Upper Extremity Nerve Transfer Surgery in Patients with Tetraplegia – A Post-Operative Rehabilitation Protocol

Written by: Christina Mirsch, MS, OTR/L

Virtual Hand to Shoulder Fellow ’24 -‘25

Patients with cervical spinal cord injury (SCI) often cite improved upper extremity (UE) function as their most important goal of rehabilitation (Wagner et al., 2007). While tendon transfer surgery has historically been a means to improving upper extremity function in SCI, over the past 5-10 years we have seen an increase in patients seeking motor nerve transfers (previously more used in the brachial plexus injury population) as a means to improve UE function. Timing and phases of rehabilitation of post-nerve transfer have significant differences from tendon procedures with some important factors to consider when working with the tetraplegic patient specifically. 

Upper Extremity Rehabilitation Post-Nerve Transfer Protocol for Tetraplegia

The goal of nerve transfer surgery is to restore innervation to a paralyzed muscle. It involves transfer of a redundant nerve. Unlike tendon transfers, nerve transfers do not change the biomechanics of a joint, but change the pattern of innervation to the target muscle. End-to-end transfers are commonly performed motor neuron transfers. With this technique, the original recipient nerve is cut, proximal end removed from the myelin sheath, and the donor nerve plugged in, as close to the target motor endpoint as possible. (Gordon, 2016). 

Timing of the nerve transfer surgery is important, especially with injuries that have resulted in a lower motor neuron injury (LMN) such as a brachial plexus injury or spinal cord injury with zone of direct LMN damage. With LMN injuries, it is ideal to have reinnervation restored within approximately 1 year after injury to prevent denervation atrophy from causing the tissues to undergo irreversible damage (Fox et al., 2018) Evaluation 3-6 months post-injury is recommended in our clinic with patients with acute SCI to identify patients with potential LMN denervation. When the recipient muscle is not functioning due to upper motor neuron damage, this window of time is not as significant.

The goal of the transfer is for the donor nerve to now supply the recipient musculature. Thus, for rehabilitation, this will initially require activation of the recipient muscle through activation of the donor nerve’s muscle function, known as a synergistic pairing or pattern.  This is why it is important that the patient become familiar with the surgical process and the synergistic patterns to facilitate cortical remapping and promote successful establishment of new motor patterns after nerve transfer (Kahn & Moore, 2016; Novak, 2008; Hill et al., 2019, Novak & von der Heyde, 2015).

Pre-operative evaluation with an interdisciplinary team prior to surgery is key to successful outcomes for any surgery targeting UE function in patients with tetraplegia. For nerve transfers specifically, it is imperative to assess patients UE strength and function, understand goals, and assess for zones of LMN vs UMN damage. Specific to tetraplegia, understanding the patient’s compensatory movements and skilled manual muscle testing for donor strength as well as redundancy can make or break patient outcomes.

Pre-Operative Phase

Once a surgical plan is developed, it is ideal to initiate education about the nerve transfer rehabilitation process during the pre-operative phase.  Knowing which synergistic patterns and precautions the patient will likely need post-op is not always possible since during the surgery viability of donor and recipient nerves are assessed via electrical stimulation and the surgeon may select a different donor nerve or modify the plan during surgery. Therefore, general education regarding what to expect post-operatively is best, including initiation of education in the concept of synergistic pattern movement as appropriate. The therapist should aim to obtain baseline strength and function measures, strengthen potential donor musculature, improve overall strength and conditioning and maximize ROM of all UE joints via a comprehensive home exercise program (HEP) prior to surgery when possible (Hill et al., 2019; Tung & Mackinnon, 2010).

Splint/Immobilization	Treatment
None	·       Initiate education in nerve transfer process and phases of rehabilitation ·       Strengthening HEP for potential donor muscle groups ·       Initiate general education regarding synergistic patterning and visualization exercises

Immobilization Phase (approximately 0-3 weeks post-op, surgeon dependent)

The primary goal during the immobilization phase is to protect the coaptation site.  The patient may be in a sling, cast, or splint. Immobilization and weightbearing precautions are dictated by the surgeon and should be clarified as needed. Gentle AROM can be maintained in the non-affected joints, including scapular mobility, within the limits of precautions. Edema management and monitoring for good orthosis fit as appropriate should be considered, as well as education in and watching for any signs of infection or poor healing to the incision site.

Initiating education about which synergy patterns will be used and visualization techniques of how those synergy patterns will look are key features of this phase to promote successful cortical remapping (Tung & Mackinnon, 2010; Corbet et al., 2018). The patient can be educated in practicing synergistic patterns with the unaffected extremity if able. In patients with tetraplegia, this is often not possible due to bilateral impairments, however, visualization strategies can be implemented.

Isometric contraction and activation of donor musculature, within limits of precautions, can be implemented and will assist in prevention of donor atrophy and maintaining nerve impulses in the donor nerve. 

The patient may progress to the mobilization phase earlier when cleared by the surgeon.

Immobilization: 0-3 weeks (Surgeon dependent)

Treatment

Immobilization depending on procedure – typically involved joints completely immobilized  *May be cleared for daily hygiene maintaining restrictions depending on postop dressing/immobilization method

·       Continue with therapy that does not involve the affected UE as directed  ·       NO PROM/stretch to involved UE  ·       Gentle AROM to uninvolved joints as allowed by the surgeon  ·       Initiate education with patient regarding synergistic pairings of donor and recipient and include visualization exercises of desired synergistic muscle movements  ·       Perform isometric contraction and activation of donor musculature if able to perform within limits of ROM and WB precautions (this may not be possible with many of the distal transfers that are performed)

Regeneration/Mobilization Phase (approximately 3 weeks once immobilization lifted and continued until signs of reinnervation )

The regenerative/mobilization phase focuses on resuming mobility in the affected joints, resuming exercises to increase donor strength and high repetition donor activation for neural pathway excitement, learning and practicing synergy patterns, and other techniques to promote successful reinnervation. If intercostals or phrenic nerves were involved and the transfer crosses the axilla, shoulder abduction and flexion ROM may still be limited to 90 degrees so as not to rupture the coaptation site.  The patient should also now be safe to resume weightbearing positions as tolerated and within limits of any shoulder ROM precautions unless otherwise specified.

Reinnervation will become available at the recipient muscles depending on the distance between nerve terminals, however, is unlikely early on as the regeneration process is slow. The time from surgery to reinnervation of the recipient muscle is variable and dependent on the distance from the coaptation site to the target motor end plates. In general the timeframe for the proximal nerve stump to regenerate is approximately 1 mm per day (Hill et al., 2019). Knowing this rate and where the transfer took place can help the therapist understand a rough timeline of expected reinnervation and provide the patient with realistic expectations (Corbet et al., 2018; Novak & von der Heyde 2015).

At this time, the patient may resume a bout of care addressing other goals, however, therapy sessions targeting the nerve transfer specifically may better be allocated to when signs of reinnervation are present. It is important to discuss goals, timelines, and expectations related to the nerve transfer surgery and their general SCI rehabilitation process with the patient to determine how to best plan their rehab and maximize their time and insurance benefits. It is still important for the patient to understand signs of early reinnervation and it is recommended the patient check in with their surgeon or a skilled therapist for monitoring for signs of reinnervation, starting at about 3-6 months post operatively. In our clinic, the patient will be followed to assess progress and signs of reinnervation then scheduled for an intense bout of therapy once they enter the Reinnervation/Activation Phase. The first sign of muscle reinnervation has been reported as tenderness upon deep palpation of the recipient muscle, but is often determined by twitch motor activation in the recipient muscle (Hill et al., 2019). When performing MMT in this early stage, apply strong isometric resistance to the donor muscle, while palpating for trace contraction at the recipient muscle tendon (Kahn & Moore, 2016).

Scar management, including massage and kinesiotaping can be initiated early in this phase to minimize adhesions and make sure neural gliding is not restricted. Desensitization techniques can be applied to the surgical site in the presence of hypersensitivity or pain to promote ROM, activity, and reduce guarding.  The HEP should now focus on high repetition, low resistance donor activation to flood the neural pathway, donor strengthening, and visualization exercises of full synergistic patterning, initiating synergistic pairing plus PROM of the recipient and visualization of synergy patterns, practicing with contralateral UE if available, maintaining joint integrity, and overall strength and endurance of non-affected muscle groups (Novak, 2008; Hill et al., 2019; Novak et al., 2015). Essentially, the patient wants to activate that donor nerve frequently and purposefully throughout the day to provide as much input as possible without overfatiguing.

Neuromuscular electrical stimulation (NMES) and cervical transcutaneous spinal cord stimulation (cTSS) can be reinitiated now to facilitate sensory awareness and sensorimotor re-education, prevent atrophy of surrounding muscles, and provide input to the spinal cord in patients without other contraindications. For targeted NMES, using low pulse width, low-mid frequencies can assist with bringing patient awareness to the recipient muscle with appropriate electrode size selection and accurate placement during synergy pattern practice paired with PROM.  A tetanic motor response is unlikely at this phase as regeneration of the donor nerve has not happened yet.

Immobilization: 3 weeks +

Treatment

No restrictions, cast/sling removed  Resting orthosis in intrinsic plus position at night if hand or wrist involvement

·       Daily PROM as tolerated  ·       PROM of shoulder may be limited to 90deg when intercostal/phrenic nerves used as donor, progressing dictated by surgeon   ·       Resume weight bearing positions as tolerated (prone on elbows, walker, etc.)   ·       Resume HRP targeting non-affected muscles to maintain overall strength and endurance   ·       Initiate/resume cTSS if not otherwise contraindicated  ·       Scar management, including desensitization to surgical site and kinesiotaping as appropriate   ·       Electrical stimulation to recipient and surrounding musculature once incisions are well healed and cleared by the surgeon  ·       Continued donor strengthening    ·       Massed practice donor musculature contraction with PROM of recipient muscle contraction in affected UE within limits of precautions   ·       Visualization techniques for promoting motor learning and cortical re-mapping of synergy patterns   ·       Monthly monitoring with clinic for reinnervation

Reinnervation/Activation Phase (approximately 6-12 months post-op or sooner)

Once signs of reinnervation are present, intense rehabilitation is indicated.  The patient should begin a bout of focused care targeting the nerve transfer. Focus on synergistic pairings should continue, but ultimately, the goal is to slowly phase out the need for activation of the donor musculature over time signifying successful cortical remapping and motor re-learning. 

Once a palpable muscle contraction is present, exercises should begin in gravity reduced and gravity eliminated positions.  A stronger trace contraction will likely be elicited with resistance being applied to the donor nerve (Kahn & Moore, 2016).  Electrical stimulation to recipient musculature should be used in conjunction with synergy practice and functional exercises to strengthen and promote activation of the desired muscle movement with careful consideration of avoiding excessive fatigue.  cTSS can also continue to be paired with activity. Donor activation will continue to be required until sufficient strength is available in the recipient to begin de-pairing the two movements. Again, the focus is repetition and low load exercises to promote massed practice and motor learning (Kahn & Moore, 2016).  If the recipient muscle fatigues quickly, low repetitions performed frequently throughout the day can be added as part of the HEP. Synergy patterns are now performed with AAROM of recipient muscle to allow for full movement and motor practice, progressing to AROM as strength improves.  When full gravity eliminated movement is achieved, exercises can then begin in an against gravity plane. Place and hold exercises when against gravity movement is available should be incorporated into practice.  Aquatic therapy can be introduced at this point or sooner if the patient is appropriate, as it promotes gravity reduced, bilateral movements.  Interventions requiring massed practice, repetition, bimanual and functional movements, mirror therapy and biofeedback should be incorporated (Novak & von der Heyde, 2015).

The donor motion should be back to full strength reliant on the redundancy of musculature. Additionally, the recipient muscle may not be expected to gain full 5/5 strength as the nerve supply has changed and fewer motor units now supply the recipient muscle. Timeline to full reinnervation post-nerve transfer varies from patient to patient, but recovery may take anywhere from 2-5 years for adequate strength to return in a successful nerve transfer. It is important to follow the patient as they progress for monitoring and updates to their home programs and plans of care.

Immobilization: 6 mo. +

Treatment

None

·       Daily PROM or AAROM   ·       Resisted donor activation with active-assisted movement of recipient, motor level electrical stimulation to recipient  ·       Progressive strengthening of recipient with motor level electrical stimulation  ·       Gravity eliminated  ·       Against gravity place and hold  ·       Against gravity through available range of motion progressing to full AROM   ·       Progressive resistance and isometric strengthening  ·       Functional retraining as appropriate throughout the process, with donor de-pairing as strength progresses  ·       Biofeedback, visualization techniques  ·       Motor level FES  ·       Robotic training (ex: Amadeo)

Summary

Patients with tetraplegia often cite improved UE function as a top goal and nerve transfers can be an effective surgical procedure to provide improved strength and function. Key factors in working with a patient with SCI with nerve transfer rehabilitation include often a lack of a contralateral side to compare to as a baseline when performing assessments and training in synergy patterns. Understanding importance of donor strength and redundancy as well as being trained in assessing isolated muscle function when possible is key as patients often rely heavily on compensatory movements for function. Additionally, consideration of functional mobility and ADL performance and ensuring adequate caregiver assist during the recovery and immobilization phase is crucial. As with most aspects of rehabilitation a multi-disciplinary team approach to pre and post-op care is always best to ensure best outcomes.

References

Aguirre-Guemez, A. V., Mendoza-Munez, M., Jimenez-Coello, G., Rhaodes-Torres, G. M., Perez-Zavala, R., Barrera-Ortiz, A., & Quinzanos-Fresnedo, J. (2019). Nerve transfer rehabilitation in tetraplegia: Comprehensive assessment and treatment program to improve upper extremity function before and after nerve transfer surgery, a case report. Journal of Spinal Cord Medicine. DOI: 10.1080/10790268.2019.1660841

Corbet, T., Iturrate, I. Pereira, M., Perdikis, S., & Millan, J. (2018). Sensory threshold neuromuscular electrical stimulation fosters motor imagery performance. NeuroImage. 176.

Dorsi, M. D. & Belzberg, A. J. (2011). Nerve transfers for restoration of upper extremity motor function in a child with upper extremity motor deficits due to transverse myelitis: Case report. Microsurgery. 2012(32). 64-67.

Fox, I. K., Novak, C., Krauss, E. M., Hoben, G. M., Zaidman, C. M., Ruvinskaya, R., Jukins, N., Winter, A. C., & Mackinnon, S. E. (2018). The use of nerve transfers to restore upper extremity function in cervical spinal cord injury. Physical Medicine & Rehabilitation. 2018(10), 1173-1184.

Gigo-Benato, D., Russo, T. L., Geuna, S., Domingues, N., Salvini, T. F., & Parizotto, N. A. (2010). Electrical stimulation impairs early functional recovery and accentuates skeletal muscle atrophy after sciatic nerve crush injury in rats. Muscle & Nerve. 685-693.

Gordon, T. (2016). Nerve regeneration: Understanding biology and its influence on return of function after nerve transfers. Hand Clinic. 2016(32). 103-117.

Gordon, T., Sulaiman, O., & Boyd, J. G. (2003). Experimental strategies to promote functional recovery after peripheral nerve injuries. Journal of Peripheral Nervous System. (8). 236-250.

Gordon, T., Sulaiman, O. A. R., & Ladak, A. (2009). Electrical stimulation for improving nerve regeneration: Where do we stand? International Review of Microbiology. 87(9). 433-444.

Hill, J. L., Turner, L. C., Jones, R. D., Jimulia, D. T., Miller, C., & Power, D. M. (2019). The stages of rehabilitation following motor nerve transfer surgery. Journal of Musculoskeletal Surgery and Research. 0(0).

Huang, J., Samuel, O. W., Wang, Y., Cui, H., & Fang, P. (2018, Oct 25-27). Influence of functional electrical stimulation on muscle and nerve rehabilitation in post targeted muscle reinnervation surgery. International Conference on Cyborg and Bionic Systems. Shenzhen, China.

Kahn,  L. C. & Moore, A. M. (2016). Donor activation focused rehabilitation protocol: Maximizing outcomes after nerve transfers. Hand Clinics. 32. 263-277.

Khalifeh, J. M. Dibble, C. F., Voorhis, A. V., Doering, M., Boyer, M. I., Mahan, M. A., Wilson, T. J., Midha, R., Yang, L. S., & Ray, W. Z. (2019). Nerve transfers in the upper extremity following cervical spinal cord injury. Part 1: Systematic review of the literature. Journal of Neurosurgery, Spine. DOI: 10.3171/2019.4.SPINE19173

Khalifeh, J. M. Dibble, C. F., Voorhis, A. V., Doering, M., Boyer, M. I., Mahan, M. A., Wilson, T. J., Midha, R., Yang, L. S., & Ray, W. Z. (2019). Nerve transfers in the upper extremity following cervical spinal cord injury. Part 2: Preliminary results of a prospective clinical trial. Journal of Neurosurgery, Spine. DOI: 10.3171/2019.4.SPINE19173

Kern, H., Hofer, C., Leofler, S., Zampieri, S., Gariulo, P., Baba, A., Marcante, A., Piccione, F., Pond, A., & Carraro, U. (2017). Atrophy, ulta-structural disorders, severe atrophy and degeneration of denervated human muscle in SCI and aging: Implications for their recovery by functional electrical stimulation. Neurological Research. 39(7). 660-666.

Novak, C. (2008). Rehabilitation following motor nerve transfers. Hand Clinic, 24.

Novak, C. B. & von der Heyde, R. L. (2015). Rehabilitation of the upper extremity following nerve and tendon reconstruction: When and how. Seminars in Plastic Surgery. 21(1)

Tung, T. H. & MacKinnon, S. E. (2010). Nerve transfers: Indications, techniques, and outcomes. Journal of Hand Surgery. 35(2)

Wagner, J. P., Curtin, C. M., Gater, D. R., & Chung, K. C. (2007). Perceptions of people with tetraplegia regarding surgery to improve upper-extremity function. The Journal of hand surgery, 32(4), 483–490.

Willand, M. P., Nguyen, M., Borschel, G. H., & Gordon, T. (2016). Electrical stimulation to promote peripheral nerve regeneration. Neurorehabilitation and Neural Repair. 30(5). 490-496.

Yang, L. J., Chang, K. C., & Chung, K. C. (2012). A systematic review of nerve transfer and nerve repair for the treatment of adult upper brachial plexus injury. Neurosurgery. 71(2)