Nerve transfers for restoration of finger flexion in patients with tetraplegia

Abstract

OBJECTIVE The purpose of this paper was to report the authors' results with finger flexion restoration by nerve transfer in patients with tetraplegia. METHODS Surgery was performed for restoration of finger flexion in 17 upper limbs of 9 patients (8 male and 1 female) at a mean of 7.6 months (SD 4 months) after cervical spinal cord injury. The patients' mean age at the time of surgery was 28 years (SD 15 years). The motor level according to the ASIA (American Spinal Injury Association) classification was C-5 in 4 upper limbs, C-6 in 10, and C-7 in 3. In 3 upper limbs, the nerve to the brachialis was transferred to the anterior interosseous nerve (AIN), which was separated from the median nerve from the antecubital fossa to the midarm. In 5 upper limbs, the nerve to the brachialis was transferred to median nerve motor fascicles innervating finger flexion muscles in the midarm. In 4 upper limbs, the nerve to the brachioradialis was transferred to the AIN. In the remaining 5 upper limbs, the nerve to the extensor carpi radialis brevis (ECRB) was transferred to the AIN. Patients were followed for an average of 16 months (SD 6 months). At the final evaluation the range of finger flexion and strength were estimated by manual muscle testing according to the British Medical Research Council scale. RESULTS Restoration of finger flexion was observed in 4 of 8 upper limbs in which the nerve to the brachialis was used as a donor. The range of motion was incomplete in all 5 of these limbs, and the strength was M3 in 3 limbs and M4 in 1 limb. Proximal retrograde dissection of the AIN was associated with better outcomes than transfer of the nerve to the brachialis to median nerve motor fascicles in the arm. After the nerve to the brachioradialis was transferred to the AIN, incomplete finger flexion with M4 strength was restored in 1 limb; the remaining 3 limbs did not show any recovery. Full finger flexion with M4 strength was demonstrated in all 5 upper limbs in which the nerve to the ECRB was transferred to the AIN. No functional downgrading of elbow flexion or wrist extension strength was observed. CONCLUSIONS In patients with tetraplegia, finger flexion can be restored by nerve transfer. Nerve transfer using the nerve to the ECRB as the donor nerve produced better recovery of finger flexion in comparison with nerve transfer using the nerve to the brachialis or brachioradialis.

Keywords: AIN = anterior interosseous nerve; ASIA = American Spinal Injury Association; ECRB = extensor carpi radialis brevis; ECRL = extensor carpi radialis longus; ICSH = International Classification for Surgery of the Hand; ISNCSCI = International Standards for Neurological Classification of Spinal Cord Injury; nerve transfer; spinal cord injury; tetraplegia.