Nerve Transfer Surgery a 'Game Changer' for Spinal Cord Injury

July 05, 2019

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.

"Expendable" Nerves

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.

The authors note that cervical spinal cord injury is a devastating, life-changing injury, which affects 250,000–500,000 people worldwide each year, with more than 50% of these injuries resulting in tetraplegia.

They point out that nerve transfers are an attractive option: the procedure can reanimate more than one muscle at a time and multiple nerve transfers can be completed simultaneously. The procedure also requires a smaller operative incision and a shorter recovery than tendon transfer.

The Lancet article describes a case series of 16 patients with early (<18 months post-injury) cervical spinal cord injury of motor level C5 and below who 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. A total of 59 nerve transfers were performed in 27 limbs.

Results at 24 months showed clinically significant improvements from baseline in median Action Research Arm Test total score (16.5 to 34.0) and Grasp Release Test (35.0 to 125.2). Mean Spinal Cord Independence Measure (SCIM) also showed clinically meaningful improvements.

"There isn't a measure for open-hand action but actually that is where I think the maximum benefit is to be had," Van Zyl said.

A "Huge" Advantage

In 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."

Not All Patients Are Candidates

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."

Van Zyl said her hope is that this study will encourage more surgeons to do these procedures and raise awareness of the whole area of both nerve and tendon transfer.

"Many people think that there is nothing that can be done to improve hand function for patients with tetraplegia," she said, "but actually great results are achievable with these techniques."

This study was funded by the Institute for Safety, Compensation and Recovery Research, based in Melbourne, Australia. The authors have disclosed no relevant financial relationships.

The Lancet. Published online July 4, 2019. Abstract, Editorial

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