Nerve transfer in the spastic upper limb: anatomical feasibility study

Nerve transfers represent an innovative tool in the surgical treatment of upper limb paralysis. Well-documented for brachial plexus sequalae and under evaluation for tetraplegic patients, they have not yet been described for spastic upper limbs. The typical spastic deformity involves active and spastic flexor, adductor and pronator muscles, associated with paralysed extensor and supinator muscles. Experience with selective neurectomy has shown an effective decrease in spasticity together with preservation of muscle strength. We conceptualized a combination of neurectomy and nerve transfer, by performing a partial nerve transfer from a spastic elbow flexor muscle to a paralyzed wrist extensor muscle, hypothesizing that this would reduce the spasticity of the former and simultaneously activate the latter.

Ten cadaveric dissections were performed in order to establish the anatomic feasibility of transferring a motor branch of the brachioradialis (BR) onto the branch of the extensor carpi radialis longus (ECRL) or brevis (ECRB). We measured the emergence, length, muscle entry point and diameter of each branch, and attempted the transfer.

We found 1-4 motor nerve for the BR muscle and 1-2 for the ECRL muscle. In all cases, the nerve transfer was achievable, allowing a satisfactory coaptation. The ECRB branch emerged too distally to be anastomosed to one of the BR branches.

This study shows that nerve transfers from the BR to the ECRL are anatomically feasible. It may open the way to an additional therapeutic approach for spastic upper limbs.