Journal Article Review May 2016

Do you need your C7 nerve root?

Leblebicioglu G, et al:  Recovery of upper extremity function following endoscopically assisted contralateral C7 transfer for obstetrical brachial plexus injury.  J Hand Surg Eur Vol. 2016 Mar 17. pii: 1753193416638999. [Epub ahead of print]

Even if you do not take care of patients with brachial plexus injuries (and most of us do not), this article has a lot to say about the healing capacity of babies, the ingenuity of surgeons, and the critical role that therapists play in the rehabilitation of patients with complicated injuries.

Investigators from Turkey report on 20 babies with severe birth-related brachial plexus injuries. Between 4 and 19 months of age, these patients underwent brachial plexus reconstruction using the C7 nerve root from the contralateral side (CC7) as the donor nerve. The surgeons extended the CC7 nerve root with sural nerve grafts so that it could reach beyond the injured area on the affected side.

Two infants had CC7 transfers to upper nerve roots, nine had transfers to both upper and lower nerve roots, and nine had transfers to just the lower roots. The donor C7 nerve root was divided as far distally as possible, and the sural nerve grafts were sutured to it. The CC7 nerve, extended with the grafts, was then brought to the injured side with the aid of an endoscope, which was passed from the injured to the non-injured side between the anterior surface of the spine and the posterior surface of the esophagus. The ends of the nerve graft were then sutured to portions of the brachial plexus distal to the site of injury.

16 05contralateral C7 nerve root transfer

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Post-operative immobilization was continued for 6 weeks with the treated limb positioned to minimize tension on the nerve transfer. This usually meant externally rotating the shoulder and abducting it 90 degrees and flexing the elbow 90 degrees. Thereafter, rehabilitation included sensory education to enhance awareness of the affected limb and its representation in the brain. Also the therapists and parents positioned the limb within the child’s field of vision during play to increase awareness. Aquatic therapy aided sensory feedback and provided a gravity-neutral exercise environment.

Neuromuscular electrical stimulation of target muscles began when there was early electrical evidence of reinnervation. According to the overall motor development of each child, alternate limb exercises, midline-crossing activities, and mirrors were used to facilitate bilateral upper limb rehabilitation.

All patients were evaluated immediately before surgery and then at three-month intervals for an average of 45 months (range 2-6 years) after surgery. Motor development for shoulder, elbow, and wrist was scored on established 5 point scales. These scales take into account active motion and any contractures. Previous studies have shown that scores of 3-5 indicate some useful hand function, and that lower scores do not. Sensory assessment was on the Narakas four-point scale: S0, no reaction to any stimulus; S1, reaction to painful stimulus but not to touch; S2, reaction to touch but not to light touch; and S3, apparently normal sensation.

RESULTS: The motor recovery varied considerably according to which roots had been injured and grafted. About half of the patients who did not have useful hand function before surgery, developed useful hand function after surgery. Those infants with some useful hand function before surgery all showed improvements following treatment. Most patients without useful shoulder and elbow function before surgery recovered useful if not full active motions in these joints after treatment. Sensory function in the hand was seen by 8 months after surgery in all patients. Two patients recovered S2 sensation, the others recovered S3.

Two patients had transient weakness of elbow extension on the donor side, which recovered within 6 months. The others had no impairment of donor limb function.

COMMENT: The results were neither spectacular nor entirely predictable. They varied in part according to the extent of the original injury and the timing of the surgery.  Considering the limited alternative means of reconstructing these devastating injuries, however, the CC7 transfer is both bold and generally helpful.

Other investigators have performed and reported CC7 nerve transfers both for infants and for adults. The present authors add the idea of threading the grafted CC7 donor nerve across the neck using an endoscope, which allows for less extensive surgical exposure and tissue damage. It also allows for the shortest course from donor-side to recipient side, thereby minimizing the distance the axons need to grow. The shortest distance hastens both motor and sensory recovery. This should allow for maximal integration of cortical representation of the injured limb, which was previously disconnected from the brain.

Usually in adults undergoing this nerve transfer, only half of the fibers of the CC7 root are used, and donor side deficits, if apparent at all, are usually transient. Of course the babies in this series cannot complain about numbness in their middle finger (C7 distribution) or weakness of C7 muscles, but taking the entire C7 root at least in  babies does not apparently cause any lasting harm. This is a tribute to the plasticity and adaptability of the human brain.   

Therapists may find that the rehabilitation techniques used in this study have application for other patients with complicated problems and who are unable to fully cooperate.