wrenches, and 5.4 m/s²(A8) for rock drills. A stronger association was found with the cumulative exposure for rock drills compared with impact wrenches, and for the second finger compared with the fifth finger.

CONCLUSIONS

HAV exposure was associated with elevated VPT, also at exposure levels below the common exposure action value of 2.5 m/s²(A8). Lowering the HAV exposure can contribute to prevent increasing VPTs in these workers.

Hand Pain and Sensory Deficits: Carpal Tunnel Syndrome

The Academy of Orthopaedic Physical Therapy and the Academy of Hand and Upper Extremity Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on hand pain and sensory deficits in carpal tunnel syndrome. J Orthop Sports Phys Ther 2019;49(5):CPG1-CPG85. doi:10.2519/jospt.2019.0301.

Vibration thresholds in carpal tunnel syndrome assessed by multiple frequency vibrometry: a case-control study

Background

Carpal tunnel syndrome (CTS) is the most common compression neuropathy, but there is no gold standard for establishing the diagnosis. The ability to feel vibrations in the fingertips is dependent on the function in cutaneous receptors and afferent nerves. Our aim was to investigate vibration perception thresholds (VPTs) in patients with CTS using multi-frequency vibrometry.

Methods

Sixty-six patients (16 men and 50 women) with CTS, diagnosed from clinical signs and by electroneurography, and 66 matched healthy controls were investigated with multi-frequency vibrometry. The VPTs were assessed at seven frequencies (8, 16, 32, 64, 125, 250, and 500 Hz) in the index finger and little finger bilaterally. The severity of the CTS was graded according to Padua and the patient’s subjective symptoms were graded according to the Boston carpal tunnel questionnaire. Touch thresholds were assessed using the Semmes-Weinstein monofilaments.

Results

Patients with CTS had significantly higher VPTs at all frequencies in the index finger and in 6 out of 7 frequencies in the little finger compared to the controls. However, the VPT was not worse in patients with more severe CTS. Patients with unilateral CTS showed significantly higher VPTs in the affected hand. There were no correlations between VPTs and electrophysiological parameters, subjective symptoms, or touch threshold.

Conclusions

Patients with CTS had impaired VPTs at all frequencies compared to the controls. Since the VPTs are dependent on function in peripheral receptors and their afferent nerves, multi-frequency vibrometry could possibly lead to diagnosis of CTS.

A Novel Device to Evaluate the Vibrotactile Threshold

This paper presents the initial prototype design of a vibrotactile threshold evaluator for the workplace (VTEW), which is portable and configurable in terms of the probe diameter (2–10 mm), applied frequency (1–500 Hz), angle of probe (0–120 deg), and displacement of probe (1–1500 μm), and is operated with a customizable LABVIEW interface. The vibrotactile threshold is the minimum amplitude of vibration that is perceived at a particular frequency by a subject and is analogous to a hearing test. It can be used to evaluate neuropathy, for instance due to carpal tunnel syndrome or peripheral neuropathy secondary to diabetes. The vibrotactile threshold (VT) at 50 Hz was evaluated using VTEW and an established device, the Vibrotactile Tester (VTT). These results were compared for validation of VTEW. Each subject underwent Phalen’s and Tinel’s test, and the results of these clinical evaluations for carpal tunnel syndrome were used to classify subjects as symptomatic and asymptomatic. The results of the VTEW and the VTT were statistically similar and the age correction developed for both devices from this study were similar to the previously conducted studies. The mean VT values from the VTEW showed an increased VT for symptomatic subjects. The low frequency range of the VTEW was used to evaluate the VT at 4 Hz, and a comparison of VT at 4 Hz and 50 Hz showed a higher sensitivity of subjects to 50 Hz as compared to 4 Hz. The gender effect on VT was also studied and discussed, along with recommendation for further investigation. A novel and highly customizable device for testing the vibrotactile threshold is presented, with results demonstrating identification of symptomatic subjects. This device could be used to regularly test workers at risk for developing carpal tunnel syndrome (e.g. assembly line workers) to monitor for elevations in VT. Other applications include using the low frequency to evaluate peripheral neuropathy.

Progress in vibrotactile threshold evaluation techniques: a review

Vibrotactile threshold (VT) testing has been used for nearly a century to investigate activation of human somatosensory pathways. This use of vibrotactile stimuli provides a versatile tool for detecting peripheral neuropathies, and has been broadly used for investigation of carpal tunnel syndrome. New applications include investigation of drug-induced neuropathies and diabetes-related neuropathies. As a feedback device, the vibrotactile stimuli could be used as an information delivery system for rehabilitative feedback devices for upper limb musculoskeletal disorders or as information channels for the visually impaired. This review provides a comprehensive review of the advancement in VT measurement techniques over time and a comparison of these techniques in terms of various hardware features used and the testing protocols implemented. The advantages and limitations of these methods have been discussed along with specific recommendations for their implementation and suggestions for incorporation into clinical practice.

Vibrotactile sense in patients with diabetes and carpal tunnel syndrome

AIM

To evaluate vibration perception thresholds of patients with and without diabetes, before and after surgical carpal tunnel release.

METHODS

In a prospective study, 35 consecutive patients with diabetes and carpal tunnel syndrome were age and gender matched with 31 patients without diabetes having idiopathic carpal tunnel syndrome. Preoperatively, 6, 12 and 52 weeks after surgery, the vibration perception threshold of the index and little finger (median and ulnar nerve, respectively) was measured at seven different frequencies (8, 16, 32, 64, 125, 250 and 500 Hz).

RESULTS

At several frequencies, patients with diabetes and carpal tunnel syndrome demonstrated significantly impaired vibration perception thresholds of both the index and the little finger, before as well as after carpal tunnel release, compared with patients without diabetes with idiopathic carpal tunnel syndrome. After surgery, the overall sensibility index improved for the index finger [patients with diabetes and carpal tunnel syndrome (0.79 to 0.91, P < 0.001), patients without diabetes with idiopathic carpal tunnel syndrome (0.91 to 0.96, P > 0.05)] as well as for the little finger [patients with diabetes and carpal tunnel syndrome (0.82 to 0.90, P < 0.008), patients without diabetes with idiopathic carpal tunnel syndrome (0.95 to 0.99, P < 0.05)]. For the index finger, the sensibility index improved to a significantly higher degree for patients with diabetes and carpal tunnel syndrome not having signs of peripheral neuropathy (0.83 to 0.95, P < 0.001) compared with those with neuropathy (0.74 to 0.84, P < 0.02). Vibration perception threshold correlates with age of both patients with diabetes and carpal tunnel syndrome and patients without diabetes with idiopathic carpal tunnel syndrome, while no relationship was found based on duration of diabetes.

CONCLUSIONS

Vibrotactile sense is significantly impaired in patients with diabetes before and after carpal tunnel release compared with patients without diabetes. However, patients with diabetes obtained significant recovery of vibration perception threshold, particularly those without peripheral neuropathy.

Improved sensibility of the foot after temporary cutaneous anesthesia of the lower leg

Cutaneous anesthesia (EMLA_cream) of the forearm results in rapid improvement of hand sensibility, and here we applied this concept in the lower extremity. This double-blind study with 40 volunteers randomized to cutaneous application of anesthetic cream to the lower leg showed a significant improvement 2 h after treatment in touch thresholds in the EMLA group as compared with the placebo group. In 12 volunteers, fMRI examination was performed before and after treatment. Improvement was not associated with a visible cortical expansion of the cortical foot area. This novel finding may have considerable therapeutic potential in the treatment of foot sensibility disturbances in various neuropathies, such as diabetic neuropathy.

Evaluation of nerve injury and nerve compression in the upper quadrant

Evaluation of the patient with nerve compression and/or nerve injury should include a complete motor and sensory evaluation to establish the level and degree of injury and/or compression. No one test has been accepted as the standard procedure for the evaluation of sensibility. The various sensory tests available for patient assessment will yield different information regarding the integrity of the quickly and slowly adapting sensory receptors. Tests such as provocative maneuvers and sensory thresholds (cutaneous and vibration) will be more sensitive in the evaluation of patients with nerve compression, and other discriminatory measures will yield better functional information in patients with nerve injury.

Clinical diagnosis of carpal tunnel syndrome: a systematic review

The purposes of this systematic review were to examine the properties of clinical tests used in the diagnosis of carpal tunnel syndrome (CTS) and to provide estimates of their sensitivity and specificity. A literature search was conducted using two databases-PubMed and the Cumulative Index to Nursing and Allied Health Literature (CINAHL)-from 1986 to June 2003, and hand-searching reference lists of retrieved articles. Two reviewers evaluated the papers for quality using an evaluation tool developed by one of the authors. Estimates of sensitivity and specificity were determined by averaging values across studies weighted by sample size. Although 60 studies were reviewed in detail, many were of poor quality (mean quality score was 6.6 of 12, with only 15 of 60 obtaining a score of 8 or greater). The most frequently studied test was Phalen's, with an overall estimate of 68% sensitivity and 73% specificity. Next was Tinel's, with estimates of 50% and 77%, and then carpal compression, with estimates of 64% and 83% for sensitivity and specificity, respectively. Two-point discrimination and testing of atrophy or strength of the abductor pollicis brevis proved to be specific but not very sensitive. The estimates determined in this review should help therapists choose clinical tests with the appropriate balance of sensitivity and specificity required for diagnosing carpal tunnel syndrome in their specific clinical environments.

Tingling/numbness in the hands of computer users: neurophysiological findings from the NUDATA study

OBJECTIVES

To investigate whether tingling/numbness of the hands and fingers among computer users is associated with elevated vibration threshold as a sign of early nerve compression.

METHODS

Within the Danish NUDATA study, vibratory sensory testing with monitoring of the digital vibration threshold at seven frequencies on the second and fifth fingers of both hands was performed on 20 cases with unilateral tingling/numbness in the hands and fingers, and 20 gender- and age-matched controls. Both cases and controls were identified from questionnaire information about tingling/numbness at least once a week or daily within the last 3 months. Participants with more than slight muscular pain or disorders of the neck and upper extremities, excessive alcohol consumption, previous injuries of the upper extremities, or concurrent medical diseases were excluded. The two groups had a similar amount of work with mouse, keyboard, and computer.

RESULTS

Seven of the 20 cases (35%) had elevated vibration thresholds, compared with 3 of the 20 controls (15%); this difference was not statistically significant (chi2=2.13, P=0.14). Compared with controls, cases had increased perception threshold for all frequencies, but the difference was statistically significant for only 2 out of 14 measurements. Comparison between left and right hand threshold values within the case group did not show any significant difference at any frequency.

CONCLUSIONS

The results indicate that tingling/numbness of the hands and fingers among computer users cannot be explained by nerve compression.

Clinical and electrodiagnostic testing of carpal tunnel syndrome: a narrative review

Carpal Tunnel Syndrome (CTS) is a pressure-induced neuropathy that causes sensorimotor disturbances of the median nerve, which impair functional ability. A clear history that elicits relevant personal and work exposures and the nature of symptoms can lead to a high probability of a correct diagnosis. Hand diagrams and diagnostic questionnaires are available to provide structure to this process. A variety of provocative tests have been described and have variable accuracy. The Phalen's wrist flexion and the carpal compression tests have the highest overall accuracy, while Tinel's nerve percussion test is more specific to axonal damage that may occur as a result of moderate to severe CTS. Sensory evaluation of light touch, vibration, or current perception thresholds can detect early sensory changes, whereas 2-point discrimination changes and thenar atrophy indicate loss of nerve fibers occurring with more severe disease. Electrodiagnosis can encompass a variety of tests and is commonly used to assess the presence/severity of neuropathic changes and to preclude alternative diagnoses that overlap with CTS in presentation. The pathophysiologic changes occurring with different stages of nerve compression must be considered when interpreting diagnostic test results and predicting response to physical therapy management.

Quantitative vibration threshold testing in carpal tunnel syndrome: analysis strategies for optimizing reliability

Tuning forks and electronic vibrometers have been used to quantify vibration sensation thresholds, which are thought to be affected early in carpal tunnel syndrome (CTS). The purpose of this study was to identify a reliable testing procedure for a newly designed, computer-controlled vibrometer (PCV50; Ztech, Salt Lake City, UT). Fifty-two patients (mean age 48+/-8 years) with electromyographically confirmed CTS were tested on one occasion. The computer-controlled vibrometer, with a fixed frequency of 50 Hz, used stepwise changes in amplitude to determine vibration sensation threshold. Each patient had three vibrometer measures (trials) taken on the pulp of the third digit of their right and left hands during the first test session and were retested by a single repetition 40 to 60 minutes later (retest). Intraclass correlation coefficients (ICCs) were used to examine several data analysis strategies. The strategy that generated the highest ICCs for both the right and left hands assumed that the first trial was a learning or practice attempt, and compared the average of the second and third trials with the score from the second session (ICC=0.86 and 0.89, respectively). The computer-controlled vibrometer offered an easily administered, quantitative, and comfortable means to assess median nerve function. Using this reliable testing procedure will allow for additional investigations to determine its usefulness in the early detection and accurate quantification of CTS-related impairment.

Recovery of touch after median nerve lesion and subsequent repair

Many techniques have been developed for the evaluation of peripheral nerve function. Consequently, physicians use different techniques in the clinic. This study describes the evaluation of touch after median nerve lesions in the forearm and repair. In order to evaluate touch, 25 patients, aged 11-51 years (mean, 29 years), were evaluated 3-10.5 years (mean, 5 years) after median nerve repair. The evaluation included the moving two-point discrimination test and Semmes-Weinstein monofilaments. We showed that 32% good-excellent results can be obtained with difficult nerve lesions. The results could have been improved if a sensory reeducation regime had been applied.

Evaluation of the nerve-injured patient

The evaluation of patients with nerve injury or nerve compression requires an accurate history and subjective report to determine the tests that are the most useful in providing the essential information. Motor and sensory evaluation is necessary inglobal mixed-nerve injuries, but in cases of nerve compression, tests of provocation give more accurate information for detecting the site of nerve compression. There is no gold standard test in the evaluation of patients with nerve injury or compression; therefore, a battery of valid and reliable sensory and motor tests provides the most complete information to formulate a treatment plan.

Perceptual changes in the anterior maxilla after placement of endosseous implants

BACKGROUND

The innervation of skin and oral mucosa plays a major physiologic role in exteroception. It is also of interest clinically, as illustrated by sensory changes after neurosurgical procedures.

PURPOSE

The goal of this study was to assess the perception of mechanical stimuli applied to the anterior maxilla in denture wearers and subjects rehabilitated with osseointegrated implants compared with that in subjects with a natural dentition.

MATERIALS AND METHODS

Five groups of subjects were selected and tested in the maxillary region only. Test groups included patients with a complete denture, an implant-supported fixed prosthesis (full or partial), or a single-tooth replacement. Light-touch sensation and two-point discrimination were performed on the buccal side of the alveolar mucosa and vibrotactile function was determined for natural teeth, full dentures, or implant-supported prostheses.

RESULTS

For light-touch sensation, no significant differences could be found between the groups. For two-point discrimination, full-denture patients showed higher threshold levels than the other groups. The threshold levels for vibrotactile function were higher in both full dentures and implant-supported prostheses compared with natural dentitions.

CONCLUSION

Natural dentitions offer superior vibrotactile function compared to any other dental status. Full dentures often show a stronger deterioration of the (vibro)tactile function compared with implant-supported prostheses.

Evaluation of hand sensibility: a review

Many assessment devices and measures have been described to evaluate sensibility, with little consensus on the optimal measurement tool. The purpose of this paper is to review the assessment methods and devices used in the evaluation of hand sensibility. Consideration is given to the characteristics of each measurement tool, the information necessary for complete patient evaluation, and the battery of valid and reliable measurements that provide the most complete and accurate patient assessment.

Peripheral nerve function is increasingly impaired during puberty in adolescents with type 1 diabetes

OBJECTIVE

To evaluate the impact of puberty on peripheral nerve function in adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Of 138 eligible patients with type 1 diabetes, 100 patients (age >9 years and diabetes duration >2 years) attending an outpatient diabetes clinic and 100 age- and sex-matched healthy control subjects took part in this cross-sectional study. Peripheral motor and sensory nerve conduction tests, cardiovascular reflex tests on the autonomic nervous system, and measurements of vibration-perception threshold (VPT) were performed.

RESULTS

Nerve conduction velocity (NCV) in the distal motor and sensory nerves, the motor nerve distal latency, and the sensory nerve action potential (SNAP) amplitude were impaired in the adolescent patients with type 1 diabetes. The deterioration in motor NCV, H-reflex latency, and SNAP amplitude became more conspicuous in late puberty and postpuberty and was related to poor metabolic control. A total of 10 patients had distal diabetic polyneuropathy (DP) neurophysiologically, and these patients had significantly lower heart-rate variation in the deep breathing test than the other patients. Three of the patients with DP had peripheral neurological signs or symptoms. A slight difference in the VPT between the patients and control subjects was observed after puberty.

CONCLUSIONS

Increasing subclinical motor nerve impairment can be detected during late puberty and after puberty, and sensory NCV and SNAP amplitude are reduced in adolescents with type 1 diabetes. Poor metabolic control during puberty appears to induce deteriorating peripheral neural function in young patients with type 1 diabetes.

The force/time relationship of clinically used sensory testing instruments

The stimuli of commonly used sensibility measurement instruments tested in this study demonstrate unequivocally that "hand-held instruments" produce variations in application force from one stimulation to another, one instrument to another, and from one examiner to another. These application force variations cannot be compensated for by care in technique and need to be controlled for measurement reliability. Only the Semmes-Weinstein monofilaments provide some control of force during application and can be considered force controlled if calibrated and applied correctly. The monofilaments, too, become less controllable if applied too quickly and bounced against the skin. Two-point discrimination instruments, in particular, lack control of application force, with the force of one point significantly different from two points. A difference in applied force makes it possible for a patient to solve the two-point discrimination test by discerning the difference between heavier and lighter forces, rather than one or two-point recognition. Tuning fork instruments for vibration testing have even larger variations in application force amplitude rendering their stimulus highly uncontrolled and masking the actual vibration of the tuning fork. Spectral analysis of the force frequency signal produced by hand held sensibility measurement instruments shows they all produce both high and low frequency signals sufficient in strength to stimulate both slowly adapting and quickly adapting end organs, and are not capable of stimulating one particular group. These dynamic properties of testing stimuli explain why our tests are not as repeatable and sensitive as desired. The understanding of these dynamic properties in sensibility measurement is a key for improved instruments and more repeatable findings in clinical testing.

Evaluation of the psychophysical detection threshold level for vibrotactile and pressure stimulation of prosthetic limbs using bone anchorage or soft tissue support

In the present study the psychophysical detection threshold levels mechanical stimulation of 32 prosthetic limbs were determined. Prosthetic limbs were anchored to the bone by means of an implant (n=17) or supported by a socket enclosing the amputation stump (n=15). Detection threshold levels were assessed for pressure and vibratory stimulation of the prosthesis and the limb at the contralateral side (control). Following vibratory stimulation, thresholds were increased on an average 20% for socket prostheses. but approached those of the control for bone-anchored prostheses. For pressure stimulation, thresholds were increased up to 60% for socket prostheses and 40% for bone-anchored prostheses compared to the control. While bone-anchored prostheses yielded significantly lower threshold levels than socket prostheses, there was no significant difference between both treatments regarding pressure stimulation. Results were applicable to both upper and lower limb amputees. It could be concluded that detection thresholds for pressure and especially vibratory stimulation of prosthetic limbs were generally higher than for control limbs. The outcome was related to the prosthetic limb design with bone-anchored prostheses yielding better perception than socket prostheses.

Vibrotactilometry as a diagnostic tool in ulnar nerve entrapment at the elbow

Vibrotactilometry with testing of the thresholds of the vibration sense at seven frequencies between 8-500 Hz in different intensities has been correlated with nerve conduction studies of the ulnar nerve to evaluate its diagnostic power in neuropathies at the elbow. Thirty-nine patients with entrapment symptoms were studied. Vibrotactilometry was abnormal in 33 patients (85%) and nerve conduction studies were abnormal in 19 (49%). The sensitivity of vibrotactilometry in relation to nerve conduction studies was 89%, and in relation to the patients' symptoms was 85%. We conclude that vibrotactilometry is a sensitive test that correlates well with the patients' symptoms, while nerve conduction studies are less sensitive (49%) in relation to the patients' symptoms. Vibrotactilometry in the frequency area of 8-500 Hz is recommended in the screening of ulnar nerve entrapment. Nerve conduction studies are recommended in clinically doubtful cases to localise the entrapment to the elbow region.

Hand function in workers with hand-arm vibration syndrome

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. Semmes-Weinstein monofilament testing for perception of light touch-deep 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.

Clinical applications of quantitative sensory testing (QST)

Quantitative sensory testing (QST) has been used clinically for the last two decades, yielding a substantial number of publications regarding these applications. In this review we tried to amass together the major findings of these publications into one monograph, excluding those dealing with pain. This was done with the aim of assisting clinicians in the better use of QST techniques for the benefit of their patients.

Preliminary evaluation of a sensory and psychomotor functional test battery for carpal tunnel syndrome: Part 1--Confirmed cases and normal subjects

Two new computer-controlled functional tests were developed, known as the Wisconsin test battery, for carpal tunnel syndrome (CTS). The gap detection sensory test quantifies tactile thresholds for areas of the hand innervated by the median nerve. The rapid pinch and release psychomotor test measures the initiation and control of specific muscles innervated by the median nerve motor branch. Ten confirmed CTS patients (based on electrophysiological parameters and examination; 18 CTS hands) and eight confirmed normal subjects (16 hands) with a similar average age were administered both tests. The CTS patients showed significant functional deficits for both tactility and psychomotor tests. Average CTS performance was 24 to 104% poorer than for the normal subjects, depending on the performance measure. The results indicated high correlations (r = 0.5 to 0.8) between median nerve electrophysiological parameters and tactility or psychomotor performance variables. No single functional test variable had sufficient sensitivity for detecting CTS among the subject pool. The combination of the two tests using 95% confidence level cutoff points achieved a sensitivity of 0.78 and a specificity of 0.81. Stepwise discriminant analysis resulted in two performance variables capable of a sensitivity of 0.72 and a specificity of 0.94 for differentiating well-defined CTS subjects from normal subjects. Despite these promising results, limitations of the study include small sample size and subject selection bias. Further studies are needed for verifying the utility of the functional test battery for detecting CTS in a general population.

Vibrotactile sense and hand symptoms in blue collar workers in a manufacturing industry

OBJECTIVES

To study whether vibrotactile sense combined with questionnaires (subjective complaints) and a clinical examination (including scoring of the Stockholm workshop scale (sensorineural staging)) could serve as a screening procedure, in the health care service, for sensorineural symptoms. A group of blue collar workers exposed to vibration in a manufacturing industry (rock crushing plants) was used as the study group. Another group of workers not exposed to vibration but subjected to heavy manual work served as the control group.

METHODS

Vibrotactile sense was determined. The index and the little fingers of both hands were investigated. A clinical examination was performed. Questionnaires were used for exposure data and for assessment of symptoms.

RESULTS

Important findings were that impairment in vibrotactile sense correlated with impairment in grip force, cold sensitivity, and other sensorineural symptoms--such as numbness and tendency to drop items. Clinical findings such as Phalen's test and two point discrimination were related only in those workers with the poorest vibrotactile sense. There was a relation between vibrotactile sense and the Stockholm workshop scale (sensorineural staging) for the sensorineural symptoms. Muscle and joint problems were more often seen in workers with decreased vibrotactile sense.

CONCLUSIONS

Tactilometry for assessment of vibrotactile sense is a useful tool in assessing and evaluating the severity of vibration induced neuromuscular symptoms and verifying the patients' clinical complaints. Heavy manual work without exposure to vibration may contribute to impairment of vibrotactile sense. The relation between impairment in vibrotactile sense and grip strength indicates that impaired sensory feedback may contribute to muscle weakness.

The occurrence of Raynaud's phenomenon in a general population: the Framingham Study

The prevalence and predisposing conditions for primary and secondary Raynaud's phenomenon (RP) were examined in The Framingham Study based on 16 years of follow-up of a cohort of 4182 men and women. The association with atypical chest pain and migraine headache was also investigated. Over the 16 years of follow-up there were 130 men and 171 women who developed primary RP. The prevalence in women (9.6%) was somewhat higher than in men (8.1%) and 81.4% of the RP was primary. Secondary RP was equally prevalent in men (18.6%) and women (19.7%). The most common causes of secondary RP were beta-blocker use (34.2%), carpal tunnel syndrome (10.5%) and rheumatoid arthritis (7.2%). Primary RP cases differed from noncases by having lower systolic blood pressure (p < or = 0.001) and diastolic blood pressure (p < 0.0001), and more coronary disease (p = 0.009), smoking (p < or = 0.01) and higher blood sugars (p < or = 0.009). Atypical chest pain was present more often than noted previously in The Framingham Study general population survey, and was equally prevalent in primary and secondary RP and in the two sexes. Associated migraine was more prevalent in women (14.4%) than men (5.0%). Vibrating tool use with associated RP occurred in 14.6%.

Sensory function after median nerve decompression in carpal tunnel syndrome. Preoperative vs postoperative findings

The sensory recovery was monitored for up to 1 year after decompression of the median nerve in 69 patients with carpal tunnel syndrome. Special attention was paid to the rate of recovery, the importance of constant or intermittent numbness or paraesthesiae preoperatively and the influence of gender. Most patients with numbness/paraesthesiae and those with abnormal two-point discrimination recovered within 10 days. Perception of touch and vibration recovered within 3 weeks in most patients but those with abnormal nerve conduction/sensory amplitude recovered slowly during follow-up. After 1 year patients with intermittent preoperative symptoms were significantly more likely to achieve normal nerve conduction and perception of touch. Women were more likely to achieve normal nerve conduction and perception of touch. A comparison of recovery between matched men and women with identical preoperative status showed no significant difference. The results indicate the importance of early treatment of carpal tunnel syndrome.

Evaluation of cutaneous vibration thresholds in medical transcriptionists

This study was designed to determine whether vibration thresholds of transcriptionists varied significantly from the thresholds of individuals not exposed to keyboard activities. Using a multifrequency vibrometer, we obtained vibration threshold values from 31 medical transcriptionists who perform work on computer keyboards and compared them to values obtained from 40 control subjects. Thresholds tended to become more abnormal at higher frequencies, although this difference was statistically significant only at frequencies of 125 Hz, 250 Hz, and 500 Hz in the index and small fingers. Vibration thresholds were not found to increase significantly with age or years of occupation. Vibration thresholds were significantly increased in medical transcriptionists at the higher frequencies, suggesting subtle neural dysfunction.

Repetitive use and static postures: a source of nerve compression and pain

Nerve compression or musculoskeletal diagnoses require consideration of both the repetitive movements and static postures that may be contributing to the problem. Certain postures and positions assumed at home, at work, and during sleep will have three major influences: (1) directly increasing pressure on nerves at entrapment sites; (2) placing muscles in shortened positions so that adaptive muscle shortening may then secondarily compress nerves; and (3) placing some muscles in elongated and weakened positions, resulting in other muscles being over-used, thus creating the cycle of muscle imbalance. Successful management of the patient with upper extremity pain, paresthesia, and numbness should begin with initial identification of all sites that are contributing to the presenting symptoms. Treatment must then be directed toward the sources of nerve compression and musculoskeletal dysfunction. Upper quadrant symptomatology can be alleviated with an appropriate therapy program, even in the patient with chronic symptoms, but only with patient education, compliance with an exercise program, and behavioral modification at home, work, and during sleep.

Recovery of sensory and motor function after nerve repair. A rationale for evaluation

In order to identify an effective test for evaluating the results of nerve repair, 25 patients, age 10-53 years (mean 27 years), were evaluated two to five years after median or ulnar nerve repair at the distal forearm level. The initial assumption was that evaluation after nerve repair should reflect four aspects of recovery: reinnervation, tactile gnosis, integrated sensory and motor functions, and pain or discomfort. The evaluation included a number of assessment methods addressing these aspects. Attention was paid to the usefulness of the tests with reference to their relevance for assessing hand functions. Clinical utility and possibilities for standardization and quantification of the results were considered important. Statistical analysis showed no correlations between the results obtained in clinical tests for reinnervation and the results from neurophysiologic examination. Grip strength and cold intolerance together accounted for a significant 51% of the variance in activities of daily living (ADL) capacity. Tactile gnosis correlated weakly with ADL capacity and strongly with age. Based on these findings, the following design for evaluating the result after median and ulnar nerve repair is suggested. To assess reinnervation: Semmes-Weinstein monofilaments and manual muscle-testing; to assess tactile gnosis: classic 2PD and a test with the features of the used shape identification test; to assess integrated functions: selected parts of Sollerman's grip test and grip-strength test with Jamar dynamometer; to quantify pain and discomfort: a four-ranked scale for grading perceived problems from cold intolerance and hypersensitivity.

Digital sensory nerve conduction velocity and vibration perception threshold in peripheral neurological test for hand-arm vibration syndrome

To evaluate peripheral neuropathy in patients with vibration syndrome, an examination was conducted of sensory nerve conduction velocity (SCV) in the digital segment of the median nerve in the middle finger and vibration perception threshold (VPT) at 125 Hz on the same middle fingertip. In addition, possible correlations were investigated between the two measurements. SCVs in the digital segment were measured by stimulating at the wrist electrically and recording from two pairs of electrodes in the finger. Fractionated SCVs were also measured in the palm-to-finger, wrist-to-palm, and elbow-to-wrist segments. The subjects were 52 patients with vibration syndrome and 40 healthy controls of similar age. SCVs in the digital segment and the wrist-to-palm segment were significantly slower in the patients than in the controls, and VPTs were higher in the patients. The strongest correlation of VPTs with SCVs among nerve segments measured was shown in the digital segment. With an increase in VPTs, SCVs in the digital segment tended to be slower, and slowed digital SCVs were encountered more frequently: 13% in VPTs below 5.0 dB and 56% in VPTs above 17.5 dB. Slowed digital SCVs were found in 43% of the patients and increased VPTs were encountered in 92%.

Assessment of vibrotactile sensitivity in patients with carpal tunnel syndrome

The effectiveness of using vibrotactile threshold measures to aid in the diagnosis of carpal tunnel syndrome (CTS) was evaluated. Thresholds for detecting 1-, 10-, and 300-Hz vibratory stimuli were measured on the fingertips of 24 CTS patients and 20 healthy control subjects. There were no significant differences in threshold for 1- and 300-Hz between the two groups. Although there were significant differences for 10-Hz stimuli, the mean patient threshold was within 1 standard deviation of the mean threshold for the control group. These results indicate that threshold testing is not a suitable diagnostic tool for CTS. Additionally, we examined whether thresholds were elevated in the presence of pain. Seven patients reported experiences of pain and no pain sessions. No significant differences in threshold were found between the two pain conditions, indicating that the presence of pain related to CTS does not affect threshold.

Osseointegrated thumb prostheses: a concept for fixation of digit prosthetic devices

Three patients with traumatic amputation of the thumb at the metacarpophalangeal joint level underwent a two-stage reconstruction aimed at fixation of a thumb prosthesis to the first metacarpal bone via an osseointegrated titanium fixture. The first stage included insertion of the fixture into the medullary cavity of the first metacarpal bone in combination with transplantation of cancellous bone from the iliac crest. After 3 months, when the fixture was firmly osseointegrated into the bone, a skin-penetrating abutment was placed on top of the fixture, the surrounding skin being thinned to the thickness of a split-skin graft to minimize relative mobility. A thumb prosthesis could then be firmly attached to this fixture. At follow-up examinations between 18 months and 3 years; postoperatively perfect osseointegration of the implant persisted. There were no skin problems. Some extent of tactile discrimination was achieved in the prosthesis hypothetically based on transfer of tactile stimuli to endosteal nerves in the bone via the titanium fixture.

A comparison of traditional electrodiagnostic studies, electroneurometry, and vibrometry in the diagnosis of carpal tunnel syndrome

In 49 patients (98 hands), referred to an electrodiagnostic laboratory, assessments were made by conventional nerve conduction studies on the upper extremity and by two more portable modalities, namely electroneurometry (skin surface electrical stimulation of the motor nerve) and single-frequency (120 Hz) vibrometry. Tests were performed on median and ulnar nerves. Correlations with motor nerve conduction studies for each screening test on the median nerve were r = .81 for the electroneurometer and r = .48 for the vibrometer. When carpal tunnel syndrome was diagnosed either by clinical criteria only or by nerve conduction abnormality, the association with electroneurometry was characterized by high sensitivity and low specificity, while the opposite relationship prevailed with vibrometry. These associations were highly dependent on the methods used to select normal values from a reference population. While the manufacturer's recommended normal values offered good predictability, with thresholds that corresponded to nerve conduction studies, normal values generated in a more standard way produced much weaker and less useful associations. The selection of an appropriate electrical screening test for peripheral nerve injury, such as entrapment neuropathy, depends on the prevalence and seriousness of the target disease and the relative consequences of over- and underdiagnosis.

Temperature effects on vibrotactile sensitivity threshold measurements: implications for carpal tunnel screening tests

This study examines the effect of skin temperature on fingertip vibrotactile sensitivity measurements and the resulting implications for carpal tunnel syndrome screening tests. Twenty subjects (11 men, 9 women) were tested for fingertip vibrotactile thresholds using the method of limits at four different frequencies (31.5, 125, 250, and 500 Hz) and six temperature categories (17 degrees-20 degrees C, 20 degrees-23 degrees C, 23 degrees-26 degrees C, 26 degrees-29 degrees C, 29 degrees-32 degrees C, 32 degrees-35 degrees C). Vibrotactile sensitivity thresholds increased with decreasing fingertip skin temperature. Furthermore, the relationship was a function of vibration frequency. Higher frequencies were more affected by temperature than lower frequencies, with significant effects beginning at 29 degrees C. These temperature-related effects may lead to possible false positive results in screening for carpal tunnel syndrome or other neuropathies. To minimize potential temperature-induced misclassification errors during these screening tests, fingertip skin temperature should be recorded before measurement and probably maintained above 29 degrees C during the measurement.

Detecting cumulative trauma disorders in workers performing repetitive tasks

On-site testing of 157 poultry processors disclosed that 50% had three or more abnormal upper extremity findings out of a total of 22 possibles. The average worker had five to six abnormal findings. Impaired pinch strength, decreased vibration sensitivity in the fingertips, and reports of current numbness were the most prevalent. Of workers with signs, 25% reported no symptoms, whereas only 8% of workers reported symptoms but had no signs. The investigators concluded that this measurement method has utility for assessments of worker populations to determine prevalence of CTDs and, potentially, for preclinical detection of these disorders to permit early intervention, reduce medical costs, and minimize disability. The need for accurate measurement to enhance early detection and prevention is discussed.

Neuropathy in female dental personnel exposed to high frequency vibrations

OBJECTIVE

To evaluate early neuropathy in dental personnel exposed to high frequency vibrations.

METHODS

30 dentists and 30 dental hygienists who used low and high speed hand pieces and ultrasonic scalers were studied, and 30 dental assistants and 30 medical nurses not exposed to vibration (all women). Vibrotactile sensibility, strength, motor performance, sensorineural symptoms and signs, and vascular symptoms in the hands, as well as mercury concentrations in biological samples and cervicobrachial symptoms, were studied.

RESULTS

The two groups exposed to vibration had significant impairments of vibrotactile sensibility, strength, and motor performance, as well as more frequent sensorineural symptoms. In the dentists there were significant associations between the vibrotactile sensibility and strength, motor performance, superficial sensibility, and sensorineural symptoms. There were no associations between these findings and cervicobrachial symptoms, mercury concentrations, or smoking. There was no increase of vascular symptoms of the hands in the groups exposed to vibration.

CONCLUSION

Dental hygienists and dentists had a slight neuropathy, which may be associated with their exposure to high frequency vibrations, and which may be detrimental to their work performance. Thus, development of safer equipment is urgent.

Pain, nerve dysfunction and fatigue in a vibration-exposed population

The long term use of hand-held vibrating tools may cause vasospastic and neuromuscular problems. Symptoms include painful blanching of the fingers at low temperatures, intermittent paresthesia and numbness, impaired dexterity, a tendency to drop tools, and an increasing inability to identify small objects by touch alone. Neurological as well as vasospastic problems are graded according to the Stockholm workshop scales. Accurate and early diagnosis is particularly important (e.g., in vibration-exposed patients presenting a carpal tunnel syndrome, it is necessary to distinguish whether compression of the median nerve occurs at the digital, skin receptor or carpal tunnel levels). A variety of improved diagnostic techniques are discussed.

Raynaud's phenomenon associated with the use of pneumatically powered surgical instruments

Five patients developed symptoms of Raynaud's phenomenon and upper extremity paresthesias after 7-32 months of exposure to air-powered surgical instruments used for the harvest of bone for bone banks. Results of cold challenge plethysmography, nerve conduction studies, vibrotactile thresholds, and quantitative sensory testing were as follows: all patients had significant reproducible vasospasm with nondetectable finger systolic blood pressure (FSBP = 0) after local digital cooling; nerve conduction abnormalities included delayed median nerve sensory conduction (< 48 m/s) across 5 of 10 wrists; and no ulnar nerve abnormalities were detected. Vibrotactile thresholds were only modestly elevated, an unexpected outcome given the frequently recognized association between vibrotactile tests and nerve conduction studies. These abnormalities occurred with exposures to frequencies previously thought to be too high to be harmful to medical personnel.

Quantitative vibrometry and electrophysiological assessment in screening for carpal tunnel syndrome among industrial workers: a comparison

Vibrometry has been demonstrated to be an effective adjunct to electrophysiological evaluation of nerve integrity in diffuse peripheral neuropathies but there is controversy over its value in the diagnosis of isolated compression neuropathy such as carpal tunnel syndrome (CTS). One hundred thirty factory workers were screened for peripheral nerve impairment using both vibrometry and electrophysiologic testing of digits 2 and 5 in both hands. Vibrometry had a low sensitivity in identifying individuals with symptoms of CTS or a median mononeuropathy defined by nerve conduction studies (NCS). The correlation of vibratory and the sensory evoked latencies were modest in the median nerve distribution (r = 0.297 to 0.370, p = 0.001). Using a comparison between vibration thresholds from digit 2 to 5 was not helpful in identifying cases of CTS and the difference in thresholds did not correlate with the difference in sensory evoked latencies. CTS is primarily a demyelinating process and can be easily detected with NCS. Because vibration threshold sensation is related to axonal loss it is not as sensitive in early CTS. Our results do not support the use of quantitative vibrometry as a screening tool median nerve impairment among industrial workers.

A comparison of vibrotactile thresholds on the finger obtained with different equipment

Vibrotactile thresholds on the finger have been compared using two alternative systems. One system prescribed the push force, the contact force, and the surround, while this was not defined for the other system. The experiment was performed with nine male subjects attending on three different days. It was found that the two systems yielded vibrotactile thresholds which were significantly different. The dependence of vibrotactile thresholds on the frequency of vibration, the area of contact with vibration, the conditions surrounding the contact area, the contact force, the push force, the finger temperature, and the distortion of waveform must be considered when quantifying vibrotactile thresholds.

Nerve repair: correlation of restitution of functional sensibility with specific cognitive capacities

To test the hypothesis that cognitive capacity is correlated with the outcome of functional sensibility after nerve repair, 19 patients were evaluated 2 to 5 years after median or ulnar nerve repair at the distal forearm level. The sensory evaluation included tests for functional sensibility as well as assessments addressing perception thresholds for touch/pressure and vibration. Psychometric tests for cognitive capacity were also carried out. Multiple regression analysis, correcting for the effect of age and the ability to perceive touch/vibration, was used to investigate the relationship between functional sensibility and cognitive capacity, and to determine which of the tested central nervous factors had the greatest influence on the outcome of recovery of functional sensibility. On a ranking list of such factors verbal learning and visuo-spatial logic capacity were the most important ones, indicating significant correlations with functional sensibility. It is concluded that cognitive capacity factors may play an important role for the functional outcome following nerve repair and that variations in such factors may help to explain the variability in the outcome of nerve repair.

Tubular repair of the median nerve in the human forearm. Preliminary findings

Transected median nerves in the forearm of two male patients, 12 and 21 years of age, were treated with a chamber technique leaving a 3 to 5 mm gap between the nerve ends. The nerve ends were enclosed in a silicone tube of such a dimension that would not cause compression of the nerve. Post-operative examination including sensory evaluation and assessment of muscle contraction force was carried out after 3 years. In both cases there was excellent motor recovery of the thenar muscles. Outgrowth of sensory fibres was remarkably fast, resulting ultimately in functional sensibility allowing almost normal hand function. 2PD was < or = 6 mm (12-year-old patient) and 8 to 10 mm (21-year-old patient) respectively. In one case the silicone tube was re-explored because of minor local discomfort 2 years after the repair. The former gap was bridged by a smooth continuous nerve-like structure of the same diameter as the adjacent nerve trunk and with no signs of neuroma formation or compression of the nerve.