Influence of gender on nerve
conduction parameters of median and ulnar nerves in healthy individuals
Samol S1, Hui M2, Parmar
D3, Dixit R4
1Dr. Shaesta Samol, Resident, Department of Physiology, Government
Medical College, Surat, 2Dr.Mohsin Hui, Surat General Hospital, Surat,
Gujarat, 3Dr. Dharitri Parmar, Professor Head, Department of
Physiology, 4Dr. R.Dixit Dean, Government Medical College, Surat,
Gujrat, India
Address for
Correspondence: Dr. Shaesta I Samol, Department of
Physiology, Government Medical College, Surat. E-mail:
dr.shaesta.samol@gmail.com,
Abstract
Background &
objectives: Nerve conduction studies are used to diagnose
disorders of the peripheral nervous system. They are influenced by
number of variables i.e. age, gender, height, temperature, fiber
diameter, degree of myelination, inter nodal distance etc. This study
was conducted to analyze the effect of gender on nerve conduction
parameters of upper limb nerves. Materials
& Methods: The study comprised of 50 males and 50
females between the age group of 18-25 years. Distal latency, amplitude
and conduction velocity of Median and Ulnar nerve were recorded using
standardized technique. Results:
The mean distal latency of sensory Median and Ulnar nerve were found to
be significantly greater in males (p<0.05), whereas mean sensory
amplitude was found to be significantly higher in female subjects, but
the conduction velocity did not show any statistically significant
difference (p>0.05). Mean distal latency and amplitude of motor
median and ulnar nerve was found higher in males than females whereas
conduction velocity was found to be higher in females but the
difference was statistically insignificant. Conclusion: Gender
has definite and significant influence on various Nerve Conduction
Parameters. Without adjustment for this factor, the sensitivity and
specificity of NCS will decrease when using the same reference data in
patients with different gender.
Key words: Compound
Muscle Action Potential; Median Nerve; Nerve Conduction Velocity;
Sensory Nerve Action Potential; Ulnar Nerve
Manuscript received:
20th September 2016,
Reviewed: 30th September 2016
Author Corrected:
10th October 2016,
Accepted for Publication: 19th October 2016
Introduction
In the past few decades, major changes have taken place in the field of
peripheral nerves especially in the relation to its ultra structure,
neurophysiology and axonal transport system. The widespread interest in
disorders of peripheral nervous system, which has increased in recent
years, primarily has its origin in the introduction of new
investigating techniques. The electro-diagnostic assessment of
peripheral nerves includes two major components: nerve conduction (NCS)
and needle electromyography (EMG) studies [1]. Nerve conduction study
is a part of electro diagnostic procedures that help in establishing
the type and extent of the abnormality of the nerves. It assesses motor
and sensory functions by recording the evoked response to electrical
stimulation of peripheral nerves.
Nerve conduction studies are most often used to diagnose disorders of
the peripheral nervous system. They help in differentiating between the
two major peripheral nerve diseases: demyelination and axonal
degeneration [2]. Routine NCS includes assessment of compound muscle
action potential (CMAP) and sensory nerve action potentials (SNAP) of
accessible peripheral nerves in upper and lower limbs including median,
ulnar, radial, common peroneal, tibial and sural nerves. Commonly
measured parameters of CMAP include latency, amplitude, duration,
conduction velocity and late response, e.g. F-waves. Similarly for
SNAP, latency, amplitude, duration and conduction velocity are
routinely measured [1]. Among the NCS parameters, conduction velocity
and latency quantify the speed of nerve impulse propagation and are
altered in diseases causing demyelination. Amplitude reflects the
number of functioning nerve fibers and is reduced in diseases causing
axonal degeneration [3].
The conduction velocity of the nerve depends on the fiber diameter,
degree of myelination and the inter nodal distance. Other factors such
as age, temperature, height, gender, and limb are the physiological
variables affecting nerve conduction study [4]. The use of conduction
velocity measurement as a diagnostic procedure in neurology requires a
knowledge of the range of values encountered in healthy individuals.
The present study was conducted to analyze the effect of gender on
nerve conduction parameters of upper limb nerves. The motor as well as
sensory nerve conduction parameters of Median and Ulnar nerve have been
studied in both the sex.
Materials
& Method
This study was conducted at Government Medical College, Surat with
prior approval from institutional ethical committee. The study was
performed in 50 male and 50 female healthy subjects of age group
between 18 to 25 years. Written and informed consent was taken.
Procedure was explained. Relevant clinical history was taken and
clinical examination was done. Age, sex, height (in cm), and weight (in
kg) were recorded. BMI was calculated [5].
Subjects were selected on the basis of inclusion & exclusion
criteria. Those with the history of diabetes, hypertension, alcohol
intake, smoking, obese (BMI ≥ 24.99kg/m2) or any other disease
likely to affect nerve conduction parameters like Limb injury,
Neuropathy, Neuromuscular transmission disorder and Myopathy were
excluded.
A NEUROSTIM EMG/NCV/EP machine NS: 4-4 CHANNEL manufactured by Medicaid
systems provided by Department of Physiology, GMC Surat was used.
Median and Ulnar Nerves were tested for motor and sensory conduction.
The electroneurographic setting was as follows:
For motor study filters were set at 2 Hz to 5 kHz and sweep speed 2-5
ms per division and for sensory study filters were set at 20 Hz to 3
kHz and sweep speed 1- 2 ms per division. Duration of stimulus for both
motor and sensory study was 100 us. Supramaximal strength of stimulus
was used. For motor and Sensory nerve conduction following parameters
were recorded:-
1. Latency in milli-seconds (ms)
2. Amplitude in milli-volt (mV) and micro-volt (μV) for Motor
and Sensory nerves respectively.
3. Conduction velocity in meters per second (m/s).
To ensure adequate skin contact, skin was cleaned with the spirit and
electrode gel was used between the electrodes and the skin.
The ground electrode was placed on the dorsum of the hand, between the
stimulating and the recording electrodes. For the motor evaluation, the
active electrodes were placed over the motor point of the abductor
pollicis brevis for the median nerve, and over the abductor digiti
minimi for the ulnar nerve. The reference electrode was placed 3 cm
distal over the 1st metacarpo-phalangeal joint for the median nerve and
over the 5th metacarpo-phalangeal joint for the ulnar nerve. The sites
of stimulation for both were the wrist and elbow. With surface
electrodes, distal stimulations were performed at the wrist (3 cm
proximal to the distal wrist crease) between the flexor Carpi radialis
and the Palmaris longus tendon for the median nerve, while they were
performed posterior to the flexor Carpi ulnaris for the ulnar nerve.
Similarly stimulation of the median nerve at the elbow was performed
medial to the biceps tendon, on the volar crease of the brachial
arterial pulse, whereas for the ulnar nerve, stimulation was 3-4cm
distal to the medial epicondyle, with the wrist and the elbow in
135° of flexion [4]. For the sensory studies, the median and
the ulnar nerves were examined antidromically. The ring electrode was
placed over the 2nd and 5th digits to record the responses along the
median and the ulnar nerves, respectively. The reference electrode was
placed about 3 cm distal to the ring electrode. The median nerve
stimulation was performed 14 cm proximal to the active electrode and
medial to the flexor Carpi radialis tendon. For the ulnar sensory
nerve, the stimulation was performed 10cm proximal to the active
electrode and posterior to the flexor Carpi ulnaris tendon [4].
Statistical Analysis-Values
are expressed as mean ± SD. Microsoft Office Excel 2007 and
Graph pad software were used for data analysis. Comparison between two
groups is done by T test. The probability level for significance was
set at p< 0.05.
Results
Median and Ulnar Nerves were tested for motor and sensory conduction in
50 male and 50 female healthy subjects of age group between 18 to 25
years in Department of Physiology.
The various anthropometric measurements of males and females are
summarized in Table 1. Descriptive statistics of various parameters of
motor and sensory Median and Ulnar nerves for both sexes are shown in
Table 2 and 3.
The data was separately analyzed for males and females. On analyzing
nerve conduction parameters of motor median and ulnar nerves in 50 male
and 50 female subjects, mean distal latency and CMAP amplitude of motor
median and ulnar nerve was found higher in males than females but the
difference was statistically insignificant whereas conduction velocity
was found to be higher in females for both the nerves but the
difference was statistically insignificant (p>0.05).
On analyzing nerve conduction parameters of sensory median and ulnar
nerves in 50 male and 50 female subjects, mean sensory latency was
found significantly longer in male subjects for both median and ulnar
nerves (p<0.05) whereas mean sensory amplitude was found to be
significantly higher in female subjects for both the nerves
(p<0.05), but the conduction velocity did not show any
statistically significant difference (p>0.05).
Table-1: Various
anthropometric measurements in males and females
|
Variable
MEAN±SD
|
Males(N=50)
|
Females(N=50)
|
p-value*
|
|
Age(years)
|
18.36±0.48
|
18.42±1.07
|
p>0.05
|
|
Height(cm)
|
172.46±6
|
158.18±5.26
|
p<0.05
|
|
Weight(kg)
|
62±7.46
|
50.9±6.73
|
p<0.05
|
|
BMI(kg/m2)
|
20.78±1.69
|
20.42±4.23
|
p>0.05
|
* p>0.05 considered as not significant p˂0.05 is taken as
significant
Table-2: Gender wise
distribution of Motor Nerve Conduction Study Parameters
|
Nerve
|
Parameters
|
Males(N=50)
MEAN±SD
|
Females(N=50)
MEAN±SD
|
p-value*
|
|
Motor
right Median
|
LATENCY(ms)**
|
3.48±1.02
|
3.27±0.87
|
p>0.05
|
|
AMPLITUDE(mv)***
|
11.79±4
|
11.67±3.17
|
p>0.05
|
|
CONDUCTION VELOCITY(m/s)
|
62.31±5.12
|
63.72±4.12
|
p>0.05
|
|
Motor
left Median
|
LATENCY(ms)**
|
3.56±1.1
|
3.37±0.94
|
p>0.05
|
|
AMPLITUDE(mv)***
|
12.79±3.19
|
12.22±3.16
|
p>0.05
|
|
CONDUCTION VELOCITY(m/s)
|
62.01±4.18
|
63.60±4.11
|
p>0.05
|
|
Motor
right Ulnar
|
LATENCY(ms)**
|
3.53±1.03
|
3.34±0.81
|
p>0.05
|
|
AMPLITUDE(mv)***
|
12.3±3.84
|
12.21±3.24
|
p>0.05
|
|
CONDUCTION VELOCITY(m/s)
|
62.97±3.5
|
63.85±4.15
|
p>0.05
|
|
Motor
left Ulnar
|
LATENCY(ms)**
|
3.52±0.96
|
3.38±0.98
|
p>0.05
|
|
AMPLITUDE(mv)***
|
12.59±3.31
|
12.02±3.12
|
p>0.05
|
|
CONDUCTION
VELOCITY(m/s)
|
62.26±3.22
|
63±4.34
|
p>0.05
|
* p>0.05 considered as not significant p˂0.05 taken as
significant when various parameters of both the sexes were compared.
**Distal motor latency measured from onset of action potential.
***Amplitude measured from peak to peak.
Table-3: Gender
wise distribution of sensory nerve conduction study parameters
|
Nerve
|
Parameters
|
Males(N=50)
MEAN±SD
|
Females(N=50)
MEAN±SD
|
p-value*
|
|
Sensory
right Median
|
LATENCY(ms)**
|
2.45±0.27
|
2.31±0.28
|
p<0.01
|
|
AMPLITUDE
(μv)***
|
62.18±31.56
|
74.58±31.09
|
p<0.05
|
|
CONDUCTION VELOCITY(m/s)
|
54.77±5.35
|
54.81±5.5
|
p>0.05
|
|
Sensory
left Median
|
LATENCY(ms)**
|
2.47±0.34
|
2.25±0.26
|
p<0.01
|
|
AMPLITUDE(μv)***
|
57.36±26.67
|
80.75±37.97
|
p<0.01
|
|
CONDUCTION VELOCITY(m/s)
|
55.14±6.12
|
55.74±4.83
|
p>0.05
|
|
Sensory
right Ulnar
|
LATENCY(ms)**
|
2.41±0.27
|
2.3±0.25
|
p<0.05
|
|
AMPLITUDE(μv)***
|
59.57±30.02
|
81.25±34.27
|
p<0.001
|
|
CONDUCTION VELOCITY(m/s)
|
55.19±5.21
|
54.4±4.97
|
p>0.05
|
|
Sensory
left Ulnar
|
LATENCY(ms)**
|
2.38±0.33
|
2.23±0.29
|
p<0.05
|
|
AMPLITUDE(μv)***
|
58.08±27.02
|
84.58±45.70
|
p<0.01
|
|
CONDUCTION VELOCITY(m/s)
|
55.99±5.93
|
56.67±5.95
|
p>0.05
|
*p>0.05 considered as not significant, p˂0.05 considered as
significant, p<0.01 and p<0.001 considered as very
significant when various parameters of both the sexes were compared.
**latency measured from onset of action potential.
***Amplitude measured from peak to peak.
Discussion
This study aimed to investigate the effect of gender on various
parameters of nerve conduction study of median and ulnar nerves in
normal healthy individuals. Latencies of both the nerves i.e. median
and ulnar for motor and sensory were observed to be longer in males
than the females but motor distal latency difference was statistically
insignificant. Results are similar to previous researches done by
LaFratta & Smith, (1964) [6], Stetson DS et al, (1992) [7],
Shehab DK, (1998)[8], Kimura (2005)[9]. Probably, the reason behind
this finding may be the greater height and limb length of the male
volunteers [10].
Huang et al, (2009) [11] found that female subjects had higher median
and ulnar sensory amplitude. Robinson et al (1993) [10] in their study
found that three of the four sensory amplitudes were larger in women;
two of four motor amplitudes were larger in men and women had
significantly faster conduction velocities than men for all nerves
except median motor. Our study has some similarity and some
dissimilarity with this study, in our study sensory nerve amplitudes of
both the nerves were significantly higher in the females than males and
motor nerve amplitudes did not show any statistically significant
difference, whereas the conduction velocity for motor and sensory
median and ulnar nerve was observed to be greater in females but the
difference was not statistically significant.
Hennessey et al [12] and Fujimaki et al [13] in their study found that
women had greater sensory nerve action potential (SNAP) amplitude than
men in the upper limb nerves which is in accordance with our study.
Whereas Stetson D S et al [7] (1992) in their study in the upper limb
nerves (median, ulnar) confirmed that gender did not have any
statistically significant effect on SNAP amplitude.
Garg R et al [14] in their study of upper limb in malwa region had
found that sensory nerve action potential (SNAP) amplitude of Median
and Ulnar nerves was significantly greater in females than males.
Bolton CF et al [15] had found that the amplitude of human, antidromic,
sensory nerve action potentials recorded from median and ulnar digital
nerves is greater in females than males.
The negative linear correlation between sensory nerve action potential
amplitude and circumference holds true for persons of the same sex. The
possible cause of gender differences in median and ulnar sensory
amplitude study may be related to smaller finger circumference in
females [7, 12, 15,16 ]. The less subcutaneous tissue in fingers closer
to the recording of sensory response in females can explain the higher
sensory nerve action potential amplitude than males [1]. Thicker
subcutaneous tissue provides greater distance between digital nerve and
surface ring electrode in males and this may diminish SNAP amplitude
[7,12,15,16].
Conclusion
In conclusion, our study demonstrates that gender has definite and
significant influence on various nerve conduction study parameters.
These effects are not identical in different motor and sensory nerves
of upper limb. Males have longer motor and sensory nerve latencies
while conduction velocity as well as Sensory nerve action potential
(SNAP) amplitude is greater in Females. The results of the present
study have many similarities and some dissimilarity with the reported
NCS variables, the probable reasons could be the true differences among
populations, and small sample size.
Using the same reference data in patients with different gender may
result in erroneous reporting; thus both the sexes should have their
own reference data for clinical purpose to differentiate between normal
and abnormal cases.
Funding:
Nil, Conflict of
interest: None initiated.
Permission from IRB:
Yes
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How to cite this article?
Samol S, Hui M, Parmar D, Dixit R. Influence of gender on nerve
conduction parameters of median and ulnar nerves in healthy
individuals. Int J Med Res Rev 2016;4(10):1738-1743.doi:10.17511/ijmrr.
2016.i10.04.