Nerve Transfer to Restore Hand Function for C6/7 Spinal Cord Injury
Cervical level spinal cord injury can significantly affect hand function. Depending on the level and type of injury, surgery to improve hand and arm function may be an option. Surgical treatment may include nerve transfers, tendon transfers, or other procedures.
It is important to recognize nerve transfer surgery can only benefit patients with specific types of spinal cord injury. To be eligible, a patient must have incomplete quadriplegia with a motor level C6 or C7 spinal cord injury. Because the procedure relies on working nerves above the C6 level, it will not benefit patients at the C5 level or higher spinal cord injuries. The goal of the procedure is to improve hand function with the ability to pinch the thumb and index finger.
Restoring Elbow Flexing Function
Bending of the elbow occurs because of the movement of two different muscles — the biceps muscle and the brachialis muscle. In a double fascicular nerve transfer, Dr. Barbour uses portions of two other nerves not normally connected to the biceps and brachialis muscles to restore elbow flexion. During the procedure, redundant segments of the ulnar nerve and the median nerve are cut and transferred directly to the biceps and brachialis branches as they enter the muscles in the upper arm.
Patients should still be able to move their fingers and wrist after surgery. However, as they regain function from the nerve transfer, they also use the transferred nerves to trigger movement in the upper arm that allows them to flex their elbow. With the help of experienced therapists, the brain then learns which nerves control certain muscles, and eventually the patient is able to activate the biceps directly.
Restoring Shoulder Function
When an upper brachial plexus injury limits the ability to bring the arm up and rotate it out, it may be possible to perform a nerve transfer to restore function to these muscles. Four muscles play an important role in moving the shoulder. The supraspinatus muscle works to bring the arm up, and the infraspinatus muscle rotates it out. In this type of nerve transfer, Dr. Barbour can attempt to cut part of the distal spinal accessory nerve and transfer that nerve to the suprascapular nerve, which provides function to the supraspinatus and infraspinatus muscles. Patients are still able to move their shoulder blade after surgery. However, as they regain function from the nerve transfer, they will also be trained to use the nerve that used to bring the shoulder blades together to now bring the arm up and rotate it out to the side.
Nerve Transfers for Shoulder Weakness due to Deltoid Paralysis
When the deltoid muscle in the shoulder is paralyzed due to an upper brachial plexus injury or axillary nerve injury, the person may be unable to move the shoulder. However, the triceps may still function, providing the ability to extend the arm. For this type of shoulder paralysis, Dr. Barbour makes an incision on the back of the arm to gain access to nerve branches that innervate the triceps and to the axillary nerve, which provides function to the deltoid muscle. Specific branches of the nerve that connects to the triceps are transferred to the axillary nerve. As only one branch of the nerve to the triceps is used for this procedure, patients are still able to activate their triceps muscle and extend their arm after surgery. However, as they regain function from the nerve transfer, our therapists will help them learn to use the triceps nerve to raise the arm up and out to the side independently.
Nerve Transfers for Winged Scapula
A winged scapula is an injury in which the scapula (shoulder blade) sticks out in the back. Sports injuries or any trauma to the neck and shoulder can result in a winged scapula. This can be painful and disabling because of the resulting limitation of shoulder elevation. This condition can result from two causes: either a compression of the long thoracic nerve at the level of the brachial plexus or a complete injury to that nerve. Sometimes the compression injuries can be corrected with proper physical therapy. When therapy is ineffective, this type of injury can be addressed by a procedure similar to what may be done for thoracic outlet syndrome. In this case, structures compressing the nerve are cut and removed until the nerve is completely free and nothing is compressing it beneath the skin. Oftentimes, patients will quickly recover strength and experience pain relief after this operation. When the nerve is permanently injured, Dr. Barbour can perform a nerve transfer procedure to correct a winged scapula when more conservative treatment fails. In patients with a long thoracic nerve injury causing a winged scapula, Dr. Barbour will cut a few branches of the thoracodorsal nerve, which innervates the latissimus dorsi muscle, and transfer them to the long thoracic nerve, which activates the serratus anterior muscle. After surgery, patients will still be able to use their latissimus dorsi muscle, pulling their shoulder down. However, as they regain function from the nerve transfer, they also will be trained to use this muscle to raise the arm in front of their body over their head.
Nerve Transfers for Radial Nerve Injuries
An isolated radial nerve injury is the most common nerve injury after orthopedic trauma. Proximal nerve injuries result in lack of wrist and finger extension, leading to diminished grip strength and hand function. Reliable tendon transfers exist for radial nerve palsy; however, the main advantage of radial nerve transfers is the potential for independent finger extension, which is not possible with standard tendon transfers. The disadvantage is the extended recovery time. Muscle reinnervation is not usually clinically evident for four to eight months, and then rehabilitation for strengthening and motor reeducation is still needed. In the proximal forearm, both the median and radial nerves have divided into their terminal branches, which are readily dissected, and the identity of donor branches can be verified by stimulation. The preferred nerve transfer for restoration of radial nerve function is a dual nerve transfer from the median to the radial nerve. The transfer of a flexor digitorum superficialis branch of the median nerve to the extensor carpi radialis brevis branch of the radial nerve will restore wrist extension. The flexor carpi radialis and/or palmaris longus branch is transferred to the posterior interosseous nerve to restore finger and thumb extension. This combination of transfers capitalizes on synergistic tenodesis motion of the wrist and hand, assisting post-operative reeducation. In some patients, a pronator teres–to–extensor carpi radialis brevis tendon transfer is performed to allow for immediate wrist extension while reinnervation occurs.
Nerve Transfers for Median Nerve Injury
The median nerve carries the majority of sensation to the hand and innervates forearm pronation; wrist, finger, and thumb flexion; and a significant component of thumb opposition. Reconstructive options depend on the location and severity of the nerve injury. In high injuries, forearm pronation; wrist, finger, and thumb flexion; thumb opposition; and sensation to the radial three and a half digits are lost. Traditional tendon transfers restore flexion of the index finger and thumb, and provide thumb opposition. If the injury is in the upper arm, primary repair or short nerve grafting may result in good median extrinsic function. If nerve repair is not feasible, tendon or nerve transfer is an option. For tendon transfers, finger flexion can be reconstructed with side-to-side tenodesis to the ulnar innervated flexor digitorum profundus tendons and the brachioradialis tendon transferred to the flexor pollicis longus tendon. Nerve transfer donor options include branches of the radial nerve, the brachialis branch of the musculocutaneous nerve, and branches of the ulnar nerve. Nerve transfers to restore pronation are a valid option. Transfer of the extensor carpi radialis brevis branch of the radial nerve to the pronator teres branch is now the preferred choice given that many functions require simultaneous use of wrist extension and pronation, making the motor reeducation relatively intuitive. Finger and thumb flexion can be restored with nerve transfers to the anterior interosseous nerve from branches of the musculocutaneous, radial, or ulnar nerve. In high median nerve injuries, or in lower plexus injuries, the brachialis branch of the musculocutaneous nerve can be transferred directly to the anterior interosseous nerve fascicle, with successful return of thumb and finger flexion. This transfer is only performed when the musculocutaneous is intact to avoid downgrading elbow flexion. Transfer of branches of the radial nerve has also been reported for anterior interosseous nerve function. The patient also had a sensory transfer of the lateral antebrachial cutaneous nerve to the sensory portion of the median nerve, with return of light touch in the thumb and index finger. In low median nerve injuries not amenable to direct repair or grafting, thumb opposition has been provided by transfer of the terminal anterior interosseous nerve supplying the pronator quadratus muscle to the recurrent motor branch. An interposition graft is usually needed.
Nerve Transfers for Ulnar Nerve Injury
Injury to the ulnar nerve results in significant loss of power grip and pinch strength. Recovery of intrinsic function is rare in high injuries, even with immediate repair, because of the long distance of regeneration required. For distal reinnervation of intrinsic hand muscles, transfer of the terminal branch of the anterior interosseous nerve to the motor branch of the ulnar nerve can improve pinch and grip strength and decrease clawing. This is most commonly performed as an end-to-end coaptation, and an interpositional graft can be avoided with neurolysis of the ulnar motor branch proximally. New concepts have been applied to the reconstruction of ulnar nerve injuries to minimize the negative effects of taking donor nerves close to the hand, and Dr Barbour has been a leader in publishing these newer techniques. The reverse end-to-side or “supercharge” nerve transfer can also increase intrinsic function and also allow the ulnar nerve to recover spontaneously. Dr Barbour described the technique for the transfer of the anterior interosseous nerve to the ulnar motor branch or to the thenar branch of the median nerve to provide nerve reinnervation faster to the intrinsic muscles of the hand in The Journal of Hand Surgery in 2012. More recently, Dr. Barbour described transfer of the extensor digiti minimi and extensor carpi ulnaris branches of the posterior interosseous nerve to restore intrinsic hand function.
Intercostal Nerve Harvest As Donor Nerves
The brachial plexus is a complex network of nerves that lies partly within the axilla (armpit) and supplies nerves to the chest, shoulder and arm. A total injury to this network leaves a person without the use of their shoulder, arm and hand. Intercostal nerves are used to assist the diaphragm with deep breaths and can flex the chest wall to some degree by bringing the ribs together. Nerve transfers using intercostal nerves can restore function to a number of muscles such as the deltoid muscle, elbow flexors (biceps and brachialis muscles), elbow extensors (triceps muscle) or serratus anterior. During the surgery, a large incision is made along the chest wall, and some of the intercostal nerves are cut and transferred to the muscles that move the shoulder or arm. Patients have no difficulty breathing and can still use their chest muscles after surgery. However, as they regain function from the nerve transfer, they also will be trained to flex the chest wall to activate the muscle that received the nerve transfer.
Nerve Transfers for Foot Drop
A person who has foot drop may have difficulty walking and may need to wear a brace on the leg. Possible causes of foot drop include lumbar disc herniation, damage to the peroneal nerve near the knee, or damage to the large nerve in the thigh (the sciatic nerve). A foot drop can begin after an injury to the back or leg, an operation on the knee, or even such benign activities as squatting for prolonged periods of time or crossing the legs. When the weakness is due to compression of the peroneal nerve, a simple operation can be performed to improve the situation. At times, these procedures will not be sufficient to restore the function of the foot. A nerve transfer for correcting foot drop may involve taking branches of the tibial nerve, which supplies muscles that push the foot down, and transferring them to nerves that supply muscles involved in pulling the foot up. Normally the branches of the tibial nerve that bend the toes are used as donor nerves. After this procedure, patients will still be able to activate their donor muscles; that is, they will still be able to push the foot down. However, as they regain function from the nerve transfer, they also will be trained to use these muscles to pull the foot up. The brain then learns this trick, and the patient is able to pull the foot up simply by thinking about pulling the foot up. Physical therapists trained in motor re-education after these nerve transfers can help patients learn this technique. Recovery of function after nerve transfer is a long process. Patients generally see small signs of recovery three to six months after the operation, but in most cases, return of movement takes six to 12 months.
To schedule your consultation with Dr. Barbour, contact our office today.