P78-T Intracortical inhibition and facilitation after arm and face transplantation

Abstract

Background Facial tissue and hand area are among the most specific regions of the cortex. The intracortical inhibition (ICI) and facilitation (ICF) of the human motor cortex is seen as a marker of brain plasticity. Material and methods In this study, ICI and ICF changes in the motor cortex were compared between six arm and face transplantation patients (3 arms/3 faces) and seven healthy volunteers. Paired-pulse transcranial magnetic stimulation was used to examine the presentation of Abductor Pollicis Brevis (APB) muscle in the brain. The MEP responses were recorded with surface EMG electrodes. The hot spot, subthreshold and supramaximal amplitude values of APB muscle were determined by single pulse TIntracortical inhibition and facilitation was examined by 1,2,3,4,5,6,7,8,9,10 ms interstimulus interval (ISI) double stimulation for ICI and 10,12,14,16,18,20,22,24,26,28,30 ms ISI for ICF. Results In normal cases, there was an inhibition of 76 ± 21% in 1–10 ms ISI double stimulation and there was 111 ± 14% facilitation in 10–30 ms ISI. No significant ICI (94 ± 4%) and ICF (81 ± 26%) was observed in the patients with face transplantation. However, ICI was more prominent in arm transplant cases (68 ± 46%) than normal cases and inhibition is continued to 10–30 ms ISI (64 ± 23%). Conclusions We found different cortical excitability pattern in arm and face transplantation patients; there is an intracortical inhibition in arm transplants but a reduction of intracortical inhibition and intracortical facilitation. We conclude that after transplantation there are dissimilar changes in the activity of intracortical interneuronal circuits of APB area in arm and face patients. This Project (215e012) was supported by TUBITAK.