American Society for Peripheral Nerve

Spring 2015   •   Volume 5, Issue 1
Case Discussion - Difficult Nerve Injury

Difficult Nerve Injury Case presentation to ASPN Experts:
Jonathan Isaacs, MD
Director, Upper Extremity and Peripheral Nerve Center
Professor and Chief, Division of Hand Surgery
Department of Orthopaedic Surgery
Virginia Commonwealth University
Richmond, Virginia

Commentary by:
Zhongyu John Li, MD, PhD
Associate Professor
Department of Orthopaedic Surgery
Wake Forest Baptist Medical Center
Winston-Salem, North Carolina

Greg Borschel, MD
Associate Professor
University of Toronto Dept of Surgery
and the Hospital for Sick Children Division of Plastic and Reconstructive Surgery

Thomas H. Tung, MD
Associate Professor
Director of Microsurgical Reconstruction
Co-Director, Center for Nerve Injury and Paralysis
Division of Plastic and Reconstructive Surgery
Washington University School of Medicine
St. Louis, MO

Seventy one year old male presented to our trauma center after an accidental self inflicted shot gun injury to his nondominant left brachium while intoxicated. Other than alcoholism which evidently is cured after this incident (he reports that he no longer consumes alcohol), he is otherwise healthy. He undergoes emergent brachial artery reconstruction by our trauma and vascular teams. The median nerve is reported to be intact but contused and the ulnar nerve is not inspected. Both are clinically out post operatively though radial nerve appears to be functioning. The soft tissue envelope is stable despite the high-energy insult. Patient presents to the Peripheral Nerve Clinic three months post injury. Hand is viable but stiff. He is insensate in the median and ulnar nerve distributions and has no active wrist or finger flexion, pronation, or intrinsic function.

What would you do next? Further imaging, testing, therapy, surgery?

Li: We would start therapy emphasizing passive stretching and active ROM, pain control and neuromuscular electrical stimulation therapy. We would also obtain a baseline EMG/NCV and nerve ultrasound. Neurologists would routinely perform nerve ultrasound with EMG/NCV in our institution. Ultrasound would be very help in determining nerve continuity and neuroma formation in this case.

Borschel: He needs aggressive hand therapy to improve his PROM. I would plan on EMG/NCS in about 1 month before considering surgery, for at least 4 months of observation since many GSWs will have some spontaneous recovery but may take just a little longer. I do not believe that any imaging studies would be informative at this time as the median nerve was already observed to be intact, it wouldn’t change management at this time, and surgery appears to be likely.

Tung: In the setting of ballistic trauma it is suspicious that the radial nerve is functioning but the adjacent median and ulnar nerves are not, even though they lie in close proximity in this anatomic location. This finding suggests that the ulnar nerve may be disrupted. If high resolution ultrasound is available it may help confirm that suspicion. The main diagnostic tool is the history and physical examination, which indicates no clinical return of function of median and ulnar nerves at three months post injury. Is there a Tinel sign anywhere along the course of the median or ulnar nerves? MRI may also be useful in helping make that determination, and EMG/NCS is warranted to check for motor unit action potentials. At a minimum I would consider a release the anatomic compression points, including the cubital tunnel, arcade of Struthers, the carpal tunnel and Guyon’s canal. I would also want to explore the ulnar nerve and the median nerves at the level of the injury itself to see whether they are in fact intact.

We initiated therapy to loosen up fingers and obtained a base line EMG/NCS which showed no conduction in motor or sensory components of ulna and median nerves. Selected muscles (PT, FPL, 1st Dorsal interosseus) showed increased insertional activity, +4 fibs, and no recruitment on EMG.

He’s now about 4 months out…What now? More studies? Time? Surgery?

Li: This is obviously a challenging situation. We might continue therapy and follow signs of recovery as the median nerve was reported in continuity. We would consider exploration if there is no signs of recovery in 6 months.

Borschel: I would proceed with surgery at this point to explore the nerves, and plan potential nerve graft reconstruction for sensation and distal nerve transfers for motor reconstruction.

Tung: Plan for surgery as outlined above.

We took him to the OR with plans to explore and do intraoperative studies.

Surgery:
Both nerves (ulnar and median) intact (no images) but feel “firm” in several places.

Now what?

Li We would release all fibrous tissue that was compressing the nerves, neurolysis including removal of the thickened epineurium. We would hope for some recovery as both nerves were in continuity. We are not sure if large gap nerve graft would provide any better chance of functional recovery than neurolysis alone in a 71 years old with high median and ulnar nerve injuries.

Borschel: If neuroma in continuity is found, I would resect the neuroma and plan reconstruction.

If no neuroma is found, but the nerves demonstrate ‘firm’ scarring, intra-operative nerve studies would verify if there is any regeneration through the lesions.

We did intra-operative nerve studies which showed no conduced action potentials across either nerve.   Do you use these studies? Why or why not?

Li: We use intra-operative nerve stimulations and conduction studies. We have no experience in nerve active potential (NAP) evaluation.

Tung: I have not used these studies , and it may be premature to expect conduction across the entirety of the nerve. If there is a lot of blast injury then the growth cones may not have extended very far. It may be worth looking very proximally and checking for conduction.

Based on the studies we resected back to normal nerve:

Case Presentation Image 1
Click to view larger image

Median nerve defect right around 7cm and ulnar nerve defect around 5cm. How would you fix these? Or would you do something else?

Li: We most likely would stop after neurolysis as we are not sure the results of nerve graft would be any better than neurolysis. Sometimes we see surprising recoveries in patients who we thought having no chance to recover based on the intraoperative findings. It is not unusual to see partial recoveries in motor and sensory function after neurolysis in patients with enlarged, firm nerves that were not responsive to the intraoperative electrical stimulation.

If nerve repair is indicated as in this case, we would cable graft both the nerves and transfer a supinator branch of radial nerve to the AIN. We would have more tendon transfer options if the transfer works and the graft fails.

Borschel: I would reconstruct the median nerve with cabled sural nerve grafts and wait to see if he reinnervates his proximal forearm flexors, pronator. If not, then I would consider radial to median (ECRB to pronator teres, supinator to AIN) nerve transfers, and perform EIP opponensplasty in 1-1.5 years. I would harvest ipsilateral MABC to obtain at least 2 cables from proximal and distal to the injury level, and reconstruct the ulnar nerve. If not enough is obtainable, I would harvest the ipsilateral LABC distal to the brachialis branch of the MCN for at least one cable. Reconstruction of the ulnar nerve would be for sensation and to prevent pain and neuroma formation.  He will need an anti-claw procedure and possible thumb adductorplasty since there is no chance of intrinsic recovery. He is also likely to need in the future a side-to-side flexor tenodensis for ring and small finger flexion if this is not recovered by the cabled autograft reconstruction of the ulnar nerve.

Tung: I would graft both with sural nerve, and also release all downstream compression points including the cubital tunnel, Guyon’s canal and the carpal tunnel.

We fixed the median with sural nerve cable graft and the ulnar with 5mm diameter by 5cm long acellular nerve allograft:

Case Presentation Image 2
Click to view larger image

Editor discussion:
The median nerve needed autograft based on length of defect but also (at this level) greater importance (more proximal muscles to benefit from reinnervation and more important sensory distribution). Unlikely that hand intrinsics will be reinnervated by either nerve regardless or grafting technique so ulnar nerve was relatively less important. We had already harvested sural from one leg and decided not to give him a third surgical site on his contralateral leg. Local nerve graft options such as medial anterbrachial and medial brachial were damaged from the trauma but even if they were not, I prefer not to take more sensation from a compromised limb. Therefore, we decided to use allograft. Of course, when you use the argument I’m going to try acellular allograft because I don’t think even an autograft will work… then you are setting yourself up for failure and must be careful not to blame the tool!

Borschel: There is no evidence that acellular allografts beyond 2-3 mm diameter size and 3 cm length work. In fact, I would be concerned about neuroma formation and pain which we have seen with ‘over-extended’ allograft reconstruction, potentially requiring resection and proximal transposition in the future. I have no concerns about taking MABC or LABC from this limb since he already has a compromised limb both in terms of function and sensation, and losing some forearm sensation is of little consequence to hand or overall extremity function.

If you believe autograft reconstruction of the median nerve has a good chance of recovering proximal forearm flexors/pronator, then the same should apply to the ulnar nerve for recovery of ring/small finger FDP and FCU, and autograft reconstruction should be considered, even though the primary reason is for sensation and the prevention of neuroma formation and pain. As stated above, recovery of hand intrinsics is of course not expected and is managed by distal tendon transfer.

We also wrapped our repairs with collagen matrix (porcine intestinal submucosa):

Case Presentation Image 3
Click to view larger image

Do you believe that this has any benefit?

Li: Cost is obviously a concern. Although it appears to be a common practice nowdays, but we do need more scientific studies to prove the benefit of using collagen matrix wraps at the nerve repair sites.

Borschel: No. I do not believe there is any convincing supportive data.

Tung: I am not sure if there is data to suggest its use in this clinical situation.

Any other comments?

Tung: It may be worth considering radial to median nerve transfers to try to obtain some flexion in the digits and wrist. It may also be worth considering tendon transfers now, given the age of the patient. For example, using some of his expendable wrist and digital extensors to power digital flexors.


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