Characterising manual dexterity, motor cortex neuroplasticity, and intracortical inhibition long after burn injury

Purpose Persistent motor dysfunction after burn injury may be due to altered motor cortex and corticospinal tract function. This study examined manual dexterity, motor cortex neuroplasticity, and intracortical inhibition in former burn patients 1–3 years post-minor injury (<10% TBSA). Methods Thirty former burn patients (TBSA: 0.78 ± 1.08%) and 30 non-injured controls participated. Manual dexterity was assessed using the Purdue Pegboard. Transcranial magnetic stimulation (TMS) was used to measure motor cortex excitability (motor evoked potential (MEP) amplitude) and short- and long-interval intracortical inhibition (SICI, LICI) before and after paired-associative stimulation (PAS) to induce neuroplasticity. Results Former burn patients performed worse than controls on the bilateral assembly subtest of the Purdue Pegboard. PAS did not induce changes in MEP amplitude but increased LICI in both former burn patients and control participants. In former burn patients, greater baseline SICI and LICI were associated with better bilateral performance. Conclusions These findings suggest that poorer motor function persists following minor burn injury and is associated with reduced excitability of motor cortex inhibitory circuits. Further research should explore whether targeting motor cortex inhibitory circuits can improve motor performance following burn injury. Highlights Former burn patients 1–3 years post-minor injury had poorer manual dexterity than controls. Paired associative stimulation increased long-interval intracortical inhibition. Greater motor cortex inhibition at rest linked to better manual dexterity in former burn patients.