Pakistan Journal of Medical Sciences

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ORIGINAL ARTICLE

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Volume 25

 April - June 2009 (Part-II)

Number  3


 

Abstract

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Frequency of Sensory Neuropathy in Foot of Asymptomatic
Type2 Diabetic Patients Using Semmes-Weinstein Monofilament

Syed Rehan Ahmed1, Bader Faiyaz Zuberi2, Salahuddin Afsar3

ABSTRACT

Objective: To detect neuropathy in diabetics who are clinically asymptomatic, using SW monofilament and to correlate the frequency of detected neuropathy with the duration of diabetes.

Methodology: Known patients of type 2 diabetes that do not have symptoms of peripheral neuropathy were included. Height, weight and duration of diabetes were measured and BMI calculated. SW monofilament was pressed perpendicular to the test site with enough pressure to bend it for one second. Comparison of frequency of SW monofilament test among gender was done by x2 test. Bivariate correlation of SW monofilament test result with duration of diabetes was done by Kendall’s test.

Results: A total of 700 patients including 324 males and 376 females were examined. Asymptomatic neuropathy was detected in 14.4% of patients. The mean age of males was significantly more (50.4 ±9.0 vs 46.7 ±8.4 yrs; P < 0.0001) but BMI was lower than females (24.4 ±2.8 vs 26.2 ±4.2; P < 0.0001). No correlation of asymptomatic neuropathy with duration of diabetes was detected (P = 0.995).

Conclusions: Asymptomatic neuropathy is prevalent in our diabetic population and it does not correlate with the duration of diabetes. Diabetics should be actively screened for asymptomatic neuropathy by SW monofilament.

KEY WORDS: Semmes-Weinstein Monofilament, Neuropathy, Diabetes mellitus.

Pak J Med Sci    April - June 2009 (Part-II)    Vol. 25 No. 3    349-352

How to cite this article:

Ahmed SR, Zuberi BF, Afsar S. Frequency of Sensory Neuropathy in Foot of Asymptomatic Type2 Diabetic Patients Using Semmes-Weinstein Monofilament. Pak J Med Sci 2009;25(3):349-352.


1. Dr. Syed Rehan Ahmed, MBBS
2. Dr. Bader Faiyaz Zuberi, FCPS
3. Prof. Salahuddin Afsar, FRCP
1-3: Department of Medicine,
Dow University of Health Sciences,
Karachi, Pakistan.

Correspondence

Dr. Bader Faiyaz Zuberi
Assistant Professor, MU-III
Dow University of Health Sciences
Baba-e-Urdu Road,
Karachi, Pakistan
Email: bader@zuberi.net

* Received for Publication: January 20, 2009
* Revision Received: March 31, 2009
* Revision Accepted: April 16, 2009


INTRODUCTION

Diabetes Mellitus is a syndrome with a disordered metabolism and inappropriate hyperglycemia.1 Type-2 diabetes mellitus is the more prevalent form of diabetes.2 It results from a combination of insulin resistance and defective insulin secretion.1 Type 2 diabetic patients are asymptomatic initially. Late clinical manifestations of diabetes include a large number of pathologic complications such as micro and macrovascular complications and cranial and peripheral neuropathies.3-5 Diabetic peripheral neuropathy is a debilitating complication affecting as many as one half of all patients with diabetes during the course of their disease.6,7 Distal Symmetric Polyneuropathy has a variable prevalence of around 30% and increases the risk of ulcers and amputations in diabetic foot patients.8

It has been reported that 3% of the patients had overt neuropathy and 10% had borderline neuropathy at the time of diagnosis of diabetes mellitus; while another 10% subsequently developed neuropathy.7,9 Early detection of Peripheral neuropathy can therefore reduce the development of foot ulcers.10 Although nerve conduction studies have been used as the gold standard; International Diabetic Federation and World Health Organization have recommended the 5.07/10 gm Semmes-Weinstein (SW) monofilament as a simple and inexpensive tool for the detection of peripheral neuropathy, in a primary care setting.10,11 Till date there are no reports from Pakistan regarding frequency of neuropathy in asymptomatic diabetic patients.

METHODOLOGY

This cross sectional study was conducted at diabetic clinic & medical OPD of Civil Hospital Karachi during the period of January 2008 to November 2008. Known patients of type 2 diabetes that do not have symptoms of peripheral neuropathy at the time of examination were included after taking informed consent. Patients with systemic illnesses such as chronic renal failure, hypothyroidism, alcohol intoxication, Gullian-Barre Syndrome, leprosy, vesicular dermatosis, allergic contact dermatitis and furunculosis were excluded. Patients previously diagnosed as having neuropathy were also excluded. Patients were labeled diabetic if they fulfilled any one of the following criteria:

* Fasting plasma glucose (FPG) > 126 mg/dl on two separate occasions.

* Two hours post-load glucose >200mg/dl during an oral glucose tolerance test (OGTT).

Patient was labeled as hypertensive if their blood pressure was more than 135/85mm of Hg. Patient’s age, gender, duration of diabetes was recorded. A detailed clinical examination was done. Patient’s height, weight, and blood pressure were recorded.

SW monofilament testing procedure: The 5.07 filament has been accepted as the medical standard for the screening of the minimum level of protective sensation in the foot. The reproducible buckling stress force required to bend the 5.07 filament is 10 gram of force. The rationale of monofilament is to measure the patient’s ability to sense a point of pressure. Inability to sense a 10gm of force pressure is considered as "insensate". The foot under examination was wiped with alcohol. The SW monofilament is pressed perpendicular to the test site with enough pressure to bend it for one second.12 The test were applied on the following sites ; the dorsal surface of foot between the base of the first and second toes, the first, third and fifth toes, the first, third and fifth metatarsal heads, the medial and lateral midfoot and the heel were tested in random order. Results were recorded in the proforma.

Sample size: The prevalence of neuropathy at the time of diagnosis of diabetes in asymptomatic subjects has been reported at 3%.7 Using this value and to detect the difference of 2% at the power of 80% with 2-sided error of 0.05 the sample size is calculated as 571.

Statistical analysis: Means of age, weight, height, BMI, systolic pressure and diastolic pressure were compared among gender by Student’s‘t’ test. The data for duration of diabetes was skewed so it was reported in median ± inter-quartile range (IQR) and compared using Mann-Whitney U test. Frequency of hypertension and SW monofilament test among gender was done by X2 test. Bivariate correlation of SW monofilament test result with duration of diabetes was done by Kendall’s test. Significance level was set at <0.05. SPSS version 17.0 was used for analysis.

RESULTS

A total of 700 patients fulfilling inclusion/exclusion criteria were selected. These included 324 (46.3%) males and 376 (53.7%) females. Mean age ±SD for males was 50.4 ±9.0 yrs and that for females was 46.7 ±8.4 yrs. The mean age of females was significantly less as compared to males using Student’s‘t’ test (P < 0.0001; 95% CI 2.4 to 5.0). Mean weight of all selected patients was 64.5 ±10.2 kg while that of males and females was 67.4 ±8.9 kg and 61.9 ±10.6 kg respectively. The mean weight of females was significantly less as compared to males (‘t’ test: P < 0.0001; 95% CI 4.0 to 6.9). Similarly mean height of the females was also significantly less. Height of all patients was 159.6 ±8.5 cm, males 166.4 ±5.5 cm, females 153.8 ±5.8 cm (‘t’ test: P < 0.0001; 95% CI 11.7 to 13.4). Although both mean height and weight of females were less but mean BMI was found significantly more in females. Mean BMI of total patients was 25.4±3.7 while that of males was 24.4 ±2.8 and that of females was 26.2±4.2 (‘t’ test: P < 0.0001; 95% CI -2.3 to -1.3). Mean systolic pressure of males was 130.1 ±16.1 mm of Hg while that in females was 132.6 ± 16.7 mm of Hg, the difference was statistically significant (‘t’ test: P = 0.045; 95% CI -4.9 to -0.05). But the difference in means of diastolic pressures was not statistically significant with males having 86.7 ±11.1 mm of Hg while females having 88.0 ±12.1 mm of Hg (‘t’ test: P = 0.165; 95% CI -2.9 to 0.5). Hypertension was present in 312 (44.6%) of patients out of which 129 (41.3%) were males and 183 (58.7%) were females. Hypertension was statistically more prevalent in females (X2 test: P = 0.019, df = 1). The median duration of diabetes ± IQR in males was 57.1 ±44.1 months while that in females was 58.6 ±43.7 months. The difference in duration of diabetes between genders was not statistically significant. (Mann-Whitney U test: P = 0.565). (Tables-I)

The SW monofilament test detected insensate in 101 (14.4%) out of these 41 (40.6%) were males and 60 (59.4%) were females. The difference in frequency of insensate when tested by X2 test did not reveal any significant difference in frequency among gender (X2 test: P = 0.215, df = 1). The presence of insensate result on SW monofilament test was tested for correlation with duration of diabetes by Kendall’s Bivariate Correlation test did not show any correlation between duration of diabetes with frequency of insensate result by SW monofilament (P = 0.995).

DISCUSSION

The study showed a high frequency of 14.4% of patients with probable neuropathy in diabetics without any symptoms thereof. SW monofilament has been extensively validated previously to detect neuropathy.13-16 Autonomic, central, optic and multifocal motor neuropathies have been documented presenting asymptomatically.17-22 Detection of asymptomatic neuropathy in foot is important for better management and care of foot in diabetic patients who are susceptible to complications and amputations.8,23 Frequency of insensate was not different among gender thus both genders are equally susceptible. The mean height and weight of males were significantly more than females but BMI of females was significantly higher.

Amputations of lower extremity are more common in patients with poor glycemic control and it has also been shown that incidence of lower extremity amputations was greatly reduced when organized foot care was instituted.8,24 SW monofilament testing could detect these patients before they become symptomatic and thus foot care could be started before overt complications occur, some have also coined the term of silent neuropathy in such cases.14,25 It has been equally effective in detecting neuropathy in older adults too.26 A study from Karachi has also shown that complications of diabetes were more prevalent in those who had inadequate blood pressure and diabetic control and in those who were hyperlipidemic.27

Another important finding in our study was absence of any correlation of neuropathy detected in asymptomatic patients with duration of diabetes. This could be due to the fact that we recruited only asymptomatic patients and with long duration these patients become symptomatic and thus were excluded. This finding highlights the fact that SW monofilament testing should be done routinely in asymptomatic patients regardless of duration of diabetes.

CONCLUSION

Neuropathy is prevalent in asymptomatic diabetics that could easily be detected by SW monofilament test and asymptomatic neuropathy has no correlation with duration of diabetes.

REFERENCES

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10. Lee S, Kim H, Choi S, Park Y, Kim Y, Cho B. Clinical usefulness of the two-site Semmes-Weinstein monofilament test for detecting diabetic peripheral neuropathy. J Korean Med Sci 2003;18:103-7.

11. Niazi P, Ahmad K, Hussain A, Butt A, Alam A. Electrodiagnostic Evaluation of Diabetic Polyneuropathy. Pak Armed Forces Med J 2001;51:75-7.

12. McGill M, Molyneaux L, Yue DK. Use of the Semmes-Weinstein 5.07/10 gram monofilament: the long and the short of it. Diabet Med 1998;15:615-7.

13. Bourcier ME, Ullal J, Parson HK, Dublin CB, Witherspoon CA, Ward SA, et al. Diabetic peripheral neuropathy: how reliable is a homemade 1-g monofilament for screening? J Fam Pract 2006;55:505-8.

14. Kamei N, Yamane K, Nakanishi S, Yamashita Y, Tamura T, Ohshita K, et al. Effectiveness of Semmes-Weinstein monofilament examination for diabetic peripheral neuropathy screening. J Diabetes Complications 2005;19:47-53.

15. Nagai Y, Sugiyama Y, Abe T, Nomura G. 4-g monofilament is clinically useful for detecting diabetic peripheral neuropathy. Diabetes Care 2001;24:183-4.

16. Armstrong DG. The 10g monofilament: the diagnostic divining rod for the diabetic foot? Diabetes Care 2000;23:887.

17. Uzun N, Uluduz D, Mikla S, Aydin A. Evaluation of asymptomatic central neuropathy in type I diabetes mellitus. Electromyogr Clin Neurophysiol 2006;46:131-7.

18. Reisin RC, Zurru C, Buso C, Marchesoni C, Pardal AM, Jadzinsky M. Multifocal motor neuropathy, type 1 diabetes and asymptomatic Hashimoto’s thyroiditis: an unusual association. Neuromuscul Disord 2005;15:358-60.

19. Rutter MK, McComb JM, Brady S, Marshall SM. Autonomic neuropathy in asymptomatic subjects with non-insulin-dependent diabetes mellitus and microalbuminuria. Clin Auton Res 1998;8:251-7.

20. Koistinen MJ, Airaksinen KE, Huikuri HV, Pirttiaho H, Linnaluoto MK, Ikaheimo MJ, et al. Asymptomatic coronary artery disease in diabetes: associated with autonomic neuropathy? Acta Diabetol 1992;28:199-202.

21. Slavin ML. Chronic asymptomatic ischemic optic neuropathy. A report of two cases in adults with diabetes mellitus. J Clin Neuroophthalmol 1987;7:198-201.

22. Hume L, Oakley GD, Boulton AJ, Hardisty C, Ward JD. Asymptomatic myocardial ischemia in diabetes and its relationship to diabetic neuropathy: an exercise electrocardiography study in middle-aged diabetic men. Diabetes Care 1986;9:384-8.

23. Miranda-Palma B, Sosenko JM, Bowker JH, Mizel MS, Boulton AJ. A comparison of the monofilament with other testing modalities for foot ulcer susceptibility. Diabetes Res Clin Pract 2005;70:8-12.

24. Imran S, Ali R, Mahboob G. Frequency of lower extremity amputation in diabetics with reference to glycemic control and Wagner’s grades. J Coll Physicians Surg Pak 2006;16:124-7.

25. Santhanam A. Silent neuropathy: detection and monitoring using Semmes-Weinstein monofilaments. Indian J Dermatol Venereol Leprol 2003;69:350-2.

26. Modawal A, Fley J, Shukla R, Rudawsky D, Welge J, Yang J. Use of monofilament in the detection of foot lesions in older adults. J Foot Ankle Surg 2006;45:76-81.

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