A new technique in which working nerves are rerouted to
paralyzed sites in patients with spinal cord injury provides patients with
significant functional improvement in upper limb and hand function and is being
described as "a game changer."
A prospective case series of 16 patients undergoing this
nerve transfer surgery at an Australian hospital has shown meaningful
improvements in elbow extension and grasp-and-pinch hand functions.
In some cases, the nerve transfer surgery was successfully combined
with tendon transfers to maximize functional benefits.
The current report — the largest prospective, consecutive
case series of nerve transfers done at a single center in the tetraplegic
population — was published online July 4 in The Lancet.
"Our results show that nerve transfer gives
particularly good results for hand function. This includes grasping and
pinching, and the open hand position needed for using a computer or smartphone.
This gives patients a whole new realm of independence," lead author
Natasha van Zyl, MBBS, Austin Health, Melbourne, Australia, told Medscape
Medical News.
"The improvements in hand function we have achieved
with nerve transfer have allowed patients to do their own personal care, handle
money, feed themselves with normal utensils, hold a cup or glass and drink
independently, and go to the toilet themselves. The ability to use their hands
for functions like this is what spinal cord injury patients want most — more so
than being able to walk," she added.
Van Zyl explained that the procedure involves taking a nerve
that is working but is expendable (it is supplying a muscle that is also
supported by other working nerves) and rerouting it to a muscle that is
paralyzed.
"Many spinal cord injury patients still have the
ability to move their shoulders, bend their elbows and expand their wrists —
this means we have the nerves to these muscles at our disposal," she said.
"It's like unplugging the power source to the toaster
and plugging it into the kettle instead."
She explained that nerve transfer is not a new concept.
"We have been doing this for peripheral nerve and brachial plexus injuries
for many years, but its use in spinal cord injury only started recently, and
before this publication there have only been single cases reported."
Van Zyl has been pioneer in this area.
"I was doing a lot of brachial plexus nerve transfer
surgeries and I thought it might work in spinal cord injury so we started doing
it and found good results.; Here we are reporting a case series with careful
documentation of methodology and outcomes so that other surgeons can learn
about the techniques that work best," she said.
She notes that tendon transfer is already an established
technique for patients with spinal cord injury, but nerve transfer gives
different benefits.
"‘Tendon transfer generally gives more strength to a
muscle but nerve transfer gives more natural subtle movements better for fine
motor control," Van Zyl said.
The two techniques can be complementary and are sometimes
performed in opposite limbs.
"We often do tendon transfer in one arm and nerve
transfer in the other. The patient then has one strong hand and one more suited
to the intricate actions needed for everyday life," Van Zyl explained.
"If they have to pick something up from the floor, patients say they would
use their tendon-transfer hand to hold the wheel and stabilize their wheelchair
and their nerve-transfer hand to pick up the object."
Nerve transfer can also allow elbow extension so patients
can reach out to perform tasks such as propel their wheelchair, turn off
lights, or wash their hair, Van Zyl reported.
"It is very important for people in a wheelchair to be
able to reach up in a world designed for individuals standing up," she
said...
n an accompanying commentary, Elspeth J. R. Hill, MBChB, and
Ida K. Fox, MD, surgeons from Washington University in St. Louis, Missouri, who
also perform this procedure, note that nerve transfers "represent a huge
advance in reconstruction to restore hand function following spinal cord
injury."
"Nerve transfers are a cost-effective way to harness
the body's innate capability to restore movement in a paralyzed limb,"
they write.
Reached for comment, Fox described the results shown in the
current report as "phenomenal for patients."
"They can go from not being able to use their hands at
all to being able to conduct everyday tasks needing fine motor control such as
making a drink, holding onto a cup, using a computer keyboard, smartphone, and
television remote control. That is a real game changer," she told Medscape
Medical News.
Fox said the current article was "ground breaking"
as it "diligently documents the benefits, which can take several years to
become apparent."
"The nerves take time to re-innervate the target
muscles, but also time is needed for motor re-education and cortical
remodeling. The brain has to figure out how to use the rewired muscles again.
"This paper documents the largest series and longest
follow-up so far reported. I think this publication will make a difference and
this option will be now be considered more widely.
"Too often desperate patients pay for procedures that
have not been proven, but this approach now has good data behind it. This is
compelling work — people can see clearly that it works and has a good success
rate," said Fox.
However, she added, It's important to select the right
patients, the right surgeon, the right nerves to transfer, and make sure the
patient gets the right aftercare — with dedicated physiotherapy a crucial part
of the process."
Van Zyl pointed out that the technique is not applicable to
all patients with spinal cord injury.
"The patients we describe here had C5 or C6 injuries.
It probably would not work in those with injuries further up — if there is no
movement in the shoulder then the functioning nerves will not be available. But
C5 and C6 are the most common type of spinal cord injuries."
"Patients need to have some nerve function to
steal," said Fox.
As for the timing of the surgery, Van Zyl said earlier is
probably better.
"Around 6 months post-injury is thought to be optimum,
but I have some patients for whom this technique has been successful many years
after injury," she said. "If the muscle can be stimulated by an
electrode then the nerve junction with the muscle is still functioning and we
can transfer into that."
This technique is only offered at a few centers worldwide.
Van Zyl's team has been doing it the longest. She advises surgeons considering
it to start with rerouting the nerve supplying the supinator muscle to the posterior
interosseous nerve to restore hand opening. "We have gotten incredible
results with this procedure and hand opening cannot be achieved with tendon
transfer. Some centers are just offering this one procedure."
Natasha van Zyl,
BridgetHill, CatherineCooper, JodieHahn, Mary P Galea. Expanding traditional tendon-based techniques
with nerve transfers for the restoration of upper limb function in tetraplegia:
a prospective case series. Lancet 4 July
2019. https://doi.org/10.1016/S0140-6736(19)31143-2
Summary
Background
Loss of upper extremity function after cervical spinal cord
injury greatly affects independence, including social, vocational, and
community engagement. Nerve transfer surgery offers an exciting new option for
the reanimation of upper limb function in tetraplegia. The aim of this study
was to evaluate the outcomes of nerve transfer surgery used for the reanimation
of upper limb function in tetraplegia.
Methods
In this prospective case series, we consecutively recruited
people of any age with early (<18 months post-injury) cervical spinal cord
injury of motor level C5 and below, who had been referred to a single centre
for upper extremity reanimation and were deemed suitable for nerve transfer.
All participants underwent single or multiple nerve transfers in one or both
upper limbs, sometimes combined with tendon transfers, for restoration of elbow
extension, grasp, pinch, and hand opening. Participants were assessed at 12
months and 24 months post-surgery. Primary outcome measures were the action
research arm test (ARAT), grasp release test (GRT), and spinal cord
independence measure (SCIM).
Findings
Between April 14, 2014, and Nov 22, 2018, we recruited 16
participants (27 limbs) with traumatic spinal cord injury, among whom 59 nerve
transfers were done. In ten participants (12 limbs), nerve transfers were
combined with tendon transfers. 24-month follow-up data were unavailable for
three patients (five limbs). At 24 months, significant improvements from
baseline in median ARAT total score (34·0 [IQR 24·0–38·3] at 24 months vs 16·5
[12·0–22·0] at baseline, p<0·0001) and GRT total score (125·2 [65·1–154·4]
vs 35·0 [21·0–52·3], p<0·0001) were observed. Mean total SCIM score and
mobility in the room and toilet SCIM score improved by more than the minimal
detectable change and the minimal clinically important difference, and the mean
self-care SCIM score improved by more than the minimal detectable change between
baseline and 24 months. Median Medical Research Council strength grades were 3
(IQR 2–3) for triceps and 4 (IQR 4–4) for digital extensor muscles after 24
months. Mean grasp strength at 24 months was 3·2 kg (SD 1·5) in participants
who underwent distal nerve transfers (n=5), 2·8 kg (3·2) in those who had
proximal nerve transfers (n=9), and 3·9 kg (2·4) in those who had tendon
transfers (n=8). There were six adverse events related to the surgery, none of
which had any ongoing functional consequences.
Interpretation
Early nerve transfer surgery is a safe and effective
addition to surgical techniques for upper limb reanimation in tetraplegia.
Nerve transfers can lead to significant functional improvement and can be
successfully combined with tendon transfers to maximise functional benefits.
Funding
Institute for Safety, Compensation, and Recovery Research
(Australia).
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