Technical Pearls of Tendon Transfers for Upper Extremity Spasticity

Selective transfer of nerve to supinator to restore digital extension in central cord syndrome: An anatomical study and a case report

BACKGROUND

Nerve transfers are increasingly used to restore upper extremity function in patients with spinal cord injury. However, the role of nerve transfers for central cord syndrome is still being established. The purpose of this study is to report the anatomical feasibility and clinical use of nerve transfer of supinator motor branches (NS) to restore finger extension in a central cord syndrome patient.

MATERIALS AND METHODS

The posterior interosseous nerve (PIN), its superficial division, and branches were dissected in 14 fresh cadavers, with a mean age of 65 (58-79). Measurements included number and length of branches of donor and recipient, diameters, regeneration distance from coaptation site to motor entry point and axonal counts. A NS transfer to extensor carpi ulnaris (ECU), extensor digiti quinti (EDQ) and extensor digitorum communis (EDC) was performed in a 28-year-old patient, with central cord syndrome after a motorcycle accident, who did not recover active finger extension at 10 months post injury.

RESULTS

The PIN consistently divided into a deep and superficial branch between 1.5 cm proximal to, and 2 cm distal to the distal boundary of the supinator. The superficial branch provided a first common branch to the ECU and EDQ. In 12/14 dissections, the EDC was innervated by a 4 cm long branch that entered the muscle on its radial deep surface. In all cases, the superficial branch of the PIN could be separated in a retrograde fashion from the PIN and coapted with NS. The mean myelinated fiber count in nerve to EDC was 401 ± 190 compared to 398 ± 75 in the NS. At 48 months after surgery, with the wrist at neutral, the patient recovered full metacarpophalangeal extension scoring M4. Supination was preserved with the elbow extended or flexed.

CONCLUSIONS

Restoration of finger extension in central cord syndrome is possible with a selective transfer of the NS to EDC, and is anatomically feasible with a short regeneration distance and favorable axonal count ratio.

The Spastic Upper Extremity in Children: Multilevel Surgical Decision-making

Multilevel surgery for upper extremity spasticity is the current surgical standard. While the literature details surgical techniques and outcomes, a comprehensive guide to surgical planning is lacking. Patients commonly present with posturing into shoulder internal rotation, elbow flexion, forearm pronation, wrist flexion with ulnar deviation, finger flexion, and thumb adduction, although variations exist. Multiple surgical options exist for each segment; therefore, repeated examinations for contracture, pathologic laxity, and out of phase activity are necessary to optimize the surgical plan. To avoid decreasing function, one must carefully balance the benefits of contracture release and tendon transfers with their weakening effects. In certain cases, stability from joint fusion outweighs the loss of motion. Failure to recognize dynamic posturing, grasp and release requirements, or hand intrinsic spasticity can worsen function and cause new deformities. Surgical indications are formulated for individual deformity patterns and severity along with personal/family goals. General comprehension, voluntary control, and sensation, although not modifiable, influence decision making and are prognostic indicators. Functional improvement is unlikely without preexisting voluntary control, but appearance and visual feedback may be improved by repositioning nonetheless. Appropriate interventions and management of expectations will optimize limb appearance and function while avoiding unexpected sequelae.