Should surgeons operate on a radial nerve not improving 2 months after humerus fracture?
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Rare to operate after 2 months
One of my observations of nerve injury is that it is rare to encounter the same nerve injury twice.
In general, it would be rare in my practice to operate on a radial nerve not improving 2 months after humerus fracture – with the implications that the humerus fracture is being managed nonoperatively. The indications for surgical exploration and repair or reconstruction would be influenced by the suspicions for a catastrophic nerve injury, ie, one that would not recover without intervention.
The risk of a neurotmesis injury would be increased with an open injury, a post-reduction nerve deficit or a violent injury that imparted a substantial force across the radial nerve that could cause a nerve rupture or laceration. The risks of the latter scenario may be increased with increasing fracture displacement noted at the initial injury radiographs; evidence of a high energy injury could include severe fracture displacement, multiple concomitant nerve injuries and/or complete radial nerve deficit.
Serial examinations, nerve imaging with ultrasound and neurodiagnostic studies may all assist the clinician in determining timely management. Opportunities for primary surgical repair are rare due to the adverse influence of the zone of injury; however, reconstructive options such as intercalary nerve grafting, nerve transfers or tendon transfers may be considered.
Fraser Leversedge, MD, is professor and chief of the section of hand, wrist and elbow surgery, associate director of the Hand & Upper Extremity Surgery Fellowship and co-director of the Brachial Plexus and Peripheral Nerve Injury Program in the department of orthopedic surgery at the University of Colorado School of Medicine in Aurora, Colorado.
Surgeons should not ‘wait-and-see’
I believe this answer is much different today compared to 10 to 15 years ago. When I see a patient with radial nerve palsy after humerus fracture, I get advanced imaging of MR neurography and ultrasound to determine if the radial nerve is injured and if there is fascicular continuity throughout the zone of injury. I am also looking to see if there is any neuroma formation. Other questions I ask the radiologist is whether there is external compression on the nerve, impingement from bone fragments, scar tether, compression from hematoma or other findings. There is more suspicion for operative nerve injury if the fracture is open and if the palsy occurred after manipulation. I also use advanced imaging for gunshot wounds. High resolution imaging can show if the bullet or projectile fragments have made the nerve partially or fully discontinuous.
If the advanced imaging shows the above signs of physical change to the nerve that can be addressed, then I believe surgery is indicated and can include external neuroplasty, internal neurolysis and nerve repair or reconstruction with nerve grafts.
There is a time course that needs to be respected. The distal nerve, motor endplates and muscle degenerate after 12 months of denervation, so time is of essence when treating nerve injuries. This algorithm also applies to other nerve injuries. A wait-and-see attitude should not be the current practice. Fortunately, we now have more reliable diagnostic tools to guide us in surgical decision making.
Steve K. Lee, MD, is chief of hand and upper extremity surgery at Hospital for Special Surgery and professor of orthopedic surgery at Weill Medical College of Cornell University in New York.
Open vs. closed fractures
Typically, no. For about half the radial nerve palsies associated with open fracture of the humeral diaphysis, the radial nerve is pulled apart and not in continuity (neurotmesis, avulsion). Routine exposure of the radial nerve is important for open fractures with radial nerve palsies. The surgeon should plan a relatively lateral skin incision to provide good exposure to the proximal and distal parts of the nerve. The damaged nerve is typically resected for a few centimeters proximal and distal after at least 1-week delay from injury for better distinction of healthy and unhealthy nerve, and the gap is grafted.
In contrast, among closed fractures of the humeral diaphysis, less than one in 20 radial nerve palsies is a neurotmesis. Intact nerves will recover. There is no reliable and accurate method for diagnosis of neurotmesis other than nerve exposure. Electrodiagnostic testing after 3 weeks (time enough for Wallerian degeneration) can distinguish axonotmesis and neurotmesis from neurapraxia. But it gives no information on the distinction between axonotmesis, which will recover, and neurotmesis, which will not. Electrodiagnostic testing seems to detect muscle reinnervation about 1 or 2 months prior to muscle function detectable on examination.
If a person perceives sufficient potential benefits to operative fixation of a closed fracture of the diaphyseal humerus to outweigh the inherent and potential harms of surgery, and there is a radial nerve palsy, the surgeon should plan to explore the radial nerve and make a lateral skin incision for adequate access to the proximal and distal aspects of the nerve in case it is discontinuous.
Let’s consider the setting of a person who chooses nonoperative treatment for radial nerve palsy associated with a closed, diaphyseal fracture of the humerus. A person who desires sophisticated hand function, such as playing a musical instrument, might accept the notable possibility of operative exposure identifying an intact nerve that will recover (unnecessary surgery) for the possibility of earlier identification of a neurotmesis that will recover with a nerve graft. Because most radial nerves have signs of sensory or motor recovery within 2 to 3 months and nerve grafts work just as well after this amount of delay, there is no harm in initial observation.
Most people who choose nonoperative fracture treatment do not find the notable risk of unnecessary nerve exploration acceptable. And most are satisfied with a hand that opens and a wrist that extends, which can be achieved with tendon transfers (a reconstructive procedure) and is, therefore, not time sensitive. People with these mindsets can use a simple wrist splint or a low-profile radial nerve palsy splint (with elastics to passively extend the metacarpophalangeal joints) to help with hand use while they wait to see if the nerve recovers. The hand is quite functional with one of these braces, and that makes it easier to be patient with the recovery process. There is no point getting a neurophysiological test unless nerve surgery would be considered. For people who might consider nerve grafting if there is no recovery around 6 months after injury, if there are no signs of sensory or motor recovery of the radial nerve 4 months after injury, electrodiagnostic tests can “look into the future” by detecting muscle reinnervation before notable muscle contraction is possible, which might reduce the possibility of unnecessary surgery for an intact nerve. If there are any signs of reinnervation, nerve surgery will not be helpful.
David Ring, MD, PhD, is the associate dean for comprehensive care, professor of surgery, courtesy professor of psychiatry and behavioral sciences and courtesy professor of health social work at Dell Medical School of The University of Texas at Austin in Austin, Texas.
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