Does age matter? The role of patient age in brain plasticity analyzed after a nerve transfer

Nerve transfers, which are increasingly applied not only for traumatic peripheral nerve injuries but also in oncologic reconstructions, spinal cord injuries, and a wide range of neurological disorders, rely heavily on the capacity of the central nervous system to reorganize and reassign motor control pathways. Among the multiple factors influencing postoperative recovery, age-dependent brain plasticity appears to play a critical role in determining the degree to which patients can regain functional control after reinnervation. This study aims to characterize this correlation in depth and to identify clinically meaningful age-related thresholds that may guide treatment planning and optimize surgical outcomes.

We examined two patient groups who underwent a nerve transfer: (1) neonatal brachial plexus palsy (NBPP) and (2) non-neonatal brachial plexus injury (NNBPI). The Plasticity Grading Scale (PGS) was utilized to assess the degree of volitional control achieved, with scores ranging from 1 (indicating poor brain plasticity) to a maximum of 4 (indicating complete independence of movements, a sign of excellent brain plasticity). Additionally, we analyzed the relationship between age, selected nerve transfer, and PGS outcomes.

A total of 168 patients underwent nerve transfers, including 34 with NBPP and 134 with NNBPI. The median PGS scores were 4 and 3 respectively. Age was significantly associated with PGS scores in NNBPI patients receiving extra-plexual nerve transfers (p < 0.001). Optimal scores were observed in patients under 5 years of age, regardless of the donor type. In NNBPIs, intra-plexual transfers demonstrated early and sustained plasticity across all ages, whereas extra-plexual donors showed superior outcomes in patients aged 14-20, followed by a plateau after age 21.

Age significantly impacts neural plasticity after nerve transfer. This effect is further modulated by the properties of the donor nerve and the target muscle.