Introduction
It has been 25 years since the world’s first case of contralateral C7 nerve transfer
finished in our clinic in August 1986 [[1]]. We now summarize our experiences regarding this technique.
Brachial plexus avulsion injury represents one of the most devastating injuries of
the upper extremity. Nerve transfer is the most frequently used method in restoring
limb function. So far, various techniques have been used, intraplexus or extraplexus,
including accessory nerve transfer, intercostal nerve transfer, phrenic nerve transfer
etc. However, with the fast development of high-velocity traffic, there have been
increasing high-energy accidents over the recent years which resulted in more extensive
trauma. In these cases, even fewer donor nerves could be used in neurotization. This
prompts us to seek more donor sources for brachial plexus reconstruction.
Clinical case
In June 1986, a 28-year old man sustained hemopneumothorax due to 3rd-6th costal fractures
and brachial plexus injury in the left side during a motor cycle accident. He was
referred to our clinic 2 months after initial trauma due to there has been no spontaneous
recovery of the upper limb function. Upon physical examination, a positive Claude
Bernard-Horner’s sign was found. The function of the shoulder, elbow, wrist and hand
was completely lost. Plain chest X-ray film also showed elevation of the left diaphragm.
Electromyogram detected no SEP from C5-T1 nerve roots and NAP could be recorded. The
diagnosis was preganglionic injury of the C5-T1 nerve roots, ie., total root avulsion
injury of the brachial plexus. The EMG exam also suggested concomitant complete palsy
of the accessory nerve and phrenic nerve. Based on our observation of over 1000 cases
of brachial plexus injuries, no patient suffered functional loss from single C7 root
injury, therefore we postulated that C7from the healthy limb may be sacrificed and
used as a donor nerve to reconstruct the injured plexus. During surgical exploration
of the affected plexus, C5-T1 nerve roots were found avulsed. Due to extensive scarring
in the neck/shoulder region, the accessory nerve and motor branches of the cervical
plexus could not be used. The phrenic nerve was found to be buried in the scarry tissue
on the surface of the fibrosed anterior scalenus muscle and a neurolysis was performed.Upon
electrical stimulation a strong contraction of the diaphragm could be induced which
indicated the viability of phrenic nerve. It was then divided with its proximal stump
transferred directly to the anterior division of the upper trunk (fascicles destined
to the musculocutaneous nerve). Since there were no further donor nerves to be used
in the injured side, the contralateral C7 nerve was decided to be used and therefore
exposed and divided. In the injured side, the ulnar nerve was freed from the wrist
level to upper arm and then transposed and tunnelled subcutaneously to the incision
in the healthy side to be sutured with the contralateral C7 nerve. The ulnar vessels
were dissected along with the ulnar nerve and the anastomosis was performed: ulnar
artery with the transverse cervical artery and ulnar vein with a tributary of the
external jugular vein.
On first postoperative day, sensory deficits were found in the index finger and middle
finger and motor function of the healthy upper limb was normal. The muscle strength
of latissimus dorsi, triceps brachii, extensor digitorum communis, flexor carpi ulnaris
and extensor carpi radialis was all above M4. The grip strength was 36 kg (40 kg before
operation) and the pinch strength was 4 kg (same as before operation). The patient
did not manifest any signs of respiratory disorder. The paraesthesia in the healthy
hand disappeared 2 weeks later and the grip strength returned to 40 kg and all joint
function of the healthy side was normal.
In October 1987, 14 months after the first stage, percussion along the ulnar nerve
from the healthy side toward the injured side showed Tinel’s sign positive at the
midpoint of the upper arm indicating the regeneration reached the site, which corresponded
with the regenerating rate of approximately 1 mm per day, (38 cm over 420 days). The
muscle strength of the biceps recovered to M3. Therefore the regenerated ulnar nerve
was divided in the upper arm and transferred to the median nerve. In February 1989,
30 months after first stage, the muscle strength of the flexor carpi radialis recovered
to M3, the flexor digitorum superficialis of 2nd - 5th fingers was M2, and sensation
recovered to S2 in the radial 3 fingers. The muscle strength of biceps was M4 and
the patient could freely flex the elbow without initiated by respiration. In August
1990, 4 years after first stage, the muscle strength of flexor carpi radialis, palmaris
longus and flexor digitorum superficialis was M4, flexor digitorum profundus and flexor
pollicis longus was M3 and sensation in the radial 3 fingers recovered to S3.
Therefore we conclude the indications for contralateral C7 transfer as follows:
-
1, No available neurotizers in the affected side;
-
2, Used as one of the neurotizers in multiple neurotization in total root avulsion
injury;
-
3, When one of the multiple neurotizations fails for any type of avulsion injury
Technical aspects
Under general anesthesia, the patient is put in supine position.
Dividing contralateral C7 nerve
The brachial plexus of the healthy side is explored through a transverse incision
parellel to the clavicle (about 2 cm above the clavicle) starting from the posterior
margin of the sternocleidomastoid muscle. The small branches of the external jugular
vein can be ligated and the omohyoid muscle is divided and retracted to the side.
The transverse cervical vessels are ligated and the C5-T1 nerve roots are exposed.
Before dividing C7, a little amount of 2% lidocaine is injected epineurially to protect
the proximal neurons. The C7 nerve can be severed at the common trunk level or its
posterior division or anterior division level depending on the diameter of the ulnar
nerve graft and the recipient nerve to be reconstructed.
Harvesting ulnar nerve graft
Harvesting ulnar nerve graft
In the injured side, the ulnar nerve (the main trunk and the dorsal cutaneous branch)
is cut at the wrist level and freed proximally to the upper arm. Attention needs to
be paid to protect the superior ulnar collateral vessel for blood supply to the upper
segment of the ulnar nerve graft. Then a cross-chest subcutaneous tunnel is made to
bring the ulnar nerve to the divided contralateral C7 for a tension-free nerve suture.
The patient is required to wear a head-shoulder spica for 4 weeks after operation
to prevent rupture of the nerve suture.
Second stage transfer of ulnar nerve
Second stage transfer of ulnar nerve
When nerve regeneration from contralateral C7 has reached axilla of the affected side
as judged by clinical and electrophysiological studies, usually about 10 months, the
ulnar nerve is divided in the upper arm and transferred to the recipient nerve [[2],[3]].
Results from different authors
Results from different authors
In our adult series of contralateral C7 transfer followed up for over 2 years, the
overall motor recovery rate (> = M3) was 50-80% depending on different recipient nerves
and the sensory recovery rate (> = S3) was above 60%. [Table 1] shows the demographic data of the cases and [Table 2] shows the functional recovery based on various recipient nerves. In our separate
series on infants and children, noteworthy function was achieved in 10 of 12 patients
and sensory function was gained in all patients (age 6-93 months, average 17 months,
followed up for a mean of 42 months) [[4]].
Table 1
Demographic data of the cases
|
Male
|
47
|
|
Female
|
15
|
|
Left side
|
36
|
|
Right side
|
26
|
|
Age
|
16-50 years
|
|
(Average: 27.8 years)
|
|
Causes
|
|
|
Traffic accident
|
47
|
|
Machine traction injury
|
8
|
|
Fall from height
|
4
|
|
Heavy object falling on the shoulder
|
3
|
Table 2
Functional recovery of contralateral C7 nerve transfer
|
|
Motor Recovery
|
Sensory Recovery
|
|
Target nerve
|
No.
|
M4
|
M3
|
M2-1
|
M0
|
S4
|
S3
|
S2-1
|
S0
|
|
Musculocutaneous N
|
14
|
5
|
6
|
2
|
1
|
2
|
8
|
3
|
1
|
|
Median N
|
36
|
8
|
12
|
9
|
7
|
4
|
19
|
8
|
5
|
|
Radial N
|
10
|
3
|
2
|
3
|
2
|
0
|
7
|
1
|
2
|
|
Thoracodorsal N
|
2
|
1
|
0
|
0
|
1
|
0
|
0
|
0
|
0
|
Terzis recently reported the fair (M2+~M3), good (M3+~M4-) and excellent (M4+~M5-)
rates of 56 cases were 74% for biceps; 57% for triceps; 50% for deltoid; 62% for wrist
and finger flexors and 50% for wrist and finger extensors, respectively [[5]].
But in a report of 96 cases by Waikakul, only 52% of patients had > = M3 recovery
after contralateral C7 transfer to musculocutaneous nerve, and 20% recovery for the
extensor of wrist/finger and 29% recovery for finger flexor [[6]]. Sammer et al reported results from 2 groups of hemi-contralateral C7 transfer,
that no patient developed useful function after median nerve repair and only 23% >
= M3 recovery after suprascapular or axillary nerve repair [[7]]. The most optimistic result was reported by Hierner that 100% M3 biceps recovery
was achieved in 6 patients while for median nerve the recovery rate was 25% [[8]].
Various results obtained from different authors might be contributed to a few factors.
Apart from patient age and surgical delay, we consider the following 2 factors are
of paramount importance to the good surgical outcome.
1, Fascicle selection of contralateral C7: anterior division, posterior division or
whole C7?
In most of our patients, the ulnar nerve is used as nerve graft. And in the majority
of the cases, the diameter of C7 exceeds that of the ulnar nerve. Therefore, sometimes
partial C7 was used for neurotization. In a previous study, it has been demonstrated
that posterior division of C7 contains more motor fibers than anterior division [[9]]. Therefore if the aim of the transfer is to restore motor function eg wrist/finger
flexion, the posterior division should be used and if the sensory function is desired,
eg. to restore protective sensibility of hand, the anterior division should be used.
This may also explain the low motor recovery rate in Waikakul’s series since only
anterior division was used to neurotise median nerve while the sensory recovery was
good (83%) in his group. Sammer et al also used hemi-C7 to repair median nerve (0%)
and suprascapular/axillary nerve (23%). Therefore we prefer using whole C7 for neurotization
to fully utilise the large source C7 can provide, which was also the way Terzis did
in her series [[4]].
2, Vascularization of the nerve graft
In adults, the distance between contralateral C7 and recipient nerve in the injured
arm is over 30 cm. In such case, the blood supply of the long nerve graft is essential
to maintain the regenerative potential of C7. Therefore, we strongly advocate performing
contralateral C7 transfer in 2 stages. In the first stage, the distal end of ulnar
nerve is transposed and connected with contralateral C7 to allow nerve regeneration,
while the proximal part of ulnar nerve is intact to preserve blood supply of the ulnar
nerve graft. This might be another reason for the low recovery rate in Waikakul’s
and Sammer’s series, when C7 was immediately transferred to median nerve and/or axillary
nerve. We have also compared different patterns of bridging the C7 to the recipient
nerve: free sural nerve graft, sural nerve graft vascularised through saphenous vein,
pedicled ulnar nerve based on superior ulnar collateral artery and ulnar nerve graft
with anastomosis of ulnar vessels. The results appear to be better in the patients
with better blood supply of the nerve graft [[1],[10],[11]]. It has also been proved that when the diameter of superior ulnar collateral artery
was over 0.5 mm, it could provide sufficient blood supply to full-length ulnar nerve
(length/width ratio about 45:1) [[12]], Therefore we prefer using this vessel instead of performing ulnar artery and vein
anastomosis [[13]].
Safety in dividing contralateral C7
Safety in dividing contralateral C7
C7 forms middle trunk and no single muscle in the upper limb is innervated solely
by C7. Therefore, dividing C7 will cause no permanent loss in sensory and motor function.
Usually, the patients will undergo numbness in the fingers in the first 3 months after
operation. The most affected fingers are index finger (74%), middle finger (58%) and
thumb (38%) [[14]]. There will be temporary decrease in the grip strength but the pinch strength is
not affected [[15]]. It is worth pointing out that the C7 transection site should not be too distal
(should never go infraclavicularly) and otherwise the fibers from upper and lower
trunk may be injured and permanent motor and sensory deficits will be caused [[12]].
Multiple use of contralateral C7 transfer
Multiple use of contralateral C7 transfer
One single C7 nerve carries vast nerve fibers that exceed total number from the frequently
used donor nerves such as accessory nerve, phrenic nerve and intercostal nerve. Therefore,
it is reasonable to use it to neurotise more than 1 recipient nerve [[4]]. In a preliminary clinical study on double use of contralateral C7 transfer, acceptable
recovery was achieved in C7 to musculocutaneous nerve and median nerve, while the
result was poor in C7 to median and radial nerve [[16]]. This is probably due to the brain plasticity transformation is more difficult
for 2 nerves of antagonistic functions, eg. finger flexion and extension. Therefore
the double use of contralateral C7 transfer should only be cautiously used in well
selected cases and two recipient nerves are better of synergistic functions, eg. elbow
flexion and finger flexion.
Cross-chest subcutaneous route vs prespinal route contralateral C7 transfer
Mcguiness reported one case of prespinal route in contralateral C7 transfer in 2002
[[17]] and other author also reported their experience of this technique more recently
[[18]]. The advantage of this route is it saves the regeneration distance of nerve graft
and therefore early functional recovery is expected. However, it puts patients under
risk in making the retropharyngeal space to pass the graft. The benefits from this
route, together with the safety of this technique (eg, bleeding, phrenic nerve or
esophagus injury) are to be evaluated on these early cases after longer observation
period.
Brain plasticity in contralateral C7 nerve transfer
Brain plasticity in contralateral C7 nerve transfer
After contralateral C7 nerve transfer, the patient is encouraged to perform more exercises
of the healthy limb especially elbow extension and shoulder adduction thus to stimulate
regeneration from contralateral C7 toward the injured side along the nerve graft.
In the early stage of functional recovery, all patients experience problem with involuntary
movement of the injured arm-the motion has to be initiated by the movement of the
healthy arm. In majority of patients this phenomenon lasts for 5 years and usually
independent movement can be obtained when the muscle strength recovered to M3 [[2]]. Brain plasticity plays an important role in the transformation process. With the
advanced brain imaging technology such as fMRI and PET scan, it is now possible to
look into the changes in the brain and contralateral C7 transfer opens a unique venue
to study the connections between 2 hemispheres.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
CGZ carried out the followup study and collection of data. YDG conceived of the study
and participated in its design and coordination. All authors have read and approved
the final manuscript.
Cite this article as: Zhang and Gu: Contralateral C7 nerve transfer - Our experiences over past 25 years. Journal of Brachial Plexus and Peripheral Nerve Injury 2011 6:10.
