Neurometer

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I have been seeing this device called the "neurometer" demonstrated at conferences for many years and considered buying one, primarily to aid differential diagnosis for suspected compression related neuropathy but also to get better handle on whole spectrum of peripheral neuropathy suspected in foot.

Although unreasonably expensive replacement for Semmes Weinstein Monofilaments purely for risk stratification of diabetes mellitus patients it also seems to have established credibility in this area too from laudable researchers (Boulton and others).

Technology and theoretical framework appear sound to me with my limited knowledge of nerve physiology and experience with other neurophysiologic testing.

Some info below for the curious, the website has lots of references and detailed info.

Anyone on mailbase using/used one or thought about this and care to comment?


Traditional electrodiagnostic nerve tests, such as the sensory nerve conduction velocity (sNCV) examine fewer than 10% of sensory fibers within an isolated segment of a peripheral nerve. These traditional tests are insensitive to early stage hyperesthesia and functional complications, and rely on a non-standardized single-blinded test procedures. Neurometer® devices quantify the functional integrity of the large myelinated, small myelinated and unmyelinated sensory fibers (>90%) using a standardized double-blinded (p<0.006) automated test procedure. Standardized measures are objectively evaluated through computerized comparison to clinically established normative values. Also, unlike traditional electrodiagnostic procedures, Neurometer® tests are painless and can be conducted anywhere on the body - including the most distal cutaneous sites as well as mucosal locations. Neurometer® measures are not confounded by skin temperature, edema or electromagnetic interference. More than 500 peer-reviewed studies document the high sensitivity, specificity and intra-rater and inter-rater reliability of the Neurometer® sensory nerve tests and their advantages over traditional procedures.

http://www.neurotron.com/site/index.html

cheers

Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
Phone [204] 837 FOOT (3668)
Fax [204] 774 9918
www.winnipegfootclinic.com

 

I spent a couple of hours doing some internet and literature probing on this last night.

It proved more interesting than I had imagined and is an exercise demonstrating the need for caution in taking what is read at face value, particularly when the financial interests in manufacturers and professionals with vested interests are involved.

A bit of synopsis below and a couple of attachments for anyone interested.
In addition to giving an example of why we need to question what we take from peer reviewed articles the content does provide from different sources a nice overview of the features and limitations of investigating peripheral neuropathy.

Cheers

Martin
The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
Phone [204] 837 FOOT (3668)
Fax [204] 774 9918
www.winnipegfootclinic.com




From the WEB site of the USA’s the largest health insurer in the Northwest/Intermountain Region:

Current Perception Threshold Testing

In 1999 the American Association of Electrodiagnostic Medicine (AAEM) published a technology review of the Neurometer® device. (2) This evaluation suggested the following criteria for the evaluation of the device:
• A prospective study
• Independent ascertainment of the clinical condition evaluated
• A detailed description of the methodology
• Attention to testing conditions that could potentially affect the results
• A suitable reference population from the same laboratory
• Criteria for abnormality obtained from the reference population and defined in statistical terms

The AAEM assessment concluded that there is inadequate scientific literature meeting the above criteria to validate the clinical role of current perception threshold testing. Much of the literature compares the results of the Neurometer® testing to nerve conduction studies in patients with known disease. In many instances the results of the Neurometer® testing demonstrated more numerous or pronounced abnormalities compared to nerve conduction studies, consistent with the hypotheses that abnormalities of small nerve fibers precede those of the large nerve fibers tested in nerve conduction studies. However, this observation could also be related to the fact that use of the Neurometer® involves testing at multiple sites with 3 different frequencies and that any identified abnormality is considered significant. Testing the perception threshold at different frequencies is designed to evaluate the function of different subclasses of nerve fibers. However, this hypothesis has not been adequately evaluated, in part due to a lack of a diagnostic gold standard for comparison purposes. In this situation, validation of a diagnostic technology requires study of how the technique is used in the management of the patient and whether subsequent changes in the management of the patient are associated with improved health outcomes. Finally, results of the Neurometer® testing are compared to a normal reference population. The review by the AAEM found that the source of the normal values was not apparent from the published literature. The AAEM assessment concluded with the following recommendations regarding research to validate the clinical utility of the Neurometer®:

• Reference values need to be established for well-characterized and representative populations.

• Reproducibility and interoperator variability of the Neurometer® CPT normal values need to be established and expressed statistically in control subjects and patients with specific diseases.

• The sensitivity and specificity need to be established and compared to an appropriate standard.

http://www.regence.com/trgmedpol/medicine/med91.html

Now read the 2 attached .pdf papers which relate to this.

Some other abstracts below which may be of interest on this subject.


Small-Fiber Neuropathy: Answering the Burning Questions
Ezekiel Fink, and Anne Louise Oaklander
The authors are at the Nerve Injury Unit, a division of the Departments of Anesthesiology, Neurology, and Neuropathology at Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. E-mail: efink@partners.org (E.F.)
http://sageke.sciencemag.org/cgi/content/full/2006/6/pe7
Key Words: small-fiber neuropathy • pain • punch skin biopsy • neuralgia • neuropathic pain
Abstract: Small-fiber neuropathy is a peripheral nerve disease that most commonly presents in middle-aged and older people, who develop burning pain in their feet. Although it can be caused by disorders of metabolism such as diabetes, chronic infections (such as with human immunodeficiency virus), genetic abnormalities, toxicity from various drugs, and autoimmune diseases, the cause often remains a mystery because standard electrophysiologic tests for nerve injury do not detect small-fiber function. Inadequate ability to test for and diagnose small-fiber neuropathies has impeded patient care and research, but new tools offer promise. Infrequently, the underlying cause of small-fiber dysfunction is identified and disease-modifying therapy can be instituted. More commonly, the treatments for small-fiber neuropathy involve symptomatic treatment of neuropathic pain.
Citation: E. Fink, A. L. Oaklander, Small-Fiber Neuropathy: Answering the Burning Questions. Sci. Aging Knowl. Environ. 2006 (6), pe7 (2006).


Current Perception Thresholds in Ageing
ELLEN R. EVANS, MARC S. RENDELL, JAMES P. BARTEK, OLA BAMISEDUN, SHARON CONNOR and MICHAEL GIITTER
Creighton University Geriatric Center and the Creighton Diabetes Center 601 N. 30th Street, Omaha, NE 68131, USA
We studied 40 healthy elderly and 31 healthy young volunteers and 25 elderly diabetic and 37 young diabetic patients. All subjects received detailed neurological examinations focusing particularly on sensory symptom and physical evaluations. Standardized assessment of symptoms and physical testing of light touch, pain, vibratory and thermal sensation were performed at the hand, wrist, elbow, foot, ankle and knee. The total symptom score (SS) and the total physical score (PS) were defined by summing test scores at each site. Current perception threshold (CPT) testing using constant current sine wave alternating current was completed at the same anatomical sites. CPT findings did not differ significantly between young and old healthy subjects. Older diabetic patients had higher CPTs than younger diabetic patients, but the severity of clinical diabetic neuropathy was greater in the older group. CPTs correlated with the degree of clinical diabetic neuropathy (r = 0.47 with SS and r = 0.60 with PS) rather than with age (r=0.12). We conclude that current perception does not decline with age. Nor does ageing by itself worsen CPT values in patients with neuropathy. CPT testing is easily performed, clinically applicable and the first objective sensory measure not affected by the process of ageing.
Anesthesia & Analgesia, Vol 84, 1071-1075, Copyright © 1997 by International Anesthesia Research Society


Quantitative assessment of differential sensory blockade after lumbar epidural lidocaine
B Tay, MS Wallace and G Irving
Department of Anesthesiology, University of Texas, Houston, USA.
A cutaneous current perception threshold (CPT) sensory testing device measures both large and small diameter sensory nerve fiber function and may be useful in evaluating differential neural blockade. Eight subjects received both lumbar epidural saline and lumbar epidural lidocaine. Five milliliters of normal saline was administered and the CPTs were measured. After the saline, 10 mL of 2% plain lidocaine was administered. CPTs, and sensation to touch, pinprick, and cold were subsequently measured. Saline had no effect on any measurements. Lidocaine caused an increase in all CPTs at the umbilicus and the knee reaching a statistical significance at 5 Hz for the umbilicus only. The great toe showed a slight increase of the 5 Hz stimulus and no increase of the 2000 or 250 Hz stimulus. There was a significant decrease in touch, pinprick, and cold sensation at the umbilicus and knee and a significant decrease in the cold sensation at the great toe. There was no effect on any measurements made at the mastoid. Epidural lidocaine resulted in a differential neural blockade as measured by a CPT monitor but not with crude sensory measurements

A Quantitative Analysis of Sensory Function in Lumbar Radiculopathy Using Current Perception Threshold Testing.
Diagnostics
Spine. 27(14):1567-1570, July 15, 2002.
Yama****a, Toshihiko MD *; Kanaya, Kunihito MD *; Sekine, Masatoshi MD *; Takebayashi, Tsuneo MD *; Kawaguchi, Satoshi MD *; Katahira, Genichirou MD +
Abstract:
Study Design. Peripheral sensory functions in patients with radiculopathy resulting from lumbar disc herniation and in control individuals were analyzed using current perception threshold testing.
Objective. To evaluate the severity of sensory disturbance quantitatively in patients with lumbar radiculopathy.
Summary of Background Data. Subjective evaluation of the severity of sensory disturbance associated with spinal disorders using conventional methods often is difficult. Current perception threshold evaluation is a recently proposed method for studying peripheral nerve dysfunction. This is a quantitative sensory test for analyzing functions of A-beta, A-delta, and C fibers.
Methods. In this study, 48 patients with lumbar radiculopathy resulting from lumbar disc herniation were examined. The mean age of the patients was 37.9 years. All the patients had pain distribution from the compression of one lumbar nerve root (L5 or S1), and unequivocal unilateral disc herniation of the corresponding level was shown by magnetic resonance imaging. Eleven healthy volunteers were used as control subjects. Their mean age was 38.2 years. Current perception threshold evaluation using a Neurometer device was performed at three frequencies: 2000, 250, and 5 Hz. The stimulus sites were located on the dorsal side of the first metatarsus (the L5 dermatome) and the dorsal side of the fifth metatarsus (the S1 dermatome). These sites were investigated on both legs in all the patients and control subjects. The intensity of pain was scored using a visual analog scale.
Results. In the control group, there were no significant differences in current perception threshold values at any frequency between the left and right legs. In the patient group, the current perception threshold values in the affected legs were significantly higher than those in the contralateral legs at all frequencies. The current perception threshold values in the affected legs in the patient group were significantly higher than those in the control subjects at 2000 and 250 Hz, whereas there were no significant differences at 5 Hz. The current perception threshold values in the affected legs were significantly higher in patients with hypesthesia than in those without hypesthesia at 2000 and 250 Hz, and in patients with severe pain than in those with less pain at 5 Hz.
Conclusions. Current perception threshold testing showed that the functions of A-beta, A-delta, and C fibers deteriorated in patients with lumbar radiculopathy. This technique may be useful for quantifying sensory nerve dysfunction in patients with radiculopathy.


© The Author 2007. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org
Nerve conduction studies and current perception thresholds in workers assessed for hand–arm vibration syndrome
Lina Lander1,2, Wendy Lou1 and Ron House1,3
1 Department of Public Health Sciences, University of Toronto, Toronto, Ontario, Canada
2 Department of Environmental Health, Harvard School of Public Health, 665 Huntington Avenue, Building I, Room 1418A, Boston, MA 02115, USA
3 Occupational and Environmental Health Clinic, St Michael's Hospital, Toronto, Ontario, Canada
Background Workers exposed to hand–arm vibration are at risk of developing the neurological abnormalities of hand–arm vibration syndrome (HAVS). The Stockholm classification of the neurological component of HAVS is based on history and physical examination. There is a need to determine the association between neurological tests and the Stockholm scale.
Aims The main objective of this study was to compare the Stockholm neurological scale and the results of current perception threshold (CPT) tests and nerve conduction studies (NCS).
Methods Detailed physical examinations were done on 162 subjects referred for HAVS assessment at a specialist occupational health clinic. All subjects had NCS and measurement of CPT. The Stockholm neurological classification was carried out blinded to the results of these neurological tests and compared to the test results.
Results The nerve conduction results indicated that median and ulnar neuropathies proximal to the hand are common in workers being assessed for HAVS. Digital sensory neuropathy was found in only one worker. Neither the nerve conduction results nor the current perception results had a strong association with the Stockholm neurological scale. Exposure to vibration in total hours was the main variable associated with the Stockholm neurological scale [right hand: OR 1.30, 95% CI (1.10–1.54); left hand: OR 1.18, 95% CI (1.0–1.39)].
Conclusion Workers being assessed for HAVS should have nerve conduction testing to detect neuropathies proximal to the hand. Quantitative sensory tests such as current perception measurement are insufficient for diagnostic purposes but may have a role in screening workers exposed to vibration.
Keywords Current perception; HAVS; nerve conduction; neurological; vibration


1: Diabet Med. 1991;8 Spec No:S63-6. Links
The Neurometer: validation and comparison with conventional tests for diabetic neuropathy.
Masson EA, Boulton AJ.
Department of Medicine, Manchester Royal Infirmary, UK.
The Neurometer is a portable constant current sine wave stimulator, which has recently been advocated for the quantification of peripheral nerve dysfunction by the measurement of detection thresholds for constant current stimulation. Stimuli are applied through surface electrodes at three frequencies and a forced choice method is used to determine the minimum amplitude for detection. The possible application of the Neurometer to the diagnosis and measurement of diabetic neuropathy was evaluated. The preliminary Neurometry results in comparison to those of conventional nerve testing techniques, including thermal and vibration detection thresholds, are discussed. It appears that the device may be a useful screening instrument which could give a fairly comprehensive idea of the functional integrity of different nerve fibre populations, and a full assessment takes only 10 to 15 min, in contrast to the conventional alternatives.


Differences in peripheral and autonomic nerve function measurements in painful and painless neuropathy. A clinical study.
Veves A, Young MJ, Manes C, Boulton AJ.
University Department of Medicine, Manchester Royal Infirmary, U.K.
OBJECTIVE--To examine the differences in peripheral and autonomic nerve function measurements between diabetic patients without neuropathy (group 1, n = 38, mean age 50.9, range 29-71 years), with painless neuropathy (group 2, n = 32, mean age 49.2, range 30-71 years), and with painful neuropathy (group 3, n = 52, mean age 51.5, range 28-73 years). RESEARCH DESIGN AND METHODS--The evaluation of neuropathy was based on clinical symptoms, signs, and quantitative sensory testing, including current perception threshold (CPT) with a neurometer and electrophysiology. RESULTS--The Neuropathy Symptom Score and the Neuropathy Disability Score were higher in patients with painful neuropathy compared with patients with painless neuropathy (6.8 +/- 2.7 vs. 0.5 +/- 0.8 [mean +/- SD], P < 0.0001, and 12.5 +/- 6.2 vs. 8.6 +/- 6.8, P < 0.01, respectively). In contrast, no differences were found in the quantitative sensory testing, including CPT measurements, the electrophysiological measurements, and the autonomic nerve system function tests in the two groups. Significant differences were found in all the above measurements when groups 2 and 3 were compared with diabetic patients without neuropathy (group 1). When all diabetic patients were considered as one group, significant correlations were found between CPT and the other peripheral nerve function assessments. In particular, peroneal nerve motor conduction velocity correlated with CPT at 2 kHz (r = -0.48, P < 0.001) and vibration perception threshold (r = -0.50, P < 0.001). CONCLUSIONS--We conclude that no difference could be found in the function of small and large nerve fibers between painful and painless diabetic neuropathy using conventional tests currently used. The CPT evaluation failed to quantify painful symptoms, but it compared favorably with other quantitative sensory tests in quantifying peripheral neuropathy.

Variability in function measurements of three sensory foot nerves in neuropathic diabetic patients.
Donaghue VM, Giurini JM, Rosenblum BI, Weissman PN, Veves A.
Deaconess-Joslin Foot Center, Harvard Medical School, Boston, MA 02215, USA.
We have examined the variability in function measurements of three sensory foot nerves in neuropathic diabetic patients and have compared them to measurements from healthy non-diabetic subjects. Sixty-six healthy, non-diabetic subjects (30 (45%) males, mean age 56 years (range, 21-84 years)) and 61 age and sex matched diabetic patients (33 (54%) males, mean age 55 years (range, 34-78 years) Type 1 diabetes mellitus (DM), mean duration of DM 24 years (range, 2-48 years)) were tested. Current perception threshold (CPT) at 250 Hz was employed to test the sensory function of three nerves: superficial peroneal, sural and posterior tibial. The vibration perception threshold, (VPT) and the cutaneous perception threshold (CCPT) were also assessed at the great toe. According to the results of the neuropathy disability score (NDS), mild neuropathy was present in 8 (13%) patients, moderate in 33 (54%) and severe in 20 (33%). In both groups the CPT of the posterior tibial nerve was higher than the other two nerves (P < 0.0001) while no difference was found between the superficial peroneal and sural nerves (P = NS). CPT was different between the two feet at the superficial peroneal nerve in 39 (64%) diabetic patients and 34 (52%) controls (P = NS), at the sural nerve in 40 (65%) and 45 (68%) (P = NS), and at the posterior tibial in 36 (59%) and 33 (50%), respectively (P = NS). VPT was different by more than 10% at the great toes in 26 (43%) diabetic subjects and CCPT in 21 (34%). We conclude that although there is variation in sensory nerve function tests in diabetic patients this is similar to that noticed in healthy subjects. The great variability of all quantitative sensory testing indicates that more than one site should be tested.
© 2005 American Academy of Neurology
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Special Article
Distal symmetric polyneuropathy: A definition for clinical research
Report of the American Academy of Neurology, the American Association of Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation
J. D. England, MD, G. S. Gronseth, MD, G. Franklin, MD, MPH, R. G. Miller, MD, A. K. Asbury, MD, G. T. Carter, MD, J. A. Cohen, MD, M. A. Fisher, MD, J. F. Howard, MD, L. J. Kinsella, MD, N. Latov, MD, R. A. Lewis, MD, P. A. Low, MD and A. J. Sumner, MD
From the American Academy of Neurology, St. Paul, MN; the American Association of Electrodiagnostic Medicine, Rochester, MN; and the American Academy of Physical Medicine and Rehabilitation, Chicago, IL.
Address correspondence and reprint requests to American Academy of Neurology, 1080 Montreal Avenue, St. Paul, MN 55116.
The objective of this report was to develop a case definition of distal symmetric polyneuropathy to standardize and facilitate clinical research and epidemiologic studies. A formalized consensus process was employed to reach agreement after a systematic review and classification of evidence from the literature. The literature indicates that symptoms alone have relatively poor diagnostic accuracy in predicting the presence of polyneuropathy; signs are better predictors of polyneuropathy than symptoms; and single abnormalities on examination are less sensitive than multiple abnormalities in predicting the presence of polyneuropathy. The combination of neuropathic symptoms, signs, and electrodiagnostic findings provides the most accurate diagnosis of distal symmetric polyneuropathy. A set of case definitions was rank ordered by likelihood of disease. The highest likelihood of polyneuropathy (useful for clinical trials) occurs with a combination of multiple symptoms, multiple signs, and abnormal electrodiagnostic studies. A modest likelihood of polyneuropathy (useful for field or epidemiologic studies) occurs with a combination of multiple symptoms and multiple signs when the results of electrodiagnostic studies are not available. A lower likelihood of polyneuropathy occurs when electrodiagnostic studies and signs are discordant. For research purposes, the best approach to defining distal symmetric polyneuropathy is a set of case definitions rank ordered by estimated likelihood of disease. The inclusion of this formalized case definition in clinical and epidemiologic research studies will ensure greater consistency of case selection.