Case series investigating the cortical silent period after burns using transcranial magnetic stimulation

Objective: The study aimed to investigate intracortical inhibition following a burn injury, and to establish transcranial magnetic stimulation (TMS) as a useful and sensitive tool to investigate the cortical response to a burn injury. Methods: Thirteen burn injured patients and 12 uninjured subjects underwent TMS to measure the cortical silent period (cSP), a marker of intracortical inhibition. Results: In burn injury patients, cSP was similar in the burn-injured and less-injured arm (133 and 132 ms respectively; p = 0.96). cSP was numerically shorter in burns patients than control subjects, however, these differences were not statistically significant (133 vs 148 ms, p = 0.24). Subgroup analysis revealed cSP was shorter in the burn arm of patients compared to the uninjured control subjects in patients with upper-limb burn (cSP 120 ms vs 148 ms, p = 0.03), those with <10% TBSA (cSP 120 ms vs 148 ms, p = 0.01), those <2 years’ post-burn (cSP 110 ms vs 148 ms, p = 0.01), and patients with partial thickness burns (cSP 120 ms vs 148 ms, p = 0.02). Conclusions: These results demonstrate significantly shorter cSP in the burned arm in patients with upper limb burn sustained <2 years ago, those with partial thickness burns, those with upper limb burns only, and those with burns of less than 10% TBSA. The results are consistent with the existing literature, which demonstrates a reduction in cSP duration in patients with a range of peripheral nerve injuries. There is a strong suggestion that cortical inhibition is altered following burn injury, and that TMS is a useful and sensitive method for investigating changes in cortical inhibition in burn patients.