Background
There are a lot of scientific contributions related to obp lesions, either general
or focused on specific aspects of diagnosis and treatment [[1]].
Few of them deal with surgical details about nerve exposure and reconstruction and
their possible influence on the outcome [[2],[3],[4],[5]].
After 10 years of regular surgical practice on brachial plexus lesions in children
and adults, it seems to me that technical aspects and details should be described
and discussed more often, although this expertise wount fulfill criteria of EBM (evidence
based medicine), but rather reflect surgical practice and its attempt to improve functional
results for the paralysed limb [[1]].
Indication for surgery, patient’s age
According to an agreement among most of the international experts, we operate non
or poorly recovering plexus lesions early – the total lesion with a flail hand and a Horner sign at 3 months; the upper lesion
between 6 and 9 months – this delay just to appreciate the quality of reinnervation
in the proximal nerves and muscle targets (shoulder and biceps muscles): when recovery
in an upper lesion is very poor, we operate earlier (between 3 and 6 months), when
the recovery seems promising and continous, we add time up to the 9th month.
Our decision for surgical exposure and reconstruction is only based on clinical arguments
– although we are aware that electrophysiologic criteria like in Birch’s group [[6]], where a continous co-operation between the surgeon and the neurologist exists,
are extremily worthfull in the decision-making for upper lesions with various recovery.
Preoperative imaging
Children born with a breech presentation and showing a severe upper obp lesion often
present avulsions of the upper C5 and C6 roots. Although the indication for surgery
is evident, preoperative MRI may give further evidence of root avulsion (unvisible
radicellae on thin transverse sections, presence of meningoceles).
As our patients come from all over Germany with individual preoperative assessment,
we have to share different qualities of both imaging technique and expertise in interpretation.
The risk of false negative results is high – where the myelon seems intact and the
avulsion is found intraoperatively.
Centers with interdisciplinary brachial plexus teams (like our neighbours in Heerlen
and Leiden, The Netherlands) certainly would better integrate the preoperative imaging
(neurosurgeons often perform themselves myelography just before starting plexus exploration),
although these informations are not decisive for establishing the surgical indication.
The time schedule proposed for the plexus exploration might be non respected if the
child is ill just before the scheduled day of surgery (upper airway infection) or
if it presents late on the first consultation. Occasionally, we explored children
with severe upper lesions even 18 and 21 months old, when the proximal recovery in
the shoulder was very bad and biceps activity absent.
Exposure
The child is supine, the head turned to the contralateral side, no pillow. We always
use a single transverse supraclavicular incision, about 4 cm long, 1 cm above the
clavicle in total lesions and about 2 cm above in upper lesions.
Once subcutaneous tissue and platysma has been sectioned, we dissect a large quadrangular
space limited by the clavicle beneath, the internal jugular vein medially, the emergence
of the phrenic nerve from C5 upward, and the upper trunk laterally. The fat-lymphatic
tissue bulk is reflected laterally and the upper trunk identified exiting under the
scalenus anterior muscle.
Dissection and neurolysis
The phrenic nerve is identified on the anterior scalenus muscle, stimulated, and followed
more proximally to identify the contribution from C5 and the sensitive branches of
the cervical plexus.
Than, the trunks and roots down to their foramen are identified progressively and
put on rubber loops.
In our country, most of the upper and total lesions are within the supraclavicular
space and can be exposed completely by the unique supraclavicular transverse incision,
as the soft tissue is elastic and might be spread easily by a self-retaining distractor.
When an extended infraclavicular approach is necessary, a vertical delto-pectoral
incision may be added and the clavicle might be isolated on a loop, to identify a
retroclavicular lesion or adhesions.
We spend enough time to follow all the roots onto the foramen, analyse the scalenus
muscle shape (we actively search for the presence of anatomic variants like a scalenus
minimus muscle or suprapleural bands) and underlying bone prominences (hypertrophied
transverse process of 7th vertebra, between the roots C7 and C8, or a cervical rib).
The emergence of the long thoracic nerve exiting from C5 and C6 very proximally must
be identified and spared; as the nerve than enters the middle scalenus muscle, it
is more protected.
Distally, normally at the level of the upper clavicular rim, we identify the branches
of the upper (and sometimes middle trunk) and especially the suprascapular nerve (SSC).
We appreciate if this nerve has been delocalised from its initial topography; sometimes
it appears under the clavicle – which is a stigma of a severe traction injury.
If there is a need for proper exposure or grafting, the clavicle is osteotomized in
about 10%; we prepare 4 drill wholes to synthetize it by a 3/0 Maxon suture immediately
after the grafting.
Once the lesion appears clearly and is delimitated, we perform an intraoperative electrostimulation.
Electrical stimulation of roots and distal branches
Actually, we only use a stimulation device (Stimuplex® DIG, Braun Melsungen AG, Germany), delivering direct current (monophasic, rectangular,
duration 0,1 msec, frequency 1 or 2 Hz) between 0–5 mA (by steps of 0,01 mA – but
used at 0,1 mA for our purposes) through a Contiplex® needle (1.2 × 45 mm length), normally used by our anaesthesiologists to perform peripheral
nerve blocks, to identify muscle targets and the conductiveness of neuromas. We don’t
have experience with SSEP or NCV measurements.
Only recently, we added in isolated cases a multichannel neurologic monitoring (Eclipse
by ANT software bv, Jodoigne Belgium), especially to study SSEP.
We then perform a drawing of the lesion and have a talk to the parents outside the
OR, explaining the exact amount of lesion, the reconstructive plan and possible outcome.
Meanwhile, the sural grafts may be taken and probes of the proximal and distal coaptation
sites are sent for specialised neuropathological examination.
Graft harvest
The sural nerve(s) are harvested through 4 or 5 short oblique skin incisions. No pull
is exerted on the nerve. The nerve is kept within a moist swab, until conditioning
occurs just before the grafting. The skin is closed by single inverted dermal stitches
and elastic Steristrips are applied.
Neuropathology
When the decision of neuroma resection has been made, we continue dissection of the
rootlets onto the foramen and we resect at a level of macroscopic healthy tissue.
To prepare the grafting, we want to assure good proximal and distal nerve stump quality.
Each root sample is marked by ink on the proximal side and sent on a moist swab for
immediate neuropathological examination. The distal nerve (trunk or cord level) might
be examined more easily under magnification; here histologic samples are not taken
routinely from all targets, but only from major trunks or connections with doubtful
quality.
The examination takes about 30 minutes, after a car transfer to the Institute of Neuropathology
(Professor Dr J. Weis) at Aachen University, lasting for another 15 minutes.
We get the results when the grafts have been harvested, normally around noon.
The quality of samples is described by the fascicular pattern (number and orientation
of nerve fascicles, presence of peri- or endoneural fibrosis), remnants of nerve degeneration
(clusters of Schwann cells called „Büngner” bands), indirect signs of reinnervation
(presence of minifascicles, level of myelinisation), and the absence of ganglion cells.
Using this type of macro-(through the surgeon’s magnification loop while dissecting)
and micro-(through the neuropathologist’s microscopic view) confrontation, we try
to improve our quality of root microdissection.
We prepare a good fascicular surface to receive sural graft stumps and we look actively
for any argument related to more proximal root damage (intraforaminal rupture, partial
or total root avulsion) to prevent a grafting on rather worthless stumps.
A root specimen taken too distal on an avulsed root would show normal nerve fibers,
without ganglion cells, and thereby the neuropathologist would qualify this a good
root – so the level, skill and experience of root dissection is mandatory.
The surgical benefit of this histopathological examination results in the increased
attention to the coaptation partners; a risk might emerge if the histologic quality
is quoted without analysing other arguments like absence of local neuroma formation
(this could indicate a partial avulsion), rapid and complete denervation of targets
(without any electric reactivity), or a very proximal lesion (with high risk of centripedal
neuron death and lack of regeneration anyway).
We have tried to correlate root quality and clinical outcome in every patient follow-up;
and there seems to be a strong concordance, but we still doubt on issues where a rather
good stump e.g. put on the inferior trunk gave a insufficient motor recovery of finger
flexors.
We also recognise that so far, we don’t have a valuable staining tool to distinguish
motor from sensitive fascicles or areas, and that topographic arrangement within a
root might be random in small roots, with less predictable outcomes (although the
topographic description by Millesi et al. [[7]] is a wonderful work, needing further consideration and refinement).
Reconstruction, coaptation
As a principle, we distinguish the strategy in total lesions from the (extended) upper
lesions.
Total lesion
According to Gilbert [[4]], we consider the hand to be the priority in (sub)total lesions. The root Th1 seems
to deliver the major motor contribution to the hand – therefore in a total lesion
with a Horner sign we always graft on the contribution from Th1 to the inferior trunk.
We also would graft on a distal C8 contribution to enhance hand function in a setting
without Horner sign where a basic grip is powered by a good Th1 root and C8 seems
damaged.
The other functions are supplied depending on available roots. Priorities are the
biceps and shoulder function, than the radial nerve. The long thoracic nerve is often
spared.
In general, we favor intraplexic neurotisation on the remaining 2 or 3 proximal roots.
C6 seems to be the best motor donor, so we reserve it for the upper trunk; C7 is suitable
for the hand function. C5 is often very small, it might neurotise the middle trunk
– but this last structure might even be neglected in very severe cases where proximal
donors are lacking.
Indication for primary intercostal nerve neurotisation is very rare (3 cases, put
on the motor musculocutaneus nerve) and a contralateral C7 transfer (on the median
nerve) only has been performed once.
There might be debate if the suprascapular nerve in these total lesions (where medial
rotation of the shoulder will be weak) should be neurotised by the distal branch of
the accessory nerve; as this nerve might be spared to keep the trapezius muscle intact
and to provide a good motor donor for secondary free gracilis muscle transfers.
Upper lesion
Biceps and triceps activity easily might become co-activated, so we always separate
grafts and roots for the upper and middle trunk (resp. the musculocutaneous and radial
nerve area).
The shoulder (the axillary nerve and pectoral muscle reinnervation) needs a major
motor input and we regularly attribute this role to the best motor root, believed
to be C6.
For the suprascapular nerve in upper obp lesions, we strongly advocate extraplexic
neurotisation by the distal branch of the spinal accessory nerve, as we need a counterbalance
to the medial rotators, as rotational dysbalance at the shoulder level with increasing
glenohumeral dysplasia is a frequent issue [[8]].
A graft from C5 onto the SSC nerve is not reliable to provide enough motor power to
the infraspinatus muscle, as the topographic arrangement might not be matched reliably.
Some neurotisations of the SSC nerve give bad results; this might reflect a very distal
lesion to this nerve close to the scapula, within the narrow supraspinal notch. This
is a place rather difficult to explore surgically, as the spinati muscle must be removed
out of their fossae to see the motor nerves entering the muscles from behind – this
is a much too agressive procedure, but in cases with concomittant connatal glenohumeral
subluxation, where direct trauma to the shoulder girdle is obvious, the hypothesis
of a distal lesion of the SSC nerve should be debated.
We spend enough time to prepare the grafts (2 to 4 cm long), resecting the ends, orientating
them in an antidromic way and giving enough length to intercalate them as a preformed
bundle without tension between good quality proximal and distal targets, proofed by
neuropathological examination.
The coaptation is performed fascicle per fascicle under magnification 5 fold or the
microscope.
We prefer fibrin glue (Tissucol) when there is no tension; sometimes adaptive stitches
are mandatory before the glue. As in severe proximal lesions, the root tissue might
be cut back onto/into the foramen, only glue fixation can be applied on these sites.
After all connections have been completed, and the clavicle synthetized, the soft
tissue paddle is put over the grafted brachial plexus. Skin closure is done by intracutaneous
running suture.
Immobilisation
We actually immobilize the child in a custom – made plaster helmet ([figure 1]) for 3, in extreme extended lesions 4 weeks. The dressing is refreshed weekly, while
holding the child to immobilize the affected arm and the neck.
Figure 1
immobilisation helmet.
After plaster removal, the arm is fixed for one additional week along the chest, the
hand on the belly, to prevent any distraction on the retroclavicular coaptation.
Follow-up
The plaster is removed in our Unit and children are seen every 6 months after surgery.
Active movements are tested and contractures especially at the shoulder joint actively
searched for.
Recovering muscle activities are recorded using BRMC and ROM scores.
Possible errors
Some of them where real, some are hypothetic – as nobody can see again what happens
to the reconstructed peripheral nerves.
Errors might be classified in various manners:
1. intellectual
wrong timing
waiting too long before surgical decision:
This happens in the begin of experience... and is corrected once iterative surgical
exposure of the brachial plexus shows how extended and real the lesions are. In all
operated cases, the intraoperative status exceeded the preoperatively suggested extend
of damage – so all the explorations were worth to be done!!
In one selected case, it took 6 months to decide: this girl had an upper lesion with
a well recovering biceps, but a very bad shoulder... time and physiotherapy did not
allow to show an improvement of abduction, and a single extraplexic neurotisation
for the SSC nerve did not seem to be enough. Surgery showed an avulsed root C6; C5 was well conducting and was the donor for grafting to the whole upper trunk with
a good recovery in shoulder and biceps ([figures 2] to [5]).
Figure 2
elective C6 avulsion: the lesion.
Figure 3
same case, drawing of the brachial plexus lesion.
Figure 4
same case, after surgery (grafting of the upper trunk from root C5): recovery of shoulder
abduction.
Figure 5
recovery of elbow flexion.
wrong strategy
there was a neurosurgical tradition in our country operating total obp lesions with
the same reconstructive strategy like in adults, thus only upper roots where reconstructed
and we heritated older children after total obp lesions and neurolysis or upper trunk
grafts with totally flail hands.
2 of them have actually been reconstructed successfully by a free functional gracilis
muscle transfer to the finger flexors ([figure 6]).
Figure 6
free functional gracilis transfer for finger flexors in a total lesion with flail
hand.
Neurolysis alone in severe lesions (non conducting neuromas, avulsed roots) is worthless
[[9]]. We performed neurolysis alone in only 3 cases, where a scarring cuff surrounded
fascicular trunk tissue. The recovery was good, but not as excellent (near normal)
than expected.
2. technical
Tension on nerve sutures or grafts must be avoided. In one „ideal” case of upper root reconstruction after
excision of a short neuroma, direct coaptation and suture seemed possible and interesting
while avoiding grafts.
Recovery was bad, a revision showed rupture of the coaptation site. Tension-free grafting
led to a good functional recovery.
Glue or suture?
In ideal, tension free conditions, glue seems equal to suture. But the underface of
the cable graft is difficult to be secured by glue- and glue does not prevent fascicle
dislocation when an axial pull is exerted.
Sutures are more time-consuming, foreign material remains close to the fascicles,
but slight tension might be compensated and the site of anastomosis might be visualised
through the remaining operation.
Type and timing of immobilisation
10 days should be sufficient for a nerve coaptation – but what about the proximal
and distal coaptation of a 4 cm graft, where the reinnervation cone reaches the distal
junction only after 40 days (1 mm per day) – this period exceeds the usual immobilisation
period of one month. What about passive stretching exercises on these shoulders and
limbs, where the grafts have no extensive extra tissue?
Matching errors
Millesi [[7]] studied the nerve root topography in adults – should and could we apply this on
tiny rootlets in 3 months old babies?
3. compliance and reeducation
We still lack sound experience about the type and timing of physiotherapy. How strong
parents should participate and put her children into reeducation patterns? How may
this interfere with the conscious and motivated use of the operated arm in the long
course?
As a conclusion, we ask several questions to the experts about technical details we
would like to share:
-
1. How should the grafted nerves be enveloped, to assure better vascularisation and
protection from scarring?
-
2. Could we decide about a unique immobilisation type and timing?
-
3. Which additional tools are helpful for good nerve regeneration: regular electrical
stimulation? vitamine B complex? specific training regimens?
-
4. How should we glue? How extended must be the glue cone? Would it interfere with
the regenerating fascicles jumping over the coaptation site?
-
5. Do we really need ongoing research on bioartificial nerve grafts, as we seldom
lack grafts in children?
-
6. Could we focus on reinnervation markers, which would allow a postoperative monitoring
– without re-operating ?
-
7. Are there factors promoting the muscular trophicity, while the nerve is regenerating
and the muscle continues to atrophy?
