Pearls of wisdom: Finding the best way forward when treating nerve transfer patients
A dancer moves. The text reads “The human body is a beautiful, fine-tuned machine of movement. Limbs are levers. Muscles are engines. Nerves are power cords. Damage these cords and movement stops. What will it take to move again?”
The film opening asks a question that every patient, surgeon and physical therapist ask when faced with a devastating nerve injury. A Spark of Nerve could be the answer!
Lorna C. Kahn, PT, CHT is featured in this important documentary for all physical therapists. Nerve transfer surgery is a life-changing surgery for restoring movement to paralyzed limbs, but it needs unique physical therapy to retrain the patient’s brain to learn how to make to new nerve connections work.
The film highlights Dr. Susan E. Mackinnon (The Center for Peripheral Nerve Injury and Paralysis at Washington University, www.nerve.wustl.edu) who has received the American College of Surgeons Innovation Award for her pioneering work in nerve transfer surgery. She is restoring movement to limbs that many doctors believe to be permanently paralyzed.
Loren was fifteen when she was brutally stabbed five times, severing the nerves in her neck. Michael was facing a dead-end diagnosis after a freak chainsaw accident paralyzed his arm. Chelsey survived a horrific late-night car accident but her arm was also now useless. None of these patients was willing to accept paralysis or possible amputation.
A Spark of Nerve follows the Canadian trained Mackinnon and these patients for three years as their emotional stories unfold from trauma and disappointment to hope and finally joy as freedom of movement is slowly regained. Physical therapist Lorna Kahn helps viewers understand the importance of the non-standard therapy needed for these recovering patients.
Below, Lorna shares some pearls of wisdom she has gathered throughout her years of work with patients who have received nerve transfers:
(Introduction by four-time Emmy winner, Linda Schaller. She is the Producer/Director of the documentary, A SPARK OF NERVE (www.sparkofnerve.com)
Pearls of nerve transfers
At the recent 2015 AAHS meeting in the Bahamas, Dr. Susan Mackinnon, in her keynote address, spoke of the paradigm shift in nerve repair surgery. For decades nerve grafting was the dominant choice in peripheral nerve repair, but in recent years the successes of nerve transfers have changed this paradigm. Nerve transfers allow the surgeon to “rescue” muscles once thought to be too far from the repair site to be reachable given the constraints of the inch a month rule of nerve growth. By taking fascicles from nearby motor neurons considered to be “redundant” in their function and moving them to the denervated motor nerve close to its target muscle, there is an improved chance of regaining function in that muscle.
While the literature supports and describes these surgeries, there is limited guidance on how the physical therapist should approach the post-operative care of these patients. My goal here is to share some treatment pearls I have gleaned from working with this patient population over the past eight years. Some would assume that the rehabilitation approach is the same as that for tendon transfers; however, there are some significant differences. Patients with tendon transfers have a fully innervated muscle to re-educate. Following a nerve transfer the muscle remains denervated until the transferred nerve fibers advance and reconnect to the muscle. This process can take anywhere from two to six months. In addition, the recipient muscle, once re-innervated, has an entirely new efferent source making the motor re-education that much more challenging.
One of the golden rules for nerve transfer surgeries is to avoid tension on the nerves. Therefore, guarded movement should do no harm and rehabilitation may commence following the standard of care 10-14 day rest period. Initial treatment should address scar, edema and any passive range of motion limitations that may exist. Motor re-education should also be initiated within the first post-operative month. Patient education is critical, starting with an explanation of the anatomy of the transfer. It is helpful to describe the muscles involved in terms of ‘donor’ and ‘recipient’ muscles.
The use of metaphors to explain the transfer(s) in terms of “rewiring” the muscle allows some patients to better grasp this concept. Ultimately, you want your patient to understand what “drives“ the recipient muscle. Even though it may be months before the nerve connection is made you want the patient to “flood” the efferent pathway by activation of the donor muscles. Studies in the animal model support such exercise. Udina, et al showed that maintaining some activity in the muscle by active or passive exercise may increase trophic factor release on regenerating nerve. And Van Meeteran, et al demonstrated that exercise training improves functional recovery and motor nerve conduction velocity after nerve lesion.
The performance of these exercises do not need to be highly specialized and should be as simple as possible. For the DFT or double fascicular nerve transfer (median/FDS and ulnar/FCU to musculocutaneous nerve) the patient is instructed to make 10 fists and flex the wrist hourly. Similarly, for the radial (triceps branch) to axillary nerve transfer the patient will flex his triceps by simply sliding the hand along the thigh towards the knee hourly. Over time this may be advanced to resisted exercise but frequency is emphasized over resistance. Limiting the level of resistance will prevent donor fatigue.
A timeline for prognosis is described early on in the patient’s education to give them a realistic expectation of their recovery and help them avoid becoming discouraged by their lack of or slow functional progress. I have found it helpful to show the patient the manual muscle scale (0-5) on a linear model. By describing the nerve regeneration that must occur just for them to get to a 1/5 from zero they start to gain perspective on the time frame of this process. From there, each muscle grade is described in terms of what they will see. In this way when they get the first twitch of movement they can appreciate the major milestone they have achieved even though it is not immediately useful to them. This can be extremely motivating for the patient who has been without volitional control of a muscle for many months. By sharing the entire muscle grading scale you may also set realistic goals early on. I typically tell patients that we do not expect the muscle to achieve a grade 5 but if they can get to a grade 3 they will have significantly improved function. The fact that the recovery may take 2-3 years is driven home early.
In addition to donor activation exercises patients are also instructed in passive donor muscle exercise with simultaneous active recipient muscle activation to start to embed the new motor pattern. For example, with a DFT the patient is instructed in supine bilateral elbow flexion with a dowel/stick. They are encouraged to squeeze the dowel and flex the wrist while pulling the stick to the chest. This will obviously be a passive exercise for the denervated elbow flexors on one side but as the muscles regain function the exercise will become active assisted and ultimately active. The challenge is to find similar models for other transfers where positioning may require a great deal of creativity on the part of the therapist in order to make the exercise gravity assisted or lessened.
As the muscle becomes re-innervated, the challenge for the therapist is to encourage activity without overwhelming the neurologically weak muscle. Keep in mind that the ‘power source’, in terms of number of fascicles, is much less than normal. It has been demonstrated in the animal model that intense exercise may have negative effects on axonal regeneration. Other studies, which support the use of exercise following peripheral nerve injury, promote low intensity, mild exercise and task-dependent activities.
Unless they have underlying issues of passive restriction that need more frequent attention, these patients are followed once a month. This allows us to monitor progress and advance their program as they improve. It also allows the therapist to conserve therapy visits over an extended period of time. Once the patient achieves a muscle strength grade 2 the treatment frequency may increase to weekly or bi-monthly. This is especially helpful in complex cases involving multiple transfers where understanding several new motor patterns is more challenging.
Patients with nerve transfers offer the physical therapist an exciting opportunity to aid in the recovery of completely denervated muscle. These patients require skilled guidance to maximize function and to limit the discouragement that often accompanies this type of injury. The potential rewards are huge for the patient as well as for the therapist who helps them realize their goals.
"Reprinted with permission from the Academy of Hand and Upper Extremity Physical Therapy, APTA”.
A Spark of Nerve has been endorsed by the United Brachial Plexus Network. For updates on the film, visit www.facebook.com/asparkofnerve. Filmmakers Linda and Tim Schaller give a personal perspective to the film as parents of one of the patients. Linda’s director statement about the documentary and how to purchase the DVD are on www.sparkofnerve.com, “A Spark of Nerve can now be seen on Video on Demand! It’s free on Amazon Prime”
Lorna C. Kahn PT, CHT is a graduate of Washington University. She has been a hand therapist for over 20 years and is currently employed by the Milliken Hand Rehabilitation Center with The Rehabilitation Institute of St Louis. As liaison to the Center for Nerve Injury and Paralysis at Washington University for ten years Lorna has developed a sub-specialty in the area of peripheral nerve. She presents both locally and nationally and has coauthored several papers on the subject of nerve transfers. She has been a guest lecturer and lab assistant at the Washington University Physical Therapy program for over 20 years
Hand Clinics; Nerve Transfers. November 2008 Volume 24, Issue 4, p319-488
Edited by Susan E. Mackinnon, Christine B. Novak
Udina, E, Puigdemasa, A, and Navarro,Z. "Passive and active exercise improve regeneration and muscle reinnervation after peripheral nerve injury in the rat." Muscle & nerve 43.4 (2011): 500-509.
Herbison, G. J., M. Mazher Jaweed, and J. F. Ditunno. "Effect of swimming on reinnervation of rat skeletal muscle." Journal of Neurology, Neurosurgery& Psychiatry 37.11 (1974): 1247-1251