Electroencephalography and clinical Neurophysiology, 85 (1992) 229-235 © 1992 Elsevier Scientific Publishers Ireland, Ltd. 0924-980X/92/$05.00
229
ELMOCO 91606
Changes in motor and sensory nerve conduction parameters with temperature in normal and diseased nerve Peter Dioszeghy and Erik St~lberg Department of Clinical Neurophysiology, UniversityHospital, Uppsala S-75185 (Sweden) (Accepted for publication: 22 January 1992)
Summary The effects of temperature on conventional motor and sensory nerve conduction parameters were studied in normals and in some pathological conditions. Surface stimulating and recording electrodes were used to examine the function of the median nerve. The motor and sensory conduction velocities, the parameters of compound muscle action and sensory nerve potentials were correlated with skin temperature. In the control subjects all nerve conduction parameters changed with temperature. These findings were similar to those published previously, but the mean slope for MCV was lower than that reported in the literature. The amplitude values widely scattered as a consequence of methodological factors, which may mask effects of temperature. Only minor differences were revealed between control subjects and patients. The effect of temperature proved to be similar in the patients and in the normal controls. Therefore, the correction factors determined in normals may be acceptable for abnormal nerves in standardising the measured values with respect to temperature. However, in pathological cases, above all in diabetes mellitus, the slightly reduced changes of conduction velocities vs. temperature may be the source of false negative results in borderline cases when using the normal correction factors. The combination of preserved temperature dependence but decreased conduction velocities may indicate that demyelination and temperature influence the conduction velocities via different mechanisms. Key words: Diabetes mellitus; Guillain-Barr6 syndrome; Nerve conduction; Nerve membrane; Temperature
It is well k n o w n that nerve c o n d u c t i o n p a r a m e t e r s (velocity, a m p l i t u d e , d u r a t i o n ) alter with t e m p e r a t u r e . T h e effect of t e m p e r a t u r e m u s t be t a k e n into consideration w h e n using these p a r a m e t e r s in diagnosis a n d w h e n m o n i t o r i n g p a t i e n t s with n e u r o p a t h i e s . T o acc o u n t for the effect of t e m p e r a t u r e , different m e t h o d s have b e e n used. A s s u m i n g that the c h a n g e is linear a n d that the a b n o r m a l nerve reacts to cooling and w a r m i n g in the same way as the n o r m a l nerve, some l a b o r a t o r i e s n o r m a l i z e the m e a s u r e d values with respect to t e m p e r a t u r e , u s i n g c o r r e c t i o n factors ( H e n ricksen 1956; D e J o n g et al. 1966; D e Jesus et al. 1973). I n o t h e r l a b o r a t o r i e s the limb is w a r m e d to a s t a n d a r d t e m p e r a t u r e before the investigation. Both m e t h o d s may have their drawbacks. F o r the first: r e f e r e n c e materials for c o r r e c t i o n factors in pathology for differe n t nerves do n o t exist. For the second: it is u n k n o w n w h e t h e r the c h a n g e with t e m p e r a t u r e is such that pathological nerves show distinct deviation from normal only w h e n cooled or w a r m e d . This study was p e r f o r m e d to reveal the effect of
Correspondence to: Erik St~lberg, Dept. of Clinical Neurophysiology, University Hospital, Uppsala S-75185 (Sweden). Tel.: 46 18 663430; Fax: 46 18 551132.
t e m p e r a t u r e o n n e r v e c o n d u c t i o n p a r a m e t e r s in conditions with d e m y e l i n a t i o n , m o t o n e u r o n e disease and in which the m e m b r a n e p r o p e r t i e s may be affected.
Methods M o t o r a n d sensory nerve c o n d u c t i o n s of the right m e d i a n n e r v e were studied. Motor nerve studies T h e nerve was s t i m u l a t e d with a b i p o l a r surface electrode using square wave pulses of 0.1 msec d u r a tion. T h e stimulus was delivered at the wrist (with a c o n s t a n t distance of 8 cm proximal to the r e c o r d i n g electrode) a n d at the elbow. A surface recording disc electrode was attached over the e n d - p l a t e region of the a b d u c t o r pollicis brevis muscle. T h e r e f e r e n c e electrode was placed o n the distal i n t e r p h a l a n g e a l j o i n t of the t h u m b . Sensory nerve studies T h e nerve was s t i m u l a t e d by a b i p o l a r surface electrode using square wave pulses of 0.1 msec d u r a t i o n o n the radial side of the third digit. T h e sensory p o t e n t i a l s were r e c o r d e d with a b i p o l a r surface felt p a d electrode
230
with an interelectrode distance of 23 m m at the same point as used for motor nerve stimulation on the wrist, usually 14-15 cm from the stimulation site.
P. DIOSZEGHY, E. ST,~LBERG TABLE I Age and number of patients. Diagnosis
Experimental protocol After obtaining the first motor and sensory records at room temperature the forearm, including the elbow, was cooled in a water bath of 20°C for 20 min. The arm was then lifted from the bath.and dried, the electrodes were reapplied over marked spots and the recording was performed again. The arm was immersed in the water again, usually within 2 min and always within 3 min, and warming started. In relationship to the speed of temperature changes during cooling and warming, the time outside the bath was short. The water temperature was changed stepwise, to 25, 30 and 35°C, every 10 rain. Measurements were performed at each of these temperature levels. The skin t e m p e r a t u r e was measured a t the site of the recording and stimulating electrodes (third digit, thenar, wrist and elbow) with a digital infrared therm o m e t e r (C-600M Biotherm, Los Altos, CA 94022). The t h e r m o m e t e r had an accuracy of 0.1-0.2°C. Its response delay was 0.2-0.3 sec. Our pilot studies showed very similar relationships between temperature and changes in various neurophysiological parameters irrespective of the place for temperature measurements. We therefore chose the temperature values obtained at the wrist to be presented in tables and figures. The E M G equipment was connected to a PC with analysis program. The following motor nerve p a r a m e t e r s were measured at all temperatures: distal latency (DL) from the stimulus artefact to the first deflection from the baseline according to a special algorithm (StSlberg and St~lberg 1989); motor conduction velocity (MCV) for the nerve segment between elbow and wrist; amplitude of the negative component of the compound muscle action potential (CMAP); duration of CMAP from the onset to the end of the last positive deflection and to first baseline crossing - - these two measures were closely correlated and only the former is presented; area of the CMAP calculated as the integrated area between the signal and the baseline over the total duration o f the potential. The following sensory nerve p a r a m e t e r s were measured: latency to the first positive peak or, if absent, to onset of the negative peak; amplitude peak-to-peak; duration b e t w e e n the positive peaks; sensory conduction velocity (SCV) for the nerve segment between third digit and wrist.
Statistical methods Depending on the pattern of data in X-Y plots, linear regression analysis was performed for all param-
Healthy subjects Diabetes mellitus Type I Type II Guillain-Barr6 syndr. ALS * Phenytoin treated (epilepsy) Primary amyloidosis Carpal tunnel syndrome (CT)
Age (years) No.
Mean
Range
10 13 6 7 4 8 10 1 3
36.7 44.7
25-46 20-83 20-43 33-83 21-59 45-63 25-54 39 27-56
40,0 53.9 36.6
* Amyotrophic lateral sclerosis.
eters. For analysis of significance of differences, Student's t test was used. The t e m p e r a t u r e coefficients (Q10) of different parameters were computed to 25-35°C in controls. The Q10 value represents the ratio of highest to lowest value over a 10°C range.
Subjects and patients The subjects and patients are presented in Table I. Informed consent was obtained from both the healthy subjects and the patients in compliance with our hospital's regulations for H u m a n Studies. The healthy controls had no symptoms or signs of peripheral nerve involvement. Patients had additional neurography of left ulnar and median nerves, and sural, peroneal or tibial nerves and F waves bilaterally. We selected clinically typical cases for the different groups of patients. An attempt was made to have mild, moderate and severe cases. Four of the patients with diabetes mellitus were free of clinical symptoms and signs of polyneuropathy, but electroneurography in two of them showed slight abnormalities. The other 9 had mild or moderate symptoms a n d / o r signs of polyneuropathy. Electroneurography revealed severe polyneuropathy in 2, moderate in 3, mild in 3 and was normal in 1 of the patients. Of the 4 patients with Guillain-Barr6 syndrome three were classified as chronic with symptoms more than 6 months, and one as acute, investigated within 2 weeks of onset of symptoms. All were typical clinically and neurographically. Two patients with amyotrophic lateral sclerosis (ALS) had predominantly bulbar symptoms. Two patients were severely and one moderately affected. Three had mild atrophy of the studied arm with moderate reduction of force. Three patients with clinical and neurophysiologically confirmed carpal tunnel syndrome (CT) were also studied.
E F F E C T S OF T E M P E R A T U R E ON N E R V E C O N D U C T I O N P A R A M E T E R S
231
T A B L E II
70
Mean values of individual slope and intercept data of motor nerve parameters. Diagnosis
E >
Slope value Mean
50
Y scale crossing + S.D.
Mean
+ S.D.
MCV (m /sec) Controls Diabetes mellitus Guillain-Barr~ ALS Phenytoin
r,.)
1.13 0.93 0.96 1.00 0.90
r~s Ns NS NS
0.28 0.31 0.26 0.43 0.30
18.00 16.91 9.74 15.26 22.06
8.07 8.63 15.39 10.99 8.88
- 0.24 - 0.26 -0.36 - 0.30 - 0.26
r~s ** NS Ns
0.04 0.06 0.11 0.14 0.04
11.40 12.60 17.27 13.94 12.26
1.34 2.46 4.11 5.95 1.54
NS r~s NS NS
0.14 0.26 0.22 0.45 0.22
34.72 38.10 37.44 32.39 36.45
5.09 9.81 4.98 14.45 7.26
NS NS ** NS
0.33 1.19 1.15 1.12 2.06
109.34 93.49 67.50 58.01 116.71
12.75 46.99 49.11 47.39 40.32
NS NS r~s r~s
0.15 0.18 0.09 0.11 0.10
16.29 10.26 8.82 7.64 13.96
5.63 6.00 4.32 6.17 3.17
DL (msec)
254
-[
21
'
2'5
.
.
.
.
3'5
Temperature (°C) Fig. 1. Correlation between motor conduction velocities (MCV) and skin t e m p e r a t u r e measured at wrist. Regression lines of 10 normal subjects (R 0.87-0.99; P < 0.01-0.001).
The patients treated with phenytoin did not show symptoms of peripheral nerve involvement but two had slightly reduced motor and sensory conduction velocities on the median nerve under study.
Results
Controls Diabetes mellitus Guillain-Barr6 ALS Phenytoin
Duration of CMAP (msec) Controls Diabetes mellitus Guillain-Barr~ ALS Phenytoin
- 0.71 -0.76 - 0.60 - 0.58 - 0.76
Area of CMAP (msec × mV) Controls Diabetes mellitus Guillain-Barr~ ALS Phenytoin
-
2.24 1.84 1.55 1.25 1.89
Amplitude of CMAP (mV)
Controls In the control subjects all nerve conduction parameters changed with temperature. In general, both the MCV (R = 0.87-0.99, P < 0.01-0.001) (Fig. 1) and the SCV (R = 0.93-0.99, P < 0.01-0.001) (Fig. 2) increased significantly with rewarming, as demonstrated
Controls Diabetes mellitus Guillain-Barr6 ALS Phenytoin
-0.14 -0.04 -0.13 -0.07 -0.13
NS = not significant; * P < 0.05; ** P < 0.025.
35
by the slopes of the regression lines. For details see Tables II and III. Distal latencies (R = - 0 . 9 6 to - 1 . 0 , P < 0.001) (Fig. 3), duration (R = - 0 . 8 8 to -0.99, P < 0.01-0.001) and area (R = - 0 . 8 0 to -0.98, P < 0.05-0.001) of the CMAP increased at low temperature. There was a significant (R = - 0 . 9 3 to - 1 . 0 , P < 0.01-0.001) negative correlation between temperature and the duration of the sensory potential. Often, but not always, the amplitudes of CMAPs and sensory potentials were larger after cooling from room temperature but the change did not reach statistical significance ( P < 0.1). The Q10 values for different parameters in controls are listed in Table IV.
Fig. 2. Correlation between sensory conduction velocities (SCV) and skin temperatu re measured at wrist. Regression lines of 10 normal subjects (R 0.93-0.99; P < 0.01-0.001).
Patients In the patient material, the mean slope (mean of individual slope values) of M C V vs. temperature was slightly but statistically insignificantly lower than for
7° t
T
21
•
I
I
I
I
I
25
I
I
Temperature (°C)
P. DIOSZEGHY,E. ST,~d.,BERG
232 T A B L E III
Individual slopes of MCV
Mean values of individual slope and intercept data of sensory nerve parameters. Diagnosis
Slope value Mean
3-
Y scale crossing + S.D.
Mean
+ S.D.
0.4l 0.36 0.64 0.36 0.33
-7.94 -0.16 11.44 -3.67 -- 8.28
11.33 6.05 14.31 11.65 8.61
SCV (m /sec) Controls Diabetes mellitus Guillain-Barr6 ALS Phenytoin
2.17 1.46 1.72 1.79 1.92
*** NS * NS
2
E O o
g o
o
8
I
Duration of sensory pot. (msec) Controls Diabetes mellitus Guillain-Barr6 ALS Phenytoin
- 0.07 - 0.05 -0.10 - 0.07 - 0.07
NS NS NS NS
NS
=
0.10 -0.17 - 0.03 - 0.48 - 0.29
NS NS NS NS
§
•
o
o°
o
0.02 0.04 0.05 0.05 0.02
3.28 2.84 4.79 3.51 3.26
o
0.60 0.94 1.94 1.46 0.51
oo
o
o~
o ~ AmyloldoeiJ Carlml tunnel)
o 0
i
i
i
Control
GB$
0.67 0.42 0.49 1.20 0.48
24.47 8.90 7.31 30.63 13.78
i
Phenyto/n ALS Miscellaneous
Diabetes
Amplitude of sensory pot. (tzV) Controls Diabetes mellitus Guillain-Barr6 ALS Phenytoin
o
o
Fig. 4. Individual slopes ( m / s e c / ° C ) and mean slope values (solid lines) of MCV in normal controls and patients. The interrupted lines represent the normal limits (normal mean value + 2 S.D.). Skin temperature was measured at wrist. GBS = G u i l l a i n - B a r r 6 syndrome; ALS = amyotrophic lateral sclerosis.
22.66 14.22 15.33 42.97 8.21
not significant; * P < 0.05; * * * P < 0.005.
the controls (Table II). In 2 diabetic patients the slope was definitely lower but was not associated with clinical findings (Fig. 4). One patient treated with phenytoin had a decreased slope and slowing of MCV. One patient with bulbar ALS had an increased slope. Compared with controls the mean slope of SCV vs. temperature was lower in the patients and reached significant levels in diabetes mellitus and ALS (Table liD. For individual data only 5 patients (4 diabetes mellitus, 1 Guillain-Barr6) had values outside the normal limit (mean - 2 S.D.) (Fig. 5).
10"
5
O
Individual
~ 21
25
slopes
of SCV
35
Temperature (°C)
3
........................................................................................... o
Fig. 3. Correlation between distal latencies (DL) and skin temperature measured at wrist. Regression lines of 10 normal subjects (R - 0 . 9 6 to - 1.0; P < 0.001).
o o o o
229
ELMOCO 91606
Changes in motor and sensory nerve conduction parameters with temperature in normal and diseased nerve Peter Dioszeghy and Erik St~lberg Department of Clinical Neurophysiology, UniversityHospital, Uppsala S-75185 (Sweden) (Accepted for publication: 22 January 1992)
Summary The effects of temperature on conventional motor and sensory nerve conduction parameters were studied in normals and in some pathological conditions. Surface stimulating and recording electrodes were used to examine the function of the median nerve. The motor and sensory conduction velocities, the parameters of compound muscle action and sensory nerve potentials were correlated with skin temperature. In the control subjects all nerve conduction parameters changed with temperature. These findings were similar to those published previously, but the mean slope for MCV was lower than that reported in the literature. The amplitude values widely scattered as a consequence of methodological factors, which may mask effects of temperature. Only minor differences were revealed between control subjects and patients. The effect of temperature proved to be similar in the patients and in the normal controls. Therefore, the correction factors determined in normals may be acceptable for abnormal nerves in standardising the measured values with respect to temperature. However, in pathological cases, above all in diabetes mellitus, the slightly reduced changes of conduction velocities vs. temperature may be the source of false negative results in borderline cases when using the normal correction factors. The combination of preserved temperature dependence but decreased conduction velocities may indicate that demyelination and temperature influence the conduction velocities via different mechanisms. Key words: Diabetes mellitus; Guillain-Barr6 syndrome; Nerve conduction; Nerve membrane; Temperature
It is well k n o w n that nerve c o n d u c t i o n p a r a m e t e r s (velocity, a m p l i t u d e , d u r a t i o n ) alter with t e m p e r a t u r e . T h e effect of t e m p e r a t u r e m u s t be t a k e n into consideration w h e n using these p a r a m e t e r s in diagnosis a n d w h e n m o n i t o r i n g p a t i e n t s with n e u r o p a t h i e s . T o acc o u n t for the effect of t e m p e r a t u r e , different m e t h o d s have b e e n used. A s s u m i n g that the c h a n g e is linear a n d that the a b n o r m a l nerve reacts to cooling and w a r m i n g in the same way as the n o r m a l nerve, some l a b o r a t o r i e s n o r m a l i z e the m e a s u r e d values with respect to t e m p e r a t u r e , u s i n g c o r r e c t i o n factors ( H e n ricksen 1956; D e J o n g et al. 1966; D e Jesus et al. 1973). I n o t h e r l a b o r a t o r i e s the limb is w a r m e d to a s t a n d a r d t e m p e r a t u r e before the investigation. Both m e t h o d s may have their drawbacks. F o r the first: r e f e r e n c e materials for c o r r e c t i o n factors in pathology for differe n t nerves do n o t exist. For the second: it is u n k n o w n w h e t h e r the c h a n g e with t e m p e r a t u r e is such that pathological nerves show distinct deviation from normal only w h e n cooled or w a r m e d . This study was p e r f o r m e d to reveal the effect of
Correspondence to: Erik St~lberg, Dept. of Clinical Neurophysiology, University Hospital, Uppsala S-75185 (Sweden). Tel.: 46 18 663430; Fax: 46 18 551132.
t e m p e r a t u r e o n n e r v e c o n d u c t i o n p a r a m e t e r s in conditions with d e m y e l i n a t i o n , m o t o n e u r o n e disease and in which the m e m b r a n e p r o p e r t i e s may be affected.
Methods M o t o r a n d sensory nerve c o n d u c t i o n s of the right m e d i a n n e r v e were studied. Motor nerve studies T h e nerve was s t i m u l a t e d with a b i p o l a r surface electrode using square wave pulses of 0.1 msec d u r a tion. T h e stimulus was delivered at the wrist (with a c o n s t a n t distance of 8 cm proximal to the r e c o r d i n g electrode) a n d at the elbow. A surface recording disc electrode was attached over the e n d - p l a t e region of the a b d u c t o r pollicis brevis muscle. T h e r e f e r e n c e electrode was placed o n the distal i n t e r p h a l a n g e a l j o i n t of the t h u m b . Sensory nerve studies T h e nerve was s t i m u l a t e d by a b i p o l a r surface electrode using square wave pulses of 0.1 msec d u r a t i o n o n the radial side of the third digit. T h e sensory p o t e n t i a l s were r e c o r d e d with a b i p o l a r surface felt p a d electrode
230
with an interelectrode distance of 23 m m at the same point as used for motor nerve stimulation on the wrist, usually 14-15 cm from the stimulation site.
P. DIOSZEGHY, E. ST,~LBERG TABLE I Age and number of patients. Diagnosis
Experimental protocol After obtaining the first motor and sensory records at room temperature the forearm, including the elbow, was cooled in a water bath of 20°C for 20 min. The arm was then lifted from the bath.and dried, the electrodes were reapplied over marked spots and the recording was performed again. The arm was immersed in the water again, usually within 2 min and always within 3 min, and warming started. In relationship to the speed of temperature changes during cooling and warming, the time outside the bath was short. The water temperature was changed stepwise, to 25, 30 and 35°C, every 10 rain. Measurements were performed at each of these temperature levels. The skin t e m p e r a t u r e was measured a t the site of the recording and stimulating electrodes (third digit, thenar, wrist and elbow) with a digital infrared therm o m e t e r (C-600M Biotherm, Los Altos, CA 94022). The t h e r m o m e t e r had an accuracy of 0.1-0.2°C. Its response delay was 0.2-0.3 sec. Our pilot studies showed very similar relationships between temperature and changes in various neurophysiological parameters irrespective of the place for temperature measurements. We therefore chose the temperature values obtained at the wrist to be presented in tables and figures. The E M G equipment was connected to a PC with analysis program. The following motor nerve p a r a m e t e r s were measured at all temperatures: distal latency (DL) from the stimulus artefact to the first deflection from the baseline according to a special algorithm (StSlberg and St~lberg 1989); motor conduction velocity (MCV) for the nerve segment between elbow and wrist; amplitude of the negative component of the compound muscle action potential (CMAP); duration of CMAP from the onset to the end of the last positive deflection and to first baseline crossing - - these two measures were closely correlated and only the former is presented; area of the CMAP calculated as the integrated area between the signal and the baseline over the total duration o f the potential. The following sensory nerve p a r a m e t e r s were measured: latency to the first positive peak or, if absent, to onset of the negative peak; amplitude peak-to-peak; duration b e t w e e n the positive peaks; sensory conduction velocity (SCV) for the nerve segment between third digit and wrist.
Statistical methods Depending on the pattern of data in X-Y plots, linear regression analysis was performed for all param-
Healthy subjects Diabetes mellitus Type I Type II Guillain-Barr6 syndr. ALS * Phenytoin treated (epilepsy) Primary amyloidosis Carpal tunnel syndrome (CT)
Age (years) No.
Mean
Range
10 13 6 7 4 8 10 1 3
36.7 44.7
25-46 20-83 20-43 33-83 21-59 45-63 25-54 39 27-56
40,0 53.9 36.6
* Amyotrophic lateral sclerosis.
eters. For analysis of significance of differences, Student's t test was used. The t e m p e r a t u r e coefficients (Q10) of different parameters were computed to 25-35°C in controls. The Q10 value represents the ratio of highest to lowest value over a 10°C range.
Subjects and patients The subjects and patients are presented in Table I. Informed consent was obtained from both the healthy subjects and the patients in compliance with our hospital's regulations for H u m a n Studies. The healthy controls had no symptoms or signs of peripheral nerve involvement. Patients had additional neurography of left ulnar and median nerves, and sural, peroneal or tibial nerves and F waves bilaterally. We selected clinically typical cases for the different groups of patients. An attempt was made to have mild, moderate and severe cases. Four of the patients with diabetes mellitus were free of clinical symptoms and signs of polyneuropathy, but electroneurography in two of them showed slight abnormalities. The other 9 had mild or moderate symptoms a n d / o r signs of polyneuropathy. Electroneurography revealed severe polyneuropathy in 2, moderate in 3, mild in 3 and was normal in 1 of the patients. Of the 4 patients with Guillain-Barr6 syndrome three were classified as chronic with symptoms more than 6 months, and one as acute, investigated within 2 weeks of onset of symptoms. All were typical clinically and neurographically. Two patients with amyotrophic lateral sclerosis (ALS) had predominantly bulbar symptoms. Two patients were severely and one moderately affected. Three had mild atrophy of the studied arm with moderate reduction of force. Three patients with clinical and neurophysiologically confirmed carpal tunnel syndrome (CT) were also studied.
E F F E C T S OF T E M P E R A T U R E ON N E R V E C O N D U C T I O N P A R A M E T E R S
231
T A B L E II
70
Mean values of individual slope and intercept data of motor nerve parameters. Diagnosis
E >
Slope value Mean
50
Y scale crossing + S.D.
Mean
+ S.D.
MCV (m /sec) Controls Diabetes mellitus Guillain-Barr~ ALS Phenytoin
r,.)
1.13 0.93 0.96 1.00 0.90
r~s Ns NS NS
0.28 0.31 0.26 0.43 0.30
18.00 16.91 9.74 15.26 22.06
8.07 8.63 15.39 10.99 8.88
- 0.24 - 0.26 -0.36 - 0.30 - 0.26
r~s ** NS Ns
0.04 0.06 0.11 0.14 0.04
11.40 12.60 17.27 13.94 12.26
1.34 2.46 4.11 5.95 1.54
NS r~s NS NS
0.14 0.26 0.22 0.45 0.22
34.72 38.10 37.44 32.39 36.45
5.09 9.81 4.98 14.45 7.26
NS NS ** NS
0.33 1.19 1.15 1.12 2.06
109.34 93.49 67.50 58.01 116.71
12.75 46.99 49.11 47.39 40.32
NS NS r~s r~s
0.15 0.18 0.09 0.11 0.10
16.29 10.26 8.82 7.64 13.96
5.63 6.00 4.32 6.17 3.17
DL (msec)
254
-[
21
'
2'5
.
.
.
.
3'5
Temperature (°C) Fig. 1. Correlation between motor conduction velocities (MCV) and skin t e m p e r a t u r e measured at wrist. Regression lines of 10 normal subjects (R 0.87-0.99; P < 0.01-0.001).
The patients treated with phenytoin did not show symptoms of peripheral nerve involvement but two had slightly reduced motor and sensory conduction velocities on the median nerve under study.
Results
Controls Diabetes mellitus Guillain-Barr6 ALS Phenytoin
Duration of CMAP (msec) Controls Diabetes mellitus Guillain-Barr~ ALS Phenytoin
- 0.71 -0.76 - 0.60 - 0.58 - 0.76
Area of CMAP (msec × mV) Controls Diabetes mellitus Guillain-Barr~ ALS Phenytoin
-
2.24 1.84 1.55 1.25 1.89
Amplitude of CMAP (mV)
Controls In the control subjects all nerve conduction parameters changed with temperature. In general, both the MCV (R = 0.87-0.99, P < 0.01-0.001) (Fig. 1) and the SCV (R = 0.93-0.99, P < 0.01-0.001) (Fig. 2) increased significantly with rewarming, as demonstrated
Controls Diabetes mellitus Guillain-Barr6 ALS Phenytoin
-0.14 -0.04 -0.13 -0.07 -0.13
NS = not significant; * P < 0.05; ** P < 0.025.
35
by the slopes of the regression lines. For details see Tables II and III. Distal latencies (R = - 0 . 9 6 to - 1 . 0 , P < 0.001) (Fig. 3), duration (R = - 0 . 8 8 to -0.99, P < 0.01-0.001) and area (R = - 0 . 8 0 to -0.98, P < 0.05-0.001) of the CMAP increased at low temperature. There was a significant (R = - 0 . 9 3 to - 1 . 0 , P < 0.01-0.001) negative correlation between temperature and the duration of the sensory potential. Often, but not always, the amplitudes of CMAPs and sensory potentials were larger after cooling from room temperature but the change did not reach statistical significance ( P < 0.1). The Q10 values for different parameters in controls are listed in Table IV.
Fig. 2. Correlation between sensory conduction velocities (SCV) and skin temperatu re measured at wrist. Regression lines of 10 normal subjects (R 0.93-0.99; P < 0.01-0.001).
Patients In the patient material, the mean slope (mean of individual slope values) of M C V vs. temperature was slightly but statistically insignificantly lower than for
7° t
T
21
•
I
I
I
I
I
25
I
I
Temperature (°C)
P. DIOSZEGHY,E. ST,~d.,BERG
232 T A B L E III
Individual slopes of MCV
Mean values of individual slope and intercept data of sensory nerve parameters. Diagnosis
Slope value Mean
3-
Y scale crossing + S.D.
Mean
+ S.D.
0.4l 0.36 0.64 0.36 0.33
-7.94 -0.16 11.44 -3.67 -- 8.28
11.33 6.05 14.31 11.65 8.61
SCV (m /sec) Controls Diabetes mellitus Guillain-Barr6 ALS Phenytoin
2.17 1.46 1.72 1.79 1.92
*** NS * NS
2
E O o
g o
o
8
I
Duration of sensory pot. (msec) Controls Diabetes mellitus Guillain-Barr6 ALS Phenytoin
- 0.07 - 0.05 -0.10 - 0.07 - 0.07
NS NS NS NS
NS
=
0.10 -0.17 - 0.03 - 0.48 - 0.29
NS NS NS NS
§
•
o
o°
o
0.02 0.04 0.05 0.05 0.02
3.28 2.84 4.79 3.51 3.26
o
0.60 0.94 1.94 1.46 0.51
oo
o
o~
o ~ AmyloldoeiJ Carlml tunnel)
o 0
i
i
i
Control
GB$
0.67 0.42 0.49 1.20 0.48
24.47 8.90 7.31 30.63 13.78
i
Phenyto/n ALS Miscellaneous
Diabetes
Amplitude of sensory pot. (tzV) Controls Diabetes mellitus Guillain-Barr6 ALS Phenytoin
o
o
Fig. 4. Individual slopes ( m / s e c / ° C ) and mean slope values (solid lines) of MCV in normal controls and patients. The interrupted lines represent the normal limits (normal mean value + 2 S.D.). Skin temperature was measured at wrist. GBS = G u i l l a i n - B a r r 6 syndrome; ALS = amyotrophic lateral sclerosis.
22.66 14.22 15.33 42.97 8.21
not significant; * P < 0.05; * * * P < 0.005.
the controls (Table II). In 2 diabetic patients the slope was definitely lower but was not associated with clinical findings (Fig. 4). One patient treated with phenytoin had a decreased slope and slowing of MCV. One patient with bulbar ALS had an increased slope. Compared with controls the mean slope of SCV vs. temperature was lower in the patients and reached significant levels in diabetes mellitus and ALS (Table liD. For individual data only 5 patients (4 diabetes mellitus, 1 Guillain-Barr6) had values outside the normal limit (mean - 2 S.D.) (Fig. 5).
10"
5
O
Individual
~ 21
25
slopes
of SCV
35
Temperature (°C)
3
........................................................................................... o
Fig. 3. Correlation between distal latencies (DL) and skin temperature measured at wrist. Regression lines of 10 normal subjects (R - 0 . 9 6 to - 1.0; P < 0.001).
o o o o
