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Electrophysiological changes after severance of the C7 nerve root
PHYSIOLOGICAL CHANGES AFTER THE C7 NERVE ROOT Y-D.
S
CE OF
GU and L-Y. SHEN
From fhe Department of Hand Surgery, Hua Shun Hospital, Shanghai Medical University, People’s Republic of Chinu Since 1986, contralateral C7 root transfer has been used to treat brachial plexus root avulsions in our hospital. We performed post-operative electrophysiological examinations of the healthy-side limb in the first 27 patients. Electromyography and nerve conduction studies on the healthy side demonstrated mild abnormalities only of individual limb muscles in a few cases. These changes mostly recovered during the follow-up period. In the measurement of radial nerve motor conduction, median nerve sensory conduction and somato-sensory evoked potentials, we found that the amplitude of the median nerve sensory conduction alone was slightly lower than that of the control group (p < 0.05). The results showed that severance of C7 caused no permanent functional damage to the upper limb. Journal of Hand Surgery (British and European Volume, 1994) 19B: 69-71
The intercostal nerves, the accessory nerve, motor branches of the cervical plexus and the phrenic nerve (Gu et al, 1989) have been used to treat root avulsions of the brachial plexus. Because the total number of fibres in these donor nerves is far smaller than that of the brachial plexus (Narakas, 1984), the results leave something to be desired. Since 1986, we have used the contralateral C7 nerve root for neurotization bridged by the ipsilateral vascularized ulnar nerve to treat root avulsions of the brachial plexus (Gu et al, 1992). To investigate any damaging effects of severance of the C7 nerve root on the function of the healthy limb, we applied electrophysiological methods to examine the first 27 patients whose contralateral C7 root had been cut and transferred to the recipient nerve of the injured limb.
electric potential (SEP) was determined with a stairrless needle put according to the International Electroencephalography lo-20 System Electrode-put Method. 27 patients whose C7 root had been transferred were considered for study. Of these patients, three were examined once, 18 twice, four three times and two four times. Altogether 59 examinations took place in 27 patients. The timing of examination varied from 1 week to 5 1 months post-operative. Data from the last examination, including nerve conduction velocity (NCV), latency, evoked muscular action potential (EMAP) and SEP, were utilized for study. We chose 34 healthy people as controls. There was no statistical difference between the ages of the study group and the controls (Table 1).
MATERIALS
EMG
RESULTS
AND METHODS
Out of 59 examinations, two patients had positive sharp waves at rest in extensor digitorum communis and one in latissimus dorsi 6 months after operation, but their positive sharp waves disappeared at 15, 23, and 24 months respectively. No fibrillation potential was found. During strong contracture, one patient had a single-mixed pattern in latissimus dorsi 1 and 2 weeks post-operatively, but it converted to mixed pattern at 1 month. Another had single-mixed pattern in the triceps and the flexor carpi ulnaris at 20 months, however it converted to a mixed pattern at 32 months. The third had a single-mixed pattern in latissimus dorsi at 17
From October 1986 to May 1988, 27 patients with brachial plexus root avulsion were treated with contralateral C7 root neurotization. 22 of them were male and the ages of the 27 cases varied from 16 to 39 years. The right C7 root was severed in eight cases and the left in 19. The examination was performed with an electromyograph (Dantec 2000M) and a concentric needle electrode. The temperature of the examination room was kept above 24°C and of patient’s hand skin 30°C. Latissimus dorsi, triceps, flexor and extensor digitorum communis are mainly innervated by C7 and were chosen for examination. The motor nerve conduction of the radial nerve was determined using a concentric needle electrode entering extensor digitorum communis 7 cm distal to the elbow, with stimulation at the lateral muscular septum and Erb’s point with a surface electrode. The sensory nerve conduction of the median nerve was determined using antedromic stimulation, with a ring electrode on the proximal part of the middle finger for stimulation. The distance between the positive and negative electrodes was 10 mm. A surface electrode was placed on the wrist for recording. The somatic
Table 1 -Age
comparison between two groups*
croups
Age iyear) X&SE
Study group Control group
25.96k1.13 26.091-0.98
*With two-tailed f-test: r=O.O84. P>O.OS. 69
70
THE JOURNAL OF HAND SURGERY VOL. 19B No. 1 FEBRUARY 1994
Table 2-Comparison
Determining
of latency, EMPA and motor NCV of radial nerve between two groups Operation group x+SE (n=27j
items
Latency of LMS+ EDC (ms) EMAP of latency of LMS-tEDC (mv) Latency of Erb’s point+EDC (ms) EMAP of latency of Erb’s point -tEDC (mv) Motor NCV (m/s)
Control group z+SE (n=34)
t
P
3.90*0.10
4.03*0.11
0.813
>0.05
12.645 1.08
10.28 f 0.79
1.799
> 0.05
7.8550.16
7.89kO.16
0.166
> 0.05
9.15kO.56 67.12k1.23
1.634 0.169
> 0.05 > 0.05
11.50~1.00 63.41 rt 1.22
With two-tailed t-test. LMS: lateral muscular septum. EDC: extensor digitorum communis. EMAP: evoked muscular action potential. NCV: nerve conduction velocity.
months post-operatively, up further.
and has not been followed
Table 4-Comparison
Item
of median nerve SEP between two groups Operation group x,SE
Control group X*SE
t
P
21.60+0.26
29.94 i: 0.22
0.131
>0.05
2.14+0.12
0.609
>0.05
Nerve conduction velocity
Motor NCV of radial nerve There was no statistical difference in latency, EMAP, and motor nerve conduction velocity of the radial nerve between the operation group and the control group, as shown in Table 2. Sensory NCV of the median nerve Values of latency and sensory nerve conduction velocity in the operation group were not statistically different from those in the control group, whereas values of amplitude of sensory nerve action potential (SNAP) were lower in the operation group than in the controls. These were statistically different (Table 3). Sensory evokedpotential
(SEP) of the median nerve
With respect to latency and amplitude of SEP, no statistical difference was found between the operation group and the control one, as shown in Table 4.
Table 3-Comparison
Item Latency of SNAP (ms) Amplitude of SNAP (uv) NCV (&j
of sensory NCV between two groups Control group H,SE
t
P
2.28 * 0.05
2.29iO.05
0.080
9 0.05
19.44+ 1.81
26.13k1.40
2.979
i 0.005
56.10+1.50
54.27* 1.13
0.542
> 0.05
Operation group x*SE
With two-tailed f-test. SNAP: sensory nerve action potential. NCV: nerve conduction velocity.
Latency of SEP (ms) Amplitude of SEP (uv)
2.00 2 0.20
With two-tailed t-test. SEP: sensory evoked potential.
DISCUSSION
Physical examination showed that some of the patients with C7 nerve root neurotization from the healthy side had a slight reduction in muscle strength and/or paraesthesia, but recovered to normal in a short period (Gu et al, 1992). Our electrophysiological examination on four muscles mainly innervated by C7 have shown that only three patients had spontaneous electric activity in individual muscles, and this disappeared before the second follow-up examination. Most cases had an interferential, mixed, or interferential-mixed pattern in the examined muscles during strong contraction, and only a few of them had simple-mixed pattern in individual muscles, and usually the mixed pattern reappeared in 1 or 2 months. A simple pattern was not found. Only the amplitude of median nerve SNAP was found to be lower in the operation group than in the controls, whereas latency, motor nerve conduction velocity, EMAP of the radial nerve and SEP of the median nerve showed no damage in the operation group. These results are similar to those found clinically. We conclude that after division of C7, most muscles innervated by it showed no damage, and the few muscles of a few patients that did recovered in time. Apart from the amplitude of SNAP of the median nerve, the motor conduction of the radial nerve and the sensory conduction of the median nerve showed no difference between the operation group and the control group (p>O.O5). This means that severance of C7 causes only slight damage to the sensory function of
Cl EMG CHANGES
the median nerve, which is in accordance clinical observations (Gu et al, 1992).
71
with our
root transfer from the contralateral healthy side for treatment of bra&al plexus root avulsion. Journal of Hand Surgery, 17B: 5: 518-521. NARAKAS, A. 0. (1984). Thoughts on neurotization of nerve transfer in irreparable nerve lesions. Clinics in Plastic Surgery, 11:1: 153-159.
References GU; Y.-D., WU. M.-M., ZHEN, Y.-L. et al. (1989). Phrenic nerve transfer for brachial plexus motor neurotization. Microsurgery, 10: 3: 287-289. GU, Y.-D., ZHANG, G. M., CHEN, D.-S. et al. (1992). Seventh cervical nerve
Accepted: 23 June 1993 Professor Yu-dong Gu, Hua People’s Republic of China.
0 1994 The Bmrh
Society
Shan Hospital. 12, FVulumogi Zhong Road, Shanghai 200040,
for Surgery
of the Hand
S
CE OF
GU and L-Y. SHEN
From fhe Department of Hand Surgery, Hua Shun Hospital, Shanghai Medical University, People’s Republic of Chinu Since 1986, contralateral C7 root transfer has been used to treat brachial plexus root avulsions in our hospital. We performed post-operative electrophysiological examinations of the healthy-side limb in the first 27 patients. Electromyography and nerve conduction studies on the healthy side demonstrated mild abnormalities only of individual limb muscles in a few cases. These changes mostly recovered during the follow-up period. In the measurement of radial nerve motor conduction, median nerve sensory conduction and somato-sensory evoked potentials, we found that the amplitude of the median nerve sensory conduction alone was slightly lower than that of the control group (p < 0.05). The results showed that severance of C7 caused no permanent functional damage to the upper limb. Journal of Hand Surgery (British and European Volume, 1994) 19B: 69-71
The intercostal nerves, the accessory nerve, motor branches of the cervical plexus and the phrenic nerve (Gu et al, 1989) have been used to treat root avulsions of the brachial plexus. Because the total number of fibres in these donor nerves is far smaller than that of the brachial plexus (Narakas, 1984), the results leave something to be desired. Since 1986, we have used the contralateral C7 nerve root for neurotization bridged by the ipsilateral vascularized ulnar nerve to treat root avulsions of the brachial plexus (Gu et al, 1992). To investigate any damaging effects of severance of the C7 nerve root on the function of the healthy limb, we applied electrophysiological methods to examine the first 27 patients whose contralateral C7 root had been cut and transferred to the recipient nerve of the injured limb.
electric potential (SEP) was determined with a stairrless needle put according to the International Electroencephalography lo-20 System Electrode-put Method. 27 patients whose C7 root had been transferred were considered for study. Of these patients, three were examined once, 18 twice, four three times and two four times. Altogether 59 examinations took place in 27 patients. The timing of examination varied from 1 week to 5 1 months post-operative. Data from the last examination, including nerve conduction velocity (NCV), latency, evoked muscular action potential (EMAP) and SEP, were utilized for study. We chose 34 healthy people as controls. There was no statistical difference between the ages of the study group and the controls (Table 1).
MATERIALS
EMG
RESULTS
AND METHODS
Out of 59 examinations, two patients had positive sharp waves at rest in extensor digitorum communis and one in latissimus dorsi 6 months after operation, but their positive sharp waves disappeared at 15, 23, and 24 months respectively. No fibrillation potential was found. During strong contracture, one patient had a single-mixed pattern in latissimus dorsi 1 and 2 weeks post-operatively, but it converted to mixed pattern at 1 month. Another had single-mixed pattern in the triceps and the flexor carpi ulnaris at 20 months, however it converted to a mixed pattern at 32 months. The third had a single-mixed pattern in latissimus dorsi at 17
From October 1986 to May 1988, 27 patients with brachial plexus root avulsion were treated with contralateral C7 root neurotization. 22 of them were male and the ages of the 27 cases varied from 16 to 39 years. The right C7 root was severed in eight cases and the left in 19. The examination was performed with an electromyograph (Dantec 2000M) and a concentric needle electrode. The temperature of the examination room was kept above 24°C and of patient’s hand skin 30°C. Latissimus dorsi, triceps, flexor and extensor digitorum communis are mainly innervated by C7 and were chosen for examination. The motor nerve conduction of the radial nerve was determined using a concentric needle electrode entering extensor digitorum communis 7 cm distal to the elbow, with stimulation at the lateral muscular septum and Erb’s point with a surface electrode. The sensory nerve conduction of the median nerve was determined using antedromic stimulation, with a ring electrode on the proximal part of the middle finger for stimulation. The distance between the positive and negative electrodes was 10 mm. A surface electrode was placed on the wrist for recording. The somatic
Table 1 -Age
comparison between two groups*
croups
Age iyear) X&SE
Study group Control group
25.96k1.13 26.091-0.98
*With two-tailed f-test: r=O.O84. P>O.OS. 69
70
THE JOURNAL OF HAND SURGERY VOL. 19B No. 1 FEBRUARY 1994
Table 2-Comparison
Determining
of latency, EMPA and motor NCV of radial nerve between two groups Operation group x+SE (n=27j
items
Latency of LMS+ EDC (ms) EMAP of latency of LMS-tEDC (mv) Latency of Erb’s point+EDC (ms) EMAP of latency of Erb’s point -tEDC (mv) Motor NCV (m/s)
Control group z+SE (n=34)
t
P
3.90*0.10
4.03*0.11
0.813
>0.05
12.645 1.08
10.28 f 0.79
1.799
> 0.05
7.8550.16
7.89kO.16
0.166
> 0.05
9.15kO.56 67.12k1.23
1.634 0.169
> 0.05 > 0.05
11.50~1.00 63.41 rt 1.22
With two-tailed t-test. LMS: lateral muscular septum. EDC: extensor digitorum communis. EMAP: evoked muscular action potential. NCV: nerve conduction velocity.
months post-operatively, up further.
and has not been followed
Table 4-Comparison
Item
of median nerve SEP between two groups Operation group x,SE
Control group X*SE
t
P
21.60+0.26
29.94 i: 0.22
0.131
>0.05
2.14+0.12
0.609
>0.05
Nerve conduction velocity
Motor NCV of radial nerve There was no statistical difference in latency, EMAP, and motor nerve conduction velocity of the radial nerve between the operation group and the control group, as shown in Table 2. Sensory NCV of the median nerve Values of latency and sensory nerve conduction velocity in the operation group were not statistically different from those in the control group, whereas values of amplitude of sensory nerve action potential (SNAP) were lower in the operation group than in the controls. These were statistically different (Table 3). Sensory evokedpotential
(SEP) of the median nerve
With respect to latency and amplitude of SEP, no statistical difference was found between the operation group and the control one, as shown in Table 4.
Table 3-Comparison
Item Latency of SNAP (ms) Amplitude of SNAP (uv) NCV (&j
of sensory NCV between two groups Control group H,SE
t
P
2.28 * 0.05
2.29iO.05
0.080
9 0.05
19.44+ 1.81
26.13k1.40
2.979
i 0.005
56.10+1.50
54.27* 1.13
0.542
> 0.05
Operation group x*SE
With two-tailed f-test. SNAP: sensory nerve action potential. NCV: nerve conduction velocity.
Latency of SEP (ms) Amplitude of SEP (uv)
2.00 2 0.20
With two-tailed t-test. SEP: sensory evoked potential.
DISCUSSION
Physical examination showed that some of the patients with C7 nerve root neurotization from the healthy side had a slight reduction in muscle strength and/or paraesthesia, but recovered to normal in a short period (Gu et al, 1992). Our electrophysiological examination on four muscles mainly innervated by C7 have shown that only three patients had spontaneous electric activity in individual muscles, and this disappeared before the second follow-up examination. Most cases had an interferential, mixed, or interferential-mixed pattern in the examined muscles during strong contraction, and only a few of them had simple-mixed pattern in individual muscles, and usually the mixed pattern reappeared in 1 or 2 months. A simple pattern was not found. Only the amplitude of median nerve SNAP was found to be lower in the operation group than in the controls, whereas latency, motor nerve conduction velocity, EMAP of the radial nerve and SEP of the median nerve showed no damage in the operation group. These results are similar to those found clinically. We conclude that after division of C7, most muscles innervated by it showed no damage, and the few muscles of a few patients that did recovered in time. Apart from the amplitude of SNAP of the median nerve, the motor conduction of the radial nerve and the sensory conduction of the median nerve showed no difference between the operation group and the control group (p>O.O5). This means that severance of C7 causes only slight damage to the sensory function of
Cl EMG CHANGES
the median nerve, which is in accordance clinical observations (Gu et al, 1992).
71
with our
root transfer from the contralateral healthy side for treatment of bra&al plexus root avulsion. Journal of Hand Surgery, 17B: 5: 518-521. NARAKAS, A. 0. (1984). Thoughts on neurotization of nerve transfer in irreparable nerve lesions. Clinics in Plastic Surgery, 11:1: 153-159.
References GU; Y.-D., WU. M.-M., ZHEN, Y.-L. et al. (1989). Phrenic nerve transfer for brachial plexus motor neurotization. Microsurgery, 10: 3: 287-289. GU, Y.-D., ZHANG, G. M., CHEN, D.-S. et al. (1992). Seventh cervical nerve
Accepted: 23 June 1993 Professor Yu-dong Gu, Hua People’s Republic of China.
0 1994 The Bmrh
Society
Shan Hospital. 12, FVulumogi Zhong Road, Shanghai 200040,
for Surgery
of the Hand