Contralateral C7 Nerve Root Transfer Restores Hand Function After Central Cerebral Injury

Spastic paralysis of the upper extremity is unfortunately common with unilateral injury to a cerebral hemisphere, such as following stroke or trauma. This burden can profoundly affect patients’ lives—limiting their capacity for self-care, often causing chronic neurogenic pain, and weighing on caregivers.1,2 There has been some evidence of neural reorganization after injury, with the hemisphere ipsilateral to the affected limb (but contralateral to the lesion) contributing to the recovery of modest hand function.3 This contribution may be limited, however, by the low number of connecting circuits between the uninjured hemisphere and the ipsilateral affected limb. In a novel attempt to improve hand function in these patients, a Chinese team recently published the results of a prospective randomized single-blind controlled trial in which patients with longstanding unilateral arm paralysis due to central cerebral injury underwent transfer of the contralateral C7 nerve root to the affected limb.4 These patients engaged in postoperative rehabilitation, after which their outcomes were compared to a matched group who underwent rehabilitation without surgery. Functional improvement was measured by change in the Fugl-Meyer upper extremity scale (higher score reflects improving function). Each cohort consisted of 18 patients. Time lapse between original cerebral injury and trial enrollment was 15 ± 9 yr in the surgery group and 15 ± 8 yr in the control group. There were no significant differences in baseline functional status or previous attempts at treatment and rehabilitation. C7 nerve root transfer is not itself a new technique. As the end-motor functions of the C7 root are generally covered by the other roots of the brachial plexus, and there are no muscles uniquely innervated by the C7 root source, the C7 root has been transferred before in patients with peripheral injury to the brachial plexus.5 In these prior applications, there are typically only transient minor symptoms in the normal limb (ie, the side from which the root is transferred), usually consisting of reduced strength or paresthesia. The procedure used in this trial generally resembled a typical C7 nerve transfer: through an incision above the sternum, the donor C7 root (nonparalyzed side) was mobilized, sectioned distally at a point before it joined with other nerves, and anastomosed directly to the recipient C7 root (paralyzed side), which had been sectioned proximally to minimize the gap between donor and recipient nerve roots. The primary outcome was change from baseline to 12 mo in the Fugl-Meyer score. The surgery group saw an improvement of 17.7 ± 5.6 points, while the control group improved by 2.6 ± 2.0 points (P < .001). Patients in the surgery group underwent a significant increase in Fugl-Meyer score between postoperative months 10 and 12. There were no significant differences in improvement based on etiology of cerebral injury (eg, stroke vs trauma). Secondary measures included functional magnetic resonance imaging (MRI), neurophysiology studies, degree of spasticity measured by the Modified Ashworth Scale, assessment by rehabilitation experts for functional use and range of motion in the affected limb. The surgery group saw significantly greater reductions in spasticity in all measured muscle groups according to the Modified Ashworth Scale, as well as significantly greater increases in range of motion at all joints. One year after surgery, a majority of patients in the surgery group could use the affected hand for activities of daily living (eg, tying shoes, dialing a phone). By 10 to 12 mo postoperatively, neurophysiological studies revealed motor-nerve action potentials over affected arm muscle groups when stimulating the contralateral donor C7 root in all surgical patients. Further, functional MRI revealed activation of the ipsilateral hemisphere (contralateral to original lesion) with extension of the affected wrist in the surgical group, beginning at 8 mo and growing from months 10 to 12 postoperatively. A number of adverse events were reported. In both groups, patients reported pain in the affected limb or shoulder (13 surgical patients, 8 control patients). Specific to the surgery group, 12 patients reported a foreign-body sensation while swallowing, and 15 reported fatigue. A majority of surgical patients also had some loss of sensory or motor function in the donor side arm; however, these were transient and lasted a few months. By 6 mo postoperatively, there was no sensorimotor deficit in the donor side arm in any surgical patient. For neurosurgeons treating patients with impaired arm and hand function following central cerebral injury, this trial represents a step toward the return of motor function in paralyzed limbs. Perhaps most notably, this intervention is not restricted to the acute or subacute phases of injury. Meaningful improvement in hand function was obtained several years after the original injury, a point of great promise for the many patients who have already lived with disability for years. However, it must be noted that this trial was conducted in a small number of patients, all of which were men of a relatively similar age. This may limit the generalizability of these findings. Future large-scale studies will determine the ultimate utility of this novel treatment approach.