|3475 Torrance Blvd., Ste F
Torrance, CA 90503
Office hours: M-F, 9am
– 5 pm
Worker’s compensation, Medicare
and most insurance plans accepted.
In September 2008, we will be moving to a beautiful new 4,400 sq ft,
state of the art dedicated hand center located at 2808 Columbia Ave
in Torrance, CA., which will feature onsite nerve conduction studies,
occupational hand therapy and digital x-ray.
NEW ADVANCES IN NERVE REPAIR
Although the techniques of nerve repair have been refined to an eloquent
degree, they remain relatively crude from the nerve’s perspective.
There have been few advances in the practical aspects of a basic nerve
repair over the past 2 decades. There has however been exciting discoveries
which harness the nerve’s regenerative capacities following injury
that has led to nouvelle methods for nerve reconstruction. Techniques
which have been commonplace for brachial plexus surgery are now migrating
into arm, including end-to-side repairs, nerve conduits and nerve transfers.
The science and rationale behind nerve reconstruction is built upon the
understanding of nerve physiology and biomechanics in addition to an intimate
knowledge of nerve anatomy.
Nerve regeneration does not involve mitosis and multiplication of nerve
cells. Instead, the cell body restores nerve continuity by growing a new
axon. Axon sprouting has been demonstrated as early as 24 hours following
nerve transection. One axon sends out multiple unmyelinated axon sprouts
from the tip of the remaining axon or collateral sprouts from a nearby
proximal node of Ranvier. The distal sprout contains the growth cone.
This sends out filopodia which adhere to sticky glycoprotein molecules
in the basil lamina of Schwann cells, such as laminin and fibronectin
(neurite - promoting factors). The filopodia contain actin, which aid
in pulling the growth cone distally. The basil lamina of two abutting
Schwann cells form a potential endoneurial tube into which the regenerating
axon grows. These axons will deteriorate if a connection with a target
organ is not reached. There are up to 50 advancing sprouts from 1 single
axon. Initially there are many more nerve fibers crossing a nerve repair
than in the parent nerve.24 Although more than 1 axon may enter the same
endoneurial tube, there is eventual resorption of the multiple sprouts
leaving one dominant axon.
Axons grow between 1-2 mm/day. In general, axons grow approx: 1-2 mm/day.
Motor end plates degrade at approximately 1%/wk.41 There is irreversible
muscle fibrosis by 24 months. For practical purposes the maximum length
that a nerve can grow to restore motor function is approximately 35 cm.
This in part accounts for the poor motor recovery when repairing nerve
defects proximal to the elbow in adults. Sensory end organs remain viable
since there is no end plate and they retain the potential for reinnervation.
36 Reconstruction of a sensory nerve defect by comparison may provide
protective sensation even after many years.
Role of the Schwann Cell
Following nerve transection, the Schwann cell removes the axonal and myelin
debris in both the severed nerve ends. Schwann cells produce an immediate
source of nerve growth factor (NGF) which helps to support the proximal
stump. The Schwann cell expresses NGF receptors which aid in directing
the advancing growth cone. It also increases it’s production of
other neurotrophic factors including, ciliary neurotrophic factor, brain-derived
neurotrophic factor and fibroblast growth factor which promote axonal
growth. The laminin and fibronectin in the Schwann cell basil lamina act
as a rail for the advancing axon sprouts to grow down. The Schwann cell
produces a myelin sheath for the immature axon sprout. Cell biologists
have attempted to mimic these functions by incorporating Schwann cells,
laminin, fibronectin and nerve growth factors into synthetically engineered
A normal nerve has longitudinal excursion which subjects it to a certain
amount of stress and strain in situ. A peripheral nerve is initially easily
extensible but this rapidly diminishes with further elongation due to
the stretching of the connective tissue within the nerve. Chronically
injured nerves become even stiffer. Elasticity decreases by as much as
50% in the delayed repair of nerves in which Wallerian degeneration has
occurred.38 Experimentally, blood flow is reduced by 50% when the nerve
is stretched 8% beyond it’s in vivo length. Complete ischemia occurs
at 15%. Suture pullout does not occur until a 17% increase in length.
This suggests that ischemia and not disruption of the anastomosis is the
limiting factor in acute nerve repairs.8 This observation is also applicable
to nerve grafting. Nerve is a viscoelastic tissue in that when low loading
in tension is applied over time the nerve elongates, without a deterioration
in nerve conduction velocities. At 8% elongation stress relaxation results
in the recovery of blood flow within 30 minutes,. Intriguing experimental
work has been done with gradual nerve elongation to overcome nerve gaps
using tissue expansion and external fixation 29 but this cannot be considered
an accepted standard of treatment as yet.
The Nerve Gap
There is a difference between the nerve gap and a nerve defect. A nerve
gap refers to the distance between the nerve ends, whereas a nerve defect
refers to the actual amount of nerve tissue that is lost. With simple
nerve retraction following division, the fascicular arrangement is similar.
As the defect between the proximal and distal stumps increases there is
a greater fascicular mismatch between the stumps which leads to poorer
outcomes, especially if the gap exceeds 5 cm.
A peripheral nerve contains connective tissue elements and axons. The
connective tissue of nerves includes the outer epineurial layer, which
contains loosely woven collagen fibers and elastin. The epineurium protects
the nerve from compression and stretch and therefore tends to be thicker
in places that experience repetitive shear force such as the ulnar nerve
in the cubital tunnel. The perineurium separates groups of fascicles and
acts as a diffusion barrier, which protects the axons from infection and
chemical insult. The perineurium is relatively unyielding which allows
for a positive endoneurial pressure. This same property can lead to a
minicompartment syndrome when the endoneurial pressure increases such
as occurs in compressive neuropathies. The individual axons may or may
not be myelinated are surrounded by the endoneurium which provides support
and a framework for regeneration of nerve fibers after injury.
II. NERVE REPAIR (link to median nerve repair video)
The location of fascicles varies somewhat within a nerve, and there are
cross connections between them as fibers migrate from one fascicle to
another. This migration occurs because axons destined for a specific end
organ receptor may arise at more than one spinal cord level which results
in a sorting and rearranging as it moves distally. The use of intraoperative
motor and sensory nerve differentiation can diminish the risk of fascicular
mismatch when repairing or grafting a nerve. There is the anatomic method
based upon separate identification of groups of fascicles, the electrophysiologic
method and histochemical methods that rely on staining for enzymes specific
to motor or sensory nerves, which is time consuming and currently not
Electrical Fascicle Identification
Motor and sensory fascicles can be differentiated by direct stimulation.14
The median and ulnar nerves in the distal forearm are most amenable to
this technique.13 A low amperage stimulator is applied to the major fascicles
of the proximal nerve end in a systematic manner with the patient under
local anesthesia. Sensory fascicles will elicit pain, and may be localized
to a specific digit. Motor fascicles elicit no response at lower intensities
and poorly localized pain at higher intensities. A cross sectional sketch
of the proximal stump is made. The sensory fascicles are tagged with 10-0
nylon and the patient is placed under general anesthesia. The distal stump
is then stimulated in a similar fashion. The reverse picture will be seen,
with motor fascicles eliciting a muscle twitch and sensory fascicles being
silent. A cross sectional map is again made and used to match the proximal
and distal motor and sensory fascicles.
Alternatively, the author has used nerve action potentials (NAPs) in place
of the muscle twitch to map the distal stump (Figure 1 A,B) .32 The compound
motor action potential (CMAP) disappears at 7-9 days whereas the sensory
nerve action potential (SNAP) disappears at day 10-11.5 CMAPs are recorded
from the thenar/hypothenar muscles, and SNAPs are recorded from either
the index or small finger using ring electrodes. A grouped fascicular
repair is then performed as described below. In chronic injuries the awake
stimulation of the proximal stump is unchanged. Since the NAPs are no
longer present, it is necessary dissect the distal motor branch, and then
follow the motor fascicles proximally to the nerve stump (Figure 2A).
The principle indication for surgery is a patient who presents with a
laceration and a nerve deficit that does not recover within 1 week. A
tension free repair is the goal for any nerve anastomosis. When there
is a clean transection of the nerve and the gap is caused by elastic retraction,
an acute 1° repair is indicated.
Blast injuries which are heavily impregnated with debris or bacteria are
better treated by staged reconstruction. Nerve repair cannot be performed
in an infected wound. If the degree of the longitudinal injury cannot
be determined, nerve repair should be delayed.
Types of Repair (link to ulnar nerve repair video)
External Epineurial Suture: This technique is appropriate for small nerves
containing only one or two fascicles, such as digital nerves. Since they
only contain sensory fibers matching is not a problem. Usually 3-4 sutures
with 9-0 nylon is sufficient. Alternatively, fibrin glue can be used which
allows the placement of fewer sutures. Epineurial repairs are also indicated
for mixed nerves where separate motor and sensory fascicle identification
is not possible.
Group Fascicular Suture: The motor and sensory groups
of fascicles are identified as described. In a major nerve such as the
median or ulnar, four or five groups may be chosen for suture. These are
then matched appropriately with the opposite end and approximated with
sutures in both the internal and external epineurium (Figure 2 B,C).
External Epineurial Splint: Jabaley has employed the
external epineurium as a splinting device.15 The external epineurium is
incised longitudinally on its superficial surface and dissected away from
the underlying fascicles. The epineurium is left attached on the deep
surface, several millimeters from each nerve end. A few interrupted sutures
with 8-0 nylon are used to join the ends of the external epineurial strips
on the deep surface only, completing the construction of the splint. This
maneuver provides for a coaptation of individual fascicles or groups of
fascicles with little or no tension (Figure 3 A-D).
After nerve repair the rehabilitation focuses on 3 areas: Initial immobilization
to protect the repair, joint mobilization to promote longitudinal excursion
of the nerve, and sensory re-education. Prior to wound closure, the adjacent
joints are placed in various degrees of flexion and extension in order
to determine the optimum limb position that unloads the repair site. This
position is maintained with a blocking splint for 3 weeks but a protected
short arc of motion may be instituted to provide some nerve gliding.
III. NERVE GRAFTING (link to ulnar nerve graft video)
When treatment of a nerve laceration is delayed, fibrosis of the nerve
ends prevents approximation hence nerve grafting is required even though
there is no loss of nerve tissue. Nerve grafting is indicated to bridge
a defect when >10% elongation of the nerve would be necessary to bridge
the gap.38 This is a better indication for grafting than the nerve gap
per se, although 4 cm is often used as a critical defect.
Since the graft is vascularized from the tissue bed, nerve grafting cannot
be performed in burned or irradiated tissue.
Role of the Nerve Graft
The nerve graft acts to provide a source of empty endoneurial tubes through
which the regenerating axons can be directed. Any tissue which contains
a basil lamina such as freeze dried muscle or tendon, can be substituted
but only the autogenous nerve graft also provides a source of viable Schwann
cells. A normal nerve can compensate for the change in length with limb
flexion and extension because it is surrounded by gliding tissue that
permits longitudinal movement. A nerve graft becomes welded to it’s
recipient bed by the adhesions through which it becomes vascularized.
As a consequence the nerve graft is exquisitely sensitive to tension because
it has no longitudinal excursion. The harvested length of the graft must
be long enough to span the nerve gap without tension while the adjacent
joints are extended. This is also the position of temporary immobilization.
If the limb or digit is immobilized with joint flexion, the graft will
become fixed in this position. When the limb is then mobilized at 8 days,
the proximal and distal stumps will be subject to tension even though
the graft was initially long enough. Early attempts at lengthening the
graft will lead to disruption of the anastomosis.
Considerations for donor nerve grafts
Small diameter grafts spontaneously revascularize but thick grafts undergo
central necrosis with subsequent endoneurial fibrosis which ultimately
impedes the advancement of any ingrowing axon sprouts. The donor site
defect must be acceptable for the patient and the harvested nerve must
be long enough to ensure a tension free anastomosis with the adjacent
joints in full extension. For these reasons most of the available grafts
are cutaneous nerves. Typical donor nerves include the medial and lateral
antebrachial cutaneous nerves and the sural nerve. The distal termination
of the anterior and posterior interosseous nerves are suitable for digital
nerve grafts at the DIP joint level.
Millessi has written extensively on this subject. 26 If the recipient
nerve is the approximate diameter of the graft, the two stumps are transected
until normal appearing tissue without fibrosis is seen and the graft is
inserted by an epineurial repair. If the recipient nerve is larger than
the graft the fascicular pattern determines the type of preparation. If
the nerve contains 1 - 4 fascicles, the stump is resected until healthy
tissue is encountered. Multiple nerve grafts are used to completely cover
the cross sectional area of each fascicle in a 1:2 or 1:3 ratio (Figure
4 A,B). When there are 5 -12 fascicles that are the size of the nerve
graft, then each fascicle is grafted individually. When there is a polyfascicular
pattern with a group fascicular arrangement, interfascicular dissection
is performed to isolate the fascicle groups, which are then grafted individually.
If there is no group fascicular arrangement, interfascicular dissection
is not performed. Graft insertion is then guided by the intraneural topography
of the nerve for that specific level of injury.
Outcomes following repair/graft
Most series report the results of nerve repair using the British Medical
research council grading system. which has been modified by Dellon and
Mackinnon.10 In this classification S3 = recovery of pain and touch sensibility,
with 2 point discrimination of > 15 mm. S3+ equates to 2 point discrimination
of 7-15 mm. A grade of M3 equates to a recovery of muscle strength that
is sufficient to overcome gravity. M4 is strength with gravity and added
Ruijs et al performed a meta-analysis after microsurgical nerve repair
of 623 median or ulnar nerve injuries. Motor and sensory recovery were
significantly associated. In ulnar nerve injuries, the chance of motor
recovery was 71 percent lower than in median nerve injuries.30 Kallio
and co-authors evaluated 132 patients (mean age 28 years) with injuries
to the median nerve at an average 10.4 years after repair. Most of the
nerve lesions were sharp (76) or blunt (47) injuries. Division was total
in 87 cases, and most were at the wrist level. Secondary repair was performed
in 34 cases and fascicular grafting in 98 cases. The average gap was 5.8
cm. Excellent or good results were obtained in only 49.2%. The result
of nerve repair was poor in patients aged over 54 years, when the level
of the injury was more than 56 cm proximal to the finger tip, if the pre-operative
delay was more than 24 months, or if the graft length was more than 70
Secer et al reported the results of 407 ulnar nerve injuries caused by
gunshot wounds. A good outcome was noted in 15% of patients who underwent
high-level repair, 29% of patients who underwent intermediate-level repair,
and 49% of patients after low-level repair. The critical period for surgery
was within 6 months of injury. Although the optimal graft length was found
to be 5 cm, this finding was not statistically significant.31 Kim and
coauthors examined 45 patients following surgically treated posterior
interosseous nerve entrapments (21) or injuries (23). Seven underwent
suture repair, 7 were grafted and the rest underwent neurolysis. Most
muscles achieved LSUHSC Grade 3 or better.20
Kallio et al studied 95 patients with 254 completely divided digital nerves
at an average of 12.4 (5-20) years after repair. Secondary epineurial
suture was used in 53, fascicular grafting in 37 and fascicular suture
in five. Useful sensory function was recovered in 79% of the nerves operated
on with epineurial or fascicular suture and in 56% with fascicular grafting.16
It is commonly accepted that the results are far better in children than
in adults. Tomei evaluated 25 nerve repairs at the wrist in children under
age 15 years with a minimum follow-up of 12 months. The sensory results
were often excellent (S4 or S3+ in 23 cases/25) whereas motor recovery
ranged between from M2 and M3.37
Frykman and Gramyk reviewed 8 studies of nerve grafting published prior
to 1990.12. This included 167 patients who underwent median nerve grafting.
In this pooled data 81% achieved 81% achieved a grade of M3, while 79%achieved
S3. In more recent series Dauotis et al. M3 or better was achieved in
68% and S3 or better in 75% of 47 patients with median nerve grafts.9
Kim et al reported M3/S3 in 72% of 50 patients.19 Milessi achieved M4
or better in 61% and S3 or better in 42%. For the ulnar nerve, he reported
M4 or better in 49% and S3 or better in 27%, whereas he reported S3+ or
better in only 22% for digital nerve repairs.26
IV. ALTERNATE METHODS OF NERVE RECONSTRUCTION
Experimental data in both rabbit and primate models have shown that intact
donor nerves have the ability to sprout lateral branches from their axons
that can grow through endo, peri- and epineurium and reinnervate target
organs with functional sensory and motor results.18, 44 These results
have also been duplicated in human studies which have included root avulsions
of the brachial plexus, as well as patients with large gaps in peripheral
nerves. A standard end-to-side anastomosis involves suturing the recipient
nerve into an epineural window that is created in the donor nerve. An
advantage of this technique is that the donor nerve does not lose any
End-to-side repairs cannot replace a sound primary repair, but they have
been used as an adjunctive procedure in the following situations: intact
nerve to the musculocutaneous to neurotise the biceps muscle, distal stump
of the ulnar nerve to the median nerve at the wrist in high ulnar nerve
palsies or vice versa and ulnar digital nerves to intact median sensory
nerves (Figure 5). The limb is splinted for 3 weeks in a tension free
position, followed by motor and sensory re-education. The procedure is
best done early since the results deteriorate if delayed beyond 6 months.
In Mennen’s series of 56 patients which included 33 ulnar to median
and 7 median to ulnar repairs, $M3/S3 was achieved in 56%.25
Brunelli pioneered the concept of direct neurotization of denervated muscles
in situations where the motor nerve has been avulsed and direct nerve
suture or grafting is not possible.4 He demonstrated in rat and rabbit
models that an axon that is in contact with a denervated muscular fiber
can form a new neuromuscular junction. The motor end-plate is in fact,
not an anatomical formation but rather a functional alteration of the
axon endings and the muscular fibers that develop when they are in contact
with each other. A prerequisite for this procedure is that there is some
residual trophism of the muscle. This is manifested by the presence of
fibrillation potentials on the EMG. The procedure in contraindicated if
there is muscle atrophy without fibrillation potentials or if there is
extensive scarring or joint stiffness.
The donor nerve is retrieved and sectioned transversely until healthy
fascicles are seen. The junction of the proximal _ and distal _ of the
muscular belly is exposed. A sural nerve graft of adequate length is harvested
and sutured end to end to the donor nerve. The distal part of the nerve
graft is freed from the epineurium and is divided into as many artificial
fascicles as possible. The epineurium of the graft is sutured to the muscle
epimysium in order to prevent graft retraction. A number of slits are
made at different depths and as widely separated as the graft will permit.
The artificial fascicles are then implanted into the muscle and held in
place with fibrin glue and epineurial sutures. The limbs are immobilized
for 15 days in order to prevent avulsion of the implanted nerve. Re-education
is started with joint mobilization and electrotherapy. In Brunelli’s
series of 80 patients, M4/M5 motor strength was achieved in 72 of the
Neurotrophism is the ability of chemotactic hormonal or growth factors
to enhance the rate of nerve regeneration. Neurotrophic factors produced
by the target end-organ undergo retrograde axonal transport and help support
the cell body. Neurotropism describes the directional accuracy of that
regeneration. The growth cone is attracted to neurotropic proteins that
are derived from the distal degenerating nerve segment after nerve transection.
These phenomena have been exploited through the use of synthetic or natural
conduits to bridge the nerve gap. Histologically, fibrin clot develops
inside the tube within hours. Within the first week longitudinally oriented
fibrin matrix bridges span the nerve gap. In the second week, fibroblasts,
Schwann cells, macrophages and endothelial cells permeate the matrix.
Axon sprouts from proximal nerve reach the distal stump and become myelinated
by the 4th week. The axons elongate down intact the distal endoneurial
tubes and reinnervate the target organs. Nondegradable tubes out of silicone
were initially used. More recently natural prosthetic tubes have included
freeze/thawed muscle (which contains a basal lamina) and autogenous vein
grafts. Biodegradable synthetic material includes polyglycolic acid, caprolactone,
and collagen. The postoperative rehabilitation includes early mobilization
of the part since tension on the repair site is not a consideration, followed
by appropriate sensory and/or motor retraining.
Lundborg compared tubulation with a silicone conduit, after intentionally
leaving a 3-4 mm nerve gap (11 cases) v.s. conventional microsurgical
repair of transected median and ulnar nerve repairs (7 cases) in the forearm.
The results showed no significant differences between the two techniques
although the silicone tubes had to be removed at a later date due to compression
of the reformed nerve.23. Chiu et al did a series of animal experiments
bridging gaps of 1.0 - 6.0 cm using autogenous vein grafts.6 The technique
includes suturing a reversed vein graft in place distally so that the
valves in the vein cannot collapse and block axonal migration. The proximal
repair is performed after filling the vein with saline to present clot
formation that will produce scarring that can obstruct the axons (Figure
6 A-C) In their clinical series, Chiu and Strauch reported comparable
results to those obtained with nerve repair and grafting for sensory nerve
defects of < 3 cm.7
Weber et al performed a randomized prospective multicenter evaluation
on 98 subjects with 136 nerve transections in the hand comparing a polyglycolic
conduit with either end-to-end or a nerve graft for nerve repair. There
were 56 nerves repaired in the control group and 46 nerves repaired with
a conduit available for follow-up. The overall results showed no significant
difference between the two groups as a whole. Nerves with gaps of 4 mm
or less had better sensation when repaired with a conduit; the mean moving
two-point discrimination was 3.7 +/- 1.4 mm for polyglycolic acid tube
repair and 6.1 +/- 3.3 mm for end-to-end repairs (p = 0.03). All injured
nerves with deficits of 8 mm or greater were reconstructed with either
a nerve graft or a conduit. This subgroup also demonstrated a significant
difference in favor of the polyglycolic acid tube. The mean moving two-point
discrimination for the conduit was 6.8 +/- 3.8 mm, with excellent results
obtained in 7 of 17 nerves, whereas the mean moving two-point discrimination
for the graft repair was 12.9 +/- 2.4 mm, with excellent results obtained
in none of the eight nerves (p < 0.001 and p = 0.06, respectively).40
Bertleff et al examined the results of using a caprolactone tube v.s.
primary repair in 34 digital nerve lesions with gaps < 2 cm. The results
with the conduits were equal to those of repair as evaluated by Pressure-Specified-sensory
testing device and 2 pd.1
Nerve Transfers (link to FDS nerve transfer video)
Perhaps one of the most exciting recent developments in peripheral nerve
reconstruction has been through the use of nerve transfers. They are indicated
when there is a need to direct a large number of motor axons quickly to
the denervated muscle in situations where there is insufficient time for
axonal ingrowth. For motor nerves, an expendable donor nerve with pure
motor fibers and a large number of axons near the target muscle is selected.
It is preferable if the donor muscle is synergistic to the target muscle.
Motor re-education is crucial and involves the recruitment of the donor
muscle and then contraction of the reinnervated muscle. Sensory nerve
transfers require sensory retraining. Some specific examples of upper
limb nerve transfers are described below.
In 1994, Oberlin described a series of 4 patients who had undergone successful
nerve transfer using redundant fascicles to the flexor carpi ulnaris (FCU)
from the ulnar nerve to the motor branch of the musculocutaneous nerve
for biceps reinnervation. 28 His group then modified this by performing
a double fascicular nerve transfer using redundant fascicles of the median
and ulnar nerve to reinnervate the biceps and brachialis muscles. 21 These
transfers are indicated in C5-C7 plexus lesions where direct nerve reconstruction
is not possible. Mixed plexus injuries can also be treated by this method
if there is adequate clinical recovery in the lower roots. Since the neurorraphy
is placed close to the target muscles, this nerve transfer is particularly
useful in patients who have had a delay in surgical treatment. Successful
restoration of elbow flexion has been reported even in cases done one
year after injury. The absolute contraindication for this nerve transfer
is a global brachial plexus palsy with no recovery of ulnar nerve function
since the transfer requires intact function of the C8 ,T1 nerve roots.
Following an isolated Oberlin transfer the patient is treated with a sling
for the initial 2 weeks followed by passive elbow motion. Once there is
evidence of reinnervation the patient is started on muscle reeducation
and isometric strengthening. Elbow flexion is enhanced by activation of
the flexor carpi ulnaris which is achieved by having the patient grip
while simultaneously trying to flex the elbow. In their review of the
literature, Sharpe and Stevanovic identified a total of 100 cases. Eighty
percent of patients recovered > M4 motor strength for elbow flexion,
9 percent recovered M3 function, and 11 percent with < M3 recovery.
Clinical evidence of biceps reinnervation was seen at an average of 3
months, with a range from 2-7 months. Recovery of M3 function ranged between
4-13 months. For those patients who recovered M4 motor function, the range
of elbow flexion strength was between 0.5 and 7 kg.33
Wrist and Finger Extension
Mackinnon et al have demonstrated that redundant median nerve branches
to the flexor digitorum sublimus (FDS), flexor carpi radialis (FCR) or
palmaris longus (PL) may be used for transfer. In a dissection of 31 cadaver
arms, they noted that double innervation of the FDS was found in 94% of
the specimens.39 They described two successful cases of transfer of the
FDS fascicles to the pronator teres branch to restore pronation. They
subsequently reported the use of this transfer to the extensor carpi radialis
(ECRB) branch and the posterior interosseous nerve (PIN) in a case of
a high radial nerve palsy and a brachial plexopathy with excellent results.22
In a separate study they noted that the FCU branch of ulnar nerve can
also be used, but this required a second incision.2
Proximal to the elbow, the median nerve is found to condense into 3 bundles.
Branches arising from the anterior bundle can be seen innervating the
FCR and pronator teres (PT) (Figure 7A). The FDS branches along with the
FCR and PL fascicles arise from the middle group. They are carefully differentiated
from the hand intrinsics using a hand held stimulator. The radial nerve
is isolated through the same incision. It can be found between the brachioradialis
and brachialis as it divides into the superficial sensory nerve branch
and the PIN branch. MacKinnon recommends use of the PL and the FDS or
FCR branches to the PIN and the ECRB branch. The redundant median nerve
fascicles are harvested in close proximity to the PIN to avoid undue tension
on the repair site. An end to end coaptation is then performed (Figure
7 B,C). If need be a short nerve graft can be interposed. Postoperatively
an above elbow splint is applied with the elbow at 90 degrees and the
shoulder, wrist, and fingers free. Gentle elbow flexion is started after
the first week followed by gradual elbow extension. Motor retraining is
akin to tendon transfers. The patient is instructed in active sublimus
contractions, which will ultimately produce wrist and finger extension.
Published clinical series on this transfer are still lacking. In Mackinnon’s
series a 51 y.o. male with a proximal left radial nerve palsy underwent
transfer of the nerve branch to the PL and the FDS to the PIN and ECRB
branch respectively. He achieved 4/5 power for wrist extension but lacked
simultaneous finger extension at 14 months postoperatively. The second
patient was a 24 y.o. female following an iatrogenic radial nerve injury
at the plexus level. The nerve branch from the PL and FDS were transferred
to the PIN. A 2nd FDS branch was transferred to the ECRB. The patient
achieved 4/5 power of wrist and finger extension.22
Intrinsic Muscle Reinnervation
The only donor nerve for intrinsic muscle reinnervation that fulfills
all of the requirements for nerve transfer is the distal anterior interosseous
nerve (AIN). It may be used to neurotize either the recurrent motor branch
of the median nerve or the deep motor branch of the ulnar nerve. It is
almost purely a motor nerve save for proprioceptive fibers to the wrist
capsule and it is expendable since there is minimal functional loss resulting
from denervation of the pronator quadratus (PQ) muscle. Just prior to
entering the PQ, the axon count of the AIN is equal to $ 75% of the deep
motor branches of the median and ulnar nerves. With sufficient proximal
interfascicular dissection of the distal median or ulnar nerves, direct
coaptation of the transected distal anterior interosseous nerve to the
fascicular origins of the thenar branch of the median nerve or the deep
motor branch of the ulnar nerve is possible.42
For thenar reinnervation Wood has noted that a transfer of the distal
anterior interosseous nerve may be used only in those patients with median
nerve loss distal to the origin of the anterior interosseous nerve and
with sparing of the entire anterior interosseous nerve branch.43 This
technique should be considered in those patients who are unlikely to recover
median innervated thenar motor function by a median nerve repair or reconstruction.
Similarly, for intrinsic muscle reinnervation transfer of the distal AIN
should be considered in any patient with an ulnar nerve transection at
or proximal to the upper forearm because in such patients recovery of
intrinsic motor function with ulnar nerve repair or reconstruction is
both poor and unpredictable, especially if there a nerve gap. In either
case, the injury should not be so distal as to interfere with identification
of the median or ulnar nerve motor fascicles. The procedure should be
carried out within 6 months from the date of injury.
Sensory Nerve Transfers
The goal of nerve transfers for digital sensation is to redirect intact
sensory input from less critical to more critical contact points. The
distal thumb, radial side of the index and ulnar side of the small finger
have priority with regards to sensory reconstruction from a functional
standpoint. Anesthesia in the thumb and index finger limit pinch and fine
motor tasks whereas anesthesia in the small finger causes a loss of proprioception
of the hand. The adjacent sides of the 3rd and 4th webspaces are by comparison
relatively expendable. When a nerve transfer is indicated for a proximal
median nerve injury, a failed distal median nerve repair/graft or an upper
trunk ( C5,6) injury, the ulnar-innervated fourth web space nerves can
be transferred into the first web space nerves in and end-to-end manner
to restore thumb and index finger sensation (Figure 8 A,B). In the case
of ulnar nerve loss, the median-innervated third web space nerves are
selected as donors for transfer to the small finger. The donor site sensory
loss may be treated with a secondary series of end-to-side transfers into
the existing sensory nerve supply which may provide at least protective
sensation. For example, after the fourth web space nerves are transferred
to the first web space using end-to-end repair, the distal end of the
fourth web space nerves are coapted end-to-side into the intact ulnar
proper digital nerve of the small finger. With proximal median and ulnar
nerve injuries the superficial radial nerve (SRN) is the only available
sensory donor. Ducic et al reported 2 cases of SRN transfer to the ulnar
digital nerve of the thumb and the radial digital nerve of the index finger
in a proximal median nerve injury with recovery of protective sensation.11.
Similarly with a C6,7 injury the dorsal cutaneous branch of the ulnar
nerve (DCBUN) provides an additional source of sensory axons.
Timing is not as crucial for sensory nerve reconstruction due to the lack
of a motor end-plate hence this can be performed at the surgeons and patient’s
discretion. As nerve regeneration progresses specific training for sensory
localization is integral to the outcome. Stock et al reported a recovery
of S3+ or S4 in 85% of patients. Some tip sensibility returns within 3
to 4 months, with gradual maturation continuing past 2 years after nerve
transfer.34 In MacKinnon’s experience recovery of at least protective
sensation can be expected following end-to-end coaptations with primary
nerve transfers for digital sensation. Using the “ten test”
designed by Strauch et al 35 evaluation, sensory recovery even in the
absence of sensory re-education will be approximately 6/10 following end-to-end
repair and 3/10 following end-to-side repair.27 Localization of sensory
stimuli to the donor digits persists for 2 to 3 years, with localization
to the recipient digit improving with time, use, and sensory re-education.
Figure 1. Intraoperative stimulation of Ulnar nerve at wrist
A. Stimulation of deep motor branch
B. CMAP with normal latency but low amplitude (recorded from ADM).
( From Slutsky, DJ. A Practical Approach to Nerve Grafting in the Upper
Extremity. Atlas of the Hand Clinics. Nerve Repair and Reconstruction:
A Practical Guide. Vol 10, No 1, March 2005, pp 73-92, with permission.)
Figure 2. Ulnar Nerve Laceration
A. Ulnar nerve motor fascicles traced from the distal stump to the deep
motor branch (*) in the palm.
B. Group fascicular repair of motor group of fascicles (*).
C. Epineurial repair of remaining sensory fascicles
( From Slutsky, DJ. A Practical Approach to Nerve Grafting in the Upper
Extremity. In Peripheral Nerve Surgery: Practical Applications in the
Upper Extremity. Slutsky DJ, Hentz VR, eds. Elsevier. Philadelphia, 2006,
Figure 3. One month old proximal radial nerve laceration.
A. Minuscule exit wound (arrow) following a stabbing with a knife from
the medial arm.
B. Knife tract (arrow) with separation of proximal and distal nerve ends
C. Strip of posterior epineurium is sutured (arrow) to take the tension
off the repair
D. Completed epineurial repair.
Figure 4. Proximal Median and Radial Nerve Grafts
A. Laceration through antecubital fossa.
B. Multiple fascicular grafts to median nerve, superficial radial nerve
and posterior interosseous nerve (PIN) nerve.
( From Slutsky, DJ. A Practical Approach to Nerve Grafting in the Upper
Extremity. In Peripheral Nerve Surgery: Practical Applications in the
Upper Extremity. Slutsky DJ, Hentz VR, eds. Elsevier. Philadelphia, 2006,
Figure 5. High Ulnar nerve palsy
End-to-side repair of common digital nerve of the small finger (*) to
the median derived common digital nerve to the 3rd web (arrow).
Figure 6. Digital neuroma
A. Neuroma of radial digital nerve.
B. Resection back to healthy fascicles and reversed autogenous vein graft
C. Completed repair.
Figure 7. Posterior Interosseous Nerve Palsy
A. Proximal median nerve dissection demonstrating the 3 different bundles
of fascicles. AIN = anterior interosseous nerve, PIN = posterior interosseous
nerve, FDS = flexor digitorum sublimus.
B. Isolation of FDS branch.
C. End to end coaptation of FDS branch (*) to posterior interosseous nerve
Figure 8. Sensory nerve transfer in the palm after failed median nerve
A. Median nerve (MN) dissection with isolation of 1st webspace branches
(arrows) and ulnar derived common digital nerve to the 4th webspace (*).
B. The 4th common digital nerve (*) is transposed and coapted to the ulnar
digital nerve of the thumb and the radial digital nerve of the index (arrows).
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