Peripheral neuropathy is a very common condition, which is often distressing and disabling [
A cross-sectional study was conducted on 50 adult overweight or obese nondiabetic volunteers recruited from the outpatient department of College of Medical Sciences Teaching Hospital, Bharatpur, Nepal, after obtaining an informed consent. The ethical approval for this study was obtained from the institutional review board. Detail history and clinical examination findings of all the participants were recorded.
The data on height, weight, abdominal girth, and waist-hip ratio were obtained and the participants were classified into two groups using WHO (World Health Organization) criteria [
NCS was performed with Neuroperfect, 4-channel EMG/NCV/EP machine 2000 by Medicaid using surface electrode for motor nerve conduction and ring electrodes for sensory NCS in the air-conditioned neurophysiology lab with control of temperature to ideal and the details of the obtained values were systematically recorded.
Motor nerve conduction studies (MNCS) were done in median nerve (a supramaximal stimulus at the wrist 3 cm proximal to the distal wrist crease, at elbow near the volar crease of brachial pulse, and at axilla, recorded from abductor pollicis brevis with the reference electrode placed 3 cm distal at first metacarpophalangeal joint), ulnar nerves (supramaximal stimulus at wrist, ulnar groove, and axilla, recorded from abductor digiti minimi), common peroneal nerve (stimulation at ankle, 2 cm distal to the fibular neck and 5–8 cm above the fibular neck, surface reading recorded from extensor digitorum brevis), and posterior tibial nerve (stimulation behind and proximal to medial malleolus and popliteal fossa, surface reading recorded from abductor digiti quinti slight below and anterior to navicular bone). Sensory nerve conduction studies (SNCS) were done in median nerve (recorded from first interphalangeal joints of second digit and stimulations at wrist, elbow, and axilla), ulnar nerve (recorded from interphalangeal joints of fifth digit and stimulations at wrist, elbow, and axilla), and sural nerve (recorded between lateral malleolus and tendoachilles and stimulation 10–18 cm proximal to the recording electrode distal to the lower border of gastrocnemius at the junction of middle and lower third of leg). F-wave latency was recorded from all the motor nerves in the same setting.
The 100 normal values for each nerve variable (motor distal latencies, sensory latency, CMAP (compound muscle action potential), SNAP (sensory nerve action potential), motor CV (conduction velocity), sensory CV, and F-wave latency) were obtained by recording the neurophysiological values of 50 healthy individuals of similar age and height. This data was used to calculate the cut-off values to determine the peripheral nerve function (normal or abnormal) of 50 nondiabetic overweight and obese individuals. Volunteers were also classified on the basis of a number of nerves involved, namely, “<2” or “≥2.” Those volunteers whose nerve function was found to be normal (no nerves involved) and those with abnormal nerve function with only one nerve involved were categorized as “<2 nerves involved,” while the rest of the volunteers (abnormal nerve function with more than one nerve involved) were categorized as “≥2 nerves involved.”
The study did not include individuals with clear signs of polyneuropathy in the NCS and individuals with any diseases or drugs known to affect PNS (peripheral nervous system) function.
The descriptive statistics for the baseline data from the study population were presented according to the main outcomes (dichotomous): nerve function (motor, sensory, and mixed) and number of nerves involved (motor, sensory, and mixed). All the continuous variables were tested for normality (Shapiro-Wilk test) and their significance of association with the outcome measurements was tested using Independent
Out of 50 volunteers, the majority had abnormal nerve function of all kinds of nerves: motor (54%), sensory (72%), and mixed (80%). Most of them (70%) had ≥2 mixed nerves’ involvement. Sensory nerves were more affected than motor nerves (54% versus 28%) (Table
Descriptive of outcome variables with nerve function and number of nerves involved in abnormality.
Type of nerves | Outcome variables | |||
---|---|---|---|---|
Peripheral nerve function ( |
Number of nerves involved ( |
|||
Normal, |
Abnormal, |
<2, |
≥2, |
|
Motor nerve | 23 (46) | 27 (54) | 36 (72) | 14 (28) |
Sensory nerve | 14 (28) | 36 (72) | 23 (46) | 27 (54) |
Mixed nerve | 10 (20) | 40 (80) | 15 (30) | 35 (70) |
There was statistically significant difference in the mean of BMI (
Baseline characteristics of volunteers according to the motor nerve. The values in the column of the motor nerves outside the small bracket are the count per total and those inside the bracket are the percentage.
Motor nerves | ||||||
---|---|---|---|---|---|---|
Variables | Peripheral nerve function | Number of nerves involved | ||||
Normal ( |
Abnormal ( |
|
<2 ( |
≥2 ( |
|
|
|
40.0 (13.0) | 41.0 (13.0) | 0.626 | 39.0 (13.0) | 42.0 (22.0) | 0.109 |
Gender (female) | 21 (42) | 24 (48) | 1.000 | 31 (62) | 14 (28) | 0.304 |
Socioeconomic status | 0.233 | 0.454 | ||||
Lower | 1 (2) | 2 (4) | 1 (2) | 2 (4) | ||
Lower middle | 3 (6) | 10 (20) | 9 (18) | 4 (8) | ||
Upper lower | 14 (28) | 11 (22) | 19 (38) | 6 (12) | ||
Upper middle | 5 (10) | 4 (8) | 7 (14) | 2 (4) | ||
Alcohol consumer | 2 (4) | 2 (4) | 1.000 | 4 (8) | 0 | 0.566 |
Smoker | 2 (4) | 2 (4) | 1.000 | 3 (6) | 1 (2) | 1.000 |
Exercise | 6 (12) | 8 (16) | 0.781 | 10 (20) | 4 (8) | 1.000 |
Obesity in family | 2 (4) | 3 (6) | 1.000 | 4 (8) | 1 (2) | 1.000 |
Diabetes in family | 0 | 1 (2) | 1.000 | 1 (2) | 0 | 1.000 |
Hypertension history | 0.235 | 0.013 |
||||
None | 16 (69.6) | 18 (66.7) | 27 (75) | 7 (50.0) | ||
<1 to 5 years | 7 (30.4) | 6 (22.2) | 9 (25) | 4 (28.6) | ||
5 to >10 years | 0 | 3 (11.1) | 0 | 3 (21.4) | ||
Time of weight gained | 0.275 | 0.008 |
||||
<1 to 5 years | 15 (65.2) | 16 (59.3) | 23 (63.9) | 8 (57.1) | ||
5 to 10 years | 4 (17.4) | 3 (11.1) | 6 (16.7) | 1 (7.1) | ||
10 to 15 years | 4 (17.4) | 4 (14.8) | 7 (19.4) | 1 (7.1) | ||
15 to >20 years | 0 | 4 (14.8) | 0 | 4 (28.6) | ||
|
1.52 (0.06) | 1.50 (0.08) | 0.384 | 1.51 (0.06) | 1.50 (0.10) | 0.356 |
|
72.78 ± 9.23 | 76.33 ± 10.62 | 0.217 | 74.67 ± 10.34 | 74.79 ± 9.70 | 0.971 |
|
31.33 ± 3.66 | 33.57 ± 4.10 | 0.048 |
32.29 ± 4.04 | 33.19 ± 4.05 | 0.485 |
BMI class | 0.188 | 1.000 | ||||
Obese-I | 8 (34.8) | 4 (14.8) | 9 (25.0) | 3 (21.4) | ||
Obese-II | 15 (65.2) | 23 (85.2) | 27 (75.0) | 11 (78.6) | ||
|
0.86 ± 0.07 | 0.88 ± 0.07 | 0.268 | 0.87 ± 0.08 | 0.89 ± 0.05 | 0.305 |
|
0.61 ± 0.06 | 0.64 ± 0.06 | 0.050 | 0.62 ± 0.05 | 0.65 ± 0.06 | 0.086 |
|
92.37 ± 9.75 | 100.17 ± 12.29 | 0.018 |
95.77 ± 12.63 | 98.66 ± 9.23 | 0.442 |
|
114.4 (25.9) | 128.1 (39.5) | 0.034 |
121.9 (33.5) | 127.85 (39.75) | 0.437 |
|
9.96 (4.08) | 11.18 (7.96) | 0.227 | 9.98 (5.00) | 12.37 (9.60) | 0.054 |
|
62.2 (43.46) | 64.41 (111.59) | 0.381 | 62.68 (68.49) | 70.51 (106.23) | 0.130 |
hsCRP | 6 (26.1) | 9 (33.3) | 0.804 | 10 (27.8) | 5 (35.7) | 0.733 |
|
2.07 (1.27) | 2.73 (1.87) | 0.087 | 2.19 (1.27) | 2.98 (2.37) | 0.039 |
HOMA-IR class | 0.189 | 0.096 | ||||
<2 | 11 (47.8) | 7 (25.9) | 16 (44.4) | 2 (14.3) | ||
>2 | 12 (52.2) | 20 (74.1) | 20 (55.6) | 12 (85.7) | ||
|
0.34 ± 0.03 | 0.33 ± 0.02 | 0.133 | 0.34 ± 0.02 | 0.32 ± 0.02 | 0.049 |
BGL, blood glucose level; hsCRP, high sensitivity C-reactive protein.
Baseline characteristics of volunteers according to the sensory nerve. The values in the column of the sensory nerves outside the small bracket are the count per total and those inside the bracket are the percentage.
Sensory nerves | ||||||
---|---|---|---|---|---|---|
Variables | Peripheral nerve function | Number of nerves involved | ||||
Normal ( |
Abnormal ( |
|
<2 ( |
≥2 ( |
|
|
|
39.5 (15.0) | 40.5 (12.0) | 0.468 | 42.0 (14.0) | 40.0 (12.0) | 0.689 |
Gender (female) | 12 (85.7) | 33 (91.7) | 0.611 | 20 (87.0) | 25 (92.6) | 0.651 |
Socioeconomic status | 0.223 | 0.381 | ||||
Lower | 1 (7.1) | 2 (5.6) | 2 (8.7) | 1 (3.7) | ||
Lower middle | 3 (21.4) | 10 (27.8) | 6 (26.1) | 7 (25.9) | ||
Upper lower | 5 (35.7) | 20 (55.6) | 9 (39.1) | 16 (59.3) | ||
Upper middle | 5 (35.7) | 4 (11.1) | 6 (26.1) | 3 (11.1) | ||
Alcohol consumer | 1 (7.1) | 3 (8.3) | 1.000 | 2 (8.7) | 2 (7.4) | 1.000 |
Smoker | 2 (14.3) | 2 (5.6) | 0.310 | 3 (13.0) | 1 (3.7) | 0.322 |
Exercise | 4 (28.6) | 10 (27.8) | 1.000 | 5 (21.7) | 9 (33.3) | 0.552 |
Obesity in family | 1 (7.1) | 4 (11.1) | 1.000 | 1 (4.3) | 4 (14.8) | 0.357 |
Diabetes in family | 0 | 1 (2.8) | 1.000 | 0 | 1 (3.7) | 1.000 |
Hypertension history | 0.535 | 0.754 | ||||
None | 10 (71.4) | 24 (66.7) | 15 (65.2) | 19 (70.4) | ||
<1 to 5 years | 4 (28.6) | 9 (25.0) | 7 (30.4) | 6 (22.2) | ||
5 to >10 years | 0 | 3 (8.3) | 1 (4.3) | 2 (7.4) | ||
Time of weight gained | 0.741 | 0.949 | ||||
<1 to 5 years | 10 (71.4) | 21 (58.3) | 15 (65.2) | 16 (59.3) | ||
5 to 10 years | 2 (14.3) | 5 (13.9) | 3 (13.0) | 4 (14.8) | ||
10 to 15 years | 1 (7.1) | 7 (19.4) | 3 (13.0) | 5 (18.5) | ||
15 to >20 years | 1 (7.1) | 3 (8.3) | 2 (8.7) | 2 (7.4) | ||
|
1.51 (0.04) | 1.50 (0.09) | 0.737 | 1.51 (0.05) | 1.50 (0.09) | 0.395 |
|
70.93 ± 7.42 | 76.17 ± 10.66 | 0.099 | 73.22 ± 9.01 | 75.96 ± 10.90 | 0.342 |
|
31.01 ± 3.20 | 33.14 ± 4.19 | 0.093 | 31.41 ± 3.31 | 33.50 ± 4.37 | 0.067 |
BMI class | 0.278 | 1.000 | ||||
Obese-I | 5 (35.7) | 7 (19.4) | 6 (26.1) | 6 (22.2) | ||
Obese-II | 9 (64.3) | 29 (80.6) | 17 (73.9) | 21 (77.8) | ||
|
0.89 ± 0.09 | 0.87 ± 0.06 | 0.305 | 0.89 ± 0.08 | 0.86 ± 0.07 | 0.231 |
|
0.63 ± 0.06 | 0.63 ± 0.06 | 0.843 | 0.63 ± 0.06 | 0.63 ± 0.06 | 0.680 |
|
95.45 ± 8.81 | 97.02 ± 12.81 | 0.676 | 97.19 ± 10.25 | 96.06 ± 13.07 | 0.740 |
|
116.3 (28.15) | 124.5 (41.92) | 0.280 | 114.7 (30.8) | 125 (39.5) | 0.192 |
|
10.27 (5.13) | 10.19 (7.69) | 0.846 | 10.10 (7.69) | 10.34 (5.73) | 0.755 |
|
60.77 (33.04) | 65.30 (86.27) | 0.531 | 60.83 (29.57) | 76.60 (86.85) | 0.471 |
hsCRP | 3 (21.4) | 12 (33.3) | 0.507 | 5 (21.7) | 10 (37.0) | 0.386 |
|
2.34 (0.95) | 2.45 (1.68) | 0.923 | 2.45 (1.93) | 2.43 (1.50) | 0.668 |
HOMA-IR class | 0.312 | 0.645 | ||||
<2 | 3 (21.4) | 15 (41.7) | 7 (30.4) | 11 (40.7) | ||
>2 | 11 (78.6) | 21 (58.3) | 16 (69.6) | 16 (59.3) | ||
|
0.33 ± 0.22 | 0.34 ± 0.03 | 0.77 | 0.33 ± 0.03 | 0.34 ± 0.03 | 0.651 |
Baseline characteristics of volunteers according to the total nerve. The values in the column of the mixed nerves outside the small bracket are the count per total and those inside the bracket are the percentage.
Mixed nerves | ||||||
---|---|---|---|---|---|---|
Variables | Peripheral nerve function | Number of nerves involved | ||||
Normal ( |
Abnormal ( |
|
<2 ( |
≥2 ( |
|
|
|
39.5 (13.0) | 40.5 (13.0) | 0.591 | 40.0 (14.0) | 41.0 (13.0) | 0.420 |
Gender (female) | 9 (90) | 36 (90) | 1.000 | 12 (80) | 33 (94.3) | 0.152 |
Socioeconomic status | 0.464 | 0.740 | ||||
Lower | 1 (10) | 2 (5) | 1 (6.7) | 2 (5.7) | ||
Lower middle | 1 (10) | 12 (30) | 3 (20) | 10 (28.6) | ||
Upper lower | 5 (50) | 20 (50) | 7 (46.7) | 18 (51.4) | ||
Upper middle | 3 (30) | 6 (15) | 4 (26.7) | 5 (14.3) | ||
Alcohol consumer | 1 (10.0) | 3 (7.5) | 1.000 | 2 (13.3) | 2 (5.7) | 0.574 |
Smoker | 1 (10) | 397.5) | 1.000 | 2 (13.3) | 2 (5.7) | 0.574 |
Exercise | 3 (30) | 11 (27.5) | 1.000 | 3 (20) | 11 (31.4) | 0.574 |
Obesity in family | 1 (10) | 4 (10) | 1.000 | 1 (6.7) | 4 (11.4) | 1.000 |
Diabetes in family | 0 | 1 (2.5) | 1.000 | 0 | 1 (2.9) | 1.000 |
Hypertension history | 0.405 | 0.420 | ||||
None | 6 (60.0) | 28 (70.0) | 10 (66.7) | 24 (68.6) | ||
<1 to 5 years | 4 (40.0) | 9 (22.5) | 5 (33.3) | 8 (22.9) | ||
5 to >10 years | 0 | 3 (7.5) | 0 | 3 (8.6) | ||
Time of weight gained | 0.203 | 0.520 | ||||
<1 to 5 years | 9 (90) | 22 (55) | 11 (73.3) | 20 (57.1) | ||
5 to 10 years | 0 | 7 (17.5) | 2 (13.3) | 5 (14.3) | ||
10 to 15 years | 1 (10) | 7 (17.5) | 2 (13.3) | 6 (17.1) | ||
15 to >20 years | 0 | 4 (10) | 0 | 4 (11.4) | ||
|
1.52 (0.04) | 1.50 (0.08) | 0.558 | 1.52 (0.04) | 1.50 (0.08) | 0.457 |
|
71.50 ± 7.59 | 75.50 ± 10.53 | 0.265 | 71.53 ± 6.61 | 76.06 ± 11.04 | 0.147 |
|
30.75 ± 3.17 | 32.99 ± 4.12 | 0.116 | 30.82 ± 2.85 | 33.28 ± 4.26 | 0.047 |
BMI class | 0.225 | 0.471 | ||||
Obese-I | 4 (40) | 8 (20) | 5 (33.3) | 7 (20.0) | ||
Obese-II | 6 (60) | 32 (80) | 10 (66.7) | 28 (80) | ||
|
0.86 ± 0.08 | 0.88 ± 0.07 | 0.433 | 0.88 ± 0.09 | 0.87 ± 0.06 | 0.736 |
|
0.62 ± 0.06 | 0.63 ± 0.06 | 0.60 | 0.62 ± 0.06 | 0.63 ± 0.06 | 0.384 |
|
93.35 ± 7.24 | 97.39 ± 12.58 | 0.337 | 95.65 ± 11.24 | 96.98 ± 12.11 | 0.719 |
|
115.85 (30.83) | 123.10 (41.92) | 0.234 | 114.70 (31.90) | 124.00 (30.90) | 0.330 |
|
10.27 (5.78) | 10.19 (6.72) | 0.896 | 9.96 (3.85) | 10.54 (7.83) | 0.433 |
|
63.18 (33.04) | 63.79 (83.19) | 0.693 | 60.83 (35.73) | 64.41 (84.52) | 0.357 |
hsCRP | 2 (20) | 13 (32.5) | 0.702 | 3 (20) | 12 (34.3) | 0.502 |
|
2.34 (1.42) | 2.45 (1.66) | 0.858 | 2.22 (1.05) | 2.47 (1.78) | 0.427 |
HOMA-IR class | 0.730 | 1.000 | ||||
<2 | 3 (30) | 15 (37.5) | 5 (33.3) | 13 (37.1) | ||
>2 | 7 (70) | 25 (62.5) | 10 (66.7) | 22 (62.9) | ||
|
0.33 ± 0.03 | 0.34 ± 0.03 | 0.869 | 0.34 ± 0.03 | 0.33 ± 0.02 | 0.441 |
The number of motor nerves involved was significantly associated with HOMA-IR and QUICKI at
Multivariable logistic regression (Model 1, Table
Model for predicting abnormal motor nerve function (Model 1).
Variables |
|
|
OR (95% CI) |
---|---|---|---|
BMI (kg/m2) | 0.136 (0.081) | 0.092 | 1.146 (0.978–1.342) |
Fasting blood glucose (mg/dL) | 0.061 (0.030) | 0.039 |
1.063 (1.003–1.127) |
Constant | −10.111 | 0.008 |
Model
Increase in age by one year (
Model for predicting ≥2 motor nerves involved (Model 2).
Variables |
|
|
OR (95% CI) |
---|---|---|---|
Age (years) | 0.114 (0.047) | 0.015 |
1.120 (1.022–1.228) |
Serum insulin at 2 h (unit) | 0.011 (0.005) | 0.034 |
1.011 (1.001–1.020) |
Constant | −6.720 (2.253) | 0.003 |
Model
Model for predicting abnormal sensory nerve function (Model 3).
Variables |
|
|
OR (95% CI) |
---|---|---|---|
Age (years) | 0.080 (0.048) | 0.093 | 1.084 (0.987–1.190) |
≤2 HOMA-IR | 2.124 (0.905) | 0.019 |
8.368 (1.420–49.322) |
Serum insulin at 2 h (unit) | 0.014 (0.007) | 0.052 | 1.014 (1.000–1.028) |
Constant | −4.099 (2.300) | 0.075 |
Model
Model for predicting ≥2 sensory nerves involved (Model 4).
Variables |
|
|
OR (95% CI) |
---|---|---|---|
BMI (kg/m2) | 0.280 (0.127) | 0.028 |
1.324 (1.031–1.699) |
Waist-hip ratio | −12.604 (6.396) | 0.049 |
<0.001 (<0.001–0.934) |
Fasting blood glucose (mg/dL) | 0.283 (0.129) | 0.028 |
1.327 (1.030–1.710) |
Serum insulin at 0 h (unit) | 2.203 (0.986) | 0.026 |
9.053 (1.310–62.577) |
Serum insulin at 2 h (unit) | 0.019 (0.009) | 0.025 |
1.020 (1.002–1.037) |
HOMA-IR | −10.125 (4.360) | 0.020 |
<0.001 (<0.001–0.206) |
Constant | −24.125 (11.197) | 0.031 |
Model
Model for predicting abnormal mixed nerve function (Model 5).
Variables |
|
|
OR (95% CI) |
---|---|---|---|
Time of weight gained (years) | 1.045 (0.648) | 0.107 | 2.843 (0.799–10.119) |
BMI (kg/m2) | 0.245 (0.135) | 0.070 | 1.277 (0.981–1.664) |
HOMA-IR | −0.242 (0.216) | 0.262 | 0.785 (0.514–1.198) |
Constant | −7.188(4.126) | 0.082 |
Model
Model for predicting ≥2 mixed nerves involved (Model 6).
Variables |
|
|
OR (95% CI) |
---|---|---|---|
Gender (male) | 2.088 (1.189) | 0.079 | 8.072 (0.786–82.917) |
BMI (kg/m2) | 0.237 (0.112) | 0.034 |
1.267 (1.018–1.577) |
HOMA-IR | −0.127 (0.206) | 0.538 | 0.881 (0.589–1.318) |
Constant | −10.317 (4.426) | 0.020 |
Model
The influence of obesity on NCS parameters has not been studied adequately to date [
Majority had involvement of sensory nerves as compared to motor nerves. In previous studies, BMI was also found to have a negative correlation with sensory nerve action potential amplitude implying sensory axonal neuropathy [
Higher BMI, FBG, and 2hPP were observed in volunteers with abnormal motor nerve function. In a study by Pal et al., motor nerve latencies, decrease in the amplitude of action potentials, and conduction velocity were impaired in obesity [
Interestingly, in logistic regression, we found that increased FBG is the significant (
HOMA-IR was the only significant predictor of sensory nerve dysfunction. The value of HOMA-IR ≤2 increased the odds of abnormal sensory nerve function by 8.368 times compared to >2 HOMA-IR values, implying that insulin has a protective role which has been demonstrated by bountiful studies [
BMI was the only significant predictor in case of mixed nerves’ (≥2 nerves) involvement in our study. Peripheral nerve dysfunction is established in obesity [
We did not measure skin temperature, which is ideal during NCS, which is one of our study’s major limitations. However, in routine practice, this may not be feasible.
Our study found evidence of deranged peripheral nerve function in overweight and obese population in various combinations. BMI, HOMA-IR, and FBG were found to be the significant predictors. Appropriate management strategies to control BMI, FBG, and insulin resistance could prevent adult overweight and obese individuals from a future neuropathic process.
The authors declare that there are no competing interests regarding the publication of this paper.
Thanks are due to Mr. S. Shrestha and Mr. R. Sharma Poudel for statistical analysis. Thanks are due to Dr. Raju, Dr. Baburam, and Dr. Ghanshyam and all the participants of the study.