Results of finger extension reconstruction in hemiplegic patients after stroke by transferring the flexor carpi radialis branch to the posterior interosseous nerve.

Abstract

Purpose: Contralateral C7 nerve transfer (CC7) surgery has demonstrated success in restoring upper limb motor function after central nervous system injuries. However, deficits in finger extension limit patient independence. This study evaluates a nerve transfer that transfers the motor branch of the flexor carpi radialis (FCR) to the posterior interosseous nerve (PIN) to improve finger extension.

Methods: Two patients with chronic brain injuries, who showed minimal finger extension recovery for over 1 year after CC7 surgery, were enrolled. Both patients then underwent the nerve transfer procedure. Upper extremity motor function was measured using the Fugl-Meyer upper extremity scale (UEFM), and changes in muscle tone were quantified with the Modified Ashworth Scale (MAS). Regular follow-up evaluations were conducted over an 18-month postoperative period to monitor motor recovery and spasticity.

Results: Within the first postoperative month, both patients exhibited significant improvements in spasticity. Although a minor rebound occurred in the second month, spasticity levels stabilized in subsequent evaluations. By 18 months after surgery, one patient regained functional finger extension, underscoring the potential efficacy of the procedure. Importantly, wrist flexion, governed by the flexor carpi radialis, remained unaffected throughout recovery.

Conclusion: FCR-to-PIN nerve transfer alleviates spasticity and partially restores finger extension in patients with limited recovery following contralateral C7 nerve transfer. Although full motor recovery was not achieved, these findings offer promising clinical implications. Overall, the results support the procedure's value in clinical practice. Further studies with larger cohorts are needed to confirm these results and elucidate underlying mechanisms.