Median and/or Ulnar Nerve Fascicle Transfer for the Restoration of Elbow Flexion in Upper Neonatal Brachial Plexus Palsy

Overview

Introduction

Transfer of a fascicle of the ulnar and/or median nerve to the musculocutaneous nerve in order to reinnervate the biceps and/or brachialis muscles has a high success rate and a low rate of complications in infants with upper (C5-C6) or extended upper (C5-C7) neonatal brachial plexus palsy.

Step 1: Make the Incision

Make a longitudinal incision along the midline of the middle third of the medial brachium.

Step 2: Mobilize the Musculocutaneous Nerve

The musculocutaneous nerve is typically found on the undersurface of the biceps muscle.

Step 3: Mobilize the Median Nerve

The median nerve runs along the neurovascular sheath medial to the brachial artery.

Step 4: Mobilize the Ulnar Nerve

The ulnar nerve lies posterior to the intermuscular septum.

Step 5: Transfer the Donor Nerve to the Recipient Nerve

Cut the donor fascicles distally and the recipient fascicles proximally to facilitate transfer.

Step 6: Close the Wound

Irrigate the wound, and close it in layers.

Step 7: Postoperative Protocol

Remove the bandages two weeks postoperatively, and encourage passive range-of-motion exercises.

Results

In our series, thirty-one patients underwent single or combined nerve fascicle transfer; twenty-seven (87%) obtained functional elbow flexion recovery (Active Movement Scale [AMS] score ≥ 6) while twenty-four (77%) obtained full elbow flexion recovery (AMS score = 7).

Indications

Contraindications

Pitfalls & Challenges

Introduction

Transfer of a fascicle of the ulnar and/or median nerve to the musculocutaneous nerve in order to reinnervate the biceps and/or brachialis muscles has a high success rate and a low rate of complications in infants with upper (C5-C6) or extended upper (C5-C7) neonatal brachial plexus palsy.

Whether or not elbow flexion returns has been used to guide treatment of, and indicate surgical intervention for, neonatal brachial plexus palsy¹. When a patient does not spontaneously recover elbow flexion by the age of one year, or has nerve root avulsions, targeted nerve transfers can be used to restore elbow flexion^{2- 10}. Additionally, when a patient recovers shoulder function but not elbow flexion, nerve transfers can be utilized to target elbow flexion recovery^{2, 3}.

During this procedure, a midline longitudinal incision is made along the middle third of the medial brachium². The fascia over the biceps and brachialis muscles anteriorly and the triceps muscle posteriorly is then released. The median nerve, ulnar nerve, and brachial artery are identified medially in the plane between these two muscles. The musculocutaneous nerve is identified in the plane between the biceps (anterior) and brachialis (posterior) and carefully mobilized. The branch of the musculocutaneous nerve to the biceps is typically identified in the middle third of the upper arm along the undersurface of the biceps muscle and tagged with a vessel loop^{3, 4, 6}. The branch to the brachialis muscle is then identified distally along the musculocutaneous nerve as a medial branch while the lateral antebrachial cutaneous nerve is identified laterally as it continues into the forearm.

Posterior to the intermuscular septum, approximately 2 cm of the ulnar nerve is dissected out, starting about 1 cm distal to the level of dissection used to isolate the branch of the musculocutaneous nerve to the biceps muscle^{3, 4, 6}. Additionally, the median nerve is dissected out anterior to the intermuscular septum approximately 1 cm distal to the level of dissection utilized to mobilize the branch of the musculocutaneous nerve to the brachialis muscle. This length is usually sufficient to mobilize the nerve fascicle pedicle to reach the donor nerve motor branch. With use of a longitudinal epineurotomy in either nerve, an intrafascicular dissection is used to identify an appropriate size-matched fascicle corresponding to the flexor carpi ulnaris or radialis muscle (i.e., a size-matched fascicle that does not respond with substantial finger flexor activation to a handheld electrical nerve stimulator). The appropriate fascicle is dissected free for approximately 1 to 3 cm depending on the intrafascicular connections between individual fascicles. This fascicle is cut distally and reflected proximally and anteriorly toward the biceps and/or brachialis branch. Coaptation is performed with fibrin nerve glue, with or without 9-0 or 10-0 nylon sutures, under loupe magnification or with an operating microscope. The incision is closed in layers, and the arm is immobilized in flexion to relieve tension on the nerve coaptation³.

Step 1: Make the Incision

Make a longitudinal incision along the midline of the middle third of the medial brachium.

• Place the patient supine, with the arm on a hand table.

• Drape out the entire arm from the shoulder to the fingers.

• A tourniquet typically obscures the proximal dissection and is not recommended.

• Palpate the intermuscular septum on the medial brachium.

• Make a longitudinal incision along the middle third of the brachium along the medial intermuscular septum ( Fig. 1).

• Utilize blunt dissection to expose the fascia, with use of bipolar electrocautery for hemostasis.

• Incise the fascia longitudinally anterior and posterior to the intermuscular septum to facilitate exposure of the nerves for transfer.

Fig. 1.

Postoperative photograph showing the location of the surgical scar in the medial brachium of a patient who underwent combined median and ulnar nerve fascicle transfer. (Reproduced with permission of Cincinnati Children’s Hospital.)

Step 2: Mobilize the Musculocutaneous Nerve

The musculocutaneous nerve is typically found on the undersurface of the biceps muscle.

• Once the fascia is incised anteriorly, carry out blunt dissection along the undersurface of the biceps.

• Mobilize the musculocutaneous nerve proximally to distally, taking care not to injure branches to the biceps and brachialis muscles.

• The motor branch to the biceps is typically encountered along the lateral side of the musculocutaneous nerve in the proximal to middle third of the brachium.

• Mobilize the motor branch to the biceps proximally until it is no longer an isolated fascicle. Then tag it with a vessel loop ( Fig. 2).

• The motor branch to the brachialis muscle is typically encountered along the medial side of the musculocutaneous nerve in the middle to distal third of the brachium.

• Mobilize the motor branch of the brachialis and tag it with a vessel loop.

• Rarely, there can be a common motor branch to the biceps and brachialis muscles arising in the middle third of the brachium.

• Using a handheld electrical nerve stimulator, grade the relative contraction strength of the biceps and brachialis muscles in comparison with the forearm flexor musculature innervated by the median and ulnar nerves ( Video 1).

Fig. 2-A.

Intraoperative photograph showing the motor branch of the musculocutaneous nerve to the biceps (red vessel loop) and the ulnar nerve (yellow vessel loops). (Reproduced with permission of Shriner’s Hospital.)

Fig. 2-B.

Close-up intraoperative photograph of the same area seen in Fig. 2-A, showing the motor branch of the musculocutaneous nerve to the biceps superficial to the brachialis muscle with the biceps muscle being retracted superficial to the red vessel loop. (Reproduced with permission of Shriner’s Hospital.)

Video 1.

Download video file ^{(8.8MB, mp4)}

DOI: 10.2106/JBJS.ST.M.00070.vid1

With use of a handheld electrical nerve stimulator, the appropriate donor and recipient nerve fascicles are identified so that they can be transferred to the recipient nerve. FCU = flexor carpi ulnaris. (With permission of Shriner’s Hospital.)

Step 3: Mobilize the Median Nerve

The median nerve runs along the neurovascular sheath medial to the brachial artery.

• Identify the median nerve as it courses along the neurovascular sheath.

• Mobilize a portion of the median nerve approximately 1 cm distal to the level at which the motor branch to the brachialis muscle was previously identified.

• Identify the motor fascicles in the median nerve that run along the medial side of the median nerve.

• Make a longitudinal epineurotomy along the median nerve above the motor fascicles under loupe magnification.

• Using jewelers forceps and microdissecting scissors, tease out the individual fascicles.

• Use a handheld electrical nerve stimulator to identify appropriate donor fascicles that innervate the flexor carpi radialis muscle.

• Mobilize and tag the selected donor fascicle that is size-matched to coapt with the brachialis motor branch.

• The donor fascicle should be mobilized 1 to 3 cm on the basis of the fascicular anatomy and be long enough to reach the coaptation site.

• An operating microscope can be utilized to facilitate identification of the appropriate fascicle and to aid in nerve transfer approximation if loupe magnification is insufficient for appropriate identification.

Step 4: Mobilize the Ulnar Nerve

The ulnar nerve lies posterior to the intermuscular septum.

• Identify the ulnar nerve through the posterior fascial incision.

• Mobilize a portion of the ulnar nerve approximately 1 cm distal to the motor branch to the biceps muscle.

• Identify the expendable motor fascicles in the ulnar nerve that run along the lateral and central part of the nerve.

• Make a longitudinal epineurotomy along the ulnar nerve above the motor fascicles under loupe magnification ( Fig. 3).

• Using jewelers forceps and microdissecting scissors, tease out individual fascicles.

• Use a handheld electrical nerve stimulator to identify appropriate donor fascicles that innervate the flexor carpi ulnaris muscle ( Video 1).

• Mobilize and tag the selected donor fascicle that is size-matched to coapt with the biceps motor branch.

• The donor fascicle should be mobilized 1 to 3 cm on the basis of fascicular anatomy and should be long enough to reach the coaptation site ( Fig. 3).

• An operating microscope can be utilized to facilitate identification of the appropriate fascicle and to aid in nerve transfer approximation if loupe magnification is insufficient for appropriate identification.

Fig. 3.

Intraoperative photograph showing a longitudinal epineurotomy along the ulnar nerve (yellow vessel loops) with the appropriate donor fascicle dissected free (red vessel loop). The nerve parallel to the ulnar nerve is the medial antebrachial cutaneous nerve. (Reproduced with permission of Shriner’s Hospital.)

Step 5: Transfer the Donor Nerve to the Recipient Nerve

Cut the donor fascicles distally and the recipient fascicles proximally to facilitate transfer.

• Sharply sever the donor fascicle of the ulnar nerve distally and reflect it anteriorly toward the biceps motor branch ( Fig. 4).

• Sharply sever the recipient biceps motor fascicle proximally and reflect it toward the ulnar nerve donor fascicle.

• Using a microsurgical background, align the donor and recipient fascicles for an end-to-end anastomosis, trimming the recipient nerve if excess is identified ( Fig. 5).

• The nerve fascicle coaptation should have a slight redundancy to allow for a tension-free range of motion at the elbow ( Video 1).

• Sharply sever the donor fascicle of the median nerve distally and reflect it anteriorly toward the brachialis motor branch.

• Sharply sever the recipient brachialis motor fascicle proximally and reflect it toward the median nerve donor fascicle.

• Using a microsurgical background, align the donor and recipient fascicles for an end-to-end anastomosis, trimming the recipient nerve if excess is identified.

• The anastomosis should be loose to allow for a tension-free range of motion at the elbow.

• Coapt the nerves with fibrin glue, with or without first placing 9-0 or 10-0 monofilament stay sutures.

• Coaptation can be performed under loupe magnification or under an operating microscope.

Fig. 4.

Intraoperative photograph showing the ulnar nerve donor fascicle (yellow background) cut distally and moved anteriorly to facilitate transfer to the biceps motor branch (red vessel loop). (Reproduced with permission of Shriner’s Hospital.)

Fig. 5.

Intraoperative photograph showing the coaptation of the ulnar nerve fascicle to the biceps branch of the musculocutaneous nerve with use of fibrin glue. The ulnar nerve fascicle has been transferred superficial to the medial antebrachial cutaneous nerve in this photograph. (Reproduced with permission of Shriner’s Hospital.)

Step 6: Close the Wound

Irrigate the wound, and close it in layers.

• Gentle irrigation can be performed outside the anastomosis sites.

• Suture the wound in layers using absorbable braided 3-0 deep cutaneous interrupted sutures and a monofilament 4-0 subcuticular suture.

• Skin closure can be augmented with skin adhesive or butterfly bandages.

• Cover the wound with sterile dressings and splint the elbow in 90° of flexion.

• Patients are typically discharged home from the recovery room unless an overnight stay is medically indicated.

Step 7: Postoperative Protocol

Remove the bandages two weeks postoperatively, and encourage passive range-of-motion exercises.

• Remove the bandages and splint two weeks postoperatively.

• Continue appropriate postoperative therapy, encouraging passive range-of-motion exercises of the shoulder and elbow.

• Three months postoperatively, begin neuromuscular electrical stimulation of the biceps and brachialis muscles if it can elicit muscle contraction.

• Recovery of elbow flexion can be noted as early as three months postoperatively. The results should be monitored for at least eighteen to twenty-four months, at least quarterly and more frequently on the basis of clinical results.

Results

In our series², thirty-one patients underwent single or combined nerve fascicle transfer; twenty-seven (87%) obtained functional elbow flexion recovery (Active Movement Scale [AMS] score¹¹ ≥ 6) while twenty-four (77%) obtained full elbow flexion recovery (AMS score = 7). All five patients who underwent combined median and ulnar nerve fascicle transfer recovered full elbow flexion (AMS score = 7) and recovered supination motion with an AMS score of ≥5. Younger age at the time of surgery correlated with improved recovery of elbow flexion and supination.

What to Watch For

Indications

• Nerve root avulsions of the upper trunk noted during brachial plexus exploration^{2- 5}.

• Failure to recover antigravity elbow flexion following previous brachial plexus exploration and nerve grafting^{2- 4}.

• Dissociative recovery of shoulder function without antigravity elbow flexion^{2- 4}.

• Late presentation (nine to twenty-one months following brachial plexus injury)^{2- 4}.

Contraindications

• Global brachial plexus palsy^{2- 5}.

• Relative contraindication: Partial recovery of lower trunk with insufficient donor axon strength to warrant transfer.

• Relative contraindication: More than twenty-one months since brachial plexus injury unless partial, incomplete recovery has been noted (as this may allow the motor end plate to survive the denervation period).

Pitfalls & Challenges

• The medial incision in the brachium can occasionally result in a widened scar. We use skin glue (Dermabond; Ethicon) to augment subcuticular closure.

• The musculocutaneous nerve is sometimes difficult to identify as it lies deep to the biceps muscle and superficial to the brachialis muscle and can be more lateral than expected.

• The bifurcation of the motor branch to the biceps is often found just proximal to the vascular pedicle to the biceps muscle from the brachial artery.

• The appropriate donor fascicle should predominantly innervate wrist flexors with limited intrinsic or extrinsic hand function detected with nerve stimulation.

• The donor fascicle should be cut as distally as possible to facilitate transfer of axons as close as possible to the motor end plate along the recipient nerve.

• Anatomic variability may be encountered, so be sure to identify the nerve branch to the muscle and trace it back to the donor nerve proper.

Clinical Comments

• We prefer to use median and ulnar nerve fascicle transfers for the restoration of elbow flexion instead of intercostal, medial pectoral, or spinal accessory nerves as donors for the following reasons: (1) the donor and recipient nerves are in the same field, which requires a single operative dissection; (2) the coaptation is made as close to the motor end plate as possible, allowing for decreased denervation time and, theoretically, earlier and improved recovery; and (3) because of distal fascicular crossover and redundancies in innervation, use of these transfers limits donor nerve deficits.

• What approach would you use for the restoration of elbow flexion in patients with global plexus injury?

• In cases of global plexus injury, we prefer to use intercostal nerves, unless a phrenic nerve palsy is noted¹².

• What method do you use to ensure an appropriate coaptation of the donor and recipient nerves?

• We approximate the nerve endings on top of background material. If they easily stay together we apply fibrin glue to hold the coaptation, otherwise we may place one or two 9-0 or 10-0 monofilament stay sutures before we apply the glue.