Case Report

Restoring antigravity elbow flexion in children with Brachial Plexus Birth Injury (BPBI) is paramount for the function of the entire limb. There is considerable debate on the optimal timing and select procedure to restore an ailing bicep. We generally accept that lack of an antigravity bicep by 6 months of age in an Erb’s or Extended Erb’s Palsy (Narakas Groups I-II) requires the attention of a microneurosurgeon. Traditional surgical management involves exploration of the brachial plexus, neurolysis, and reconstruction by means of cable nerve grafting sometime between six months and fifteen months of age.

However, the popularity of targeted peripheral nerve transfers has increased over the last decade. It is now known that providing the musculocutaneous nerve with additional innervation from fascicles from the nearby median and or ulnar nerve produces antigravity power and elbow flexion. Targeted transfers can also limit clinical setbacks seen in more proximal plexus resections that can denervate areas of functional recovery.

Certainly, the most important deciding factor in the menu of surgical options is the preoperative physical examination and assessment by a trained multidisciplinary team focused on BPBI, and including Mallet and AMS scoring by skilled occupational therapists.

Selecting your transfer: End-to-end vs supercharged end-to-side

Careful attention to the patient’s preoperative gravity assisted or eliminated bicep function can assist intraoperative decisions made concurrently with nerve mapping of the musculocutaneous nerve (MCN). Presently, the following guiding principles have assisted in intraoperative decision making:

If there is complete absence of preoperative clinical bicep function (antigravity, gravity-eliminated) and an intraoperative exam demonstrating little-to-no motor response with stimulation on 2mA, and even 20mA with the CHECKPOINT® stimulator, I am assured that there is little to no innervation of the MCN from the brain and utilize End-to-End style transfers.

Conversely, if the patient demonstrates absent to weak antigravity but present gravity-eliminated elbow flexion, and intraoperative nerve stimulation shows similar function at 0.5mA to 2mA, a supercharged end-to-side transfer (SETS) is helpful to preserve what functional recovery has already occurred as well as increase innervation from a donor nerve.

Finally, internal neurolysis of the MCN often leads to the identification of 2-4 individual motor branches branching into the bicep. Microsurgical dissection can liberate each of the feeding motor fascicles which can be individually stimulated. Utilizing the same principles as previously mentioned, each fascicle is stimulated at 0.5mA and 2mA, the weakest of which is selected as the target for transfer. Again the decision to utilize end-to-end or SETS is made based on the clinical picture and degree of activity in the OR.

Determining an appropriate donor

Traditionally the FCU fascicle of the ulnar nerve is utilized to reinnervate the MCN (the Oberlin Transfer). However, a variety of nearby fascicles can be selected in isolation or combination including the Double Fascicular Transfer (FCU/FCR Fascicles to the MCN) and or FCR fascicle in isolation. Again, in BPBI patients there may be variable reinnervation of the median, ulnar and radial nerves. Taking into consideration both the preoperative exam and intraoperative assessment, as well as preserving “life-boat” nerve-muscle groups for future transfers is necessary. For example, in an extended Erb’s palsy with weak or absent digital extension, care must be taken to preserve some innervation to either FCR or FCU for potential future use in tendon transfers should the patient fail to regain wrist or hand extension. As such, I will typically explore both the ulnar and median nerves with internal neurolysis of both FCR and FCU fascicles and utilize the CHECKPOINT stimulator to determine the most suitable donor. This donor must have M5 strength when examined preoperatively, ideally has redundant fascicles on intraoperative stimulation, and if not, there exists an alternate strong wrist flexor. Intraoperative stimulation and assessment is also critical in the median and ulnar nerves to avoid interrupting intrinsic hand function.

Taken together, the following four case examples demonstrate four different nerve transfers to address absent or weak elbow flexion in Narakas Group I-III palsies at later age (9-18 months).

Case 1

Supercharged end-to-side transfer of FCR fascicle of median nerve to musculocutaneous nerve in a 18-month old with no antigravity elbow flexion and present gravity-eliminated elbow flexion.
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Case 2

End-to-end double fascicular transfer to musculocutaneous nerve in a 9-month old with completely absent elbow flexion.

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Case 3

End-to-end FCU fascicle of the ulnar nerve to musculocutaneous transfer in a 7-month old.

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Case 4

Supercharged end-to-side transfer FCR fascicle of median nerve to musculocutaneous nerve in a 16-month old with no antigravity elbow flexion and present gravity-eliminated elbow flexion.

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About the author

Dr. Shawn Diamond received his medical degree in 2011 from Cornell University’s Weill Cornell Medical College, New York, NY. He completed residencies in General Surgery at Santa Barbara Cottage Hospital, and in Plastic Surgery at Harvard Medical School’s combined program in Boston. After completing his fellowship in Hand and Microsurgery at University of California, Irvine, Dr. Diamond joined the division of Plastic and Reconstructive Surgery at Texas Tech University Health Sciences Center in El Paso, Texas as Director Limb Restoration. He has developed the region’s first multi-disciplinary Brachial Plexus Birth Injury center at El Paso Children’s Hospital. His special interests include pediatric hand surgery, brachial plexus birth injury and reconstructive microsurgery.

The Checkpoint Stimulator is a single-use, sterile device intended to provide electrical stimulation of exposed motor nerves or muscle tissue to locate and identify nerves and to test nerve and muscle excitability. Do not use the Checkpoint Stimulator when paralyzing anesthetic agents are in effect, as an absent or inconsistent response to stimulation may result in an inaccurate assessment of nerve and muscle function.