Literature Review

Nerve transfer improves function after spinal cord injury

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Nerve transfers are “a huge advance”

The data from van Zyl et al. suggest that nerve transfers restore more natural movement and finer motor control than tendon transfers do, said Elspeth J.R. Hill, MD, PhD, and Ida K. Fox, MD, plastic and reconstructive surgeons at Washington University in St. Louis, in an accompanying editorial. Patients can engage in light activity immediately after surgery, and cortical plasticity enables function to improve over time. Two disadvantages of nerve transfers, however, are that it takes months before new motion can be observed, and years before full strength can be regained.

The heterogeneity of cervical spinal cord injury requires an individualized approach to surgical assessment and management, they continued. Physicians and patients should make treatment decisions collaboratively. “We envisage a role for nerve transfers in settings where the intensive therapy and immobilization required to optimize complementary tendon transfers are unavailable,” wrote Dr. Hill and Dr. Fox.

Continuing research will be necessary to improve surgical technique and outcomes. “This research should include efforts to compare nerve transfer with tendon transfer, find the optimal timing of such surgeries, and determine which approach produces the greatest functional improvement,” they wrote. “Detailed study of the reasons for nerve transfer failure is also required, as is improving our understanding of the effects of biopsychosocial factors, including access to information and care, psychological readiness, and social support, on patient decision making and outcomes.”

Nerve transfers are a “huge advance” in the restoration of function after spinal cord injury, the authors added. “Surgeons who integrate nerve transfers into their spinal cord injury practice should take a careful and measured approach and rigorously study and disseminate their outcomes to advance this growing field,” they concluded.


 

FROM LANCET

Early nerve transfer surgery is safe and can provide significant functional improvement to patients with cervical spinal cord injury and tetraplegia, according to research published online July 4 ahead of print in the Lancet. Combining nerve transfer with tendon transfer may maximize the functional benefit of surgery.

The loss of upper extremity function after cervical spinal cord injury can reduce independence and social and vocational engagement. People with tetraplegia rank improvement in hand function as their most important goal. Tendon transfers have been the traditional method of restoring function, but interest in nerve transfers has been increasing with the publication of successful results. Nerve transfers can reanimate several muscles at once and require a smaller incision and shorter immobilization, compared with tendon transfers.

Injury had occurred less than 18 months previously

Natasha van Zyl, MBBS, a plastic and reconstructive surgeon at Austin Health in Melbourne, and colleagues conducted a prospective case series to examine the clinical and functional outcomes of nerve transfer surgery for the reanimation of upper limb function in patients with tetraplegia. The investigators also sought to compare these outcomes with published outcomes for tendon transfer surgery.

Between April 14, 2014, and Nov. 22, 2018, Dr. van Zyl and colleagues recruited consecutive patients of any age with early cervical spinal cord injury of motor level C5 and below. Injury was required to have occurred fewer than 18 months before enrollment. Eligible participants had been referred to a single center for upper extremity reanimation and were considered candidates for nerve transfer.

Every participant underwent single or multiple nerve transfers in one or both upper limbs, and some participants also underwent tendon transfers. The goal of surgery was the restoration of elbow extension, grasp, pinch, and hand opening. An independent assessor evaluated participants at baseline and at 12 months and 24 months after surgery. The primary outcome measures were the action research arm test (ARAT), the grasp release test (GRT), and the spinal cord independence measure (SCIM).

Grasp function improved significantly

Dr. van Zyl and colleagues recruited 16 participants with traumatic spinal cord injury who underwent 59 nerve transfers. Ten participants also underwent tendon transfers. The population’s mean age at time of injury was 27.3 years. Three patients were female. Motor vehicle accidents were the most common cause of injury (31%). Follow-up data at 24 months were unavailable for three patients.

Participants’ median ARAT total score significantly improved from 16.5 at baseline to 34.0 at 24 months. Median GRT total score significantly improved from 35.0 at baseline to 125.2 at 24 months. The population’s 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. The mean self-care SCIM score improved by more than the minimal detectable change between baseline and 24 months.

The researchers observed six adverse events related to the surgery, but none had sustained functional consequences. No patients had an increase in musculoskeletal or neuropathic pain. Four of the 50 nerve transfers with 24-month follow-up failed.

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