Gender and arm length: Influence on nerve conduction parameters in the upper limb

265

Gender and Arm Length: Influence on Nerve Conduction Parameters in the Upper Limb William J. Hennessey, MD, Frank J.E. Falco, MD, Gary Goldberg, MD, Randall L. Braddom, MD ABSTRACT. Hennessey WJ, Falco FJE, Goldberg G, Braddom RL. Gender and arm length: influence on nerve conduction parameters in the upper limb. Arch Phys Med Rehabil 1994;75:265-9. l Median, ulnar, and radial nerve conduction studies (NCS) were performed in 44 subjects. Student’s t-test was used to compare nerve conduction velocities (NCV), distal latencies (DL), and distal amplitudes (DAMP) for the two sexes. Only the sensory DAMPS showed statistical significance (p < .OOl) for gender. Women had greater mean median (52.4 PV vs 31.4 PV), ulnar (52.9 FV vs 27.0 pV), and radial (46.1 PV vs 20.1 pV) sensory DAMPS. Stepwise linear regression analysis of NCVs, DLs, and DAMPS on gender and arm length showed statistical significance only for the median (R’ = .46, p < .OOl), ulnar (R’ = S9, p < .OOl), and radial sensory DAMPS (R’ = .29, p < .OOl) for gender. Arm length did not account for any additional variability. Gender showed an effect on the distal sensory DAMPS obtained by antidromic technique in this study. In contrast to the reported effect of leg length and height on lower limb studies, arm length did not affect upper limb studies. 0 1994 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitarion Nerve conduction studies (NCS) are useful in the evaluation of peripheral nerve disease. Normative data are used to evaluate NCS obtained from patients presenting with signs and symptoms of peripheral nerve disease. Variation of normative data’.” and subject data can compromise the accuracy of electrodiagnostic interpretation. Factors that influence nerve conduction parameters may account for study and subject variation.‘5m3J A thorough consideration of these factors can enhance the accuracy of electrodiagnostic study interpretation. Extrinsic factors reported to influence peripheral nerve physiology include age, limb temperature, gender, finger circumference, and height. “‘~‘2~‘5~‘7~3’ An awareness of these factors, in combination with standardized techniques. can minimize sources of error and provide accurate information to confirm clinical diagnoses. The relationship between gender and nerve conduction velocity (NCV) was first clinically characterized by LaFratta and Smith in 1963.” The mean ulnar motor NCV was greater in women than in men and was considered “probably of some clinical significance on occasion.” Limb temperature was not measured and was not deemed essential in this study. This gender difference in ulnar motor NCV was recently From

the Department

The

Ohio

State

(Dr.

Falco).

Smyma.

Goldberg).

GA;

Submitted

Georgia

of Physical

Hospital, (Dr.

and Rehabilitation

OH:

Department

and Rehabilitation

Indianapolis,

Medicine

Columbus,

Moss Rehabilitation

cal Medicme cine,

of Physical

University.

Spine

Medicine

Philadelphia,

Broddom).

(Dr.

Hennessey).

and Sports

Physicians

and Rehabilitation

PA: and Department

Indiana

University

School

(Dr.

of Physiof Medi-

IN.

for publication

January

IS.

IVY3

Accepted

in revised

form

July

12.

1993. Ttns

research

lnbtitutional proved

project

Review

and allocated

was

Board

approved

by the Staff

in abstract form at the Annual rist\

held in Albuquerque.

No commercial supporting organizatmn Reprint ment 0

with

1994

Academy

OH

n direct

which

Medicine

Hospital. This

Committee

and the

Funding

was ap-

research

of the Association

financial

was presented

of Academic

Physiat-

interest

a benefit

in the results of the research

upon

the authors

or upon

any

are associated.

J. Hennessey, and

Research

1993.

confer

the authora

Staff

Committee.

Meeting

in March

has or will

requests to Willlam

of Physical

Columbus.

NM

the

Rehabilitation

Research

Spring

party having

thic article

by

of the Moss

MD.

Rehabilitation.

The Ohio Dodd

Hall.

State University. 480

West

9th

DepanAvenue.

43110.

by the American of Physical

Congress

Medicine

0003~99Y3/94/7503-0088$3.00/O

of Rehabilitation

and Rehabilitation

Medicine

and the American

confirmed in a study conducted on elderly subjects.17 In this study, limb temperature was controlled, and the mean values were 57.6m/sec in men and 61.4mkec in women. Elderly women also had significantly faster ulnar sensory NCV. shorter ulnar motor distal latency (DL), and larger sensory distal amplitudes (DAMP) for the median. ulnar, and radial nerves. Arm length was recorded and did not correlate as strongly as gender correlated to these conduction variables. Since women are, on average, shorter than men, the question is whether these gender differences are really caused by height differences. A recent study by Stetson and colleagues showed that gender, in isolation from height, was not a significant predictor of median motor, median sensory, and ulnar sensory nerve conduction measures.‘* The relationship between height and NCS has also been studied. In the lower limb, Cambell and colleagues showed that peroneal and sural NCVs were inversely correlated with body height.*” Soudmand and colleagues also found that the peroneal and sural NCVs correlated inversely with height but also concluded that height did not affect median motor and sensory NCVs.” Rivner and colleagues found that median NCV did not correlate with height but that height did correlate with median motor DL.” Stetson and colleagues studied the effects of height on median, ulnar, and sural nerve conduction.‘* Height was negatively associated with all sensory amplitudes and positively associated with all sensory DLs in their study. No study could be identified that described the influence of arm length for all the nerve conduction parameters of routinely tested nerves in the upper limb. Previous studies examined the influence of height on upper limb NCS but only for the DL or NCV of only one or two nerves.‘“.“.” The influence of gender was described by LaFratta and Smith’” for only the ulnar motor NCV. A recent study in healthy, elderly subjects indicated that gender influenced the sensory DAMPS as well as the ulnar motor and sensory NCVs and ulnar motor DL. No study could be identified that comprehensively examined the influence of gender on nerve conduction parameters of routinely tested nerves in the upper limb of healthy, young subjects.

Arch Phys Med Rehabil Vol75,

March 1994

266 32.6%

GENDER

AND ARM 33.3%

vs 32.2%

LENGTH:

vs 33.6%

33.1 “C vs 33.4% Fig l-Mean surface skin temperatures of the 44 subjects (men vs women) at the three recording sites before testing.

The purpose of this study was to determine the influence of gender and arm length on NCS of the upper limb in a carefully screened, healthy, young population. The DLs, NCVs, and DAMPS were examined for the motor studies of the median and ulnar nerves and sensory studies of the median, ulnar, and radial nerves. METHODS AND MATERIALS The subjects were screened using a standardized interview to exclude those with a history of neuromuscular disease, cardiac pacemaker, diabetes, B, 2 or folate deficiency, thyroid disease, neck or back surgery, alcoholism, peripheral neuropathy, radiculopathy, entrapment syndromes, and chemotherapy. All medications that subjects were taking at the time of the study were documented and compared with a list of medications known to cause peripheral neuropathies.35 Forty-four paid subjects from 19 to 43 years of age were selected for this study. The sample size chosen was considered comparable with sample sizes of published A sample size of 22 men and 22 women is able NCS. ‘*3-9~‘9-2’ to detect a 0.3msec difference in DL or Sm/sec difference in NCV with a power of 0.90. The 0.3msec and Srn/sec values chosen represent a typical standard deviation for the DL and NCV, respectively. Data from both upper limbs of all subjects was analyzed to obtain the results. A physical examination was performed to exclude those with undiagnosed neuromuscular or neuropathic disease. The subjects’ gender, arm length, handedness, and age to the nearest year were recorded. Arm length, rather than height, was selected as a more representative measurement of axonal length and has been shown to be highly correlated to height.36”8 Arm length was measured from the lateral border of the acromion to the distal tip of the third digit with the subject’s arm in the adducted position while standing. An EMG Associates Dermatemp DT-1000” infrared temperature scanner with digital readout was used to record surface skin temperatures. Skin temperatures were recorded before each study at the touch pad of the index finger, midpalm, and antecubital fossa (fig 1). Subjects with a skin temperature of less than 31 degrees C at any recording site had their extremities warmed with an electric heating pad. Each extremity was warmed until all three sites were equal to or greater than 31 degrees C. No recording site was Arch Phys Med Rehabil Vol75,

March 1994

INFLUENCE

ON NCS, Hennessey

warmer than 35 degrees C. Heating time was approximately 10 minutes for the 25% of the subjects who required warming. All studies were performed in both upper limbs of each subject. Motor and sensory studies were performed on the ulnar and median nerves both proximally and distally along the forearm. The radial sensory nerve was examined distally along the forearm. The ground electrode was placed on the dorsum of the hand. All studies were performed with the subjects sitting comfortably in the upright position. Standardized techniques were used to obtain and record action potentials.” For sensory studies, the median, ulnar, and radial nerves were examined antidromically. The active ring electrode was placed over the first, third, and fifth digit to record responses along the radial, median, and ulnar nerves, respectively. The reference ring electrode was placed 4cm distal to the active electrode (fig 2). Median nerve stimulations were performed distally at 14cm proximal to the active electrode and medial to the flexor carpi radialis tendon. Proximal median nerve stimulations were performed medial to the biceps tendon at the elbow crease. Ulnar sensory nerve distal stimulations were performed 14cm proximal to the active electrode and posterior to the flexor carpi ulnaris tendon. Proximal ulnar nerve stimulations were performed just distal to the medial epicondyle with the elbow in 70” of flexion.“’ Radial nerve stimulations were performed 1Ocm proximal to the active electrode along the lateral border of the radius. Only distal studies were obtained for the radial sensory nerve. For motor studies, the median and ulnar nerves were examined orthodromically. The active electrodes were placed over the motor point of the abductor pollicus brevis for the median nerve and over the abductor digiti minimi for the ulnar nerve. The abductor pollicus brevis motor point was located one half the distance between the metacarpophalangeal joint of the thumb and the midpoint of the distal wrist crease. The reference electrode was placed 4cm distally over the first metacarpophalangeal joint. The abductor digiti

Reference

Active

Cathode Anode -

y-e-y

Fig 2-Distal nerve conduction study techniques. Ulnar and median motor nerve techniques were performed at 8cm. Ulnar, median, and radial sensory nerve techniques were performed at 14, 14, and lOcm, respectively.

GENDER

AND ARM LENGTH:

INFLUENCE

minimi motor point was located one half the distance between the metacarpophalangeal joint and the distal wrist crease. The reference electrode was placed distally over the medial aspect of the fifth metacarpophalangeal joint (fig 2). Distal median motor nerve stimulations were performed 8cm proximal to the active electrode and medial to the flexor carpi radialis tendon. The 8cm distance was measured by taking the shortest distance from the active electrode to the midpoint of the distal wrist crease with the remainder of the Xcm measured along the antebrachium (fig 2). The distal ulnar motor nerve stimulations were performed 8cm proximal to the active electrode. This distance was measured along the ulnar surface of the forearm. Stimulations were delivered medial and posterior to the flexor carpi ulnaris tendon. The same proximal stimulation points were used for the sensory and motor fibers of the median and ulnar nerves. A TECA Neurostar EMG’ instrument was used in the study. Percutaneous stimuli were delivered individually until supramaximal stimulations of adequate voltage and pulse duration were obtained. Filters were set at 2Hz and 1OkHz for motor studies and at 20Hz and 2kHz for sensory studies. The sweep speed was set at 2msec per division. One-centimeter disc recording electrodes were used for motor studies and loop ring recording electrodes were used for sensory studies. The ground was placed on the dorsum of the hand. Data collected for each supramaximal stimulation response included latency and action potential amplitude. A gain setting of 2OOpV per division was used to determine latency onset in motor studies,” and a gain setting of 2OpV per division was used to determine latency onset for sensory studies. The distance between the distal and proximal stimulations for the median and ulnar nerves was recorded for the calculation of the nerve conduction velocity.

ON NCS, Hennessey

267

as the dependent variables. Gender, arm length, and sidedness were the independent variables. Right and left arm nerve conduction parameters were highly correlated. Further statistical analysis was therefore arbitrarily performed on the right arm studies of each subject. Statistical results are displayed in table 1. The data was placed into two separate groups according to gender. A Student’s t-test analysis showed that gender had a high statistical significance @ < .OOl) for all sensory DAMPS. Women had greater mean median, ulnar, and radial sensory DAMPS. The median, ulnar. and radial sensory DLs also showed a statistically significant difference for the men and women (p 5 .05). Student’s t-test was performed on the left arm studies for the statistically significant variables identified for the right arm studies (sensory DAMPS and DLs) to further determine the validity of the results. All sensory DAMPS once again showed statistical significance (p < .OOl) for the men and women (table 2). However, no sensory DLs on the left side were significantly different for the men and women (table 2). Pearson’s product moment between arm length and each of the dependent variables (nerve conduction parameters) was calculated. Statistical significance was found for arm length with the median sensory DAMP (R’ = -0.52, p = .003), ulnar sensory DAMP (R’ = -0.61, p = .OOl), and radial sensory DAMP (R’ = -0.34, p = .03). A stepwise linear regression of the sensory DAMPS was

Table 1: Right Side Nerve Conduction Parameters With Gender and Arm Length Arm

Length Gender

DATA

ANALYSIS

The data from this study was entered into a data file using the computer database software Nutshell II.’ This file was then converted to an ASCII format for statistical analysis using routines from the SAS statistical software package.d Scatter plots were used to initially evaluate the data. Student’s t-test analysis was performed on gender and the nerve conduction variables. Pearson product correlations were examined for arm length and the conduction parameters. A stepwise linear regression was used to evaluate the influence of gender and arm length on the nerve conduction parameters. RESULTS Forty-four subjects ages 19 to 43 years (age x = 27.9) including 23 men (age x = 27.7) and 21 women (age X = 28.2) participated in this study. Data from both upper limbs of all subjects was analyzed to obtain the results. Arm lengths ranged from 66cm to 84Scm with a mean value of 77.4cm for men and 71.8cm for women. These differences were statistically significant @ < .OOl). Temperatures recorded at all three sites were similar for men and women (fig I). The majority of subjects (37 of 44) were right-handed. Scatter plots and Pearson’s r correlations were calculated for the total group. The nerve conduction parameters served

Pearson’s Product Correlation (r value)

Student’s

I Tz\t Women

(p value)

Men

Vari;ible Arm

Length

71.x

Icm)

Age (years)

(2.2F

77.4

(4.

17.7 1.5.3)

61.6

61.0

(3.X)_

hi

2.6 (0.3)

05

senwry

NCV

Median

sensory

DL

Median

sensory

Median

motor

Median

motor

DL

3.1 (0.4,

3.3 lO.Jl

Median

motor

DAMP

17.3 (?.O)Y

13.0 (3.61

NCV

61.7

61.3

Ulnar

DAMP NCV

sensory

Ulnar

wnsory

DL

Ulnar

sensory

DAMP

Ulnar

motor

NCV

Ulnar

motor

DL

Ulnar

motor

DAMP

sensory

DL

Radial

sensory

DAMP

from

(14.3)’

31.4

(4.21

59 0 t4.51

2.3 (0.2)

Eddial

Data collected

52.4 60.0

(5.2)

_

(4.X)

Median

2.5 (0.2l_

.owI

I1

2x.2 (6.1)

(X.7)

63.7

62.5

(J.4)

.0001

-0.52

47

-0.29

0.34 -0.

76

05

0.44

.ooo I

(5.7,

IY

-0.34

.h2

2.5 to.21 77.0 (7.81

IO

0.5 I

IJO

t5 71

57.9 t 13.9)

-0.

-0.61 -0.42

.3s

2.7 (0.3)

7.7 (0.3)

.90

0.06

12.1 (2.3)

13.1 12.3)

I5

0.16

2.1 to.21

02

I .9 (0.2) 46. I (26.3)

right arm wdies

20. I

IIJ.3J

of 23 men and ?I

0.49

IX)I women

-0.34

with

a mean age of

27.9 years. Mean

skm temperature

32.4

palm,

and 33.4

C at antecubital

degrees

* Mean

(standard

’ Nerve

conduction

* Distal

latencies

’ Antidromic

degrees

C at Index

much

pad.

33.7

degrees

C ;~t mid

fossa.

deviation). velocitie\ are measured

distal

are measured in nxec

sensory amplitudes

in ndiec.

to the onset of the action are measured

in PV

fmm

potential. baseline

to negative

peak. y Distal

motor

amplitude\

are measured

in mV

liom

baseline

to negative

Arch Phys Med Rehabil Vol75,

peak.

March 1994

GENDER

268

AND ARM LENGTH:

Table 2: Left Side Nerve Conduction Parameters With Gender and Arm Length Arm Length Gender

Women Variable Median sensory DAMP Ulnar sensory DAMP Radial sensory DAMP Median sensory DL Ulnar sensory DL Radial sensory DL

57.0 50.8 49.2 2.5 2.4 I .9

(14.8)* (17.5) (26.5) (0.2)’ (0.2) (0.2)

Men

33.0 27.7 24.7 2.7 2.4

(10.1)’ (9. I) (16.9) (0.6) (0.2) 1.9(0.2)

Student’s t Test (p value)

.OOOl

.OOOl ,001 .17 .98 .59

PeXS0n’s Product Correlation (r value)

-0.56 -0.48 -0.34 0.38 0.10 0.14

Data collected from left arm studies of 23 men and 21 women with a mean age of 27.9 years. Mean skin temperature 32.6 degrees C at index touch pad, 33.1 degrees C at mid palm. and 33.5 degrees C at antecubital fossa. * Mean (standard deviation). ’ Antidromic distal sensory amplitudes are measured in PV from baseline to negative peak. t Distal latencies are measured in msec to the onset of the action potential.

performed on both gender and arm length to determine the relative effects of each variable on these amplitudes. Only gender entered the model for the median sensory DAMP (R* = 0.46, p < .OOl), ulnar sensory DAMP (R* = 0.59, p < .OOl), and radial sensory DAMP (R* = 0.29, p < .OOl). Arm length did not enter the stepwise regression equation and did not account for any additional variability. Thus, the gender effect determined by the stepwise regression accounted for the statistical significance between arm length and the sensory DAMPS via Pearson’s r correlations but also accounted for additional variability. Considerations were made to validate the assumptions for the regression model. Normal distribution of the data was determined via a normal probability plot and the ShapiroWilk test. Constant variation was confirmed by White’s specification test. Statistical analysis was also performed with and without values possibly influential to the model. No influential observations were noted.

DISCUSSION This study examined the effect of gender and arm length on NCS in the upper limb. No influence was noted for the NCVs or DLs. Statistical analysis identified an effect of gender only on the sensory DAMPS. The results of this study generally agree with the results of previous studies involving NCS of the upper limb. Soudmand and colleagues concluded height did not affect median motor and sensory NCV.*’ Rivner and colleagues also concluded median motor NCV was not correlated with height.22 Stetson and colleagues also found height to be negatively associated with median and ulnar sensory amplitudes.” A few differences between this study and previous studies were observed. Height positively correlated with the median motor DL in the study by Rivner.*’ However, temperature of the upper limb was not recorded in their study and this may have affected the results. The median and ulnar sensory DLs positively correlated with height in a study by Stetson.‘*

Arch Phys Med Rehabil Vol75,

March 1994

INFLUENCE

ON NCS, Hennessey

Their correlation with height was much weaker for upper limb parameters than for parameters of the lower limb. This study also identified a statistically significant but weak correlation to gender and arm length on the right side which could not be reproduced on statistical analysis of the left arm studies. The sensory DL findings are not believed to be clinically significant. There was no correlation of arm length to upper limb NCVs in this study which indicated arm length did not have an effect on NCVs over the range of arm lengths examined. This is in contrast to the influence of leg length3’ and heightIR.20.2' on NCS of the leg where NCV has been found to be inversely correlated to height. The shorter length of an arm (compared with the length of a leg) may not provide enough of a distance to produce an observable influence of arm length on nerve conduction parameters. Arm length might possibly have had an influence on NCS if a wider range of arm lengths was studied. The influence of height on NCS only of the leg may also indicate there is a relative effect on the nerve conduction parameters only for the limbs of greater length for each individual. In this study, gender statistically showed an effect on all sensory DAMPS. This sensory DAMP phenomenon has been described in the literature by Bolton and Carter for the median and ulnar nerves.‘” They postulated that it resulted from the varying finger circumferences between men and women rather than as a direct gender influence. The negative linear correlation between sensory DAMPS and finger circumference in their study held true for persons of the same sex. Another recent study replicated these findings.” A closer approximation of the two digital nerves in a finger of a smaller diameter is one hypothesis for this finding. Thicker subcutaneous tissue in a finger of greater diameter may diminish amplitude by providing a greater distance between the digital nerves and the surface ring electrode. A nerve content to subcutaneous tissue ratio theory satisfies both theories and takes into account individual variability. Although this study did not measure finger circumference. other studlikely accounts for obies 18.‘9indicate finger circumference served gender differences in the sensory DAMPS. The authors plan to determine if performing orthodromic sensory studies eliminates the gender bias by removing finger circumference as a variable influencing the recording of the sensory DAMP.

CONCLUSIONS The influence of gender and arm length on NCS in the upper limb was examined in this study. In contrast to the influence of leg length and height reported in lower limb studies, arm length did not affect upper limb studies. This study showed that when limb temperature is controlled, arm length does not have an effect on NCS in the upper limb and should not affect study interpretation. Gender showed an effect only on the sensory DAMPS of antidromic studies in healthy young subjects. This has been reported to be due to finger circumference differences between men and women and not due to a direct influence of gender on the sensory DAMPS. Further research is planned to determine if orthodromic sensory study techniques would eliminate the influence of finger circumference and gender on the sensory amplitudes.

GENDER

AND ARM LENGTH:

Temperature control and standardized techniques, along with consideration for age and finger circumference, currently provide the most accurate information for electrodiagnostic study interpretation of NCS of the upper limb. Acknowledgment. A very special thanks to Peggy Hwang. MS, for statistical support. to the TECA Corporation, and Ronald Folberth. formerly of TECA, for providing a Neurostar EMG instrument to support our research. and to Neal Forshey and Heather House Travis for computer graphics assistance. . /

5.

6.

7. 8. 9. 10.

II. 12. 13. 14.

I5 I6 I7

IX

References Kimura J. Electrodiagnosis in diseases of nerve and muscle: principles and practice. 2nd ed. Philadelphia: Davis, 1989: 103-17. Johnson EW. Practical electromyography. 2nd ed. Baltimore: Williams & Wilkins, 1980:33-406-7. Johnson EW, Melvin JL. Sensory conduction studies of median and ulnar nerves. Arch Phys Med Rehabil 1967;48:25-30. Johnson EW. Sipski M. Lammertse T. Median and radial sensory latencies to digit I: normal values and usefulness in carpal tunnel syndrome. Arch Phys Mcd Rehabil 1987;68: l40- I. Melvin JL, Schuchmann JA, Lanese RR. Diagnostic speciticity of motor and sensory nerve conduction variables in the carpal tunnel syndrome. Arch Phys Med Rehabil 1973:54:69-74. Spiegel MH. Johnson EW. Conduction velocity in the proximal and distal segments of the motor Iibers of the ulnar nerve of human beings. Arch Phys Med Rehabil 1962;43:57-61. Jebsen RH. Motor conduction velocities in the median and ulnar nerves. Arch Phys Med Rehabil 1967;48: 185-94. Melvin JL. Harris DH. Johnson EW. Motor conduction velocity in ulnar and median nerves. Arch Phys Med Rehabil 1966;47:51 l-9. Felsenthal G. Median and ulnar distal motor and sensory latencies in the same normal subject. Arch Phys Med Rehabil 1977;58:297-302. Wagman IH. Lesse H. Maximum conduction velocities of motor fibers of ulnar nerve in human subjects of various ages and sizes. J Neurophysiol 19.52; 15235-44. Kumar BR. Gill HS. Motor nerve conduction velocities amongst healthy subjects. J Assoc Physicians India 1985;33:348-54. Mayer RF. Nerve conduction studies in man. Neurology 1962; 12: 102 I 30. Feibel A. Foca FJ. Sensory conduction of radial nerve. Arch Phys Med Rehabil 1974;55:3 14-6. Perez MC, Sosa A, Acevedo CE. Nerve conduction velocities: normal values for median and ulnar nerves. Bol Asoc Med P R 1986;78: 191. 6. Kimura J. Principles and pitfalls of nerve conduction studies. Ann Neurol 1984;16:415-28. Maynard FM. Stolov WC. Experimental error in determination of nerve conduction velocity. Arch Phys Med Rehabil 1972;53:362-72. Falco FJE. Hennessey WJ. Braddom RL, Goldberg G. Standardized nerve conduction velocities in the upper limb of the healthy elderly. Am J Phys Med Rehabil 1992;71:263-71. Stetson DS. Albers JW. Silverstein BA, Wolfe RA. Effects of age, \ex, and anthropometric factors on nerve conduction measures. Muscle Nerve 199’2:15:1095-I 104.

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269

19. Bolton CF. Carter KM. Human sensory nerve compound action potential amplitude: variation with sex and finger circumference. J Neurol Neurosurg Psychiatry 1980;43:925-8. 20. Cambell WW, Ward LC, Swift TR. Nerve conduction velocity varie\ inversely with height. Muscle Nerve 198 1:4:520-3. 21. Soudmand R, Ward C. Swift TR. Effect of height on nerve conduction velocity. Neurology 1982;32:407- IO. 22. Rivner MH, Swift TR. Crout BO. Rhodes KP. Toward more rational nerve conduction interpretations: the effect of height. Muscle Nervc~ 1990;13:23’-9. 23. Nelson C, White JA. Mitchell RU. Hall C. Median nerve F wave conduction in healthv subiects over age rixtv-live. Electromvogr I _ Clin Neurophysiol 1990;30:269-76. . 24. LaFratta CW, Smith OH. A study of the relationship of motor conduction velocity in the adult to age. sex, and handedness. Arch Phys Med Rehabil 1964;45:407- 13. 25. Checkles NS, Russukov AV. Piero DL. Ulnar nerve conduction velocity: effect of elbow position on measurement. Arch Phys Med Rehabil 1978;52:362-5. 26. Melvin JL, Burnett MS, Johnson EW. Median nerve conduction iii pregnancy. Arch Phys Med Rehabil 1969;50:75-80. 27. Bolton CF. Sawa GM, Carter K. The effects of temperature on human compound action potentials. J Neurol Neurosurg Psychiatry 1981. 44:407-14. 28. DeJesus PV. Hausmanowa-Petrusewica 1, Brachi RL. The effect of cold on nerve conduction of human slow and favt nerve fibers. Neurology 1973:33: I 182-9. 29. Halar EM, DeLisa JA. Brozovich FV. Nerve conduction velocity: relationship of skin. subcutaneous, and intramuscular temperatures. Arch Phys Med Rehabil 1980:61: 199-203. studies in upper 30. Halar EM. DeLisa JA. Soine TL. Nerve conductton extremities: skin temperature corrections. Arch Phys Med Rehabil 1985;66:605-9. 31. Denys EH. AAEE minimonograph #l-l: the influence of temperature in clinical neurophysiology. Muscle Nerve I99 1:14:795-8 11. and demyelin32. Waxman SG. Conduction in myelinated. unmyelinated. ated fibers. Arch Neurol 1977:34:585-9. 33. Waxman SG. Determinants of velocity in myelinated nerve fibers. Mus cle Nerve 1980;3: I4 I-50. and common source\ 34. Dumitru D. Walsh NE. Practical instrumentation of error. Am J Phys Med Rehabil 1988:67:55-65. 35. Physician’s Desk Reference. 47th ed. Montvale: Medical Economics. 1993. 36. Steele MF. Chenier TC. Arm-span, height. and age in black and whit{, women. Ann Hum Biol 1990;17:533-41. 37. Miller F, Koreska J. Height measurements of patients with neuromuscu lar disease and contractures. Dev Med Child Neurol 1993;34:55-60. of height in th<, 38. Haboubi NY, Hudson PR. Pathy MS. Measurement elderly. J Am Geriatr Sot 1990;38: 1008. IO. 39. Braddom RL. Johnson EW: Standardization of H-reflex and diagnostic use in SI radiculopathy. Arch Phys Med Rehabil 1974:55:161-6. Suppliers EMG Associates. PO Box 862, Stamford, CT 06904. NY 10570. :: IECA Neurostar EMG. 3 Campus Drive. Pleasantville. Nutshell Plus. 1989. Claris Corporation. Iris Software Products, StoughC. on. MA 02072. SAS Campus Drive, Gary. NC 275 I I. d. SAS Institute Incorporated,

Arch Phys Med Rehabil Vol75,

March 1994