Jonathan Isaacs, M.D.
(with expert commentary by Ida Fox, M.D.)
As the concept of nerve transfers in lieu of tendon transfers for tetraplegic patients gains momentum, I recently encountered a patient that on the surface seemed like an excellent candidate. Though I had seen this topic presented at several meetings over the last couple of years and had read some of the literature on the topic, I became quickly overwhelmed as I examined and counseled this young man. There are interesting consideratons with this presentation and his diagnosis when considering nerve transfers to restore function.
He is 22 years old right hand dominant male presenting 16 months out from idiopathic transverse myelitis at around the c6 level. Though at the initial onset, he was completely paralyzed from the neck down, he has regained some upper extremity function. Over the last few months he has noted continued improvement in strength of his shoulders (Fig 1) and elbow flexion but minimal function in his forearms and hands(Fig 2). He has spasticity for which he receives botox injections. He presents for possible tendon transfers.
His past medical history is remarkable for diabetes and high blood pressure (he does take insulin, baclofen, and lyrica)
PE: in an electric wheelchair;
He seems fairly symmetrical in his motor exam though slightly stronger on the left than the right:
Everything else 0
IC Grade 2 bilaterally. Limited options for tendon transfers but could offer Brachioradialis to Flexor Pollicis Longus and CMC fusion to improve pinch. Nerve transfer options could potentially include Posterior Branch of Axillary Nerve to Triceps Branch of Radial Nerve and Motor Branch of Brachialis to AIN.
Important unanswered questions include: 1) Are nerve transfers an option in patients with transverse myelitis? 2) has this patient’s final deficits evolved fully? 3) are triceps, FDP, FPL innervated/nonfunctional or have these muscles undergone denervation atrophy because their lower motor neurons were affected as part of the condition/disease process?
Ida Fox, M.D.
Assistant Professor of Plastic Surgery
Washington University School of Medicine in Saint Louis
This is a fascinating and challenging case of transverse myelitis that pushes the boundaries of all the areas that we at the ASPN try and think of as we evaluate and treat patients.
It demands an understanding of both peripheral (PNS) and central (CNS) nervous system pathophysiology and expected outcomes with and without intervention.
Although nerve transfers are being described for use in patients with cervical spinal cord injury (SCI) or tetraplegia, the challenges in cases of transverse myelitis are even more daunting.
In this case of a patient who is 16 months out from the primary process, understanding of the zone of injury is critical. Additional electrodiagnostic testing with nerve conduction studies to examine the integrity of the C8/T1 motor unit might be helpful.
Observation of patterns of upper extremity use and adaptive patterns is often helpful in determining further priorities of care. Tenodesis effect may be providing some hand function if the wrist extension is strong enough. In that case brachioradialis may be used as a tendon transfer to restore some thumb function. If not, it might be used to restore stronger wrist extension and subsequent tenodesis hand function.
If the electrodiagnostic studies show relative preservation of the C8/T1 motor unit, a nerve transfer may be possible even at this late date. Unfortunately, however, cases of transverse myelitis often involve a more extensive zone of injury that, at 16 months out might preclude the use of nerve transfers. Previously reported successful cases of use of nerve transfer for transverse myelitis have been completed within months of the primary process.
With patient showing continued improvement in shoulder recovery over the last couple of months, we will watch him for 6 more weeks to make sure that he shows no further signs of recovery. Pending evidence that he has truly plateaued, we will obtain a NCS (which we had not previously obtained) looking specifically at the C8/T1 motor unit. The NCS will evaluate if the Sensory Nerve Action Potentials (SNAP) and Compound Muscle Action Potentials (CMAP) are present in the median and ulnar nerve as tested by APB and FDI. If both are present then we assume that the muscles such as FPL and FDP may be intact. If CMAPs are not present using these “surrogates” then we have to assume that the lower motor neurons are involved in the disease process and at 16 months muscle reinnervation is not recoverable. Thus, patient counseling will include the possibility that nerve transfers may not be possible. We will prioritize avoidance of down grading current function and preserving the possibility of tendon transfers if nerve transfers not possible.
LegendFig 1. Patient exhibits strong but not normal shoulder abduction.
Fig 2. Patient exhibits wrist extension though it is easily “broken” by examiner.